ALBERT

Description: 〈p〉Publication date: 16 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 33〈/p〉 〈p〉Author(s): Mathilde Pantin, Florent Bodinier, Jordan Saillour, Yassine M. Youssouf, Fabien Boeda, Morwenna S.M. Pearson-Long, Philippe Bertus〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A convenient access to 2-hydroxycyclopentenones was designed from acylcyanohydrins, by using titanacyclopropane complexes as nucleophilic partners and an intramolecular aldol condensation in basic conditions. The development of a one-pot procedure allows a step- and atom-economic process, and the use of Grignard reagents other than ethylmagnesium bromide provided valuable 3,4-disubstituted 2-hydroxycyclopentenones. The utility of the hydroxy group was illustrated by further functionalization of the α-position using palladium-mediated cross-coupling reactions.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402019307525-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 16 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 33〈/p〉 〈p〉Author(s): Chuang Zhao, Gao-Feng Zha, Wan-Yin Fang, Njud S. Alharbi, Hua-Li Qin〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A simple, practical and gram-scale process for direct transformation of primary alcohols or silyl ethers to ammonium salts was developed. This method has the feathers of easy work-up (a simple filtration), mild condition, high yield, great practicality and robustness. And the application of the ammonium salts in Suzuki coupling reaction was also accomplished.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402019307495-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 16 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 33〈/p〉 〈p〉Author(s): Kazuhiro Haraguchi, Hiroki Kumamoto, Kiju Konno, Hideki Yagi, Yutaka Tatano, Yuki Odanaka, Satoko Shimbara Matsubayashi, Robert Snoeck, Graciela Andrei〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉4′-Azido- (7), 4′-〈em〉C〈/em〉-fluoromethyl- (8) 4′-〈em〉C〈/em〉-ethynyl- (9) and 4′-〈em〉C〈/em〉-cyano- (10) 2′-deoxy-4′-thiocytidines have been synthesized. In this study, it was found that the isolated yield of 4′-thiouracil nucleoside 13 in a Lewis acid-promoted Vorbrüggen-type glycosidation utilizing 12 was better than that of the electrophilic glycosidation reaction between silylated uracil and 11. This improved result prompted us to perform the glycosidation utilizing 36 and 43 for the synthesis of 37 and 44. Introduction of the azido group was carried out by nucleophilic substitution in the 4′-benzoyloxy derivative 22a. On the other hand, 9 and 10 were synthesized by way of the chemical manipulation of the hydroxymethyl group at the 4′-position of 46.〈/p〉 〈p〉Evaluation of the antineoplastic activity of 2 and 7–10 against human B-cell (CCRF-SB) and T-cell leukemia (Molt-4) cell lines revealed that 4′-azido- (7) and 4′-〈em〉C〈/em〉-fluoromethyl- (8) derivatives exhibited cytotoxic activity whereas no cytotoxicity was observed in the 4′-〈em〉C〈/em〉-ethynyl- (9) and 4′-〈em〉C〈/em〉-cyano- (10) derivatives as well as the parent compound 2. Compound 7 was also found to possess promising antiviral activity against VZV and HSV-1 without any cytotoxity against HEL host cells. It is noteworthy that 7 exhibited potent inhibitory activities against the thymidine kinase-deficient (TK〈sup〉−〈/sup〉) mutant of VZV and HSV-1.〈/p〉 〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402019307161-fx1.jpg" width="292" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 26 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 30〈/p〉 〈p〉Author(s): 〈/p〉

Description: 〈p〉Publication date: 26 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 30〈/p〉 〈p〉Author(s): 〈/p〉

Description: 〈p〉Publication date: 9 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 32〈/p〉 〈p〉Author(s): Stephen L. Buchwald〈/p〉

Description: 〈p〉Publication date: Available online 21 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron〈/p〉 〈p〉Author(s): Firdoos Ahmad Sofi, Rohit Sharma, S.N. Kavyasree, Sumi Aisha Salim, Pravin J. Wanjari, Prasad V. Bharatam〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉An environmental friendly, efficient protocol has been realized for the synthesis of 〈em〉N-〈/em〉pyridinylamides via copper catalyzed oxidative amidation of aryl alkyl ketones with 2-aminopyridines. This one pot protocol involves chemo selective cleavage of C (O)–C bond in the presence of singlet oxygen. The reaction conditions are simple, tolerates wide range of substrates and the products were formed in good to excellent yields. This method offers a moderate improvement over the earlier successful attempts in generating 〈em〉N〈/em〉-pyridinylamides.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402019308695-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 21 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron〈/p〉 〈p〉Author(s): Hanyang Bao, Xiaojun Hu, Jian Zhang, Yunkui Liu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A Cu(0)/Selectfluor system-catalyzed intramolecular C〈sub〉sp2〈/sub〉-H/C〈sub〉sp2〈/sub〉-H bond cross-dehydrogenative coupling of 2-aryloxybenzaldehydes is described. A variety of substituted xanthone derivatives are synthesized in moderate to excellent yields. Reaction can also be extended to the synthesis of 9〈em〉H〈/em〉-thioxanthen-9-one 10,10-dioxide and phenanthridin-6(5〈em〉H〈/em〉)-ones, respectively.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S004040201930866X-fx1.jpg" width="427" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 21 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron〈/p〉 〈p〉Author(s): Ziping Cao, Shikun Yan, Changyin Zhao, Xuejun Sun, Laijin Tian, Xin Meng〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A novel method for the synthesis of 〈em〉α〈/em〉-amino alkenyl-substituted hydrazone derivatives was disclosed through silver-catalyzed reaction of sulfonyl hydrazones with ynamides. The present method features mild conditions, high stereoselectivity and good yields. The proposed mechanism involves silver-mediated generation of a keteniminium ion intermediate to facilitate the stereoselective addition of hydrazones in the presence of K〈sub〉2〈/sub〉CO〈sub〉3〈/sub〉, while pyrazole ring could not be constructed under the current conditions.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402019308671-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 20 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 38〈/p〉 〈p〉Author(s): Scott Rice, Daniel J. Cox, Stephen P. Marsden, Adam Nelson〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The synthesis of large numbers of diverse molecular scaffolds with controlled molecular properties is a significant challenge in synthetic organic chemistry. A modular unified synthesis was developed, and was exploited in the synthesis of sixteen diverse three-dimensional scaffolds. The approach exploited two cyclisation precursors to be converted, using a toolkit of cyclisation reactions, into spirocyclic and fused-ring scaffolds. Remarkably, Pd-catalysed aminoarylation of substituted 〈em〉N〈/em〉-Boc-hex-5-enylamine cyclisation precursors to yield 〈em〉N-〈/em〉Boc piperidine-containing scaffolds was successful which was ascribed to a significant Thorpe−Ingold effect. Computational property analysis showed that the decorated scaffolds are shape-diverse, and enable diverse lead-like chemical space to be targeted.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402019308464-fx1.jpg" width="330" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 6 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 36〈/p〉 〈p〉Author(s): 〈/p〉

Description: 〈p〉Publication date: 6 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 36〈/p〉 〈p〉Author(s): 〈/p〉

Description: 〈p〉Publication date: Available online 19 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron〈/p〉 〈p〉Author(s): Natalia A. Devleshova, Stanislav V. Lozovskiy, Aleksander V. Vasilyev〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Reactions of alkyl 4-aryl(or 4,4-diaryl)-4-hydroxybut-2-ynoates [Ar(H or Ar')(OH)C〈sup〉4〈/sup〉–C〈sup〉3〈/sup〉≡C〈sup〉2〈/sup〉–CO〈sub〉2〈/sub〉Alk] with arenes under the action of triflic acid TfOH or HUSY zeolite result in the formation of two main compounds, aryl substituted furan-2-ones or products of propargylation of electron rich arenes. Key reactive intermediates in these transformations are the corresponding O,O-diprotonated forms of starting butynoates, Ar(H or Ar')(〈sup〉+〈/sup〉OH〈sub〉2〈/sub〉)C〈sup〉4〈/sup〉–C〈sup〉3〈/sup〉≡C〈sup〉2〈/sup〉– C(=O〈sup〉〈strong〉+〈/strong〉〈/sup〉H)(OAlk), dehydration of which gives rise to mesomeric propargyl-allenyl cations Ar(H or Ar')(OH)〈sup〉4〈/sup〉C〈sup〉〈strong〉+〈/strong〉〈/sup〉–C〈sup〉3〈/sup〉≡C〈sup〉2〈/sup〉–C(=O〈sup〉〈strong〉+〈/strong〉〈/sup〉H)(OAlk) ↔ Ar(H or Ar')(OH)〈sup〉4〈/sup〉C = C〈sup〉3〈/sup〉 = 〈sup〉2〈/sup〉C〈sup〉〈strong〉+〈/strong〉〈/sup〉–C(=O〈sup〉〈strong〉+〈/strong〉〈/sup〉H)(OAlk), having two electrophilic centers on the carbons C4 and C2 respectively. Reactions of these species with arenes at C4 lead to products of arene propargylation, alternatively, reactions at C2 result in allenylation of arenes, followed by further transformation into furan-2-ones. Using quantum chemical calculations by the DFT method, it has been shown that the reactivity of such propargyl-allenyl cations is mainly explained by orbital factors. Plausible reaction mechanism is discussed.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402019308506-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 6 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 36〈/p〉 〈p〉Author(s): 〈/p〉

Description: 〈p〉Publication date: Available online 19 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron〈/p〉 〈p〉Author(s): Anastasia A. Fesenko, Alexander N. Yankov, Anatoly D. Shutalev〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and 〈em〉p〈/em〉-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with 〈em〉H〈/em〉- (sodium borohydride), 〈em〉O〈/em〉- (sodium methylate), 〈em〉S〈/em〉- (sodium phenylthiolate), 〈em〉N〈/em〉- (pyrrolidine, sodium succinimide), 〈em〉P〈/em〉- (trialkyl phosphites), and 〈em〉C〈/em〉-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested 〈em〉in vitro〈/em〉 for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402019308609-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 19 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron〈/p〉 〈p〉Author(s): Sean P. Bew, Simon J. Coles, Mateusz B. Pitak, Wim T. Klooster, Polly-Anna Ashford, Victor Zdorichenko〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We report the efficient combination of S〈sub〉N〈/sub〉Ar and organic Brønsted acid catalysis protocols for the construction of 〈em〉cis〈/em〉-aziridine-derived biaryl and triaryl ethers. Using aza-Darzens chemistry mono-〈em〉cis〈/em〉-aziridine-biaryl and bis-(〈em〉cis〈/em〉-aziridine)-triaryl ethers have been generated; these motifs have significant potential as easily synthesised, functionalised precursors of a glycopeptide backbone.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402019308658-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 6 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 36〈/p〉 〈p〉Author(s): 〈/p〉

Description: 〈p〉Publication date: 30 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 35〈/p〉 〈p〉Author(s): 〈/p〉

Description: 〈p〉Publication date: 6 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 36〈/p〉 〈p〉Author(s): A.R. Chanysheva, T.E. Vorobyova, V.V. Zorin〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We have examined enantioselective bioreduction of acetophenone and its substituted derivatives into corresponding 〈em〉S〈/em〉-alcohols catalyzed by 〈em〉Daucus carota〈/em〉 and 〈em〉Petroselinum crispum〈/em〉 plant cells in water and isooctane. We found that the nature of the substituent has a profound effect on the relative reactivity of substituted acetophenones and enantioselectivity of biocatalytic reduction. Electron-withdrawing substituents –Br and –NO〈sub〉2〈/sub〉 enhance the initial rate of reaction and yields of products, while electron-donating substituent –OCH〈sub〉3〈/sub〉 decreases them. The reduction rates and yields of products in water were noticeably higher in comparison with similar reductions conducted in isooctane. Correlations between the initial reaction rate and the substituent constant (σ〈sup〉+〈/sup〉) in the aromatic ring characterizing its nature were established. Comparison of ρ constants of bioreduction catalyzed by 〈em〉D. carota〈/em〉 and 〈em〉P. crispum〈/em〉 shows that the sensitivity of the reduction to the nature of the substituents is more significant in the case of 〈em〉D. carota〈/em〉 biocatalyst. Comparison of ρ constants for 〈em〉D. сarota〈/em〉 and 〈em〉P. crispum〈/em〉 in water and isooctane indicates that the sensitivity of bioreduction to the nature of the substituent tends to increase from water to isooctane.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S004040201930821X-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 13 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 37〈/p〉 〈p〉Author(s): Xin-Xin Wang, Fei-Yang Tian, Ming Liu, Kai Chen, Yun-Qian Zhang, Qian-Jiang Zhu, Zhu Tao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A new water soluble tetramethyl-substituted cucurbit[8]uril (Me〈sub〉4〈/sub〉Q[8]) was easily isolated from cucurbit[〈em〉n〈/em〉]uril product mixture which was synthesized by using the dimer of glycoluril and diether of dimethyl substituted glycoluril. Crystal structure analysis shows that Me〈sub〉4〈/sub〉Q[8] is constructed of building blocks: three dimmers and two dimethyl glycolurils, the two dimethyl glycolurils are separated by a dimer of glycoluril. It is speculated that Me〈sub〉4〈/sub〉Q[8] is degraded by a larger hexamethyl substituted Q[9] or larger intermediates.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402019308154-fx1.jpg" width="392" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 6 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 36〈/p〉 〈p〉Author(s): David A. Rogers, Jillian M. Gallegos, Megan D. Hopkins, Austin A. Lignieres, Amy K. Pitzel, Angus A. Lamar〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A variety of arenes and heteroarenes are chlorinated in moderate to excellent yields using N-chlorosuccinimide (NCS) under visible-light activated conditions. A screening of known organic dye photocatalysts resulted in the identification of methylene green as the most efficient catalyst to use with NCS. According to mechanistic studies described within, the reaction is speculated to proceed via a single electron oxidation of NCS utilizing methylene green under visible-light photoredox pathway. The photo-oxidation of NCS amplifies the electrophilicity of the chlorine atom of the NCS, thus leading to enhanced reactivity as a chlorinating reagent with aromatic substrates.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402019308257-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 23 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 34〈/p〉 〈p〉Author(s): 〈/p〉

Description: 〈p〉Publication date: 13 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 37〈/p〉 〈p〉Author(s): Kavirayani R. Prasad, Vipin Ashok Rangari〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A systematic investigation of the addition of Grignard reagents to sulfinimines derived from tartaric acid diol was undertaken. It was observed that the chirality of the inherent tartrate moiety influences the diastereoselectivity of the resultant sulfinamides formed in the reaction. The formed products serve as excellent building blocks for the synthesis of natural products. This has been demonstrated in the collective total synthesis of lentiginosine, (+)-α-conhydrine and methyldihydropalustramate.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402019308233-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 6 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 36〈/p〉 〈p〉Author(s): Somayeh Behrouz, Mohammad Navid Soltani Rad, Samira Ahmadi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A facile, selective, and mild synthetic approach for one-pot N-alkylation of nucleobases and other related N-heterocycles via alcohols, using a mixture of P〈sub〉2〈/sub〉O〈sub〉5〈/sub〉 and KI is described. The reaction of structurally diverse purines, pyrimidines, and/or azoles with primary alcohols with the use of P〈sub〉2〈/sub〉O〈sub〉5〈/sub〉/KI and basic mixture of Et〈sub〉3〈/sub〉N/K〈sub〉2〈/sub〉CO〈sub〉3〈/sub〉 in refluxing DMF affords the corresponding N-alkyl derivatives (carboacyclic nucleosides) in good to reasonable yields. The influence of different parameters comprising solvent, base, temperature, and substrate/reagent ratios was assessed on the reaction progress. The secondary and tertiary alcohols were failed to react with nucleobases. The main advantageous of current protocol is formation of water soluble side products in which provides simple work-up and purification processes.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402019308269-fx1.jpg" width="371" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 23 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 34〈/p〉 〈p〉Author(s): 〈/p〉

Description: 〈p〉Publication date: 6 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 36〈/p〉 〈p〉Author(s): Aling Tang, Ya Yin, Zhao Chen, Congbin Fan, Gang Liu, Shouzhi Pu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉An aggregation-induced emission (AIE)-active fluorescent chemosensor based on a tetraphenylethene (TPE) unit has been successfully designed and synthesized. Interestingly, the luminogen could detect Zn〈sup〉2+〈/sup〉 selectively in a THF solution with the detection limit of 1.24 × 10〈sup〉−6〈/sup〉 mol L〈sup〉−1〈/sup〉. Meanwhile, the luminogen could also detect Hg〈sup〉2+〈/sup〉 selectively in a THF-water mixture with the water content of 90%, and the detection limit was 2.55 × 10〈sup〉−9〈/sup〉 mol L〈sup〉−1〈/sup〉. Furthermore, the solid-state mechanochromic fluorescence behavior of the luminogen was investigated systematically. Indeed, the AIE-active luminogen also exhibited reversible mechanofluorochromic phenomenon involving fluorescent color change from blue to green, and powder X-ray diffraction results indicated that the switchable morphology conversion between crystalline and amorphous states was responsible for this mechanochromism phenomenon.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402019308166-fx1.jpg" width="269" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 20 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 38〈/p〉 〈p〉Author(s): Yuzuki Yamamoto, Yusuke Ogura, Hidenori Watanabe, Hirosato Takikawa〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Pseudohygrophorone A〈sup〉12〈/sup〉, a highly oxygenated cyclohexenone derivative isolated from 〈em〉Hygrophorus abieticola,〈/em〉 exhibits anti-fungal activity against several phytopathogenic fungi and oomycete. The first synthesis of both enantiomers of pseudohygrophorones A〈sup〉12〈/sup〉 was accomplished starting from an optically active sulfoxide. In our approach, the diastereoselective Michael−aldol cascade reaction was featured as the key step.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402019308610-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 20 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 38〈/p〉 〈p〉Author(s): Mohammed Y. Suleiman, Yue Ma, Takafumi Nakagawa, Hiroshi Ueno, Yutaka Matsuo〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This study presents the synthesis, characterization, and electrochemical properties of four new dialkoxymethanofullerenes, as well as their performance in organic solar cells (OSCs) devices. Dialkoxymethanofullerenes were synthesized in 27%–32% yield by thermolysis of dialkoxyoxadiazolines and reaction with C〈sub〉60〈/sub〉 under reflux in toluene. The prepared compounds were then characterized and used for the first time as electron-acceptor materials in thin-film bulk heterojunction OSCs with PBTZT-stat-BDTT-8 as the electron donor material. The devices made with ethoxy-hexyloxymethanofullerene and methoxy-hexyloxymethanofullerene exhibited optimal power conversion efficiencies (PCEs) of 3.79% and 4.65%, with open-circuit voltage of 0.832 and 0.831 V, respectively. In contrast, the devices made with ethoxy-ethoxymethanofullerene and methoxy-ethoxymethanofullerene exhibited very low PCEs of 〈0.01% for both, indicating a large impact of the substituents on device performance.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402019308476-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 13 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 37〈/p〉 〈p〉Author(s): Hajime Maeda, Makoto Geshi, Kenji Hirose, Taniyuki Furuyama, Masahito Segi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Mono-, di- and oligo-ether linked (1,8)pyrenophanes 〈strong〉1〈/strong〉–〈strong〉7〈/strong〉 were synthesized, and their fluorescence and conformational properties in the absence and presence of metal ions were elucidated. Fluorescence spectra of 1.0 × 10〈sup〉−5〈/sup〉 M solutions of the mono- and di-ether linked pyrenophanes 〈strong〉1〈/strong〉–〈strong〉5〈/strong〉 were comprised of only monomer emission bands, while those of the oligoethylene glycol linked analogs 〈strong〉6〈/strong〉 and 〈strong〉7〈/strong〉 contained both monomer and intramolecular excimer emission bands. Addition of perchlorate salts of Ba〈sup〉2+〈/sup〉, Na〈sup〉+〈/sup〉 and Li〈sup〉+〈/sup〉 to 1:1 v/v CH〈sub〉3〈/sub〉CN:CH〈sub〉2〈/sub〉Cl〈sub〉2〈/sub〉 solutions of 〈strong〉6〈/strong〉 and 〈strong〉7〈/strong〉 caused decreases in the intensities of the corresponding intramolecular excimer emission bands and, in some cases, increases in the intensities of the monomer emission. Monomer and intramolecular excimer emission from the (1,8)pyrenophanes are suggested to arise from the respective 〈em〉anti〈/em〉 and 〈em〉syn〈/em〉 conformers, whose ratios are dependent on solvent polarity, temperature and kinds of added metal ions.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402019308452-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 23 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 34〈/p〉 〈p〉Author(s): 〈/p〉

Description: 〈p〉Publication date: 23 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 34〈/p〉 〈p〉Author(s): 〈/p〉

Description: 〈p〉Publication date: 13 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 37〈/p〉 〈p〉Author(s): Qingfeng Li, Elisabetta Groaz, Piet Herdewijn〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Structurally modified nucleoside analogues are a major source of therapeutic agents and building blocks for incorporation into synthetic oligonucleotides able to interfere with information transfer or other biological functions. This work describes the synthesis of non-natural 〈span〉l〈/span〉-nucleoside phosphonate mimics containing two anomeric centers. Such compounds feature either a di- or monohydroxy tetradialdose sugar as the glycone unit, while adenine is present as nucleobase. By judicious use of protecting groups at the 2- and 3-position of commercial 1-〈em〉O〈/em〉-acetyl-2,3,5-tri-〈em〉O〈/em〉-benzoyl-β-〈span〉d〈/span〉-ribofuranose, both the phosphonate and nucleobase moieties were stereoselectively introduced to provide a dihydroxylated compound with 〈em〉cis〈/em〉-configured substituents as the sole reaction product. Subsequent selective deprotection and deoxygenation at the 3′-position occurred smoothly to afford the corresponding 4′-monohydroxy tetradialdose containing analogue.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402019308245-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 20 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 38〈/p〉 〈p〉Author(s): Bing-Jie Zhang, Wen-Na Xiao, Jing Chen, Mei-Fen Bao, Johann Schinnerl, Qi Wang, Xiang-Hai Cai〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Continued interest in 〈em〉Erythrina〈/em〉 alkaloids resulted in the isolation of 38 alkaloids including 7 undescribed ones from the leaves of 〈em〉Erythrina arborescens〈/em〉 Roxburgh. Among the new compounds, erythrivarines H-I were two dimeric alkaloids, while others were 〈em〉Erythrina〈/em〉 alkaloid glucosides. Dimeric 〈em〉Erythrina〈/em〉 alkaloids and monomers, turcomanidine and isoboldine, showed medium xanthine oxidase inhibition.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402019308488-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 13 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 37〈/p〉 〈p〉Author(s): Yuta Endo, Taku Kasahara, Kenta Asakura, Ayana Mori, Mariko Funasaki, Gokithi Akisue, Tadahiro Etoh, Kenichi Harada, Yoshiyasu Fukuyama, Keiichi Matsuzaki, Masami Ishibashi, Ayumi Ohsaki〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Five new furanocassane-type diterpenoids, sucupiranins M–Q (〈strong〉1〈/strong〉–〈strong〉5〈/strong〉) were isolated from the seeds of 〈em〉Bowdichia virgilioides〈/em〉. Their structures and stereo chemistries were elucidated on the basis of spectroscopic analyses including HRESIMS, 2D NMR (〈sup〉1〈/sup〉H-〈sup〉1〈/sup〉H COSY, HSQC, HMBC, and NOESY), and ECD spectra.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402019308440-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 30 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 35〈/p〉 〈p〉Author(s): 〈/p〉

Description: 〈p〉Publication date: 30 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 35〈/p〉 〈p〉Author(s): 〈/p〉

Description: 〈p〉Publication date: 30 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 35〈/p〉 〈p〉Author(s): 〈/p〉

Description: 〈p〉Publication date: 20 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 38〈/p〉 〈p〉Author(s): Yan Zhang, Lei Wang, Zhiming Wang, Wei Chen〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A C(sp〈sup〉3〈/sup〉)–N bond forming reaction between 〈em〉N〈/em〉-alkoxyamides and simple ethers has been developed. In the presence of commercially available 2,3-dichloro-5,6-dicyano-〈em〉p〈/em〉-benzoquinone (DDQ), a variety of 〈em〉N〈/em〉-methoxyamides and ethers undergo this transformation smoothly to deliver the corresponding products in good yields under visible-light irradiation and metal-free conditions at room temperature.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S004040201930849X-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 6 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 36〈/p〉 〈p〉Author(s): Yongfei Xing, Shijie Wu, Mengxian Dong, Jie Wang, Li Liu, Huajie Zhu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A series of axially chiral biscarboline-based sulfones were synthesized from 〈span〉l〈/span〉-tryptophane and applied for enantioselective 1,2-transfer hydrogenations of ketimines using trichlorosilane. The catalyst 〈strong〉4e〈/strong〉, which had a tertiary butyl group, exhibited a good conversion and high enantioselectivities up to 96%ee in the series of reactions.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402019308221-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 6 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 36〈/p〉 〈p〉Author(s): Yui Ozaki, Tomoaki Yamada, Taisei Mizuno, Kazuyuki Osaka, Mugen Yamawaki, Hajime Maeda, Toshio Morita, Yasuharu Yoshimi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Photoinduced decarboxylative radical additions of 5-membered alicyclic α-amino acids bearing a (2-phenyl)benzoyl protective group to acrylonitrile under mild organic photoredox catalysis conditions furnished γ-amino acid derivatives with high retention of chirality via the memory of chirality (MOC) strategy. The retention of chirality in the photoinduced decarboxylation was strongly dependent on the structure of the alicyclic α-amino acids and alkenes. To the best of our knowledge, this is the first example of the decarboxylative intermolecular radical addition to alkenes with retention of chirality at the position of radical generation using the MOC strategy.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402019308208-fx1.jpg" width="493" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 13 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 37〈/p〉 〈p〉Author(s): En Gao, Meng Li, Lili Duan, Lin Li, Yue-Ming Li〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Chiral 〈em〉N,N〈/em〉′-dioxide catalysts were designed based on isosteric approach. Using 〈span〉l〈/span〉-Proline as the starting material, a variety of chiral 〈em〉N,N〈/em〉′-dioxide ligands were obtained via conventional functional group transformations and were utilized in asymmetric Henry reactions between nitromethane and aromatic aldehydes. Using the 〈em〉N,N〈/em〉′-dioxide-copper(II) complexes as the catalysts, asymmetric Henry reaction produced the corresponding β-nitroalcohols in up to 66% yields and up to 83% ee's under mild conditions. The reactions were easy to carry out, and special care such as air or moisture-free conditions was not required.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402019308191-fx1.jpg" width="406" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 25 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 4〈/p〉 〈p〉Author(s): Mohammedumar M. Shaikh, Anuj P. Patel, Kishor H. Chikhalia〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Cross dehydrogenative coupling (CDC) strategy has been employed for C-alkynylation of 4-thiazolidinone with terminal alkyne under copper catalysis. Present reaction involves coupling of C(sp〈sup〉3〈/sup〉) adjacent to sulfur of 4-thiazolidinone with C(sp) of terminal alkyne under CDC strategy is unprecedented to the best of our knowledge. Significant functional group tolerance, considerable yield and DFT study for mechanism make this synthetic task more interesting and compatible.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402018312912-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 28 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron〈/p〉 〈p〉Author(s): Alexander F. Khlebnikov, Mikhail S. Novikov, Nikolai V. Rostovskii〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉2〈em〉H〈/em〉-Azirines are versatile building blocks for the preparation of various nitrogen-containing heterocycles. Seven years ago the comprehensive review on azirine chemistry was published in Tetrahedron. Since then, there had been an explosion of research activities in the field of these strained molecules. This renaissance is primarily associated with the discovery of new reactivity of azirines and in particular new catalytic and light-induced reactions, which made possible unusual transformations of this three-membered 〈em〉N〈/em〉-heterocycle into azole and azine derivatives as well as polyheterocyclic systems. The second reason for the progress of azirine chemistry is the development of methods for the preparation of new azirine derivatives. The third reason is the discovery of new synthetic equivalents of azirines, which permitted avoiding the use of unstable azirines in some modern catalytic procedures. In the present comprehensive review, we have placed particular emphasis on discussing the new developments in the synthesis and reactivity of azirines for the period from 2012 until the end of 2018.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402019303370-fx1.jpg" width="312" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 28 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron〈/p〉 〈p〉Author(s): Richard Schroeder, Alexander J. Grenning〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Herein reported is access to allyl γ-butyrolactones and caprolactones that can undergo decarboxylative allylation/divinylcyclopropane–cycloheptadiene rearrangement. The overall sequence is brief (5 steps from commercial ketones/aldehydes) and yields diverse cycloheptadienes. The key decarboxylative allylation/divinylcyclopropane–cycloheptadiene rearrangement was unknown at the outset of our studies but recently reported by the Nemoto group. We disclose a complementary study to Nemoto's that further demonstrates the value of this transformation. Specifically, new routes to the key substrates are disclosed that ultimately results in improved scope of target cycloheptadienes.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402019303333-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 28 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron〈/p〉 〈p〉Author(s): Egor V. Verbitskiy, Oleg S. Eltsov, Ekaterina F. Zhilina, Ilya M. Pakhomov, Gennady L. Rusinov, Oleg N. Chupakhin, Valery N. Charushin〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉An efficient synthetic route towards previously inaccessible dibenzo [〈em〉f,h〈/em〉]quinazolines and [1]benzothieno [3,2-〈em〉f〈/em〉]benzo [〈em〉h〈/em〉]quinazolines through FeCl〈sub〉3〈/sub〉-mediated intramolecular oxidative cyclodehydrogenation of readily available 5-([1,1′-biphenyl]-2-yl)pyrimidines and 5-(2-phenylbenzo [〈em〉b〈/em〉]thiophen-3-yl)pyrimidines is described. Molecular orbital calculations (DFT), as well as redox and photophysical measurements for all new compounds have been performed. The data show that the reported polycyclic systems have a potential to use in organic electronic applications.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402019303461-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 28 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron〈/p〉 〈p〉Author(s): Guosheng Fang, Changwu Zheng, Dongdong Cao, Lu Pan, Haoran Hong, Hongyu Wang, Gang Zhao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A one-pot asymmetric Michael addition/Conia-ene reaction sequence, catalyzed by combination of a dipeptide-derived multifunctional quaternary phosphonium salt and Ag〈sub〉2〈/sub〉CO〈sub〉3〈/sub〉 has been developed, which provides a series of synthetically important chiral methylenecyclopentane derivatives in moderate to excellent yields (up to 97%) and enantioselectivities (up to 93%).〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402019303473-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 26 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron〈/p〉 〈p〉Author(s): Wenfeng Dong, Guangqing Xu, Wenjun Tang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉An enantioselective palladium-catalyzed C(sp〈sup〉2〈/sup〉)-H carbamoylation for the preparation of chiral isoindolines was described for the first time. With chiral monophosphorus ligand (〈em〉R〈/em〉)-AntPhos as the ligand, a series of chiral isoindolines were prepared from diarylmethyl carbamoyl chlorides in excellent yields and enantioselectivities with the palladium loading as low as 1 mol%. Initial mechanistic studies indicated the asymmetric cyclization catalyzed a palladium species with a single chiral monophosphorus ligand.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402019303357-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 25 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron〈/p〉 〈p〉Author(s): Thiago S. Silva, Manoel T. Rodrigues, Hugo Santos, Lucas A. Zeoly, Wanda P. Almeida, Rosimeire C. Barcelos, Ralph C. Gomes, Fábio S. Fernandes, Fernando Coelho〈/p〉

Description: 〈p〉Publication date: Available online 30 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron〈/p〉 〈p〉Author(s): Midori Kanda, Ko Urushibara, Soyoung Park, Shinya Fujii, Hyuma Masu, Kosuke Katagiri, Isao Azumaya, Hiroyuki Kagechika, Aya Tanatani〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉N,N′-Bis(〈em〉ortho〈/em〉-substituted phenyl)squaramides afforded chiral crystals, in which squaramide molecules are arranged in one-handed helical networks, upon simple recrystallization. Three types of crystals with different helices were obtained, depending on the substituents or recrystallization solvent. Folded-type intermolecular hydrogen-bonding interactions of squaramides play a key role in forming the helical networks.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402019303515-fx1.jpg" width="240" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 29 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron〈/p〉 〈p〉Author(s): Riku Shinohara, Hidehisa Kawashima, Narihito Ogawa, Yuichi Kobayashi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Substitution of diethyl and diphenyl benzylic phosphates, Alk-CH(Ar〈sup〉1〈/sup〉)OP(O)(OR)〈sub〉2〈/sub〉 (R = Et, Ph; Alk = Me, Et, 〈em〉i〈/em〉-Pr; Ar〈sup〉1〈/sup〉 = aryl), with the anions derived from Ar〈sup〉2〈/sup〉CH〈sub〉2〈/sub〉 (Ph〈sub〉2〈/sub〉CH〈sub〉2〈/sub〉,9〈em〉H〈/em〉-xanthene and fluorene) and 〈em〉n〈/em〉-BuLi at –15 °C was studied. For phosphates with Me as an Alk, diethyl phosphates produced Me-CH(Ar〈sup〉1〈/sup〉)CH(Ar〈sup〉2〈/sup〉)〈sub〉2〈/sub〉 (Ar〈sup〉1〈/sup〉 = 4-halo-, 4-CN, 4-Me-, 2-Me, 2-Br-, 3-MeO-phenyl and 2-naphthyl). However, an unwanted substitution at the Et group competed with phosphates of Alk = Et- and 〈em〉i〈/em〉-Pr. Fortunately, the corresponding diphenyl phosphates cleanly underwent the desired substitution. Two enantioenriched phosphates, MeCH(Ph)OP(O)(OEt)〈sub〉2〈/sub〉 and EtCH(Ph)OP(O)(OPh)〈sub〉2〈/sub〉, proceeded with complete inversion of the stereochemistry.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402019303527-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 27 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron〈/p〉 〈p〉Author(s): Yujie Dong, Junjie Shen, Weijun Li, Ruiyang Zhao, Yuyu Pan, Qingbao Song, Cheng Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this work, we report two isomers composed of 1-phenyl-1〈em〉H〈/em〉-phenanthro[9,10〈em〉-d〈/em〉]imidazole (PI), hydroxyl and tetraphenylethylene (TPE), abbreviated as 〈strong〉〈em〉m〈/em〉-PITPE〈/strong〉 and 〈strong〉〈em〉p〈/em〉-PITPE〈/strong〉. It is found that they exhibit similar aggregation-induced emission (AIE) behavior but totally different excited-state intramolecular proton transfer (ESIPT) characteristic, as a result of the different linkage sites of PI on TPE moiety. Theoretical calculations and their different experimental responses to F〈sup〉−〈/sup〉 demonstrate that only the 〈em〉para〈/em〉-linkage isomer displays ESIPT. In 〈strong〉〈em〉m〈/em〉-PITPE〈/strong〉 with 〈em〉meta〈/em〉-linkage, the electron cloud distribution only locates at the TPE part in the singlet excited (S〈sub〉1〈/sub〉) states, which results in the localized excited state without ESIPT characteristic.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402019303382-fx1.jpg" width="361" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 27 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron〈/p〉 〈p〉Author(s): Alexey V. Salin, Anton V. Il'in, Rustem I. Faskhutdinov, Robert R. Fayzullin〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Tertiary phosphines (〈em〉n〈/em〉-Bu〈sub〉3〈/sub〉P, Ph〈sub〉3〈/sub〉P) efficiently catalyze the vicinal bis-addition of dialkyl phosphites and diaryl phosphine oxides to alkynoates though the tandem α-umpolung/β-Michael addition. This reaction offers a simple metal-free method for gram-scale preparation of practically useful bisphosphonates and bisphosphine oxides under mild conditions with high atom economy and selectivity.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402019303394-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 27 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron〈/p〉 〈p〉Author(s): Jan Světlík, František Tureček, Katarzyna Hartwich, Krzysztof Kozieł, Paweł Pakulski, Aleksandra Pałasz, Justyna Kalinowska-Tłuścik, Dariusz Cież〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Ceric ammonium nitrate-mediated oxidative cyclizations of CH-acids with terpenes and terpene like substrates were investigated. Dimedone, acetylacetone, and methyl nitroacetate were condensed with pinene, norbornene, nopol, camphene, and carvone and the reaction stereoselectivity was examined. Condensation with endocyclic double bonds in pinene and nopol displayed stereoselectivity, resulting in the formation of pure enantiomers. Condensation with exocyclic double bonds in camphene and carvone produced enantiomer mixtures. The mechanism of the intramolecular annulation in a nopol derivative is discussed with the help of DFT and ab initio calculations.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402019303369-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 27 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron〈/p〉 〈p〉Author(s): Mehdi Zaghouani, Lena A.K. Bögeholz, Evan Mercier, Wolfgang Wintermeyer, Stéphane P. Roche〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A concise 7-step total synthesis of (±)-fumimycin in 11.6% overall yield is reported. An acid-catalyzed intramolecular aza-Friedel–Crafts cyclization was developed to construct the benzofuranone skeleton of the natural product bearing an α,α-disubstituted amino acid moiety in a single step. Regioselective chlorination followed by a Suzuki–Miyaura cross-coupling rapidly enabled the preparation of a library of analogues which were evaluated against peptide deformylase for antibacterial activity.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402019303345-fx1.jpg" width="496" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 30 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron〈/p〉 〈p〉Author(s): Lisa Lampp, Mykhailo Azarkh, Malte Drescher, Peter Imming〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Two new derivatives of galvinoxyl (〈strong〉1〈/strong〉), a perdeutered (〈strong〉2〈/strong〉) and an adamantyl-analog (〈strong〉3〈/strong〉) for potential applications as spin probes were synthesized. The synthesis with deuterated educts yielded 〈strong〉2〈/strong〉 with 98% D. It exhibited an 18-line EPR spectrum in octanol with narrow peak-to-peak linewidth. The EPR spectrum of 〈strong〉3〈/strong〉 was very similar to galvinoxyl, but with differences in the linewidth due to unresolved long-range couplings with adamantyl-protons. Compound 〈strong〉2〈/strong〉 showed a higher response to oxygen (4.8 μT/% O〈sub〉2〈/sub〉) than 〈strong〉1〈/strong〉 (2.8 μT/% O〈sub〉2〈/sub〉). The coupling pattern of 〈strong〉2〈/strong〉 allowed the determination of oxygen at low levels (0–6%) by a new type of analysis of the EPR pattern. The stability of the radicals strongly depended on the amount of hydrogalvinoxyl, a by-product of the galvinoxyl synthesis, and the solvent type. A molecular mechanism for the stabilization by hydrogalvinoxyl and the influence of solvent type is proposed.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402019303539-fx1.jpg" width="413" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 29 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron〈/p〉 〈p〉Author(s): Yumi Murata, Kentaro Takeuchi, Takashi Nishikata〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉α-Bromocarbonyl compound easily generates α-radicals in the presence of a proper initiator, such as copper salt. Recently, tertiary-alkylation reaction using α-bromocarbonyl compound as a tertiary alkyl source is recognized as one of the most important alkylation reactions. The reactions using α-bromocarbonyl compound are increasing, whereas synthetic methods for various functionalized α-bromocarbonyl compounds are not summarized. Generally, α-bromocarbonyl compounds can be synthesized from the corresponding carboxylic acids via α-bromo acid bromide, but the brominations of carboxylic acids are sometimes problematic. In this paper, we will report some technical information for a bromination and synthetic examples of representative α-bromocarbonyl compounds.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402019303503-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 28 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron〈/p〉 〈p〉Author(s): Xiao-Min Wan, Zi-Lin Liu, Wan-Qing Liu, Xiao-Niu Cao, Xinju Zhu, Xue-Mei Zhao, Bing Song, Xin-Qi Hao, Guoji Liu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉An efficient NNN pincer Ru(II)-catalyzed preparation of quinazolines via acceptorless dehydrogenative strategy has been developed. Under the optimized conditions, a broad range of substituted 〈em〉o〈/em〉-aminobenzyl alcohols and (hetero)aryl or alkyl nitriles were well tolerated to afford various 2-substituted quinazolines in high yields. Subsequently, a set of control experiments have been performed to elucidate the reaction mechanism, which underwent alcohol oxidation, nitrile hydration, and cyclocondensation steps. The current protocol is featured with several advantages, such as environmental benignity, operational simplicity, broad substrate scope (compatible with aliphatic nitriles, up to 87% yield), and short reaction time (mostly in 2 h).〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402019303485-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 19 April 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 16〈/p〉 〈p〉Author(s): 〈/p〉

Description: 〈p〉Publication date: 19 April 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 16〈/p〉 〈p〉Author(s): 〈/p〉

Description: 〈p〉Publication date: 19 April 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 16〈/p〉 〈p〉Author(s): 〈/p〉

Description: 〈p〉Publication date: 19 April 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 16〈/p〉 〈p〉Author(s): 〈/p〉

Description: 〈p〉Publication date: Available online 27 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron〈/p〉 〈p〉Author(s): Susanne Petz, Lars Allmendinger, Peter Mayer, Klaus T. Wanner〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The synthesis of new 2-(pyrrolidine-3-yl)acetic acid derivatives as cyclic 〈em〉γ〈/em〉-aminobutyric acid analogues, which are additionally substituted at the 4-position, is reported. A de Mayo reaction, i.e. a combination of an intermolecular [2+2]-photocycloaddition of 1,3-dioxinones with 〈em〉N〈/em〉-protected 3-pyrroline and a fragmentation reaction of the resulting cyclobutane moiety, represent the key steps.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S004040201930345X-fx1.jpg" width="418" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 8 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 6〈/p〉 〈p〉Author(s): Kazuhiko Semba, Yoshiaki Nakao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this review, cross-coupling reactions by cooperative Pd/Cu or Ni/Cu catalysis based on catalytically generated organocopper nucleophiles are summarized. Compared to conventional methods based on the use of stoichiometric amounts of pre-synthesized organometallic reagents, these methods are powerful tools for the alkynylation, arylation, alkenylation, and alkylation of organic electrophiles, especially as they can be carried out in a highly step-economical manner with readily available starting materials based on simple arenes, carboxylic acids, alkenes, and alkynes as pre-nucleophiles.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402018314789-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 25 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 4〈/p〉 〈p〉Author(s): Daria S. Timofeeva, Armin R. Ofial, Herbert Mayr〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Treatment of α-imino esters derived from glycine esters and benzophenone or benzaldehydes with potassium 〈em〉tert〈/em〉 butoxide in DMSO gave persistent solutions of carbanions at 20 °C. The kinetics of their reactions with quinone methides and benzylidene malonates (reference electrophiles) have been followed photometrically under pseudo-first order conditions. The reactions followed second-order rate laws. Since addition of 18-crown-6 ether did not affect the reaction rates, the measured rate constants correspond to the reactions of the non-paired carbanions. Plots of the second-order rate constants against the electrophilicity parameters 〈em〉E〈/em〉 of the electrophiles are linear, which allowed us to derive the nucleophile-specific parameters 〈em〉N〈/em〉 and 〈em〉s〈/em〉〈sub〉N〈/sub〉, according to the linear Gibbs energy relationship lg 〈em〉k〈/em〉〈sub〉2〈/sub〉(20 °C) = 〈em〉s〈/em〉〈sub〉N〈/sub〉(〈em〉N〈/em〉 + 〈em〉E〈/em〉). The Ph〈sub〉2〈/sub〉C = N- and PhCH = N- groups act as very weak electron acceptors with the consequence that Ph〈sub〉2〈/sub〉C = N-CH〈sup〉–〈/sup〉-CO〈sub〉2〈/sub〉R and PhCH = N-CH〈sup〉–〈/sup〉-CO〈sub〉2〈/sub〉R have a similar nucleophilicity as Ph-CH〈sup〉–〈/sup〉-CO〈sub〉2〈/sub〉Et, the anion of ethyl phenylacetate.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402018314650-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 8 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 6〈/p〉 〈p〉Author(s): Abhishek Baral, Aromal Asokan, Valentin Bauer, Bruno Kieffer, Vladimir Torbeev〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Chemical composition of tumor suppressor protein p53 is altered via multiple post-translational modifications which modulate its cellular lifetime and interactions with other biomolecules. Here we report total chemical synthesis of a 61-residue form of transactivation domain (TAD) of p53 based on native chemical ligation of three peptide segments. The experiments to characterize its binding to nuclear co-activator binding domain (NCBD) of CREB-binding protein confirmed native-like induced folding upon binding to NCBD. Thus, the synthetic approach described herein can be useful for the preparation of various post-translationally modified analogues of TAD-p53 for further functional biochemical and biophysical studies.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402018314649-fx1.jpg" width="380" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 25 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 4〈/p〉 〈p〉Author(s): 〈/p〉

Description: 〈p〉Publication date: 25 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 4〈/p〉 〈p〉Author(s): 〈/p〉

Description: 〈p〉Publication date: 25 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 4〈/p〉 〈p〉Author(s): 〈/p〉

Description: 〈p〉Publication date: 25 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 4〈/p〉 〈p〉Author(s): 〈/p〉

Description: 〈p〉Publication date: 8 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 6〈/p〉 〈p〉Author(s): Ammar Sheykhi-Estalkhjani, Nosrat O. Mahmoodi, Asieh Yahyazadeh, Meysam Pasandideh Nadamani, Hossein Taherpour Nahzomi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A facile two-directional synthesis of new pyrimido[5,4-〈em〉d〈/em〉]pyrimidine-2,8-dione was reported via an efficient reaction of premade bis-aldehydes and 1-(2-amino-1,2-dicyanovinyl)-3-phenylurea in the presence of triethylamine as the base and Cu (II) as catalyst. As there is controversy about the formation of two types of products, that is, purine or pyrimidine ring containing compounds in the reaction of diaminomaleonitrile with isocyanates and aldehydes, the computational model chemistry has been employed to obtain new insight about this reaction and determining the dominant pathway of the process. Using DFT model, two alternative pathways have been explored and geometrical isomerization of central double bond has been considered. Accordingly, the evaluated energy barriers affirm the formation of six-membered pyrimidine ring as the major product in the presence of CuCl〈sub〉2〈/sub〉 as the catalyst and MeOH as solvent.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402018315473-fx1.jpg" width="336" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 8 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 6〈/p〉 〈p〉Author(s): Vijay Vilas Shinde, Seunho Jung〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We synthesized a mono-succinyl-β-cyclodextrin (Suc-β-CD) and used it as a supramolecular organic acid catalyst for the synthesis of the therapeutically relevant indazolo[3′,2':2,3]imidazo[1,5-c]quinazolin-6(5H)-one (IIQ) via the Groebke–Blackburn–Bienaymé reaction (GBB). The Suc-β-CD was characterized using MALDI-TOF mass spectrometry, NMR spectroscopy, FT-IR spectroscopy, and SEM. A possible reaction mechanism via molecular complexation is suggested, based on 2D NMR (ROESY) spectroscopy, FT-IR spectroscopy, FE-SEM, and DSC analysis. The significant advantages of this atom-economical method include the simple single-step preparation of the catalyst, tolerance of a wide range of functional groups, easy catalyst recyclability, and absence of a tedious workup or purification; moreover, this method eschews the use of hazardous reagents/solvents.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402018315618-fx1.jpg" width="444" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 5〈/p〉 〈p〉Author(s): Yuqing Ma, Yuyang Zhang, Lin Kong, Jiaxiang Yang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Five quinoline derivatives containing different alkyl chains (〈strong〉QLACn〈/strong〉, n = 2, 4, 6, 8, 12) were synthesized to investigate the effect of alkyl chains on their photophysical properties. The fluorescent properties of the 〈strong〉QLACn〈/strong〉 were affected by the alkyl chains, which indicated obvious blue-shifting trend and fluorescence emission are alkyl chains length-dependent by grinding-induced spectral shifts (Δλ〈sub〉MFC〈/sub〉). Longer alkyl-length revealed larger Δλ〈sub〉MFC〈/sub〉. Powder X-ray diffraction (PXRD), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) measurements indicated that the transformation between microcrystalline and amorphous states upon external stimuli should be responsible for the observed reversible MFC behavior.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402018315631-fx1.jpg" width="422" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 7〈/p〉 〈p〉Author(s): Saadi Samadi, Khosrow Jadidi, Mojgan Samadi, Akram Ashouri, Behrouz Notash〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A new type of amido-oxazoline ligands was conveniently synthesized from inexpensive and commercially available materials in high yields and enantiomeric excesses. The corresponding chiral copper complexes with this class of ligands [C〈sub〉2〈/sub〉 symmetric 〈em〉S〈/em〉,〈em〉S〈/em〉-bis(amido-oxazoline-Cu(II) complex] were synthesized accordingly. The ORTEP diagram of ligand 〈strong〉6a〈/strong〉 and complex 〈strong〉6a〈/strong〉-copper were compared and characterization of the complex confirmed the involvement of both dentate parts of the ligands, the oxygen and nitrogen atoms, in complexation with copper. The utilization of this amido-oxazoline ligands in the copper-catalyzed enantioselective esterification of allylic C〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉H bonds of cyclic olefins with 〈em〉tert〈/em〉-butyl-4-nitrobenzoperoxoate resulted in the highest activities, yields (up to 95%) and enantioselectivities (up to 96%) in the presence of HZSM-5 zeolite. These new findings highlight the protocol as one of the most attractive and useful methods for the oxidation of the asymmetric allylic C〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉H bond of cycloalkenes compared to other methodologies reported in the literature.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402018315643-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 8 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 6〈/p〉 〈p〉Author(s): Masato Yasuda, Yutaka Saga, Takuya Tokunaga, Susumu Itoh, Shin Aoki〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The direct aldol reaction between a protected dihydroxyacetone derivative and 4-nitrobenzaldehyde catalyzed by chiral Zn〈sup〉2+〈/sup〉 complexes of 1-(〈em〉n〈/em〉-carboxylalkyl)-7-aminoacyl-1,4,7,10-tetraazacyclododecane is reported. New Zn〈sup〉2+〈/sup〉 complexes containing 〈span〉l〈/span〉-histidine and carboxylalkyl chains that mimic a class II aldolase, carboxypeptidase A and a serine protease were designed and synthesized. 〈em〉Syn〈/em〉-aldol products were mainly formed by an aldol reaction of acetonide-protected dihydroxyacetone with benzaldehydes and other benzaldehydes in 〈em〉N〈/em〉-methylpyrrolidone (NMP)/alcohol (MeOH, EtOH or 2-PrOH) in good yields with a high degree of diastereo- and enantioselectivity (56%∼quant., 57∼〉99% 〈em〉ee〈/em〉). Mechanistic aspect based on ESI-HRMS, elemental analysis and pH titrations of model ligands is also discussed.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S004040201831562X-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 25 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 4〈/p〉 〈p〉Author(s): Kanyapat Lumyong, Boonsong Kongkathip, Nutthawat Chuanopparat, Ngampong Kongkathip〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The asymmetric total synthesis of (−)-epiquinamide has been achieved starting from a 5-iodofuranoside synthon derived from 〈span〉d〈/span〉-glucose. The methods featured Bernet-Vasella reaction followed by Horner-Wadsworth-Emmons (HWE) reaction to provide a new chiral building block diene as the key steps. The bicyclic framework of this quinolizidine was constructed by selective reduction of α,β-unsaturated ester, intramolecular nucleophilic substitution and ring-closing metathesis.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402018315357-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 22 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 8〈/p〉 〈p〉Author(s): Leif E. Laperriere, Sam Yruegas, Caleb D. Martin〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The reactions of 9-phenyl-9-borafluorene with N〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉H, P〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉H, O〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉H, and S〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉H containing substrates were investigated. Protodeborylation reactions were observed for phenol, water, aniline, and para-bromothiophenol. In the water reaction, both O〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉H bonds reacted with 9-phenyl-9-borafluorene to furnish the oxygen bridged diborane whereas only one of the N〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉H bonds in aniline reacted. Phenylphosphine coordinated to the boron center to give an adduct that did not react further. The results were compared to the corresponding reactions with the same substrates and pentaphenylborole.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402018315126-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 5〈/p〉 〈p〉Author(s): Takuya Warashina, Daisuke Matsuura, Yoshikazu Kimura〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Practical preparations of dichloromethyl alkyl ethers are described, based on the reaction of alkyl formates with oxalyl chloride in the presence of 〈em〉N〈/em〉-methylformanilide. The method involves a simple procedure that does not require the use of harmful reagents. Dichloromethyl propyl and dichloromethyl butyl ethers represent secure synthetic equivalents to dichloromethyl methyl ether. Formylations of both electron-deficient and electron-rich aromatics with these dichloromethyl alkyl ethers in the presence of AlCl〈sub〉3〈/sub〉, FeCl〈sub〉3〈/sub〉, or TiCl〈sub〉4〈/sub〉 have been systematically investigated. A plausible mechanism of formylation is discussed.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402018315084-fx1.jpg" width="436" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 17 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron〈/p〉 〈p〉Author(s): Wei-peng Li, Yu-cheng Zhu, Yan-jun Zhou, Hong-wei Yang, Cheng-jian Zhu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We developed a method to synthesize fluorinated 1,4-unsaturated dicarbonyl compounds via photoredox catalyzed radical addition process. Commercially available ethyl bromodifluoroacetate (BrCF〈sub〉2〈/sub〉CO〈sub〉2〈/sub〉Et) as fluoroalkyl source, the corresponding fluoro-containing dicarbonyl compounds could be obtained in moderate to good yields.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402018315011-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 25 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 4〈/p〉 〈p〉Author(s): Huiting Bian, Lili Ye, Wei Zhong, Jinhua Sun〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉To deeply reveal the impact of the substituents and their special orientations in ring on conformational behaviors for substituted cyclohexanes, a comprehensive study of ethylcyclohexane, cis-, and trans-1,2-dimethylcyclohexanes has been carried out. All conformational structures for them were captured by the accurate ab intio method, that is, B3LYP/6-311++G(d,p) method was used for geometry optimizations, and MP2/6-311++G(d,p), G4, and CCSD(T)/6-311++G(d,p) methods were applied for the high-level single point energy refinements. Based on CCSD(T)/6-311++G(d,p) quantum results, the conformational populations of minima for these three substituted cyclohexanes were calculated by Boltzmann distribution over 300-2500 K. Additionally, the conformational inversion-topomerization pathways for them were thoroughly investigated. The complete characterization involved in their potential energy surfaces are clearly presented by three or two-dimensional schemes.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402018314984-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 25 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 4〈/p〉 〈p〉Author(s): Rodolfo H.V. Nishimura, Artur de L.L. Vaz, Leandro A. Bozzini, Valter E. Murie, Giuliano C. Clososki〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Magnesium- and zinc-TMP amides have come out from relative obscurity to be recognized as important tools in modern synthetic chemistry. Development of LiCl-activated metal amides like TMPMgCl·LiCl and TMP〈sub〉2〈/sub〉Zn·2MgCl〈sub〉2〈/sub〉·2LiCl has been important to obtain new organometallic reagents through highly chemo- and regioselective reactions. Herein, we review how these reagents are applied in the synthesis of important bioactive targets such as natural products and drugs.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402018314832-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 8 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 6〈/p〉 〈p〉Author(s): Mani Ramanathan, Ming-Tsung Hsu, Shiuh-Tzung Liu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉One-pot synthesis of 3-aryl-4(〈em〉3H〈/em〉)-quinazolinones has been realized through a cascade annulation. Reaction of aryldiazonium salt with a nitrile provides 〈em〉in situ〈/em〉 generation of a reactive nitrilium ion, which is attacked by the amino group of 2-aminobenzoate followed by cyclization to deliver the desired product. This strategy offers a convenient and easy access to a wide range of functionalized quinazolinone.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402018315680-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 7〈/p〉 〈p〉Author(s): Saumitra Sengupta, Goverdhan Mehta〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Approval of bortezomib has validated ubiquitin-proteasome pathway as an important target for treatment of haematological malignancies. However, clinical shortcomings of bortezomib, a covalent peptide proteasome inhibitor, has prompted a paradigm shift in anti-proteasome drug discovery towards development of non-peptidic inhibitors and targeting of upstream ubiquitin system which has drawn traction for interdisciplinary forays. It is being widely recognized that natural products provide valuable leads in the discovery of potent, chemically diverse, non-peptidic inhibitors of 20S proteasome and of key enzymes involved in ubiquitination machinery. As a result, total synthesis of natural, non-peptidic inhibitors of ubiquitin-proteasome pathway has emerged as a critical interlink between organic synthesis, medicinal chemistry, biochemical profiling and drug discovery. An up-to-date account of contextual synthetic challenges, strategies and accomplishments as well as mapping of the chemical diversity space around the natural scaffolds has been captured in this review.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402018314777-fx1.jpg" width="245" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 5〈/p〉 〈p〉Author(s): Roman O. Iakovenko, Andrea Chicca, Daniela Nieri, Ines Reynoso-Moreno, Jürg Gertsch, Mikhail Krasavin, Aleksander V. Vasilyev〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A series of 1-trifluoromethyl substituted indanes and indenes bearing aryl groups in positions 1 and/or 3 of the indane core have been synthesized mainly by electrophilic cyclization and arylation of the corresponding trifluoromethylated allyl and propargyl alcohols. The distinctly lipophilic compounds thus obtained were tested against various components of human endocannabinoid system. None of the compounds displayed affinity toward CB〈sub〉1〈/sub〉 or CB〈sub〉2〈/sub〉 receptors. Two compounds inhibited monoacylglycerol lipase (MAGL) and three compounds showed inhibition of anandamide (AEA) uptake. The latter can be related to the low-micromolar inhibition of fatty acid amide hydrolase (FAAH) inhibition displayed by one of these compounds.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402018315199-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 7〈/p〉 〈p〉Author(s): Hai-Jun Li, Soren K. Mellerup, Xiang Wang, Suning Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Several examples of laterally appended donor-π-acceptor (D-π-A) boron compounds based on a biphenyl unit have been synthesized and fully characterized. Intramolecular H bonds or n-π* interactions have been found to have a great impact on the photophysical/fluorescent properties of these compounds. Some members of these compounds have been found to display fluorescent response toward CO〈sub〉2〈/sub〉.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402018315102-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 5〈/p〉 〈p〉Author(s): Toshiro Yamashita, Hitoaki Nishikawa, Tetsuji Kawamoto〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Continuous photo flow synthesis of 〈em〉tert〈/em〉-butyl 3-oxo-2-oxabicyclo[2.2.0]hex-5-ene-6-carboxylate 〈strong〉(2b)〈/strong〉 from 〈em〉tert〈/em〉-butyl 2-oxo-2H-pyran-5-carboxylate 〈strong〉(1b)〈/strong〉 has been investigated for scale-up synthesis of 〈em〉cis〈/em〉-3-(〈em〉tert〈/em〉-butoxycarbonyl)-2,3,4-〈em〉d〈/em〉〈sub〉〈em〉3〈/em〉〈/sub〉-cyclobutanecarboxylic acid 〈strong〉(3c)〈/strong〉 as a useful building block for preparation of various biologically active compounds and those of material sciences containing cyclobutane ring system(s) labeled with deuterium atoms. Optimization of reaction conditions and modification of the photo flow reaction system have brought about the production of 〈em〉cis〈/em〉-3-(〈em〉tert〈/em〉-butoxycarbonyl)-2,3,4-〈em〉d〈/em〉〈sub〉〈em〉3〈/em〉〈/sub〉-cyclobutanecarboxylic acid 〈strong〉(3c)〈/strong〉 with excellent deuterium content in 3.6 g through the continuous photo flow synthesis for 22 h followed by hydrogenation with deuterium gas. Also, application of the product to synthesis of 〈em〉cis〈/em〉-3-((benzyloxycarbonyl)methyl-〈em〉d〈/em〉〈sub〉〈em〉2〈/em〉〈/sub〉)cyclobutane-1,2,4-〈em〉d〈/em〉〈sub〉〈em〉3〈/em〉〈/sub〉-carboxylic acid 〈strong〉(11)〈/strong〉 is described for preparation of internal standards of drug candidate compounds in quantitative mass spectrometry analyses in nonclinical and clinical pharmacokinetic studies.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402018315151-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 25 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 4〈/p〉 〈p〉Author(s): Shiho Kadotani, Toshiki Nokami, Toshiyuki Itoh〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Three types of pyridinium salts, i.e., 1-ethylpyridin-1-ium cetyl-PEG〈sub〉10〈/sub〉 sulfate (PY〈sub〉ET〈/sub〉), 1-butylpyridin-1-ium cetyl-PEG〈sub〉10〈/sub〉 sulfate (PY〈sub〉BU〈/sub〉), and 1-(3-methoxypropyl)pyridin-1-ium cetyl-PEG〈sub〉10〈/sub〉 sulfate (PY〈sub〉MP〈/sub〉), have been prepared and evaluated for their activation property of 〈em〉Burkholderia cepacia〈/em〉 lipase by comparison to the control IL-coated enzymes, 1-butyl-2,3-dimethylimidazolium cetyl-PEG〈sub〉10〈/sub〉 sulfate-coated lipase PS (IL1-PS). Among the tested pyridinium salt-coated lipases, the PY〈sub〉ET〈/sub〉-coated lipase PS (PY〈sub〉ET〈/sub〉-PS) exhibited the best results; the transesterification of 1-(pyridin-2-yl)ethanol, 1-(pyridin-3-yl)ethanol, 1-(pyridin-4-yl)ethanol, or 4-phenylbut-3-en-2-ol proceeded faster than those of the IL1-PS-catalyzed reaction while maintaining an excellent enantioselectivity (E 〉 200). This improved efficiency was found to be dependent on the increased K〈sub〉cat〈/sub〉 value.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402018315060-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 25 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 4〈/p〉 〈p〉Author(s): Sviatoslav S. Eliseenko, Fei Liu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Pyrroles are versatile chemical motifs for molecular recognition or ligand design but their utility as catalytic components are underexplored. We incorporated a pyrrole motif into our acid-switchable, MAP-based trifunctional organocatalytic system. The switching-on of this system by an external Brønsted acid, 3-methyl benzoic acid, presented proficient catalysis in both 〈em〉aza-〈/em〉Morita–Baylis–Hillman (MBH, up to 〉95% conversion and 88% 〈em〉ee〈/em〉 over 3 h) and MBH (up to 81% conversion and 77% 〈em〉ee〈/em〉 over 6 h) reactions. The enhanced catalytic generality and proficiency may be due to the new cooperativity via CH/π interactions between pyrrole and the acid switch.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402018314819-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 25 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 4〈/p〉 〈p〉Author(s): Nobuyuki Hayashi, Tomomi Ujihara, Hirotaka Ikeda〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Several hypotheses have been proposed to explain the origin of the conformational stabilities of 1,2-difluoroalkanes, for which bond orbital interactions are an important factor. However, there is a limit to the effectiveness of the traditional approach focusing on only the antiperiplanar interactions between bonding and antibonding orbitals such as σ〈sub〉C–H〈/sub〉/σ〈sub〉C–F〈/sub〉*, σ〈sub〉C–C〈/sub〉/σ〈sub〉C–F〈/sub〉*, and σ〈sub〉C–F〈/sub〉/σ〈sub〉C–F〈/sub〉*, which cannot actually explain the conformational stabilities of 2,3-difuluorobutanes. In this study, to elucidate the effect of bond orbital interactions on the conformational stabilities of 1,2-difluoroethane, 〈em〉erythro〈/em〉-2,3-difluorobutane, and 〈em〉threo〈/em〉-2,3-difluorobutane, we extended the range of interactions considered to beyond these conventional interactions. The results showed that for 1,2-difluoroethane, the conformational stability can be understood by considering all antiperiplanar bond orbital interactions around the C1–C2 bond, and for 2,3-difluorobutanes, by considering all antiperiplanar bond orbital interactions around the C2–C3 bond in addition to bond orbital interactions between the methyl groups.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402018315072-fx1.jpg" width="368" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 8 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 6〈/p〉 〈p〉Author(s): Xueting Liang, Liang Xu, Cuihua Li, Xin Jia, Yu Wei〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Formal propagation of (hetero)arylamine is achieved via a one-pot Buchwald–Hartwig C–N cross-coupling and nitro reduction sequence, enabling a rapid modular synthesis of diverse amino-di(hetero)arylamines from (hetero)arylamines and halogenated nitrobenzenes. Various functionalized aromatic amines with different electronic and steric environments can be efficiently prolongated to formally incorporate another arylamino fragments. This approach has been successfully applied in the synthesis of more than forty amino-di(hetero)arylamines. The applicability of this method has also been demonstrated in the synthesis of oligoanilines and the tyrosine-kinase inhibitor Imatinib.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉A study of the synthesis of amino-di(hetero)arylamines has been reported. The molecular structures can be constructed via a one-pot Buchwald–Hartwig C–N cross-coupling and nitro reduction sequence, from (hetero)arylamines and halogenated nitrobenzenes.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402018315138-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 5〈/p〉 〈p〉Author(s): Kukkamudi Sreenivas, Faiz Ahmed Khan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉1,6-Conjugate addition of various carbon nucleophiles to 〈em〉p〈/em〉-quinone methide surrogate is reported. The active methylene containing 〈em〉C〈/em〉-nucleophiles such as 1,3-diketones, diesters and ketoesters underwent two consecutive additions leading to bis-addition products, diarylpropanes. Whereas, nitroalkanes proceeded to contribute mono-addition products. Surprisingly, bromo analogue of 〈em〉p〈/em〉-quinone methide surrogate underwent halophilic dimerization reaction with excellent yield. The reported strategy provides an efficient synthesis of 1,3-diarylpropane derivatives bearing pharmacophoric 〈em〉ortho〈/em〉-methoxy phenol moiety under mild reaction conditions.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402018315382-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 5〈/p〉 〈p〉Author(s): O. Maduka Ogba, Zichen Liu, Daniel J. O'Leary〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉An enthalpy-entropy approach to analyzing a rate-slowing conformational kinetic isotope effect (CKIE) in a deuterated doubly-bridged biaryl system is described. The computed isotope effect (〈em〉k〈/em〉〈sub〉H〈/sub〉/〈em〉k〈/em〉〈sub〉D〈/sub〉 = 1.075, 368 K) agrees well with the measured value (〈em〉k〈/em〉〈sub〉H〈/sub〉/〈em〉k〈/em〉〈sub〉D〈/sub〉 = 1.06, 368 K). The rate-slowing (normal isotope effect) nature of the computed CKIE is shown to originate from a vibrational entropy contribution defined by the twenty lowest frequency normal modes in the ground state and transition state structures. This normal entropy contribution is offset by an inverse vibrational enthalpy contribution, which also arises from the twenty lowest frequency normal modes. Zero point vibrational energy contributions are found to be relatively small when all normal modes are considered. Analysis of the 〈em〉H〈/em〉〈sub〉ZPE〈/sub〉, 〈em〉H〈/em〉〈sub〉vib〈/sub〉, and 〈em〉S〈/em〉〈sub〉vib〈/sub〉 energy terms arising from the low frequency vibrational modes reveals their signs and magnitudes are determined by larger vibrational energy differences in the labeled and unlabeled ground state structures.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402018315412-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 8 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 6〈/p〉 〈p〉Author(s): Geoffrey Schwertz, Andrea Zanetti, Marllon Nascimento de Oliveira, Mario Andrès Gomez Fernandez, Fabienne Dioury, Janine Cossy, Zacharias Amara〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Amorphadiene is a natural product involved in the biosynthesis of the antimalarial drug artemisinin. A convenient four-step synthesis of amorphadiene, starting from commercially available dihydroartemisinic acid, is reported. The targeted molecule is isolated with an overall yield of 85% on a multi-gram scale in four steps with only one chromatography.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402018315400-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 22 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 8〈/p〉 〈p〉Author(s): Oriana Brea, Henrik Daver, Julius Rebek, Fahmi Himo〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The thermal decomposition of N-nitrosoamides has experimentally been demonstrated to depend on several factors, such as temperature, solvent and the substituents on the substrate. Consequently, a number of reaction mechanisms have been proposed for this process in the literature. In this work, we present a comprehensive computational investigation in which we examine the detailed reaction mechanisms for two N-nitrosoamides (with aliphatic and aromatic substituents) in two different solvents (mesitylene and methanol). It is shown that the reaction mechanism can change dramatically with the nature of the substrate and the choice of solvent. Importantly, it is found that the polar solvent stabilizes ion-pairs that are unstable in the non-polar solvent, which can play a key role in the mechanism.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402018315448-fx1.jpg" width="496" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 25 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 4〈/p〉 〈p〉Author(s): Eugeny P. Ivakhnenko, Pavel A. Knyazev, Galina V. Romanenko, Anastasiia А. Kovalenko, Tatyana E. Ivakhnenko, Yurii V. Revinskii, Vladimir I. Minkin〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉New carboxyl-containing 〈em〉o〈/em〉-aminophenols and phenoxazines were synthesized by condensation of 3,5-di-(〈em〉tert.〈/em〉-butyl)-quinone with 〈em〉p〈/em〉-aminobenzoic and anthranilic acids. Oxidative transformations of the 〈em〉o〈/em〉-aminophenols and intermediate 〈em〉o〈/em〉-iminoquinones occur with the formation of the ESR detected phenoxazinyl radicals, which furthermore transform to phenoxazines or the dimeric products emerged through the radical attack at the C1 carbon of a formed phenoxazine. Molecular structure of the dimer obtained by oxidation of methyl ester of 4-[3,5-di-(〈em〉tert.〈/em〉-butyl)-1-(2′-hydroxyphenyl)amino]benzoic acid was X-ray determined. Reaction of 4-[3,5-di-(〈em〉tert.〈/em〉-butyl)-1-(2′-hydroxyphenyl)amino]benzoic acid with thionyl chloride gives rise to the formation of a derivative of 2-oxido-3H-benzo[d,j][1,2,3]oxathiazol system, the structure of which was established using X-ray crystallography. Solutions of methyl-6,8-di-(〈em〉tert.-〈/em〉butyl)-10H-phenoxazine-3-carboxylate solvents display intense fluorescence covering a broad spectral region in the range of 400–600 nm.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402018315370-fx1.jpg" width="319" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 5〈/p〉 〈p〉Author(s): Alec N. Brown, Bo Li, Shih-Yuan Liu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Palladium-catalyzed Negishi cross-coupling of 3-bromo-1-(tert-butyldimethylsilyl)-1,2-dihydro-1,2-azaborine while maintaining the B−H functionality has been demonstrated. 17 examples, including dialkylzinc, alkyl-, alkenyl-, aryl-, as well as nitrogen-, sulfur-, and oxygen-containing heteroaryl-zinc halide reagents have been coupled to generate new C(3) substituted 1,2-azaborines in moderate to excellent yields.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402018315175-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 5〈/p〉 〈p〉Author(s): Dawood Hosni Dawood, Redouane Beniazza, Frédéric Robert, Yannick Landais〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A palladium-mediated double oxidative amination reaction on cyclohexa-2,5-dienes has been developed, leading to the tetracyclic indoline skeleton of 〈em〉aspidosperma〈/em〉 and 〈em〉strychnos〈/em〉 alkaloids. The allyl-palladium intermediate, generated after the double oxidative amination, could be trapped by an internal nucleophile to allow the construction of 3 rings in a single step. Approaches to the synthesis of strychnine and mossambine is finally reported.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402018315217-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 5〈/p〉 〈p〉Author(s): Emilie Petit, Rémi Jacquet, Laurent Pouységu, Denis Deffieux, Stéphane Quideau〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The reasons for the loss of characteristic odoriferous thiols during the aging of wine in oak-made barrels and subsequent storage in bottles have been in part attributed to covalent capture of these thiols by polyphenolic wine components that are dehydrogenated into electrophilic 〈em〉ortho〈/em〉-quinones upon wine oxygenation. Herein, FeCl〈sub〉3〈/sub〉 was used as oxidant in oxygen-deprived aqueous solutions to dehydrogenate grape (epi)catechins and oak ellagitannins in the presence of two typical odoriferous thiols, 2-furanmethanethiol (2FMT) and 3-sulfanylhexan-1-ol (3SH). The preparative-scale conditions used enabled the isolation of six novel 2FMT-bearing (epi)catechin derivatives, three known 3SH-bearing catechin derivatives (the structures of two of those were revised to be strictly derived from 1,6-conjugate addition), three novel 2FMT-bearing castalagin derivatives, and one novel 3SH-bearing castalagin derivative. The structures of these castalagin-based thio-adducts revealed that the capture of thiols by the different dehydrogenated pyrogallol rings of castalagin starts at ring IV, then ring III, and finally ring V.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402018314613-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 7〈/p〉 〈p〉Author(s): Weishun Liu, Lin Fang, Yinbo Wan, Jianfang Zhang, Guisheng Deng, Jianbo Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In AgSbF〈sub〉6〈/sub〉/Rh〈sub〉2〈/sub〉(OAc)〈sub〉4〈/sub〉/DCE system, two-component diastereoselective reactions of 2-diazo-3,5-dioxo-6-ynoates (phosphonates and sulphones) and alkenes provided easy access to 2-cyclopropyl-γ-pyrones through 6-〈em〉endo〈/em〉-dig cyclization-cyclopropanation. In AgOAc/Rh〈sub〉2〈/sub〉(OAc)〈sub〉4〈/sub〉/Et〈sub〉3〈/sub〉N/DCE system, two-component reaction of 2-diazo-3,5-dioxo-7-aryl-6-ynoates and alkenes afforded 2-cyclopropyl-2-alkylene-3(2〈em〉H〈/em〉)-furanones through 5-〈em〉exo〈/em〉-dig cyclization-cyclopropanation. The possible mechanism of reaction is discussed. A simple procedure and mild conditions are significant features of this strategy.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402018314340-fx1.jpg" width="418" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 26 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron〈/p〉 〈p〉Author(s): Laurence M. Harwood, Phillip Pitt, Janet L. Scott, Dora Sousa〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The ultra-high pressure Menshutkin reaction of N-substituted imidazoles and α,ω-dichloroalkanes provides access to a wide variety of bis(imidazoliumyl)alkane dichlorides in an efficient, one-pot process. Although the substitution reactions of dichloromethane at ambient pressure can be exceedingly slow, at 1.9 GPa, syntheses are usually quantitative in under 24 h. Reactions involving congested imidazole starting materials, that otherwise terminate after formation of the mono-imidazolium salt, are driven to the bis-imidazolium salt at 1.9 GPa. The rates of reaction increase with α,ω-dichloroalkane chain length, decrease with increasing bulk and imidazole N-substituent length, and the reactions of the more hindered imidazoles are more sensitive to the pressure-rate enhancement.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040402019310038-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 18 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron, Volume 75, Issue 42〈/p〉 〈p〉Author(s): 〈/p〉