ALBERT

Beschreibung: 〈p〉Publication date: 15 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 33〈/p〉 〈p〉Author(s): Mitali Mishra, Seetaram Mohapatra, Nilima Priyadarsini Mishra, Bighnanshu K. Jena, Pravati Panda, Sabita Nayak〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Heterocyclic compounds particularly five, six and seven membered ring containing heterocycles are the most abundant which constitute a staggeringly diverse and important class of molecules that occur ubiquitously in a variety of synthetic drugs, bioactive natural products, pharmaceuticals and agrochemicals. Owing to the glorious past and impressive present of the biologically active heterocyclic scaffolds, these skeletons have long been a subject of immense interest. Hence, substantial efforts have been made to the development of new and innovative synthetic strategies for the synthesis of these heterocycles involving use of different metal catalysts, organic and inorganic reagents etc. Among the different types of metal catalysts used, iron catalysts are one of the cheap and easily available. In recent time, several new and innovative iron(III) chloride catalyzed synthesis of heterocycles with structural diversity are coming in the forefront of the literature by the scientific community. This review highlights the advancements made so far by iron(III) chloride for the synthesis of different assemblies of small heterocycles covering the year 2014–2018.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919306628-ga1.jpg" width="261" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈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〉

Beschreibung: 〈p〉Publication date: 1 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 31〈/p〉 〈p〉Author(s): Tao-Shan Jiang, Yuhui Zhou, Long Dai, Xiaojun Liu, Xiuli Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A metal-free 〈em〉p〈/em〉-toluenesulfonic acid (TsOH·H〈sub〉2〈/sub〉O) mediated synthesis of 3-ketoquinolines from anilines, enaminones and DMSO has been developed. In this transformation, DMSO was activated by TsOH·H〈sub〉2〈/sub〉O and provided the one-carbon unit of the 3-ketoquinolines. A plausible mechanism involving an electrophilic sulfenium ion intermediate was proposed.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919306562-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 31〈/p〉 〈p〉Author(s): Lifeng Wang, Qingshan Tian, Chen Bin, Guozhu Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A novel copper-catalyzed amination of ethers using isocyanates and DTBP is developed. The reaction provides a unique approach to the synthesis of Boc-protected α-aminals through three-component radical cascade reactions. It provides an alternative method for the construction of this type of valuable motifs in high yield. Meanwhile, the method exhibits high tolerance of various functional groups, such as ether, halide, ester and acyl functionalities.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919306598-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 6 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Hironori Okamura, Takanobu Fujioka, Naoki Mori, Tohru Taniguchi, Kenji Monde, Hidenori Watanabe, Hirosato Takikawa〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Salinipostins are cyclic enol-phosphotriesters isolated from a marine-derived 〈em〉Salinispora〈/em〉 sp. as antimalarial compounds. Herein, the first enantioselective synthesis of salinipostin A was achieved. Organocatalyst-mediated asymmetric cyclopropanation and regioselective cyclopropane ring opening were the key steps.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919306549-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 6 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Soumen Biswas, Anubha Yadav, Debashis Majee, Shaikh M. Mobin, Sampak Samanta〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A simple, efficient, one-pot sequential process for the preparation of a family of 8,9-dihydropyrido[1,2–〈em〉a〈/em〉]indol-6(7H)-one scaffolds in acceptable yields has been established under mild conditions. The Michael-hemiaminalization-oxidation reaction proceeds between methyl 2-(3-formyl-1〈em〉H〈/em〉-indol-2-yl) acetate and 〈em〉trans〈/em〉-β-aryl/alkyl-substituted acroleins using pyrrolidine-BzOH as an efficient organocatalyst, followed by oxidation of in situ generated of C,〈em〉N〈/em〉-fused hemiaminal adducts in the presence of PDC at room temperature. Excitingly, organobase-catalyzed highly diastereoselective (up to ≤9:1 dr) construction of a series of pharmacologically attractive 1,2,3-fused tetracyclic indole scaffolds with five contiguous chiral centers including an all-carbon stereogenic center has been realized through our developed method. Moreover, pyrrolidine-BzOH and PTSA as combined catalytic systems promote the uninterrupted sequential Michael-cyclization reaction, followed by 〈em〉N〈/em〉-alkylation reaction with carbazole to produce interesting class of 6-(9〈em〉H〈/em〉-carbazol-9-yl)-6,7,8,9-tetrahydropyrido[1,2–〈em〉a〈/em〉]indole derivatives in a diastereoselective manner.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919306574-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 6 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Mahender Khatravath, Naveen Kumar Mallurwar, Saidulu Konda, Jagan Gaddam, Pallavi Rao, Javed Iqbal, Prabhat Arya〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A practical stereoselective synthesis of the central C1–C10 fragment of eribulin and its two diastereomeric analogues is developed. Our approach relied on the use of 〈span〉l〈/span〉-ascorbic acid as the starting material which allowed accessing a key intermediate with a syn diol moiety (C9 and C10 of eribulin) and a carboxylic ester group. A functionalized six membered lactone having several required hydroxyl groups was then obtained. In a number of steps, the lactone was converted to an intermediate for our key 〈em〉oxa〈/em〉-Michael reaction. A regio- and stereocontrolled intramolecular oxa〈em〉-〈/em〉Michael reaction completed the synthesis of the C1–11 fragment having a trans-fused tetrahydropyrans with the exact stereochemistry of various hydroxyl groups, as in eribulin.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919306525-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 25 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 30〈/p〉 〈p〉Author(s): 〈/p〉

Beschreibung: 〈p〉Publication date: 25 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 30〈/p〉 〈p〉Author(s): 〈/p〉

Beschreibung: 〈p〉Publication date: Available online 5 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Vladislav Y. Korotaev, Igor B. Kutyashev, Alexey Y. Barkov, Yuliya S. Rozhkova, Irina V. Plekhanova, Yurii V. Shklyaev, Vyacheslav Y. Sosnovskikh〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Ferrocene analogues of pyrrolo[2,1-〈em〉a〈/em〉]isoquinoline alkaloids, 2-(trifluoromethyl)-5,6-dihydroferroceno[〈em〉g〈/em〉]indolizine and 6-(trifluoromethyl)-8,9-dihydro-6〈em〉H〈/em〉-chromeno[4,3-〈em〉b〈/em〉]ferroceno[〈em〉g〈/em〉]indolizines, were obtained in 44–65% yield 〈em〉via〈/em〉 the Grob reaction between 1-nitro-1-(2,2,2-trifluoroethylidene)alkanes or 3-nitro-2-(trifluoromethyl)-2〈em〉H〈/em〉-chromenes and 1-alkyl-3,4-dihydroferroceno[〈em〉c〈/em〉]pyridines in 2-propanol at reflux.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919306537-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 25 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 30〈/p〉 〈p〉Author(s): 〈/p〉

Beschreibung: 〈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〉

Beschreibung: 〈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〉

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

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

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

Beschreibung: 〈p〉Publication date: 1 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 31〈/p〉 〈p〉Author(s): Hemi Borgohain, Sajal Kumar Das〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A series of 11-aryl-11〈em〉H〈/em〉-indeno[1′,2′:4,5]imidazo[1,2-〈em〉a〈/em〉]pyridines was obtained via AlCl〈sub〉3〈/sub〉-promoted, dehydrative cyclization of the corresponding aryl(2-arylimidazo[1,2-〈em〉a〈/em〉]pyridin-3-yl)methanols in moderate to good yields. The synthesized compounds can be considered as conformationally restricted, privileged aza-heterocyclic scaffold bearing triarylmethane analogs.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919306392-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 2 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Thomas P. Nicholls, Alex C. Bissember〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The scope, applications, and understanding of photoinduced, copper-catalysis have advanced considerably in recent times. Many of these transformations exploit the distinctive properties of photoactive copper species to establish original synthetic methodology and reveal novel reactivity. In this regard, the bifunctionality of copper photocatalysts has often allowed these species to direct and influence synthetic processes in new, interesting, and exciting ways. This article summarizes recent advances in the development of copper photoredox catalysts and provides an overview of the emerging applications of these, and related systems, in organic synthesis.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919306033-ga1.jpg" width="497" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈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〉

Beschreibung: 〈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〉

Beschreibung: 〈p〉Publication date: Available online 20 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Toru Amaya, Yuqing Jin, Mamoru Tobisu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The Gomberg-Bachmann reaction is an intermolecular aryl-aryl cross-coupling reaction using an arenediazonium salt and an arene. This digest review surveys recent advances in the Gomberg-Bachmann reaction. More specifically, it focuses on reaction systems that include 1) transition-metal-induced systems, 2) organic promoter-induced systems, 3) electrolytic systems, 4) photoredox systems, and 5) hybrid systems that involve photoredox and transition-metal catalysts.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919308226-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 20 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Yosuke Taniguchi, Xiuming Cao, Shigeki Sasaki〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The efficient synthesis of the highly-deuterated thymidine-〈em〉d〈sub〉9〈/sub〉〈/em〉 by the glycosylation reaction between a deuterated nucleobase and deuterated sugar is described. It is also incorporated into the oligonucleotides using a DNA synthesizer. Using this approach, it is possible to make highly-deuterated oligonucleotides for biological studies and structural analyses.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919307944-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 36〈/p〉 〈p〉Author(s): 〈/p〉

Beschreibung: 〈p〉Publication date: Available online 9 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Tong-Lin Wang, Hai-Tang Qi, Xi-Cun Wang, Zheng-Jun Quan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉An iodine-catalyzed direct allylation of chiral oxazolidinones with aldehydes and alkenes has been developed. The reaction proceeds, without use of any bases or metals, directly converted the 3-chiral oxazolidinones into 〈em〉N〈/em〉-allylated oxazolidinones. Additionally, the 3-chiral allylamine skeleton was constructed and the diastereomers were isolated by simple column chromatography.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919306641-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 10 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Masafumi Hirano, Nobuyuki Komine, Eri Arata, Tatiana Gridneva, Atsuya Hatori, Naoki Kaizawa, Kohei Kamakura, Ayumi Kuramochi, Shinnosuke Kurita, Shuhei Machida, Harumi Okada, Asami Sawasaki, Takumi Uchino〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A series of achiral and chiral diene and the related ligands in transition-metal complexes is evaluated by percent buried volume (%〈em〉V〈/em〉〈sub〉bur〈/sub〉) based on their molecular structures by X-ray analysis. Steric bulk of cyclic diene ligands in [Ru(acac)〈sub〉2〈/sub〉L] and [RhClL]〈sub〉2〈/sub〉 are sorted in the order of %〈em〉V〈/em〉〈sub〉bur〈/sub〉. Recent developments on transition-metal catalyses using these ligands such as (〈em〉i〈/em〉) conjugate arylations, alkenylation, and alkynylation, (〈em〉ii〈/em〉) imine-arylations and alkenylations, (〈em〉iii〈/em〉) kinetic resolutions, (〈em〉iv〈/em〉) allylation, (〈em〉v〈/em〉) cyclizations, (〈em〉vi〈/em〉) defluorinations, (〈em〉vii〈/em〉) C〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉H bond activations, and (〈em〉viii〈/em〉) cross-dimerizations are reviewed.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919306616-ga1.jpg" width="403" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 22 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Sampa Gupta, Alisha Ansari, Koneni V. Sashidhara〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A useful and efficient approach for the synthesis of nitroarenes from several aromatic amines (including heterocycles) using peroxide and base has been developed. This oxidative reaction is very easy to handle and afforded the products in good yields. Formation of benzamides from benzylamine was also successfully carried out with this metal-free catalytic system in good to excellent yields.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919308391-ga1.jpg" width="498" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈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〉

Beschreibung: 〈p〉Publication date: Available online 21 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Polina S. Teterina, Mariia M. Efremova, Ekaterina V. Sirotkina, Alexander S. Novikov, Olesya V. Khoroshilova, Alexander P. Molchanov〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The 1,3-dipolar cycloaddition of keto- and aldonitrones with 〈em〉N〈/em〉-arylitaconimides proceeds regioselectively giving only 5-spiroisoxazolidines. In the case of aldonitrones the reaction proceeds with high diastereoselectivity. A range of the obtained adducts were subjected to reductive cleavage of the N〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉O bond using zinc powder in acetic acid to give the corresponding spirolactones and 1,3-amino alcohols.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919308238-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈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〉

Beschreibung: 〈p〉Publication date: 5 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 36〈/p〉 〈p〉Author(s): 〈/p〉

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

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

Beschreibung: 〈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〉

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

Beschreibung: 〈p〉Publication date: Available online 9 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Richard Le Sueur, Matt Guest, Lee Belding, Melanie Pilkington, Travis Dudding〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This work demonstrates how modulating hydrogen bonding between intermolecular, bifurcated, and intramolecular interactions can be used to tune the structural, electronic, and photophysical properties of cyclopropenium ions and their respective fluorophores. The basis of this switchability was examined using X-ray diffraction analysis, 〈sup〉1〈/sup〉H NMR spectroscopy, DFT calculations, and fluorescence spectroscopy.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919306653-ga1.jpg" width="404" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 23 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Matic Proj, Izidor Sosič, Stanislav Gobec〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The benzimidazole-2-thione scaffold is present in many drugs encompassing various therapeutic areas. Due to the broad spectrum of bioactivities it also represents an important starting point in drug discovery campaigns, especially those based on fragment-based design. Despite simple structures the tautomerism and regioisomerism of substituted benzimidazole-2-thiones makes unambiguous structural analysis difficult. Tautomeric duplicates are present in commercial libraries resulting in two tautomers being sold as different products. To showcase an example of appropriate structural determination, we synthesized and characterized a set of benzimidazole-2-thiones with different positions of a chlorine atom on the ring. Using NOESY and 〈sup〉13〈/sup〉C NMR spectroscopy, we determined that the thione tautomer predominates in the thione-thiol equilibrium. Furthermore, NOESY and HMBC experiments confirmed the position of the substituents on the benzimidazole-2-thione ring.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S004040391930841X-ga1.jpg" width="479" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 36〈/p〉 〈p〉Author(s): 〈/p〉

Beschreibung: 〈p〉Publication date: Available online 23 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Min Liu, Yu-Wen Liu, Hui Xu, Hui-Xiong Dai〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A palladium-catalyzed intramolecular C〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉H acylation of indole with thioester is described, providing a direct and effective approach for the synthesis of the biologically active indole-indolone scaffolds. The method obviates the need for the prefunctionalized starting materials including organometallic reagents, alkyl halides, and NHP esters in previous metal-catalyzed cross-coupling reaction with thioester. Substrates bearing sensitive halo groups are compatible in the reaction, leaving a functional handle for further structural elaborations.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919308214-ga1.jpg" width="492" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 22 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Shuaijun Han, Qingsong Wu, Lucas Mele, Licheng Ding, Jingya Li, Dapeng Zou, Yusheng Wu, Yangjie Wu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A simple and efficient copper-catalyzed monofluoromethylation of 8-aminoquinolines with 2-bromo-2-fluoroacetate has been described with HPO(OMe)〈sub〉2〈/sub〉 (dimethyl phosphonate) as reductant. The reaction tolerates a variety of quinoline amides and monofluoroalkyl bromides. Significant advantages of this protocol include synthetic convenience and high reaction efficiency.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919308408-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 22 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Won Sik Na, Pushap Raj, Narinder Singh, Doo Ok Jang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A simple and selective chemosensor, 〈strong〉A〈/strong〉, was developed for recognizing Cu〈sup〉2+〈/sup〉. The emission spectra of receptor 〈strong〉A〈/strong〉 showed a fluorescence quenching response upon addition of Cu〈sup〉2+〈/sup〉 with a low detection limit of 4.51 nM, significantly less than the WHO recommended guideline for drinking water. In addition, the formed 〈strong〉A∙〈/strong〉Cu〈sup〉2+〈/sup〉 complex was examined for secondary sensing of anions. The 〈strong〉A∙〈/strong〉Cu〈sup〉2+〈/sup〉 complex showed selectivity for CN〈sup〉-〈/sup〉 via a recovering emission profile of 〈strong〉A〈/strong〉.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S004040391930838X-ga1.jpg" width="323" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 36〈/p〉 〈p〉Author(s): 〈/p〉

Beschreibung: 〈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〉

Beschreibung: 〈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〉

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

Beschreibung: 〈p〉Publication date: 12 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 37〈/p〉 〈p〉Author(s): Ziba Rafiee Samani, Abdolmohammad Mehranpour〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Novel 5-substituted isophthalates were synthesized from the reaction of 2-substituted 1,3-bis(dimethylamino)-trimethinium salts with 1,3-bis(alkoxycarbonyl)acetone derivatives in the presence of sodium methoxide in ethanol at reflux.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919307592-ga1.jpg" width="330" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 29 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 35〈/p〉 〈p〉Author(s): Hongbo Wei, Hongli Zhang, Shoule Han, Shan Mu, Ke Huang, Guzhou Chen, Weiqing Xie〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Asymmetric synthesis of the marine nor-sesquiterpenoid (+)-austrodoric acid and (+)-austrodoral in seven and nine steps respectively from Wieland-Miescher ketone was described herein. The synthesis featured an oxidative ring contraction of α-formyl cyclic ketone mediated by H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉 to forge the hydrindane scaffold together with the contiguous quaternary carbon centers simultaneously.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919307245-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 29 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 35〈/p〉 〈p〉Author(s): Liliia Usmanova, Dmitry Dar'in, Mikhail Krasavin〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Downstream modification of piperazin-2-ones obtained by the Castagnoli-Cushman reaction leads to a novel version of the medicinally relevant 1,2,5-benzothiadiazepin-4-one-1,1-dioxide scaffold. The relative stereochemistry remained 〈em〉trans〈/em〉 as evidenced by the spectroscopic data and the single-crystal X-ray analysis.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919307609-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 29 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 35〈/p〉 〈p〉Author(s): Sergey Miltsov, Mikhail Goikhman, Alexander Yakimansky, Alexander Misharev, Mar Puyol, Julian Alonso〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The bromination of unsymmetrical indodicarbocyanine dyes bearing electron-donating groups (–NHCOCH〈sub〉3〈/sub〉, –OH) on the aryl rings using 〈em〉N〈/em〉-bromosuccinimide produces dimeric molecules together with the corresponding 〈em〉meso〈/em〉-brominated dyes. The direction of the process depends on the reaction conditions. A possible reaction mechanism is also discussed.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919307622-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 19 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Jinyu Sun, Jesse Vanloon, Hongbin Yan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We report herein that exposure of DNA to microwave irradiation at constant temperature leads to faster strand exchange, as compared with same experiments carried out in a water bath at the same temperature. Furthermore, polymerase chain reactions carried out under microwave irradiation were faster than those in a water bath at the same temperature as well. While the causes of these differences are unclear at this time, this research suggests that microwave irradiation can lead to subtle changes in DNA structural dynamics and functions.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919308202-ga1.jpg" width="357" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 17 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Tian-Ze Li, Chang-An Geng, Ji-Jun Chen〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The first total synthesis of rhuscholide A, a benzofuran lactone possessing anti-HIV-1 activity, had been accomplished in 14 linear steps with 10.6% overall yield. In this synthesis, base-mediated phenol 〈em〉ortho〈/em〉-alkylation and piperidine promoted aldol condensation were exploited as key steps. The synthesis was flexible and allowed for the convenient preparation of two analogous natural products glabralide B and denudalide.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919308196-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 16 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Mary E. Sexton, Ami Okazaki, Zhuowen Yu, Alexis van Venrooy, Jason R. Schmink, William P. Malachowski〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Herein, we report the selective mono-γ-arylation of 7-methoxy-4-methylcoumarin under palladium-catalyzed conditions. The Buchwald G3 pre-catalyst in conjunction with either the Xantphos or 〈em〉N〈/em〉-Xantphos ligand proves to be highly reactive, engaging aryl iodides, bromides, chlorides, and triflates to effect the desired transformation. A wide range of functionality is tolerated, including the ability to activate heteroaryl halides in the transformation. The initial scope of aryl halides and limitations of this methodology are presented.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919308172-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 16 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Fang Fu, Laxman Gurung, Miklos Czaun, Thomas Mathew, G.K. Surya Prakash〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Poly(4-vinyl pyridine) supported bromine/iodine complexes were prepared and probed for 〈em〉ipso〈/em〉-bromination/iodination of arylboronic acids. These solid complexes with catalytic amount of additive are found to be safe and efficient reagent system for the 〈em〉ipso〈/em〉-bromination/iodination. The reaction occurs under mild conditions and tolerates various functional groups resulting in products with high selectivity and yields.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919307774-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 16 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Sun Woo Lee, Seung Yeob Lee, Seoung Ho Lee〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A new chemodosimeter consisting of pyrene and boronic acid (〈strong〉1〈/strong〉) for the detection of Hg〈sup〉2+〈/sup〉 ions is described. The amphiphilic nature of 〈strong〉1〈/strong〉 leads to self-assembly in aqueous solution and the high electron density throughout the aggregated pyrene units provides an outstanding platform for energy and electron transport. Self-assembled 〈strong〉1〈/strong〉 exhibits a selective and sensitive fluorescence response to Hg〈sup〉2+〈/sup〉 ions, where the Hg〈sup〉2+〈/sup〉 ion allows a fast transmetallation of 〈strong〉1〈/strong〉, which drastically reduces its fluorescence. The Stern-Volmer (SV) quenching constant for the fluorescence quenching of self-assembled 〈strong〉1〈/strong〉 by Hg〈sup〉2+〈/sup〉 ions is approximately 1.8 × 10〈sup〉6〈/sup〉 M〈sup〉−1〈/sup〉, and Hg〈sup〉2+〈/sup〉 ions can be sensed with a detection limit of 6.6 × 10〈sup〉−9〈/sup〉 M. In addition, self-assembled 〈strong〉1〈/strong〉 exhibits excellent sensing performance at nano-molar concentration levels for Hg〈sup〉2+〈/sup〉 ion contamination of tap water, fresh water, and seawater.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919308056-ga1.jpg" width="415" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 14 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Tanja M. Voser, Joshua B. Hayton, Luke P. Robertson, Anthony R. Carroll〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A chemical investigation of the eastern Australian endemic bryozoan 〈em〉Amathia lamourouxi〈/em〉 led to the isolation of two unique betaine molecules, lamouroic acid trifluoroacetate and lamourimidazolinium trifluoroacetate. The structures of these molecules were determined using (+)-HRESIMS, 2D NMR and ECD analyses. The new compounds were screened for antiplasmodial, cytotoxic and antibacterial activity but were inactive at 40 μM. Lamouroic acid trifluoroacetate is structurally related to the ubiquitous marine compound homarine, that has previously been shown to possess feeding deterrent properties, and this suggests that the new compound may also have an ecological role in the bryozoan.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919308044-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 12 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 37〈/p〉 〈p〉Author(s): Vishal Srivastava, Pravin K. Singh, Praveen P. Singh〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A mild and efficient one-pot visible light-induced method has been developed for the aerobic oxidation of saturated carbon conjugated with pyridine moiety with an important conversion in medicinal and synthetic organic chemistry. This eosin Y based organic transformations, exhibit a novel approach towards site selective functionalization of pyridine with enhance integrity and capability. This novel synthetic route may hold great potential for diverse functionalization of a wide range of pyridine moiety with an economical and sustainable manner.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919307981-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 29 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 35〈/p〉 〈p〉Author(s): 〈/p〉

Beschreibung: 〈p〉Publication date: Available online 13 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Khairujjaman Laskar, Subham Paul, Utpal Bora〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Cellulose catalyzed oxidative hydroxylation of aryl and hetero-arylboronic acids to the corresponding phenols under metal and base free strategy has been demonstrated. The sustainable 〈em〉ipso〈/em〉-hydroxylation takes place using hydrogen peroxide as an oxidant in water under mild condition in shorter period of time. Interestingly, easy recovery and reusability of heterogeneous catalyst without significant loss in catalytic yield makes the protocol environmentally benign.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919308019-ga1.jpg" width="250" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 12 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 37〈/p〉 〈p〉Author(s): D.G.S. Sudhakar, Ch. Venkata Ramana Reddy, Srinivasa Rao Alapati〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉An efficient stereoselective total synthesis of balticolid has been accomplished starting from known aldehyde. The key steps involved in this synthesis are Sharpless asymmetric epoxidation, Wittig olefination, alkylation of 1,3-dithiane and Yamaguchi macrolactonization.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919307841-ga1.jpg" width="301" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 12 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 37〈/p〉 〈p〉Author(s): Ya-Lan Wang, Chang-Run Guo, Yan Mu, Yun-Liang Lin, Hui-Jiao Yan, Zhi-Wei Wang, Xiao-Jing Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Bousigonine A (〈strong〉1〈/strong〉), an unprecedented eburnamine-voaphylline type dimeric indole alkaloid, and Bousigonine B (〈strong〉2〈/strong〉), the first example of eburnamine-eburnamine-aspidospermine type trimeric indole alkaloid were isolated from 〈em〉Bousigonia mekongensis〈/em〉. Their structures were elucidated mainly by spectroscopic analysis and compared to published data. Their preventing high glucose-induced podocyte injury activity were evaluated for the first time, and compound 〈strong〉1〈/strong〉 exhibited significant effect with EC〈sub〉50〈/sub〉 value of 2.5 μM.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919307993-ga1.jpg" width="337" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 36〈/p〉 〈p〉Author(s): Yuki Miyazawa, Makoto Sugimoto, Ayumi Tanaka-Oda, Hidefumi Makabe〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Syntheses of (+)-goniopypyrone and (+)-goniotriol isolated from 〈em〉Goniothalamus giganteus〈/em〉 were achieved. The key steps involve Pd-catalyzed carbonylation for lactone ring formation and diastereoselective reduction of ynone using the (〈em〉R〈/em〉)-CBS catalyst and borane dimethyl sulfide complex.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919307968-ga1.jpg" width="465" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 36〈/p〉 〈p〉Author(s): Kakeru Maeda, Ryo Murakami, Fuyuhiko Inagaki〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The silver catalyzed 〈em〉7-endo-trig〈/em〉 cyclization of an ene-diol for the formation of 2,2-dimethyloxepane frameworks has been developed. The spirotype dioxabicyclic products were also produced from the diene-diols. In addition, a gold catalyst featuring the Z-ligand also produced similar cyclization reactions.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919307956-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

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

Beschreibung: 〈p〉Publication date: 12 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 37〈/p〉 〈p〉Author(s): Anthony Choi, Iain Coldham〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉1-Methyl-3,4-dihydroquinoxalin-2(1〈em〉H〈/em〉)-one was heated with a range of aldehydes to generate intermediate azomethine ylides which underwent [3 + 2] cycloaddition reactions with 〈em〉N〈/em〉-methyl or 〈em〉N〈/em〉-phenylmaleimide to give substituted tetrahydropyrroloquinoxalinones. Only one (racemic) stereoisomer was formed in each case and the stereochemical outcome was verified by single crystal X-ray analysis. The products from this multicomponent reaction could be oxidised with DDQ to the pyrroloquinoxalinones.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919307804-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈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〉

Beschreibung: 〈p〉Publication date: 5 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 36〈/p〉 〈p〉Author(s): Kaori Ando, Junichiro Hattori〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A method for one-pot preparation of Julia-Kocienski sulfides and sulfones from alcohols and thiols is reported. A variety of primary alcohols were converted to the corresponding mesylates by methansulfonyl chloride and triethylamine in THF. After the reaction is complete, thiol (〈strong〉1〈/strong〉 or 〈strong〉10〈/strong〉) and either NaH or 〈em〉t〈/em〉-BuOK were added. The Julia-Kocienski sulfides 〈strong〉3〈/strong〉, 〈strong〉9〈/strong〉 and 〈strong〉11〈/strong〉 were prepared by one-pot two steps procedure from alcohols in 76–96% yields (16 examples). Furthermore, after the sulfide formation, the reaction mixture was neutralized by 〈em〉p〈/em〉-toluenesulfonic acid and treated with H〈sub〉2〈/sub〉O〈sub〉2〈/sub〉 and ammonium molybdate in EtOH to give the Julia-Kocienski sulfones 〈strong〉4〈/strong〉 in good yields except for 〈em〉trans〈/em〉-2-hexen-1-ol.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919307749-ga1.jpg" width="391" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 36〈/p〉 〈p〉Author(s): Yang Wang, Kang Liu, Zhi-Xiang Yu, Yanxing Jia〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉An attempt to access the fused 7/5 ring of the highly biologically active terpenoid caribenol A by employing intramolecular Pauson-Khand reaction of 1,8-enyne gave bridged 8-5 ring, the type-II Pauson-Khand reaction product. DFT study has been carried out to elucidate this unexpected regioselectivity.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919307580-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈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〉

Beschreibung: 〈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〉

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

Beschreibung: 〈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〉

Beschreibung: 〈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〉

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

Beschreibung: 〈p〉Publication date: 8 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 32〈/p〉 〈p〉Author(s): 〈/p〉

Beschreibung: 〈p〉Publication date: 8 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 32〈/p〉 〈p〉Author(s): 〈/p〉

Beschreibung: 〈p〉Publication date: 5 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 36〈/p〉 〈p〉Author(s): Chen Chen, Jie Ding, Yuebo Wang, Xiaonan Shi, Dequan Jiao, Bolin Zhu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A copper-catalyzed iminohalogenation of unactivated alkenes of γ, δ-unsaturated oxime esters is achieved by using readily available halide salts. Utilizing this protocol, a sequence of structurally diversiform 2-halomethyl pyrrolines are efficiently synthesized and a mechanism involving iminyl radical intermediates, which were initiated by Cu(I) species, was proposed.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919307579-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 8 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 32〈/p〉 〈p〉Author(s): 〈/p〉

Beschreibung: 〈p〉Publication date: 8 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 32〈/p〉 〈p〉Author(s): 〈/p〉

Beschreibung: 〈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〉

Beschreibung: 〈p〉Publication date: Available online 17 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Othman Al Musaimi, Ayman El-Faham, Alessandra Basso, Beatriz G. de la Torre, Fernando Albericio〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Due to the hazardous nature of CH〈sub〉2〈/sub〉Cl〈sub〉2〈/sub〉, regulatory authorities have imposed restrictions to minimize or even stop its use. It has therefore become imperative to identify environmentally benign solvents to replace it. Here we report on a bio derived solvent, γ-valerolactone, for the incorporation of the first amino acid onto p-alkoxybenzyl alcohol resin in solid-phase peptide synthesis. Satisfactory loading values (by a spectrophotometric method) were achieved. Furthermore, racemization and dipeptide formation were also checked and found to be acceptable.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919308184-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈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〉

Beschreibung: 〈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〉

Beschreibung: 〈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〉

Beschreibung: 〈p〉Publication date: Available online 8 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Zhongrui Chen, Maxime Bert, Simon Pascal, Gabriel Canard, Olivier Siri〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The transamination reaction of 2,5-diaminobenzoquinonediimine (QDI) with ethylenediamine gave fluorescent 1,2,3,4-tetrahydropyrazino[2,3-〈em〉g〈/em〉]quinoxaline (〈strong〉1〈/strong〉). When the same reaction was carried out with 〈em〉N,N’〈/em〉-bis(aminoethyl)-1,3-propanediamine, a novel cationic quinoxalinium species (〈strong〉2〈/strong〉) was isolated, which can be further condensed with 〈em〉p〈/em〉-cyanobenzaldehyde to afford a benzimidazolo-fused quinoxaline dye (〈strong〉3〈/strong〉) that is a water-soluble fluorophore in the UV–visible range.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919307816-ga1.jpg" width="382" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 36〈/p〉 〈p〉Author(s): Saverio Santi, Serena Rossi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Progresses in the design and application of conjugated small molecules, oligomers and polymers have empowered rapid development of organic electronic technology as an alternative to conventional devices. Among the numerous organic electronic materials, benzotrithiophene (BTT)-based oligomers and polymers have recently come in the limelight demonstrating great potential in organic electronics as high performance photovoltaic devices, field-effect transistors, electrochromic materials, high-area capacitors and charge carrier discotic liquid crystals. In this digest, we propose an overview of the organic electronic materials based on BTT isomers, highlighting the structure-performance relationship. The results obtained so far clearly indicate that the BTT isomers are among the most promising building blocks for the development π-extended materials for optoelectronic applications in the near future.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919307786-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 36〈/p〉 〈p〉Author(s): Sri Venkateswarlu Rayudu, Dipankar Karmakar, Pramod Kumar〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉An efficient, cost-effective and environmentally benign synthesis of novel tetracyclic bis-isoxazolopyrroloquinoline derivatives has been developed via one-pot four-component reaction of 4-amino-3-methyl-5-styrylisoxazoles, dimedone, aryl glyoxal monohydrates and 5-amino-3-methylisoxazole by employing water as a reaction medium and acetic acid (AcOH) as a green promoter. The advantages of this protocol are environmentally friendly, metal-free, less reaction time, operational simplicity, high yields, broad substrate scope and easy purification. Most significant of all, this method is green.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919307828-ga1.jpg" width="450" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 36〈/p〉 〈p〉Author(s): Michael Moir, Rochelle Boyd, Hendra Gunosewoyo, Andrew P. Montgomery, Mark Connor, Michael Kassiou〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The CB〈sub〉2〈/sub〉 receptor is an attractive target for the treatment of a wide range of diseases and pathological conditions. Compounds that selectively activate the CB〈sub〉2〈/sub〉 receptor are desirable as this avoids CB〈sub〉1〈/sub〉-mediated psychoactive effects. Heteroarylidene-benzamides have demonstrated efficacy as selective CB〈sub〉2〈/sub〉 receptor agonists. We aimed to expand the structure-activity relationship studies of this series of compounds by investigating the heteroaromatic core via the synthesis and 〈em〉in vitro〈/em〉 evaluation of a small library of various heteroaromatic benzamide analogues. As heteroaromatic amides are privileged scaffolds in drug design, methods to synthesise them are of interest. Concise and reliable synthetic strategies were developed to access these novel analogues. The –ylidene-benzamide moiety is shown to be essential for CB activity as all amide derivatives exhibit no functional activity at either CB〈sub〉2〈/sub〉 or CB〈sub〉1〈/sub〉 receptors.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉 〈p〉The synthesis of a small library of heteroaromatic benzamides as potential cannabinoid type 2 receptor agonists is described.〈/p〉 〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919307762-ga1.jpg" width="378" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉 〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 22 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 34〈/p〉 〈p〉Author(s): 〈/p〉

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

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

Beschreibung: 〈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〉

Beschreibung: 〈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〉

Beschreibung: 〈p〉Publication date: Available online 14 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Luana A. Pachechne, Vinicius F. Pereira, Guilherme M. Martins, Edmar Martendal, Fernando R. Xavier, Samuel R. Mendes〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A general method for the synthesis of 1,2,3,4-tetrasubstituted pyrroles by [NMPH]CH〈sub〉3〈/sub〉SO〈sub〉3〈/sub〉 is reported. A full factorial design was performed in order to obtain a more robust and statistically correct optimum condition. The products were obtained in moderate to excellent yields. The developed methodology is very simple, cost-effective, and applicable for tri- and tetra-component reactions.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919308007-ga1.jpg" width="453" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 14 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Yunze Li, Min Rao, Zhenwei Fan, Baoyi Nian, Yaofeng Yuan, Jiajia Cheng〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉An efficient method for visible-light-induced perfluoroalkylaion of quinolin-4-ol has been reported. In the presence of 〈em〉t〈/em〉-BuONa and perfluoroalkyl iodide, quinolin-4-ol underwent C〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉H perfluoroalkylation under the irradiation of green light. Mechanistic studies demonstrated that visible-light promoted intermolecular charge transfer within the transient electron donor-acceptor complex in the absence of any photocatalysts.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919308032-ga1.jpg" width="231" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 14 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters〈/p〉 〈p〉Author(s): Kuang Xu, Xuan Zhang, Jing Wei Chen, Yan Shen, Nan Jiang, Ren Xiang Tan, Rui Hua Jiao, Hui Ming Ge〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Three new pimarane-type diterpenoids, along with two known compounds, were isolated from an endophytic fungus 〈em〉Phomopsis〈/em〉 sp. S12. Their structures were determined by comprehensive analyses of HRESIMS, NMR, CD, as well as single-crystal X-ray diffractions. Compound 〈strong〉3〈/strong〉 exhibited anti-inflammatory activity against the production of IL-1β and IL-6 induced by lipopolysaccharide (LPS) in macrophages. A putative biosynthetic pathway for compounds 〈strong〉1〈/strong〉–〈strong〉5〈/strong〉 were also proposed.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0040403919308020-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 29 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Tetrahedron Letters, Volume 60, Issue 35〈/p〉 〈p〉Author(s): 〈/p〉

Beschreibung: 〈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〉

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

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

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

Beschreibung: 〈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〉