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  • 1
    ISSN: 1042-7163
    Keywords: Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Lithium and sodium o-lithio-4,6-di-t-butyl-phenolates 1 and 2 react, successively, with ClP(NMe2)2 and ClSiMe3 to give 2-(Me2N)2P-4,6-t-Bu2C6H2OSiMe3 3. 1 and ClP(NMe2)Ph furnish a small amount of the analogous compound 4 but mainly diastereoisomers of a C, O-diphosphinylation product 5A/B, which exhibit large through-space coupling constants (4JPP = 152 and 237.5 Hz). Under certain conditions, the P-N bond is attacked, and triphosphines 6 and 7 are formed. Alcoholysis of 3-5 and subsequent reduction with LiAlH4 yields the respective bulky primary and secondary phosphinophenols 8 and 9. Both decompose partially on distillation, affording tBu2C6H3OH and the cyclic diphosphines 10 and 11. 10, a further dihydro-benzoxadiphosphol 13 and a phosphinidene-phosphorane 14 are formed by reaction of 8 with P(NMe2)3. The molecular structure of bicyclic 10, folded at the P-P bond, is reported. The uncommon features - unselective disubstitution of 1, P…P interactions in 5 and 6, facile P-C cleavage of 8 and 9, and diphosphine formation - reveal a dramatic influence of the bulky substituents in the 6-position on the chemistry of 2-phosphinophenols. © 1998 John Wiley & Sons, Inc. Heteroatom Chem 9:183-193, 1998
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  • 2
    ISSN: 1042-7163
    Keywords: Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Several organometallic reagents such as lithium 2-lithio 4-methylphenolate 1 intermediates formed by orthometallation of o-bromoaryloxy-phosphorus(V)- 2 or -phosphorus(III)-derivatives 3 with magnesium and sodium, respectively, as well as O-methoxymethyl-protected o-lithio-4-methylphenol 4 were used to synthesize suitable precursors 5,6,9,10 of primary and secondary o-phosphinophenols. The P-C bond formation involved coupling with ClPR(NMe2), CIPR(O)(OEt) or an intramolecular carbanionic O → C shift of the P-substituent. Reduction with LiAlH4, in the cases of phosphonous or phosphinous acid amides after alcoholysis (to 7,8,11), produced primary and secondary o-phosphinophenols 12, respectively, or O-protected derivatives 13. o-Phosphinophenols 12 are easily protonated at the phosphorus atom, supported by a P+-H … O hydrogen bridge. Metallation (14), acylation, and silylation (16,17) take place preferably at the hyxdroxy group and alkylation at the phosphorus atom. Alkylation of 12 and 14 was found to be slow, but C,O-dilithiated species 15 react to give P-secondary (12b,d,e,) or P-tertiary products (20,21). Cyclization of 15a with Me2SiCl2 affords the 2,3-dihydro-1,3,2-benzoxaphosphasilol 22, cyclocondensation of 12c with RP(NMe2)2 or ClP(NMe2)2 furnishes 2,3-dihydro-1,2,3- benzodiphospholes 23 and 24. A phosphiniden-phosphoran 25 is detected in the reaction between 12a and P(NMe2)3. © 1997 John Wiley & Sons, Inc. Heteroatom Chem 8: 383-396, 1997
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  • 3
    ISSN: 1434-1948
    Keywords: Methylnickel complexes ; 2-Phosphanylphenolate ; Chelates ; Homogeneous catalysis ; Oligomerization ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactions of various substituted 2-phosphanylphenols 1a-f with half-molar amounts of cis-[MeNi(μ-OMe)(PMe3)]2 have been found to yield square-planar methyl(2-phosphanylphenolato)(trimethylphosphane)nickel(II) complexes 2a-f. 2JPP coupling constants of 305-316 Hz at low temperature indicate a trans-configuration for the products, while broad 31P-NMR signals at room temperature can be attributed to rapid dissociation of PMe3. Reaction with excess 1 gave rigid bis(2-phosphanylphenolato)nickel(II) complexes as exemplified by 3e, whereas addition of PMe3 to 2a led to the pentacoordinate methyl(2-phosphanylphenolato)bis(trimethylphosphane)nickel(II) complex 4a. Higher yields of 4a and 4d were obtained by reactions of 1a and 1d with Me2Ni(PMe3)3. Single-crystal X-ray diffraction analyses of 3e and 4a have revealed the structures as square-planar trans-bis- and trigonal-bipyramidal mono(2-phosphanylphenolato)nickel(II) P1O-chelate complexes, respectively. The methylnickel complexes 2 and 4 have been found to be effective one-component catalysts for the oligomerization of ethene. High conversions (〉 96%) were achieved with the P-basic derivatives 2e, 2f, and 4d bearing one or two branched alkyl groups (isopropyl, tert-butyl), whereas the diphenylphosphanyl derivatives were less active; 4d gave shorter oligomers than 2e or 2f.
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