- Synthesis and reactions of phosphine-boranes. Synthesis of new bidentate ligands with homochiral phosphine centers via optically pure phosphine-boranes
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Secondary and tertiary phosphine-boranes were synthesized in one-pot from phosphine oxides or substituted chlorophosphines without isolation of the intermediate phosphines. Phosphine-boranes having a methyl group were metalated with sec-butyllithium. The generated carbanions reacted with alkyl halides or carbonyl compounds to yield various phosphine-borane derivatives. The carbanions underwent copper(II)-promoted oxidative coupling without impairment of the borane functionality. Secondary phosphine-boranes reacted with alkyl halides, aldehydes, or α,β-unsaturated carbonyl compounds to give phosphine-borane derivatives having a functional group. The boranato group of phosphine-boranes was removed in a stereospecific manner with retention of configuration by treatment with a large excess of amine such as morpholine. A new route to bidentate ligands with homochiral phosphine centers has been explored by utilizing these characteristic reactivities of phosphine-boranes. Thus, optically pure (S,S)-1,2-bis(o-anisylphenylphosphino)ethane, (R,R)-1,2-bis(tert-butylphenyl-phosphino)ethane, and (S,S)-1,4-bis(o-anisylphenylphosphino)butane have been synthesized via phosphine-boranes.
- Imamoto, Tsuneo,Oshiki, Toshiyuki,Onozawa, Takashi,Kusumoto, Tetsuo,Sato, Kazuhiko
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p. 5244 - 5252
(2007/10/02)
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- Organophosphorus Intermediates.IX. The Cleavage of α,ω-Bisdiphenylphosphinoalkanes with Lithium. A 31P N.M.R. Study
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The title phosphines, Ph2P(CH2)nPPh2 (n=2-5), react with lithium in tetrahydrofuran to give the corresponding 1, n-dilithio-1, n-di(phenylphosphines) directly with little or on intermediacy of the 1-lithio-1-phenyl-n-diphenylphosphinoalkanes which can, however, be obtained by arylation of the diphosphides.Methylenebisdiphenylphosphine and 1,4-diphenyl-1,4-diphosphinane undergo exclusive phosphorus-alkyl carbon cleavage.The chemistry and 31P n.m.r. spectroscopy of the diphosphides are described and the mechanism o the cleavage reaction is discussed.Some cleavage reactions in liquid ammonia are described.
- Brooks, Peter,Gallagher, Michael J.,Sarroff, Adrian
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p. 1341 - 1351
(2007/10/02)
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