Synthesis and reactions of new phosphine - boranes

摘要: Synthesis and reactions of new phosphine-boranes have been studied. Diastereomerically pure menthyloxyphenylphosphine-boranes were prepared from dichlorophenylphosphine. These secondary underwent stereospecific alkylation arylation reactions. It is noted that the stereochemistry palladium-catalyzed cross-coupling was largely affected by solvent base used. Thus, reaction in acetonitrile proceeded with net retention configuration. In sharp contrast, THF presence K2CO3 occurred inversion configuration high degree stereospecificity. The phosphorus-oxygen bond resulting reductively cleaved at -78 "C lithium naphthalenide or liquid ammonia almost quantitative yields an excellent On other hand, elevated temperatures provided products complete racemization. This racemization proved to occur via pyramidal anionic tricoordinate phosphorus species. Based on these results, we developed methods for synthesis bidentate phosphine ligands homochiral centers. Optically bisphosphinoethanes bisphosphinobutanes possessing phenyl, t-butyl, cyclohexyl, emethomhenyl, methyl, 2methoxyethyl group phosphine-boranes. Functionalizations boranato investigated. Trimethylphosphine-borane reacted methanesulfonic acid evolution hydrogen. trimethylphosphine-methylsulfonyloxyborane subjected nucleophilic substitution boron atom arenthiols A phosphine-borane having a P-B-P-B-P-B-P-B linkage synthesized. Novel anion species generated phosphine-monoiodoboranes 4,4'-dit -butylbiphenylide.