Journal ArticleDOI
Synthesis and reactions of new phosphine - boranes
TLDR
In this paper, the synthesis and reactions of new phosphine-boranes have been studied and new methods for the synthesis of bidentate phosphine ligands with homochiral phosphine centers were developed.Abstract:
Synthesis and reactions of new phosphine-boranes have been studied. Diastereomerically pure menthyloxyphenylphosphine-boranes were prepared from dichlorophenylphosphine. These secondary phosphine-boranes underwent stereospecific alkylation and arylation reactions. It is noted that the stereochemistry of palladium-catalyzed cross-coupling reactions was largely affected by the solvent and the base used. Thus, the reaction in acetonitrile proceeded with net retention of configuration. In sharp contrast, the reaction in THF in the presence of K2CO3 occurred with inversion of configuration with high degree of stereospecificity. The phosphorus-oxygen bond of the resulting phosphine-boranes was reductively cleaved at -78 "C by lithium naphthalenide or lithium in liquid ammonia in almost quantitative yields with an excellent degree of stereospecificity. On the other hand, the reactions at elevated temperatures provided the products with almost complete racemization. This racemization was proved to occur via pyramidal inversion of the anionic tricoordinate phosphorus species. Based on these results, we developed new methods for the synthesis of bidentate phosphine ligands with homochiral phosphine centers. Optically pure bisphosphinoethanes and bisphosphinobutanes possessing phenyl, t-butyl, cyclohexyl, emethomhenyl, methyl, or 2methoxyethyl group were prepared via phosphine-boranes. Functionalizations of the boranato group of phosphine-boranes have been investigated. Trimethylphosphine-borane reacted with methanesulfonic acid with evolution of hydrogen. The resulting trimethylphosphine-methylsulfonyloxyborane was subjected to nucleophilic substitution reaction on the boron atom with arenthiols or secondary phosphine-boranes. A new phosphine-borane having a P-B-P-B-P-B-P-B bond linkage was synthesized. Novel boron anion species were generated by the reaction of phosphine-monoiodoboranes with lithium 4,4'-dit -butylbiphenylide.read more
Citations
More filters
Journal ArticleDOI
Amine- and phosphine-borane adducts: new interest in old molecules.
Journal ArticleDOI
A general and efficient method for the palladium-catalyzed cross-coupling of thiols and secondary phosphines
Miki Murata,Stephen L. Buchwald +1 more
TL;DR: In this paper, a broad substrate scope of aryl bromides and chlorides can be coupled to aliphatic and aromatic thiols using Pd(OAc)2/1, 1,1,1′-bis(diisopropylphosphino)ferrocene as the catalyst.
Journal ArticleDOI
Palladium-catalysed reactions of aryl halides with soft, non-organometallic nucleophiles
Journal ArticleDOI
Synthesis of Water-Soluble, Aliphatic Phosphines and Their Application to Well-Defined Ruthenium Olefin Metathesis Catalysts
TL;DR: Water-soluble aliphatic phosphines were synthesized from air-stable, borane-protected precursors in this paper, and the steric parameters of these new phosphines are estimated using the Pd(PR_3)_2Cl_2 complexes.
Journal ArticleDOI
Copper‐Catalyzed C–P Coupling through Decarboxylation
TL;DR: In this article, a protocol for preparation of di(phenyl)phosphoryl oxides is developed by copper-catalyzed decarboxylative coupling of alkenyl, alkynyl carboxylic acids, and N-benzylproline, respectively, with R2P(O)H.