The present invention provides compounds of the formula
wherein R is optionally substituted lower alkyl, cycloalkyl or aryl; R′ is alkyl or aryl; n is zero or an integer of 1 or 2; or an enantiomer thereof; or an enantiomeric mixture thereof.
The compounds of formula (I) are bridged C
2
-symmetric biphenyldiphosphine analogs and, thus, may be employed as ligands to generate chiral transition metal catalysts which may be applied in a variety of asymmetric reactions. The compounds of the present invention are easily accessible in high diastereomeric and optical purity according to the methods disclosed herein.
Diphosphine sulfides derived from 2,2â²-biphosphole have been efficiently synthesized in an enantiomerically pure form by a four step synthetic sequence. These S,S-ligands were used for the first time in Pd-catalyzed asymmetric allylic alkylation. Good yields and enantiomeric excess up to 73% were obtained.
Palladium-Catalyzed Intramolecular C(sp3)H Functionalization: Catalyst Development and Synthetic Applications
作者:Julien Hitce、Pascal Retailleau、Olivier Baudoin
DOI:10.1002/chem.200600811
日期:2007.1.12
system, based on a mixture of palladium acetate and tris(5-fluoro-2-methylphenyl)phosphane (F-TOTP), has been designed for the intramolecular C--H functionalization of alkane segments. Among other analogues of tris(2-methylphenyl)phosphane (P(o-tol)(3)), F-TOTP was shown to have the optimal metal-bonding properties for this reaction. This catalytic system operated under milder reaction conditions that
Synthesis of Chiral-Bridged Atropisomeric Monophosphine Ligands with Tunable Dihedral Angles and their Applications in Asymmetric Suzuki-Miyaura Coupling Reactions
construction of diastereomeric biaryl monophosphines by means of the substrate-directed asymmetric annulation reactions. A series of new chiral-bridged atropisomeric biphenyl monophosphine ligands with tunable dihedral angles was accordingly synthesized successfully without a resolution step being needed. Using these ligands, different kinds of axially chiral 1,1′-biaryl-2-phosphonates including the first
An efficient procedure for the synthesis of C-chiral bisphosphines
作者:Lydia McKinstry、Tom Livinghouse
DOI:10.1016/0040-4020(95)00390-t
日期:1995.7
A practical method for the synthesis of bisphosphines containing homochiral carbon backbones is described. This procedure entails sequential reaction of a homochiral ditosylate with the appropriate dialkyl- or diarylphosphine-borane anion followed by BH5 decomplexation mediated by HBF4 . OMe(2).