Enantioselective Deprotonation as a Vehicle for the Asymmetric Synthesis of C2-Symmetric P-Chiral Diphosphines
作者:Alexander R. Muci、Kevin R. Campos、David A. Evans
DOI:10.1021/ja00140a028
日期:1995.9
Communication is to disclose a convenient approach to the synthesis of Cz-symmetric P-chiral diphosphines4 that relies upon successive enantioselectivedeprotonation of aryldimethylphosphine-boranes or aryldimethylphosphine sulfides (eq 1) and subsequent oxidative coupling to the diphosphine precursors (eq 2) with high overall enantioselectivity (296%) for the two-step process.
Olefin Hydrogenation with Rigid Mono-<i>P</i>-stereogenic Diphosphines: A Flexible Rhodium Ring to Rule Them All?
作者:Slavko Rast、Michel Stephan、Barbara Mohar
DOI:10.1002/ejoc.201403570
日期:2015.4
The preparation of a rigid C1-symmetric P-stereogenic diphosphine series possessing a P-o-diphenylphosphinophenyl moiety and its use in RhI-catalyzed hydrogenation of benchmark olefins, is presented. This simplified ligand design, wherein some specific features (backbone flexibility, identical nature of P,P′-substituents) of related C2-symmetric ethylene-bridged diphosphines were knocked out, is a
trans-1,4-Diphosphacyclohexanes were successfully synthesized by the stereospecific intramolecular coupling reaction of the optically active bisphosphine. This is a new route for the construction of the trans-1,4-diphosphacyclohexane skeleton. A cis isomer was also prepared along with the trans isomer from a mixture of rac- and meso-bisphosphines. The coordinated boranes were easily removed to afford
P-Stereogenic 18-diphosphacrown-6 derivatives containing a chiral bisphosphine unit were synthesized. This is the first practical method for the synthesis of optically pure diphosphacrowns. The diphosphacrowns have the structure of a chiral figure "8" with chiral heteroatoms that interact directly with guest ions and molecules. Pd(II) and Pt(II) complexes with the P-stereogenic diphosphacrowns were also synthesized and characterized.