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Asymmetric Hydrogenation Catalyzed by ( S,S )‐R‐BisPast;‐Rh and ( R,R )‐R‐MiniPHOS Complexes: Scope, Limitations, and Mechanism
Author(s) -
Gridnev Ilya D.,
Yamanoi Yoshinori,
Higashi Natsuka,
Tsuruta Hideyuki,
Yasutake Masaya,
Imamoto Tsuneo
Publication year - 2001
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/1615-4169(20010129)343:1<118::aid-adsc118>3.0.co;2-z
Subject(s) - chemistry , phosphine , asymmetric hydrogenation , isopropyl , catalysis , itaconic acid , alkyl , medicinal chemistry , organic chemistry , stereochemistry , enantioselective synthesis , polymer , copolymer
A new class of chiral C 2 ‐symmetric bis(trialkyl)phosphine ligands has been prepared and used in Rh(I)‐catalyzed asymmetric hydrogenation reactions. The ligands, 1,2‐bis(alkylmethylphosphino)ethanes 1a‐g (abbreviated as BisP*, alkyl = t‐ butyl, 1‐adamantyl, 1‐methylcyclohexyl, 1,1‐diethylpropyl, cyclopentyl, cyclohexyl, isopropyl) and 1,2‐bis(alkylmethylphosphino)methanes 2a‐d (abbreviated as MiniPHOS, alkyl = t‐ butyl, cyclohexyl, isopropyl, phenyl) are prepared by a simple synthetic approach based on the air‐stable phosphine–boranes. These new ligands give the corresponding Rh(I) complexes, which are effective catalytic precursors for the asymmetric hydrogenation of a representative series of dehydroamino acids and itaconic acid derivatives. Enantioselectivities observed in these hydrogenations are universally high and in many cases exceed 99%. X‐Ray characterization of four precatalysts, study of the pressure effects, deuteration experiments, and characterization of the wide series of intermediates in the catalytic cycle are used for the discussion of the possible correlation between the structure of the catalysts and the outcome of the catalytic asymmetric hydrogenation.