Enantioselective Borohydride Reduction Catalyzed by Optically Active Cobalt Complexes
作者:Tohru Yamada、Takushi Nagata、Kiyoaki D. Sugi、Kiyotaka Yorozu、Taketo Ikeno、Yuhki Ohtsuka、Daichi Miyazaki、Teruaki Mukaiyama
DOI:10.1002/chem.200304794
日期:2003.9.22
enantioselective borohydride reduction of aromatic ketones or imines to the corresponding alcohols was developed in the presence of a catalytic amount of an opticallyactive cobalt(II) complex catalyst. This enantioselective reduction is carried out using a precisely premodified borohydride with alcohols such as tetrahydrofurfuryl alcohol, ethanol and methanol. High optical yields are obtained by choosing
Silylative Kinetic Resolution of Racemic 2,2‐Dialkyl 5‐ and 6‐Membered Cyclic Benzylic Alcohol Derivatives Catalyzed by Chiral Guanidine, (
<i>R</i>
)‐
<i>N</i>
‐Methylbenzoguanidine
作者:Shuhei Yoshimatsu、Kenya Nakata
DOI:10.1002/adsc.201900761
日期:2019.10.22
Efficient silylative kineticresolution of racemic 2,2‐dialkyl 5‐ and 6‐membered cyclic benzylic alcohols was achieved using diphenylmethylchlorosilane (Ph2MeSiCl) or phenyldimethylchlorosilane (PhMe2SiCl) as a silyl source catalyzed by chiral guanidine. The reaction could be applied to a broad range of 2,2‐dialkyl 1‐indanols with good s‐values, irrespective of the electronic nature of the substituent
Homogeneous Enantioselective Catalysis in a Continuous-Flow Microreactor: Highly Enantioselective Borohydride Reduction of Ketones Catalyzed by Optically Active Cobalt Complexes
Highly enantioselectivehomogeneouscatalysis under continuous-flow conditions was established for the cobalt-catalyzed borohydride reduction of tetralone derivatives. A microreactor allowed higher reaction temperature with the residence time of 12 min than the corresponding batch system to maintain enantioselectivity as well as reactivity. The present system was directly applied to gram-scale synthesis
An Unexpected Directing Effect in the Asymmetric Transfer Hydrogenation of α,α-Disubstituted Ketones
作者:Rina Soni、John-Michael Collinson、Guy C. Clarkson、Martin Wills
DOI:10.1021/ol201643v
日期:2011.8.19
alpha,alpha-Disubstituted ketones containing an aromatic ring or alkene are reduced in high enantiomeric excess using an asymmetric transfer hydrogenation catalyst. The sense of reduction indicates that the unsaturated region of the ketone adopts a position adjacent to the Ru-bound eta(6)-arene ring in the reduction transition state.