Asymmetric synthesis of optically active halohydrins and oxiranes by enantioselective reduction of prochiral α-haloketones with chirally modified lithium borohydride
作者:Kenso Soai、Takashi Yamanoi、Hitoshi Hikima
DOI:10.1016/0022-328x(85)87441-6
日期:1985.7
Prochiral α-haloketones are reduced enantioselectively with the asymmetric reducing system lithium borohydride N,N′-dibenzoylcystine /t-butyl alcohol to give the corresponding halohydrins with up to 86% enantiomeric excess, some of which are converted to optically active oxiranes.
Catalytic Asymmetric Bromination of Unfunctionalized Olefins with H<sub>2</sub>O as a Nucleophile
作者:Xun Zhang、Jing Li、Hua Tian、Yian Shi
DOI:10.1002/chem.201502133
日期:2015.8.10
The dimeric cinchona alkaloid (DHQD)2PHAL is used to catalyze an effective asymmetric bromohydroxylation of unfunctionalized olefins with H2O as nucleophile an N‐bromobenzamide as a bromine source. A variety of optically active bromohydrins are formed with up to 88 % ee.
Enantioselective reduction of ketones with triethoxysilane catalyzed by chiral bis-oxazoline titanium complexes
作者:Marco Bandini、Pier Giorgio Cozzi、Lucia Negro、Achille Umani-Ronchi
DOI:10.1039/a807028h
日期:——
Chiral bis-oxazoline titanium complexes [Ti(BOX)2X2] prepared from C2 chiral bis-oxazolines, BuLi and titanium salts, catalyze the enantiosective reduction of ketones in the presence of triethoxysilane.
A practical method for the asymmetric transferhydrogenation of α‐substituted ketones was developed utilizing oxo‐tethered N‐sulfonyldiamine‐ruthenium complexes. Reduction by HCO2H and HCO2K in a mixed solvent of EtOAc/H2O allowed for the selective synthesis of halohydrins from 2‐bromoacetophenone (98%) and 2‐chloroacetophenone (>99%), leading to suppressed undesired side reactions stemming from formylation