The enantioselective reduction of prochiral ketones with NaBH 4 /Me 2 SO 4 /(S)-Me-CBS is described. Borane is generated in situ via the reaction of NaBH 4 with Me 2 SO 4 in tetrahydrofuran, which is as efficient as the commercial one. Such in situ-generated borane reagent was applied to reduce prochiral ketones in the presence of chiral oxazaborolidine catalyst directly. The corresponding chiral secondary alcohols were obtained with excellent enantiomeric excesses (93-99% ee) and good to excellent yield (80-99%).
3 . -The BH 3 /THF-complex as reducing agent is prepared in situ and works as efficient as the commercial one. B(O-Me)3 is added to increase the reactivity and selectivity of the reduction. Hydroxyl groups in the aryl moiety do not need any protection. -(ZHOU, Y.; GAO, G.; LI, H.; QU*, J.; Tetrahedron Lett. 49 (2008) 20, 3260-3263; State Key Lab. Fine Chem., Dalian Univ. Technol.,
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.