Asymmetric Synthesis of Benzoin by SmI2-Mediated Enantioselective Protonation.

S Takeuchi, N Miyoshi, K Hirata, H Hayashida…

Index: Takeuchi, Seiji; Miyoshi, Norikazu; Hirata, Kenji; Hayashida, Haruyoshi; Ohgo, Yoshiaki Bulletin of the Chemical Society of Japan, 1992 , vol. 65, # 7 p. 2001 - 2003

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Citation Number: 20

Abstract

Samarium (Z)-1, 2-diphenylethen-1, 2-diolate, which is considered to be an intermediate of a SmI 2-mediated reduction of benzil, was protonated enantioselectively by quinidine to afford (R)-benzoin in 91% ee. It was found that quenching the unreacted enediolate with oxygen was crucial to obtain high enantioselectivity. The configuration of the samarium enediolate was confirmed by isolating (Z)-O, O′-diacetyl-1, 2-diphenylethen-1, 2-diol.