An efficient CuCN-catalyzed synthesis of optically active 2,3-allenols from optically active 1-substituted 4-chloro-2-butyn-1-ols.
The sequential treatment of optically active terminal propargylic alcohols with n-BuLi/(HCHO)(n) and regioselective chlorination afforded the corresponding optically active 4-chloro-2-butyn-1-ols. With R(1) being a methyl or an ethyl group, an alternative for the synthesis of the corresponding optically active propargylic alcohols is the Novozym 435-catalyzed kinetic resolution of these racemic 4-chloro-2-butyn-1-ols. The subsequent reaction of these optically active 4-chloro-2-butyn-1-ols with the corresponding Grignard reagents under the catalysis of 5 mol % of CuCN afforded the optically active secondary 2,3-allenols in good yields with up to >99% ee.
Li
Jing
J
Laboratory of Molecular Recognition and Synthesis, Department of Chemistry, Zhejiang University, Hangzhou 310027, Zhejiang, People's Republic of China.
Kong
Wangqing
W
Fu
Chunling
C
Ma
Shengming
S