Novel planar-chiralpyridiniumylides were designed, and generated in situ from the corresponding pyridinium salts with triethylamine. Ylides with a common parapyridinophane skeleton reacted efficiently with electron-deficient dicyanoalkenes, or malononitriles, to produce optically active cyclopropane derivatives with high enantioselectivity (up to 99% ee). Remotesteric effects were observed on the
Cinchonidine catalyzed the cyclopropanation reaction between chloromethyl ketones and beta-substituted methylidenemalo-nonitriles to give trans-cyclopropanes with enantioselectivity up to 82% ee. Experimental evidence suggests that cinchonidine functions as a chiral Bronsted base catalyst in the reaction and hydrogen bonding is essential for inducing high enantioselectivity. (c) 2006 Elsevier Ltd. All rights reserved.
LITVINOV, V. P.;SHESTOPALOV, A. M.;SHARANIN, YU. A.;MORTIKOV, V. YU., DOKL. AN CCCP, 309,(1989) N, S. 115-119
作者:LITVINOV, V. P.、SHESTOPALOV, A. M.、SHARANIN, YU. A.、MORTIKOV, V. YU.