Lipase-catalyzed kinetic resolution of Baylis–Hillman products
摘要:
Lipase-catalyzed kinetic resolution of the various Baylis-Hillman products, alpha-methylene-beta-hydroxy compounds, were examined. When lipase PS was used as a biocatalyst in acetonitrile, transesterification of racemic ethyl 3-hydroxy-2-methylenebutanoate or 3-hydroxy-2-methylenepentanoate proceeded in a practical enantiomeric excess. The resolution by hydrolysis of the acetate derivatives was also tried. In contrast, in case of racemic ethyl 3-acetoxy-2-methylenepentanoate, under the conditions using lipase AK, the E value of the resolution was >321. (C) 1998 Elsevier Science Ltd. All rights reserved.
Baylis-Hillnian acetates undergo S(N)2' allylic substitution with indoles in the presence of 20 mol% of indium tribromide under mild conditions to afford a new class of substituted indoles in high yields with (E)-stereo selectivity. The stereochemistry of the products was assigned by various NMR experiments. (C) 2004 Elsevier Ltd. All rights reserved.