Synthesis of (E)-alpha,beta-unsaturated amides with high selectivity by using samarium diiodide

Chemistry. 2001 Jul 16;7(14):3062-8. doi: 10.1002/1521-3765(20010716)7:14<3062::aid-chem3062>3.0.co;2-f.

Abstract

Stereoselective beta-elimination of 2-chloro-3-hydroxyamides 1 is achieved by using samarium diiodide to yield alpha,beta-unsaturated amides 2, in which the C=C bond is di- tri-, or tetrasubstituted. The starting compounds 1 are easily prepared by reaction of the corresponding lithium enolates of alpha-chloroamides with aldehydes or ketones at - 78 degrees C. The influence of the reaction conditions and the structure of the starting compounds on the stereoselectivity of the beta-elimination reaction is also discussed.