DESIGN OF DIASTEREOSELECTIVE MUKAIYAMA-MICHAEL REACTION OF KETENE SILYL ACETAL

The highly diastereoselective Mukaiyama-Michael reaction has been desi gned. Suppression of an electron-transfer process is crucial for this purpose and the following conditions should be satisfied. (1) TiCl4 is employed as a Lewis acid. (2) Ketene silyl acetals have bulky siloxy and/or alkoxy group(s). (3) alpha-Enones have a bulky acyl group. The excellent syn-selectivity up to a 99:1 ratio is attained under these c onditions. The selectivity is reversed to the anti-preference upon dec reasing the size of the alkoxy group. Copyright (C) 1996 Elsevier Scie nce Ltd