The design of diastereoselective Mukaiyama-Michael reaction of ketene silyl acetal

Article abstract of DOI:10.1016/0040-4020(96)00478-4

The highly diastereoselective Mukaiyama-Michael reaction has been designed. 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) α-Enones have a bulky acyl group. The excellent syn- selectivity up to a 99:1 ratio is attained under these conditions. The selectivity is reversed to the anti-preference upon decreasing the size of the alkoxy group.