Stereoselective conjugate additions of Grignard reagents to cyclopentadienones

Conjugate addition reactions of Grignard reagents with cyclopentadienones having trimethylsilyl groups at the α and α′ positions, and 1-hydroxyethyl substitutents at the β and β′ positions, are reported; excellent stereoselectivity was observed and the relative stereochemistry of three of the products was determined by X-ray methods.