CONJUGATE ADDITION OF GRIGNARD-REAGENTS TO N-(ALPHA,BETA-UNSATURATED)ACYLPYRAZOLES - DIASTEREOSELECTIVE BETA-ALKYLATION USING 3-PHENYL-L-MENTHOPYRAZOLE

The conjugate additions of N-(alpha,beta-unsaturated)acylpyrazoles wer e carried out by the treatment with Grignard reagents in the presence of cuprous halides. The reaction of a,beta-unsaturated)acyl-3-phenyl-l -menthopyrazoles 3a-h occurred in higher chemical yields and with asym metric inductions on beta-position, where the addition of magnesium br omide as a Lewis acid influenced to the yields and the diastereoselect ivities. In the case of alpha-methylated a,beta-unsaturated)acyl-3-phe nyl-l-menthopyrazoles 3i-n, the excellent asymmetric induction on the alpha-position was also observed through the diastereofacial protonati on.