SYNTHESIS OF OPTICALLY-ACTIVE BETA-LACTAMS BY THE REACTION OF 2-ACYL-3-PHENYL-L-MENTHOPYRAZOLES WITH C=N COMPOUNDS

The reaction of 1-acyl-3,5-dimethylpyrazoles 1 with C=N compounds was kinetically controlled with syn stereoselectivity through a lithium en olate intermediate using lithium diisopropylamide. In contrast, the an ti stereoselective reaction of 1 was caused by the action of diisoprop ylethylamine in the presence of magnesium bromide under the thermodyna mic control. Reaction of 2-acyl-3-phenyl-l-menthopyrazoles 12 with C=N compounds was observed in higher chemical and optical yields with the predominant 2'S configuration. An especially diastereomerically pure product was isolated in the reaction of 2-propanoyl-3-phenyl-l-menthop yrazole (12a) with N-benzylidene-4-toluenesulfonamide (2). The product s from N-acylpyrazoles and C=N compounds were further cyclized into be ta-lactams directly or with short conversion steps.