SYNTHESIS, REACTIONS, AND MOLECULAR-STRUCTURES OF ETHYLZINC ENOLATES OF CHIRAL N-SUBSTITUTED BETA-CARBONYL SULFOXIMINES

The preparation, structural characterization, and reactivity of ethylzinc-containing enolates and organometallics derived from beta-carbonyl sulfoximines are reported, X-ray crystal structures show significant differences between aggregated species obtained from beta-keto and beta-amido sulfoximines. Whereas the former gives an O-metalated ethylzinc enolate, the latter crystallizes as C-metalated carbonyl species, NMR investigations reveal the presence of chelated zinc enolates in solution, The relationship between structure and reactivity is demonstrated by the reaction profiles of the ethylzinc-containing compounds. A high diasteroselectivity (>90% de) was observed in the aldol reaction between the metalated beta-amido sulfoximine and benzaldehyde in the presence of trimethylsilyl chloride,