Zinc-Mediated Diastereoselective Synthesis of 3-Amino Oxindoles by Addition of Methyl and Terminal Alkynes to N-tert-Butanesulfinyl Ketimines

A zinc-mediated addition of methyl and terminal alkynes to chiral N-tert-butanesulfinyl ketimines for the preparation of optical quaternary 3-amino oxindoles was reported. In general, the operationally simple reaction affords the desired products in high yields and good to excellent diastereoselectivities. Subsequent convenient cleavage of sulfinyl protecting group under mild conditions was presented without racemization.