Diastereoselectivity in the Staudinger reaction of pentafluorosulfanylaldimines and ketimines

β-Lactams were diastereoselectively formed by the reaction of SF ₅-containing aldimines, or an SF₅-containing ketimine, with benzyloxyketene in a conrotatory ring closure process. Imine formation and cyclization were possible in spite of the acidification of protons on the carbon bound to SF₅. The reactions of the aldimines demonstrated very good 1,2-lk diastereoselectivity, however lack of stereochemical control of the C-N ketimine geometry was reflected in the stereochemistry of the product β-Lactams. Cyclization of imines with a stereogenic center bearing SF ₅ was reflected in the 1,2-lk,lk selectivity of the β-Lactams.