Diastereoselectivity in the Staudinger reaction of pentafluorosulfanylaldimines and ketimines

β-Lactams were diastereoselectively formed by the reaction of SF(5)-containing aldimines, or an SF(5)-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 SF(5). 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-lactam. Cyclization of imines with a stereogenic center bearing SF(5) was reflected in the 1,2-lk,lk selectivity of the β-lactam.