Ethyl and tert-Butyl N-(4-nitrobenzenesulfonoxy)carbamates

The title compounds have been known for many years and have been widely used to generate alkoxycarbonylnitrenes by α-elimination as well as for other synthetic transformations. Although they have previously been characterised by spectroscopic methods, their X-ray structures are reported here for the first time. They have similar folded molecular structures but, while the ethyl ester forms hydrogen-bonded ribbons consisting of two rows of molecules joined by carbamate N–H⋯O=C hydrogen bonding, the tert-butyl ester forms hydrogen-bonded dimers involving the carbamate N–H and one sulfonyl O=S.