α-Nitrosostyrenes as Three-Atom Units for the (3+1) Cyclization Reaction: Facile Access to 2,3-Dihydrodiazete N -Oxides and Their Diversified Synthetic Conversions.

An unprecedented (3+1) cyclization of α-nitrosostyrenes, generated in situ from α-bromooximes, and N -tosyloxycarbamates was developed, which enables the synthesis of a range of structurally unique and hitherto unexplored 2,3-dihydrodiazete N -oxides in moderate to high yields. The products possess a highly strained four-membered ring structure containing two nitrogen atoms. The synthetic applicability of the products was also demonstrated by many important conversions to diverse nitrogen-containing compounds.