Cyclic six-membered nitronates 1 are involved in diastereoselective C-C coupling reactions with various nucleophiles in the presence of either catalytic or stoichiometric amounts of TBDMSOTf to give the previously unknown N-siloxytetrahydrooxazines. The intermediacy of N,N-bis(oxy)iminium cations was proven by NMR data.

The first formal [3 + 3]-cycloaddition of nitronates with donor-acceptor cyclopropanes is reported. The reaction is catalyzed by ytterbium trifluoromethanesulfonate and leads to hitherto unknown bicyclic nitrosoacetals, possessing two annelated six-membered rings.