Synthesis of 1,4-Benzo- and Pyrido-oxazepinones via a Domino Process

Significance

Reported is a new regioselective domino ring-opening/carboxamidation reaction of N-tosylaziridines 1 and 2-halophenols/pyridinols 2 under phase-transfer catalysis to afford 1,4-benzo- and pyrido-oxazepinones 3. During optimization studies, it was demonstrated that the presence of the phase-transfer catalyst, TEBA, improved the yield of products (D. Albanese, D. Landini, M. Penso Tetrahedron 1997, 53, 4787). The scope of this reaction was examined by treating 2-iodophenols bearing EDGs and EWGs with cyclic (five-, six-, and seven-membered ring) and acyclic N-tosylaziridines. The 2-iodophenols bearing phenyl and methyl ester groups provide higher yield of the corresponding product 3. However, with 2-bromophenol, harsher conditions are required for the conversion of this into 1,4-benzoxazepinone 3 (18-crown-6 and PTC at 400 psi CO).