Organocatalytic synthesis of benzazetidines by trapping hemiaminals with protecting groups

Benzazetidines are highly strained and inherently unstable heterocycles. There are only few methodologies for assem-bling these compounds. Here, a protocol is presented to trap an elusive cyclic, 4-membered hemiaminal structure. This method affords several benzazetidine in moderate to good yields (up to 81%), it uses inexpensive materials and does not require catalysts based on transition metals. The high ring strain energy of these benzazetidine systems was estimated by DFT calculations to be about 32 kcal mol-1. This synthesis can be applied also on gram scale with reac-tion yield essentially unchanged.