Asymmetric synthesis of 1-(2- and 3-haloalkyl)azetidin-2-ones as precursors for novel piperazine, morpholine, and 1,4-diazepane annulated beta-lactams.

A high-yielding, asymmetric synthesis of novel 4-formyl-1-(2- and 3-haloalkyl)azetidin-2-ones was developed as valuable starting materials for the synthesis of different enantiomerically enriched bicyclic azetidin-2-ones, such as piperazine, morpholine, and 1,4-diazepane annulated beta-lactam derivatives. Especially the hydride reduction of 4-imidoyl-1-(2- and 3-haloalkyl)azetidin-2-ones turned out to be an efficient and straightforward method for the preparation 2-substituted piperazines and 1,4-diazepanes.