New regio/chemoselective synthesis of hydrogenated imidazo1,5-bpyridazines

摘要

The cascade heterocyclization of 1,2-diamino-4-phenylimidazole with ethyl 2-arylidene-2-cyanoacetates affords 1,2,3,4-tetrahydroimidazo1,5-bpyridazine-3-carbonitrile derivatives as mixtures of diastereomers. The experimental data and quantum chemical calculations were used to propose the mechanism and account for the regio/chemoselectivity of processes. The three-component processing with abovementioned diamine, ethyl cyanoacetate and aromatic aldehydes leads to the same products in generally lower yields.