Molecular iodine catalysed domino cyclization in aqueous medium: a simple and efficient synthetic route to 1,4-dihydropyridazines

A facile, efficient and environmentally friendly approach has been developed for the diverse synthesis of 1,4-dihydropyridazines from (E)-2-benzylidene-1-phenylhydrazine and alpha,beta-unsaturated aldehyde under aqueous condition using molecular iodine as a green and recoverable catalyst. This procedure features low cost and easily available starting materials, an inexpensive and recoverable catalyst, short reaction time, reliable scalability, excellent yield and mild reaction conditions, as well as use of aqueous medium. The scope of this method was thoroughly explored under three different reaction conditions resulting in the generation of a library of title compounds. In view of the various advantages of the present investigation, this methodology gives a convenient and straightforward pathway to construct 1,4-dihydropyridazines in an eco-friendly fashion.