Fe(DS)3, an efficient Lewis acid-surfactant-combined catalyst (LASC) for the one pot synthesis of chromeno[4,3-b]chromene derivatives by assembling the basic building blocks

A highly efficient multicomponent heteroannulation protocol for the synthesis of a library of chromeno[4,3-b]chromene derivative has been developed by applying a Lewis acid-surfactant-combined catalyst (LASC) [Fe(DS)3]. The LASC converted the initially floating reaction mass into a homogeneous mixture, which on stirring became a turbid emulsion of colloidal aggregates. The shape and size of the colloidal aggregates are confirmed by optical microscopy and DLS. The aqueous reaction medium, dual role of the catalyst in aqueous media, easy recovery of the catalyst, and high yield make the protocol attractive, sustainable, and economical.