[bmIm]Br catalyzed tandem construction of C-C and C-O bonds: a concise, convenient and atom-economical strategy for the synthesis of spiropyranopiperidine derivatives

摘要

A versatile one-pot domino access to chiral heterocyclic spiropyranopiperidine has been reported. This novel approach involves recyclable [bmIm]Br as a promoter as well as a reaction medium and KOH as a non-hazardous base for the facile chemical unification of DMAD, malononitrile and 1-methyl-4-piperidone, resulting in the formation of spiropyranopiperidine in an excellent yield after 3 hours under mild reaction conditions. This green and efficient methodology leads to a significant enhancement of the yield of product, elimination of the use of toxic and hazardous reagents and reduced waste formation. A plausible mechanism for the multiple bond forming heterocyclisation has also been proposed.