Stereoselective synthesis of spirooxindoles through multi component reaction catalyzed by guanidine under mild condition

Oxindole with a six-membered spirocyclic moiety is an intriguing subset with potential bioactivity and is featured in a number of natural products, as exemplified by gelsemine as well as pharmaceutically relevant compounds with remarkable structural complexity and interesting biological activities. The art of accomplishment efficient chemical transformations to generate molecular complexity and miscellany with predefined functionality in natural and biologically relevant systems is a challenging benchmark which urges chemists to increase tools of their arsenal [1]. In this study, multi component reactions by virtue of their synthetic efficiency the decline of chemical steps and energy consumption in organic processes [2], formation of several bonds in one sequence without changing the reaction conditions, isolating the intermediates or adding reagents [3]. Here in, it was found a new type of cascade simple pseudo four-component reaction of isatins, cyclic ketones and two moles malononitrile catalyzed by guanidine at room temperature. The tetracyclic spirooxindoles were stereoselectively obtained as products in 70-90% yields and short reaction times. The special stereoselectivity was accomplished on two or three centers in this pseudo four-component reaction.