Temperature-Dependent Regiodivergent [3 + 2] Cycloaddition of Azomethine Ylides With (E)-5-Benzylidenethioxoimidazolidin-4-One

Abstract

An efficient route is developed to gain access to novel dispiro[imidazolidine-4,1′-pyrrolo[2,1-a] isoquinoline-3′,3″-indoline]-2″,5-dione skeletons by a one-pot three-component [3 + 2] cycloaddition reaction of (E)-5-benzylidenethioxoimidazolidin-4-ones, isatin derivatives, and 1,2,3,4-tetrahydroisoquinoline. Interestingly we note that the reaction‘s regioselectivity depends on temperature, enabling the production of two regioisomericdispiro[imidazolidine-4,1′-pyrrolo[2,1-a] isoquinoline-3′,3″-indoline]-2″,5-dione in high yield. In agreement with the experimental results, density functional theory calculations carried out at the 6-31+g*(d,p)5 level of theory predicted that the [3 + 2] cycloaddition processes occur in an asynchronous concerted manner.