A Rh(I)-Catalyzed Cascade Cyclization of 1,5-Bisallenes and Alkynes for the Formation of cis-3,4-Arylvinyl Pyrrolidines and Cyclopentanes

The cascade cyclization reactions of 1,5-bisallenes grant access to a great variety of products by precisely tuning the catalyst system and/or the reagents involved. Herein, we present our findings that 1,5-bisallenes react with two molecules of dimethyl acetylenedicarboxylate to afford, in a completely diastereoselective manner, cis-3,4-arylvinyl pyrrolidines and cyclopentanes. DFT calculations have been used to postulate a mechanism for the developed reaction which encompasses a [2+2+2] cycloaddition reaction of the two alkynes and the external double bond of one allene, followed by a cycloisomerization involving the internal double bond of the second allene.

Automated summary

Cascade cyclization reactions of 1,5-bisallenes provide access to diverse products through catalyst system tuning and reagent control. Reacting 1,5-bisallenes with dimethyl acetylenedicarboxylate results in diastereoselective formation of cis-3,4-arylvinyl pyrrolidines and cyclopentanes. A proposed mechanism involving a [2+2+2] cycloaddition and cycloisomerization has been supported by DFT calculations.