Enantioselective Rhodium (I) Donor Carbenoid-Mediated Cascade Triggered by a Base-Free Decomposition of Arylsulfonyl Hydrazones

Abstract

The reaction of diyne arylsulfonyl hydrazone substrates under rhodium(I)/BINAP catalysis gives access to sulfonated azacyclic frameworks in a highly enantioselective manner. This new cascade process considerably increases the molecular complexity by generating two C-C bonds, one C-S bond, and one C-H bond. Theoretical calculations, competitive experiments, and deuterium labeling have jointly been used to propose a mechanism that accounts for the reaction. The mechanism involves the formation of vinyl rhodium carbenoids, hydride migratory insertion, and intermolecular stereoselective nucleophilic attack. The last two steps are the key to the stereoselectivity of the process

La reaccio catalitzada per rodi(I)/BINAP de substrats contenint dos alquins i una sulfonilhidrazona permet sintetitzar compostos nitrogenats amb un grup sulfona de forma altament enantioselectiva. Aquest nou proces en cascada augmenta considerablement la complexitat molecular ja que genera dos enllacos CC, un enllac CS i un enllac CH. Sha proposat un mecanisme per al proces desenvolupat en base als resultats obtinguts mitjancant calculs DFT, experiments de competicio i marcatge amb deuteri. El mecanisme involucra la formacio dun vinilcarbenoid de rodi, una insercio migratria dhidrur i un atac nucleofilic intermolecular estereoselectiu. Els dos darrers passos son claus per a lenantioselectivitat del proces