An Efficient and Highly Diastereoselective Synthesis of Carbocyclic Spiropyrazolones Via One-Pot Sequential Dual Organo-Silver Catalyzed Michael-hydroalkylation Reactions

An economical approach for the diastereoselective synthesis of highly functionalized carbocyclic spiropyrazolone derivatives having one quaternary and two tertiary stereocenters along with one exocyclic double bond exploiting dual organo-silver sequential catalysis has been developed. The unified method to both cyclohexyl and cyclopentyl spirocompounds involves the reaction of gamma- and beta-nitroallcynes with alkylidene pyrazolones catalyzed by Hfinig's base followed by carbophilic activation of the triple bond with a Ag(I) salt leading to cyclization via hydroalkylation. (C) 2018 Published by Elsevier Ltd.