A Simple Metal-Promoted Three- Step Access to n/5/m Angular Carbocyclic Systems

Abstract

A simple three-step access to n/5/m angular tricyclic skeleta from terminal cycloalkenylacetylenes, Cr(CO)6, and propargylmalonate esters is described. The process involves a cyclopentannulation of propargylmalonates and enynyl Fischer carbenes, followed by a metal-promoted Cope-type fragmentation of the propargyl unit. The resulting 4-allenyl-carbonyl derivatives can undergo either a 5-exo annulation via a tin enolate or an unprecedented gold catalyzed 6-endo cyclization.