Conditions for a Rh(I)-catalyzed [2+2+1] cycloaddition reaction with methyl substituted allenes and alkynes

The direct installation of the C4 and C10 methyl groups present in the 6,12-guaianolide framework using a Rh(I)-catalyzed cyclocarbonylation reaction of methyl substituted allenes and alkynes is described. High yields of bicyclo[5.3.0]decanes are afforded when low reaction concentrations involving syringe pump addition of the allene-yne to the catalyst are used. (C) 2015 Elsevier Ltd. All rights reserved.