Abstract

Protonation of the highly reactive 1:1 intermediates produced in the reaction between tributylphosphine and dialkyl acetylenedicarboxylates by acetylacetone leads to sterically congested phosphorus ylides that undergo an intermolecular addition reaction with indene-1,2,3-trione and concomitant intramolecular Wittig reaction in CH 2Cl2 at room temperature to produce dialkyl 1,1-diacetyl-8 a-hydroxy-8-oxo-a-tetrahydrocyclopenta[a]indene-2,3-dicarboxylates in fairly good yields. 1,2,8,8