Synthetic Access to Cyclopenta[a]inden-2(1H)-ones from Morita–Baylis–Hillman Products of 2-Alkynyl Benzaldehydes

A new strategy for the synthesis of cyclopenta[ a ]inden-2(1 H )-ones has been developed. An intramolecular Pauson-Khand reaction of the Morita-Baylis-Hillman (MBH) adducts, derived from 2-alkynyl benzaldehydes, provided the consequent novel cyclopenta[ a ]inden-2(1 H )-ones bearing multifunctionalities including an ester group at the fused ring junction ( tert -carbon center). The generality of this approach was illustrated by studying the several MBH derivatives containing diverse substitutions/functionalities.