A key cyclopentenone possessing the α-chain was synthesized from TBS ether of 4- cyclopentene-1, 3-diol monoacetate, and submitted to aldol reaction at the α′-position with the ω-chain aldehydes followed by dehydration to produce the title compounds. In a similar manner, 5-dehydro compounds (acetylene analogues) were synthesized successfully. In addition, palladium-catalyzed reaction of 4-cyclopentene-1, 3-diol monoacetate with ...