A Convenient Synthesis of 2-Alkylcyclopentenones, Important Prostaglandin Intermediates

2-Alkylcyclopentenones, (1) and (2), are in general useful precursors in the synthesis of the prostaglandins assembly via conjugate addition of organometallic derivatives.1 For example, the cyclopentenone (1) has served as a versatile prostaglandin intermediate for a variety of 11-deoxyprostanoids such as PGB1, 11-deoxy-PGE1, 11,15-bis-deoxy-PGE1, 11-deoxy-13,14-dihydro-PGE1, 11-deoxy-13,14-dihydro-PGF1α, and 11-deoxy-PGF1β.2a The intermediate (1) has also been converted to the hydroxy cyclopentenone (2),3,4,5 which has been successfully transformed into 15-deoxy-PGE1 6 and PGE1.7,8 Thus the synthesis of the 2-alkylcyclopentenones (1) as a versatile prostanoid synthon has been the object of intensive investigations.2