A catalytic asymmetric total synthesis of the potent and selective antileukemic Δ12-prostaglandin J3 (Δ12-PGJ3) is described. The convergent synthesis proceeded through intermediates 2 and 3, constructed enantioselectively from readily available starting materials and coupled through an aldol reaction followed by dehydration to afford stereoselectively the cyclopentenone alkylidene structural motif of the molecule.