reducing agents suitable for prostaglandinsynthesis, diisobutylaluminum 2,6-di-t-butyl-4-methylphenoxide (1) is found to be among the best. Reduction of the C-15 ketone with 1 in toluene at −78 °C produced the desired 15S-alcohol in 95% yield with 92% stereoselectivity. The present procedure is suitable for the synthesis of prostaglandin derivatives and related polyfunctional natural products as shown in