Diisobutylaluminum 2,6-Di-t-butyl-4-methylphenoxide. Novel Stereoselective Reducing Agent for Prostaglandin Synthesis

In an effort to explore the selective reducing agents suitable for prostaglandin synthesis, 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 the conversion of PGE2 methyl ester to PGF2α methyl ester in 95% yield and 100% selectivity.