Total synthesis of PGD, methyl ester and 9-epi-PGD, methyl ester

Abstract

The synthesis of the title compounds (57) and (53) is described via the dithiane substituted enone (17) itself obtained in five steps from methyl dimethoxyacetate and 7-iodoheptanoic acid. Cuprate addition of the ω-side-chain to (17) proceeds with asymmetric induction, the desired diastereoisomers (26) and (30) predominating. Reduction of the C-9 carbonyl group stereospecifically gives the 9β-alcohol which is converted into the 9α-alcohol, and thence to the title compounds by removal of protecting groups at C-11 and C-15.