Synthesis of diastereomeric bis-unsaturated prostaglandins

With the report given herein all diastereomers of PGF2, PGE2, and PGD2 which bear the naturally recognized 15-S hydroxylated center, whether in the natural or entprostanoic acid skeleton, have been prepared by a route involving initial introduction of the carboxyl (alpha) chain (1). A major advantage of the initial alpha-ylation route is the facile reduction of the 13, 14-en-15-one system with methanolic NaBH4 which proceeds without competing 1,4-reduction. The products are thus free of 13,14-dihydro-PG2 contaminants (2). The initial pharmacological evaluation of these diastereomers will be submitted for publication in this journal (3).