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 $\text{ent}$-prostanoic acid skeleton, have been prepared by a route involving initial introduction of the carboxyl (α) chain (1). A major advantage of the initial α-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 pharmaco logical evaluation of these diastereomers will be submitted for publication in this journal (3).