Total Synthesis of (15R)‐ and (15S)‐Prostaglandin A2.

From both pharmaceutical and structural perspectives, the large family of prostaglandins represent a truly remarkable class of natural products. Prostaglandin A2 is a tissue hormone naturally found in human seminal plasma and in the sea whip Plexaura homomalla with yet poorly understood biological or therapeutic effects. Herein, a novel strategy for the stereoselective construction of both naturally occurring prostaglandin A2 epimers and first insights into their functional effects on the major inhibitory neurotransmitter γ‐aminobutyric acid (GABA) type A receptors (GABAAR) are provided. The synthesis of both epimers was achieved in only 11 steps starting from commercially available 2,5‐dimethoxy‐tetrahydrofuran employing an organocatalytic domino‐aldol reaction, a Mizoroki‐Heck reaction, a Wittig reaction as well as an oxidation‐decarboxylation sequence. The (15R)‐epimer significantly reduced GABA‐induced currents through GABAA receptors while its (15S)‐epimer did not show any significant effect. These data suggest that (15R)‐PGA2 might serve as a novel scaffold for the development of selective GABAA receptor modulators. [ABSTRACT FROM AUTHOR]