Syntheses of Enantiomerically Pure Cyclopent-2-ene-1-carboxylic Acid and (Cyclopent-2-enyl)acetic Acid by Enantioselective Palladium-Catalyzed Allylic Alkylations − Synthesis of Enantiomerically Pure (−)-Chaulmoogric Acid
products (−)-2 and (+)-3b with 95 and 99.5% ee, respectively. Oxidative degradation of (+)-3b furnished (+)-(R)-cyclopent-2-ene-1-carboxylic acid [(+)-4] with > 99% ee. Alkylation product (−)-2 was transformed into enantiomerically pure (−)-(R)-(cyclopent-2-enyl)aceticacid [(−)-5] by three simple steps. Availability of (−)-5 enabled the first synthesis of enantiomerically pure (−)-chaulmoogric acid [(−)-9]