Synthesis of DL‐Prostaglandin B1 and its reduction product DL‐prostaglandin E1‐237

Abstract
Coupling of 3‐(2′‐tetrahydropyranyloxy)‐1‐octynylmagnesium bromide with 2‐(6′‐carboxyhexyl)‐2‐cyclopenten‐1‐one followed by Oppenauer oxidation and removal of the protecting group yielded crystalline DL‐2‐(6′‐carboxyhexyl)‐3‐(3′‐hydroxy‐1′‐octynyl)‐2‐cyclopenten‐1‐one. Hydrogenation of the latter substance in the presence of Lindlar's catalyst and subsequent elaidination gave DL‐2‐(6′‐carboxyhexyl)‐3‐(3′‐hydroxy‐1′‐trans‐octenyl)‐2‐cyclopenten‐1‐one ‐ shown to be identical with authentic PGB1 ‐ whereas hydrogenation in the presence of Pd on BaSO4 afforded DL‐2‐(6′‐carboxyhexyl)‐3‐(3′‐hydroxyoctyl)‐2‐cyclopenten‐1‐one known as PGE1‐237.