17,18-tritium labeled prostaglandins

The triple bond in 3α,5α‐dihydroxy‐2β‐(3α‐hydroxy‐trans‐1‐octen‐5‐ynyl)‐lα‐cyclopentylacetic acid γ‐lactone bis‐2‐tetrahydropyranyl ether (I) was reduced with tritium gas in the presence of tris‐(triphenylphosphine) ‐rhodium chloride to give 3α,5α‐dihydroxy‐2β‐(3α‐hydroxy‐5,5,6,6‐tetratritio‐trans‐l‐octenyl)‐lα‐cyclopentylacetic acid γ‐lactone (II). The diol‐lactone II was converted in five steps via modified Corey synthesis to prostaglandin E2‐17,18‐3H4 (VI). Reduction of VI gave prostaglandin E1‐17,18‐3H4 (VII) and its 13,14‐dihydro (VIII) and 13,14‐dihydro‐15‐dehydro (IX) derivatives. The prostaglandin E's were dehydrated to afford the corresponding tritium labeled prostaglandins A2 (X) and A1 (XI).