Synthesis and analgesic activity of pemedolac [cis-1-ethyl-1,3,4,9-tetrahydro-4-(phenylmethyl)pyrano[3,4-b]indole-1-acetic acid]

: The synthesis of cis-1-ethyl-1,3,4,9-tetrahydro-4-(phenylmethyl)pyrano[3,4-b]indole -1-acetic acid, pemedolac (USAN), is described. This compound has been found to be a potent analgesic agent in primary screening. Pemedolac has been resolved and the active (+)-enantiomer assigned a 1S,4R absolute configuration on the basis of a crystallographic analysis of its (S)-(-)-borneol ester.