Etodolac (1,8-diethyl-1,3,4,9-tetrahydropyrano[3,4-b]indole-1-acetic acid): a potent antiinflammatory drug. Conformation and absolute configuration of its active enantiomer.

The active (+) enantiomer of the antiinflammatory agent etodolac (1,8-diethyl-1,3,4,9-tetrahydropyrano[3,4-b]-indole-1-acetic acid) has been assigned an S absolute configuration on the basis of a crystallographic analysis of the (S)-(-)-borneol ester of (-)-etodolac, and the conformation of etodolac has been determined by a crystallographic analysis of (+/-)-etodolac. Analyses of the solid-state conformation, as well as energy-minimized conformations obtained by molecular mechanics calculations, have failed to provide a basis for identifying a probable receptor-site conformation.