NMR studies of four isomers of decahydroisoquinoline-3(S)-carboxylic acid and a potent HIV proteinase inhibitor incorporating the (S,S,S) isomer

The stereochemistry and conformations of two cis and two trans bridged isomers of decahydroiso-quinoline-3(S)-carboxylic acid (DHIQ) have been elucidated by NMR spectroscopy. A potent HIV proteinase inhibitor, Ro 31–8959, incorporating the (S,S,S)-isomer of DHIQ has also been examined, and critical conformational features compared with those found in the X-ray structure of the enzyme-bound inhibitor.