One-step, stereoselective synthesis of octahydrochromanes via the Prins reaction and their cannabinoid activities.

Novel, functionalized octahydrochromene derivatives were synthesized in a single step via the Prins reaction. Enantiomerically pure (+)-isopulegol was reacted with benzaldehyde to stereoselectively yield the corresponding octahydro-2H-chromen-4-ol derivative containing five stereocenters. A total of 10 compounds were synthesized by altering the enantiomer of isopulegol and the substituted benzaldehyde, and the resulting enantiopure octahydrochromenes were screened in vitro against the cannabinoid receptor isoforms CB1 and CB2. Compounds containing an olefin at the C4 position [(+)-3c, (-)-3c, (-)-7c, (-)-9c and (-)-11c] of the octahydrochromene scaffold were found to exhibit reasonable displacement of [3H] CP55,940 from the CB receptors, whereas the corresponding hydroxy analogs [(+)-3a, (+)-3b, (-)-3a, (-)-3b and (+)-5a] had very little or no effect.