Reaction of 6-hydroxytetrahydro-beta-carboline-3-carboxylic acids with isocyanates and isothiocyanates.

The reaction of (-)-(3,S)-6-hydroxy-1,2,3,4-tetrahydro-beta-carboline-3-carboxylic acid (3a) with isocyanates and isothiocyanates gave the (+/-)-beta-carboline-hydantoin (4a-d) and -thiohydantoin systems (5a-d). The treatment of (-)-(1S,3S)-6-hydroxy-1-methyl-1,2,3,4-tetrahydro-beta-carboline-3-ca rbo xylic acid (3b) with isocyanates yielded the (+/-)-cis diastereomer of the beta-carboline-hydantoin rings (4e-h). However, the reaction of 3b with isothiocyanates provided the corresponding trans isomer (5e-h). These results have been confirmed by 13C-NMR data and nuclear Overhauser effect (NOE) experiments. The new compounds were tested for in vitro binding affinity to the central-type benzodiazepine receptors.