5-(SULFONYL)OXY-TRYPTAMINES AND ETHYLAMINO SIDE-CHAIN RESTRICTED DERIVATIVES - STRUCTURE-AFFINITY RELATIONSHIPS FOR H5-HT1B AND H5-HT1D RECEPTORS

A number of sulfonic acid ester derivatives of serotonin (5-hydroxytry ptamine; 5-HT; 1) were prepared and their affinities are compared to t hat of the reference compound 5-[[(trifluoromethyl)sulfonyl]oxy]-trypt amine (8b). The structure-affinity relationship (SAFIR) is discussed i n terms of in vitro binding for cloned human h5-HT1A, h5-HT1B and h5-H T1D receptors. All tryptamine derivatives exhibited the best affinitie s for h5-HT1D receptors but still, these were comparatively lower than that of compound 8b. 5-Tosylated tryptamine 11b (K-i = 6 nM) and the sulfamate derivatives 13b and 14b (K-i = 7 and 11 nM, respectively) we re found to have the highest affinities for the h5-HT1D receptor. Othe r tryptamine derivatives displayed moderate binding for h5-HT1A and h5 -HT1B receptors, along with Ki values ranging from 14-20 nM for the h5 -HT1D sites. In addition, the syntheses of two alkylamino side chain r estricted derivatives are described. romethyl)sulfonyl]oxy]-1,2,3,4-te trahydrocarbazole 21, as well as uoromethyl)sulfonyl]oxy]-1H-indol-3-y l]piperidines 24 and 25, induced a shift in selectivity in favor of th e h5-HT1B receptor. The relatively longer distance between the basic a mine and a hydrogen-bond accepting oxygen in 21, 24 and 25 as compared to the non-restricted tryptamines, is likely responsible for this obs ervation. (C) 1998 Elsevier Science Ltd. All rights reserved.