Histamine H1 receptor ligands Part II.: Synthesis and in vitro pharmacology of 2-[2-(phenylamino)thiazol-4-yl]ethanamine and 2-(2-benzhydrylthiazol-4-yl)ethanamine derivatives

New 2-[2-(phenylamino)thiazol-4-yl]ethanamine and 2-(2-benzhydrylthiazol-4-yl)ethanamine derivatives were prepared and tested in vitro as H-1 receptor antagonists. The compounds with 2-phenylamino substitution with meta-halide substituents at the phenyl ring, showed weak H-1-antagonistic activity (pA(2): 4.62-5.04) and this activity was completely lost in the case of meta-methyl substituent (pA(2) < 4). When the phenylamino group was replaced by benzhydryl groups of classic antihistamines, the resulting compounds exhibited slightly improved H-1-antagonistic activity (at the meta-position pA(2): 6.38-6.15; at the para-position pA(2): 6.04-5.87). (C) 2000 Elsevier Science S.A. All rights reserved.