Synthesis of 5,6-dichloroindan-1-acids and their tetrazolyl derivatives as analgesic and anti-inflammatory agents.

Indan derivatives, namely, 5-(5',6'-dichloroindan-1'-yl)-tetrazole (12a) and 5-(5',6'-dichloroindan-1'-yl)- methyltetrazole (12b), were synthesized conveniently from 5,6-dichloroindan-1-carboxylic acid (9a) and 5,6- dichloroindan-1-acetic acid (9b), respectively, as potential analgesic and anti-inflammatory agents. The analgesic and anti-inflammatory properties of 9a, 9b, 12a and 12b were evaluated by the acetic acid induced writhing in Swiss albino mice and the carrageenan-induced rat paw edema models, respectively. Compounds 9a and 12a exhibited significant analgesic activity with the doses of 50 and 100 mg/kg body weight, comparable to that of the positive controls, phenylbutazone, indomethacin and aminopyrine. The anti-inflammatory potencies of 9a and 12a were also comparable to that of the positive control, phenylbutazone. Compounds 9b and 12b showed analgesic and anti-inflammatory activities, but were weaker than that of compounds 9a and 12a.