A series of 5, 6, 6a, 8, 9, 1la-hexahydronaphth [l', 2': 4, 5] imidazo [2, lb] thiazoles (17 and 20) and 5, 6, 6a, 9, 10, 11a-hexa-hydronaphth [2', 1': 4, 5] imidazo [2, 1-b] thiazoles (18) has been synthesized with cis-and/or trans-1, 2-diamino-1, 2, 3, 4-tetrahydronaphthalenes (12) as the key intermediates and subsequently evaluated for immunological activity (effects on antibody formation and delayed-type hypersensitivity reaction). Among the compounds ...