Polycyclic N-heterocyclic compounds. 50 [1]. Synthesis and pharmacological evaluation of 2,3,6,7-tetrahydrothieno[2,3-h]- imidazo[2,1 - f] [1,6] naphthyridines, 3,4,7,8-tetrahydro-2H-thieno[2,3-h]pyrimido[2,1- f][1,6]naphthyridines and their precursor

Some novel 5-hydroxyalkylamino-1,2-dihydrothieno[2,3- h][1,6]naphthyridines were prepared by the reaction of 5-chloro-l,2- dihydrothieno[2,3-h][1,6]naphthyridine derivatives with some aminoalcohols in the presence of base. These derivatives were cyclized to the corresponding imidazo or pyrimido derivatives. The bronchodilatory activity of these compounds was evaluated on the basis of their relaxation activity to tracheal contraction induced by carbamylcholine chloride as a primary in vitro assays. Effect of some naphthyridines on carbamylcholine chloride-induced contractions of trachea in the presence or absence of milrinone or 4-(3- butoxy-4-methoxyphenyl)imidazolidin-2-one, which is inhibitor of phosphodiesterase III or IV, were also evaluated.