1,2,3,4-Tetrahydroisoquinolines 6.10,7,8 dihydroxy substitute-1-methylanilino and use as smooth muscle relaxants

1,2,3,4-Tetrahydroisoquinolines having the formula: wherein R1 and R2 are each hydrogen, lower alkyl, lower alkenyl, acyl, aryl or ar(lower)alkyl, in which aryl and the aryl moiety of the ar(lower)alkyl may contain at least one substituent selected from the group consisting of halogen, lower alkoxy, amino, nitro, hydroxy, acyloxy, ar(lower)alkoxy, lower alkylenedioxy, halo(lower)alkyl, acylamino, ar(lower)alkylamino and aryl, and pharmaceutically acceptable salts thereof, having a relaxant activity on smooth muscles.