Here, 1-[7,8-dimethoxy-1,3,4,5-tetrahydro-2H-3-benzazepin-1,2-dion-3-yl]-3-[N-methyl-N-(6,7-dimethoxy-1,2,3,4-tetrahydronaphth-2-yl)-amino]-propane (0.70 g 0.0014 mol) is dissolved in a mixture of methanol/water=(95:5, 21 ml) then sodium borohydride (0.060 g, 0.0016 mol) is added and the mixture is stirred for 20 minutes at ambient temperature. It is then acidified with hydrochloric acid (2 mol/l), made alkaline with methanolic ammonia and extracted with methylene chloride, dried over magnesium sulphate, concentrated by evaporation and the residue is purified over a column [alumina N (50 g), activity II, eluant: methylene chloride and then with increasing amounts of ethanol (up to 3%)]. The residue is dissolved in acetone and mixed with ethereal hydrochloric acid. The precipitate obtained is suction filtered, washed with ether and dried. Yield: 0.18 g. Mp: 141°-143° C.
