Ethanol → 3-(7,8-dimethoxy-2-oxo-1,2-dihydro-3H-benzo[d]azepin-3-yl)propanal

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Reaction Steps

First, 3-(7,8-Dimethoxy-1,3-dihydro-2H-3-benzazepin-2-on-3-yl)-propionaldehyde diethyl acetal (3.5 g, 0.01 mol) is heated in 2N sulphuric acid (50 ml) and ethanol (50 ml) to 40° C. for 2 hours. The alcohol is then distilled off in vacuo, the residue is made alkaline with saturated potassium carbonate solution with cooling and extracted several times with ethyl acetate. The ethyl acetate extract is extracted twice with sodium hydrogensulphite solution. The bisulphite extract is acidified with concentrated hydrochloric acid and heated for half an hour to 40° C. in vacuo in order to eliminate the sulphur dioxide. Then, saturated potassium carbonate solution is added and the mixture is extracted several times with methylene chloride, dried over magnesium sulphate and evaporated. Yield: 1.7 g. Mp: 95°-96° C.

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