Thionyl Chloride → 3-(1-Acetyl-4-piperidinyl)propionyl chloride

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Reaction Steps

3-(1-Acetyl-4-piperidinyl)propionic acid (32.0 g, 0.16 mol) was added in small portions to thionyl chloride (150 ml) under ice cooling. After the mixture was stirred for 5 minutes, the excess thionyl chloride was distilled off and the residue was rinsed with hexane to give 3-(1-acetyl-4-piperidinyl)propionyl chloride as light-yellow solid. Aluminum chloride (66.0 g, 0.49 mmol) powders were added portionwise to a mixed solution of the above acid chloride and 3-formyl-2,3,4,5-tetrahydro-1H-3-benzazepine (23.0 g, 0.131 mol), obtained in Reference Example 2, in 1,2-dichloroethane (100 ml) with ice-bath cooling. This mixture was stirred at room temperature for 20 hours. It was then poured in ice-water and extracted with ethyl acetate. The extract was washed with saturated NaCl/H2O and dried over MgSO4. The solvent was then distilled off under reduced pressure and the residue was purified by silica gel column chromatography (eluent: ethyl acetate-methanol=9:1) to provide 3-(1-acetyl-4-piperidinyl)-1-(3-formyl-2,3,4,5-tetrahydro-1H-3-benzazepin-7-yl)-1-propanone (44 g) as light-yellow oil.

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