The present invention provides a process for the preparation of key intermediate for the synthesis 5,6-dimethoxy-2-[[1-(phenylmethyl)-4-piperidinyl]methyl]-1-indanone hydrochloride (donepezil hydrochloride). The present invention particularly provides a process for the preparation of 5,6-dimethoxy-2-(4-pyridylmethylene)-1-indanone comprising condensation of 5,6-dimethoxy-1-indanone with 4-pyridinecarboxaldehyde using an alkali metal hydroxide as a mild base in the presence of demineralized water as a solvent at a temperature in the range of 15° C. to 45° C. to yield 5,6-dimethoxy-2-(4-pyridylmethylene)-1-indanone, which is subsequently benzylated using benzyl bromide in the presence of solvent at a reflux temperature to yield 1-benzyl-4-[(5,6-dimethoxy-1-indanone-2-yl)methylene]pyridinium bromide.
本发明提供了一种制备5,6-二甲氧基-2-[[1-(苯甲基)-4-
哌啶基]甲基]-
1-茚酮盐酸盐(
多奈哌齐盐酸盐)合成的关键中间体的方法。本发明特别提供了一种制备5,6-二甲氧基-2-(4-
吡啶甲亚甲基)-
1-茚酮的方法,包括在去矿化
水溶剂存在下,以一种碱
金属氢氧化物作为温和碱,将5,6-二甲氧基-
1-茚酮与
4-吡啶甲醛缩合,在15℃至45℃的温度范围内,得到5,6-二甲氧基-2-(4-
吡啶甲亚甲基)-
1-茚酮,随后在溶剂存在下,以回流温度用苄
溴化合物苄化,得到1-苄基-4-[(5,6-二甲氧基-
1-茚酮-2-基)亚甲基]
吡啶铵溴化物。