Patent ID: 6835839
Filing Date: 2004-12-28
Classification: C07D

Abstract:
A method for the production of biperiden by reacting an exo/endo mixture of 1-(bicyclo[2.2.1]hept-5-en-2-yl)-3-piperidino-1-propanone with an exo/endo ratio of at least 4.5:1 with a phenylmagnesium compound, characterized in that the production of the exo/endo mixture of 1-(bicyclo-(2.2.1]hept-5-en-2-yl)-3-piperidino-1-propanone comprises the following steps:a) reaction of exo-1-(bicyclo[2.2.1]hept-5-en-2-yl)ethanone with a formaldehyde source and an acid addition salt of piperidine or with a formaldehyde source and piperidine in the presence of an acid in an organic solvent or in a mixture thereof with water, b) conversion of the resulting reaction mixture into an aqueous solution and extraction of this aqueous solution with an organic solvent which has limited miscibility or is immiscible with water at a pH not exceeding 7, c) extraction of the aqueous raffinate obtained in b), which contains the exo/endo mixture of 1-(bicyclo[2.2.1]hept-5-en-2-yl)-3-piperidino-1-propanone, at a pH of at least 7.5 with an organic solvent which has limited miscibility or is immiscible with water, and d) removal of the organic extract, purification of the organic extract by extraction with acid and subsequent removal of the solvent, resulting in 1-(bicyclo-[2.2.1]hept-5-en-2-yl)-3-piperidino-1-propanone with an exo/endo ratio of at least 4.5:1.