Procedure biperiden iv.

Process for producing biperiden (Ia) by reaction of exo-1- (bicyclo [2.2.1] hept-5-en-2-yl) -3-piperidino-1-propanone (II-exo) with a phenylmagnesium compound wherein the preparation of exo-1- (bicyclo [2.2.1] hept-5-en-2- yl) -3-piperidino-1-propanone (II-exo) comprises the following steps: a) conversion exo-1- (bicyclo [2.2.1] hept-5-en-2-yl) ethanone (III-exo) (III-exo) in an exo-silyl enol ether IV in which the groups R are identical or different and represent an alkyl or cycloalkyl, b) reaction of the exo-silyl enol ether IV with a N-methylenepiperidinium, wherein each of the structural formulas (II-exo) and (III-exo) shown refers to the corresponding pair enantiomeric.