Patent ID: 8362254

Claim:
A method for producing a 4-formylaminopiperidine compound of formula (I) in which n is 1 or 2, R 1 , R 2 , R 3 and R 4 , independently of one another, are identical or different and are C 1 -C 4 -alkyl or R 1 and R 2 or R 3 and R 4 together are a tetramethylene or pentamethylene group, R 5 is hydrogen or C 1 -C 4 -alkyl, R 6 is hydrogen, oxygen, C 1 -C 22 -alkyl, C 3 -C 22 -alkenyl, C 1 -C 22 -alkoxy, unsubstituted or substituted C 7 -C 12 -phenylalkyl, C 1 -C 22 -alkanoyl, C 2 -C 3 -cyanoalkyl, C 1 -C 22 -hydroxyalkyl or C 2 -C 22 -aminoalkyl and —if n=1— Y is hydrogen, C 1 -C 22 -alkyl, C 3 -C 22 -alkenyl, C 3 -C 12 -cycloalkyl or bicycloalkyl, C 2 -C 22 -alkyl substituted by cyano, hydroxy or C 1 -C 4 -alkoxy, C 4 -C 22 -alkyl interrupted by ether oxygen, nitrogen or sulfur, unsubstituted or substituted C 7 -C 22 -phenyl or diphenylalkyl, unsubstituted or substituted phenyl, a radical of formula or C 1 -C 22 -alkyl comprising a heterocyclic radical, or —when n=2— Y is C 2 -C 22 -alkylene, C 5 -C 22 -cycloalkylene, C 8 -C 14 -phenylalkylene, phenylene or C 4 -C 30 -alkylene interrupted by ether oxygen, nitrogen, sulfur or 5- or 6-membered heterocycles, and also an acid addition salt thereof, comprising reacting a 4-aminopiperidine compound of formula (II) or an acid addition salt thereof in the presence of a compound of formula (III) wherein R 7 , R 8 , independently of one another, are identical or different and are hydrogen, C 1 -C 22 -alkyl, C 3 -C 22 -alkenyl, unsubstituted or substituted C 7 -C 12 -phenylalkyl, or C 1 -C 22 -alkanoyl, and the reaction takes place in the presence of at least one protic acid and at least one Lewis acid.