Patent ID: 8344151

Claim:
A process for the preparation of a 4-aminobut-2-enolide compound of formula (I) comprising reacting a 4-alkoxyfuran-2(5H)-one compound or 4-arylalkoxyfuran-2(5H)-one compound of formula (II) with an amine of formula (III) in which R 1 is hydrogen, C 1-12 -alkyl, C 2-12 -alkenyl, C 2-6 -alkynyl, C 3-8 -cycloalkyl, C 3-8 -cycloalkyl-C 1-6 -alkyl, C 1-12 -alkoxy, C 1-6 -alkyloxy-C 1-6 -alkyl, aryl-C 1-6 -alkyl, 2-fluoroethyl, 2,2-difluoroethyl, or 2-fluorocyclopropyl; R 2 is C 1-12 -alkyl, or aryl-C 1-6 -alkyl; and A is pyrid-2-yl, pyrid-4-yl or pyrid-3-yl, which are optionally substituted in the 6-position by F, Cl, Br, CH 3 , CF 3 , or OCF 3 , or is a substituted heterocyclyl of the following formula in which X is halogen or C 1-12 -alkyl, and Y is halogen or C 1-12 -alkyl; in the presence of a Brønstedt acid.