Patent ID: 8487112

Claim:
A process for preparing an 4-aminobut-2-enolide of formula (I) in which A is pyrid-2-yl or pyrid-4-yl or is pyrid-3-yl which is optionally 6-substituted by fluorine, chlorine, bromine, methyl, trifluoromethyl or trifluoromethoxy, or is a radical in which X is halogen, alkyl or haloalkyl, and Y is halogen, alkyl, haloalkyl, haloalkoxy, azido or cyano, and R 1 is alkyl, haloalkyl, alkenyl, haloalkenyl, alkynyl, cycloalkyl, cycloalkylalkyl, halocycloalkyl, alkoxy, alkoxyalkyl, halocycloalkylalkyl or arylalkyl, comprising reacting a 4-haloacetoacetic ester of formula (II) in which R 2 is C 1 -C 12 -alkyl, C 5 -C 8 -aryl or arylalkyl, and Hal is Cl, Br or I, in the presence of a solvent at a temperature of from −20° C. to 60° C., a) with an amine of formula (IIIa) in which R 1 is as defined above, to give a compound of formula (IVa) followed by removing the solvent by distillation or under reduced pressure in a temperature range of from 20° C. to 35° C., thermally cyclizing the compound of formula (IVa) in the presence of a solvent at a temperature of from 40° C. to 150° C. to give a compound of formula (Va) isolating the compound of formula (Va) by crystallization or removal of solvent, and reacting the compound of formula (Va) with a compound of the formula (VIa) A-CH 2 -E (VIa) where A is as defined above and E is a leaving group selected from the group consisting of chlorine, bromine, iodine, mesylate, tosylate, or SO 2 CH 3 , to give compound (I); or b) with an amine of formula (IIIb) H 2 N-CH 2 -A (IIIb) in which A is as defined above, to give a compound of formula (IVb) followed by removing the solvent by distillation or under reduced pressure in a temperature range of from 20° C. to 35° C., thermally cyclizing the compound of formula (IVb) in the presence of a solvent at a temperature of from 40° C. to 150° C. to give a compound of formula (Vb) isolating the compound of formula (Vb) by crystallization or removal of solvent, and reacting the compound of formula (Vb) with a compound of formula (VIb) R 1 -E (VIb) where R 1 is as defined above and E is a leaving group selected from the group consisting of chlorine, bromine, iodine, mesylate, tosylate, or SO 2 CH 3 , to give compound (I).