Patent ID: 7022847

Claim:
Process for preparing a compound of the formula (I) in which R 1 represents hydrogen or straight-chain or branched alkyl having up to 4 carbon atoms, R 2 represents straight-chain alkyl having up to 4 carbon atoms, R 3 and R 4 are identical or different and represent hydrogen, straight-chain or branched alkyl having up to 6 carbon atoms, or represent straight-chain or branched alkoxy having up to 6 carbon atoms, comprising reaction of a compound of the formula (II) in which R 2 , R 3 and R 4 have the meaning indicated above, with a compound of the formula (III) in which R 1 has the meaning indicated above, X represents halogen; in the presence of a base and, where appropriate, of a metal iodide in an organic solvent to give a compound of the formula (IV) in which R 1 , R 2 , R 3 and R 4 have the meaning indicated above, and subsequent reaction [A] with iodine in the presence of a base in a solvent, subsequent reaction with a metal cyanide in a solvent and reaction with an acid or [B] with bromine in acidic medium, subsequent reaction with a metal cyanide in a solvent and reaction with an acid.