Patent ID: 7923571

Claim:
A process for preparing a 4-alkoxycarbonyl-3-aminothiophene of formula (I) and/or a hydrochloride of the formula (I)′ and/or a mono- or bisacetylated or mono- or bisformylated form of formulae (I)″ in which R 1 is optionally halogen- or C 1 -C 4 -alkoxy-substituted alkoxy having from 1 to 6 carbon atoms, R 2 is C 1 -C 4 -alkyl-, and R 3 is an acyl or formyl substituent, which comprises reacting an enamine of formula (II) and/or a mono- or bisacetylated or mono- or bisformylated form of formula (H)″ with a chlorinating agent in the presence of at least one diluent wherein the diluent is selected from the group consisting of chlorobenzene and methylene chloride.