| abstract |
Carboxylic acid ester derivatives of formula (1), wherein R is C1-C6 alkyl, R?2 and R3¿ are independently hydrogen or C¿1?-C3 alkyl, and Q is optionally substituted phenyl, can be easily converted by ring closing into pyridazin-3-one derivatives of formula (7). The carboxylic acids of formula (1) can be produced by reacting hydrazone compounds of formula (5), wherein R?3¿ and Q are as defined above, with malonic acid monoester derivatives of formula (6), wherein R and R2 are as defined above, in the presence of a base. |