Patent ID: 6699992
Filing Date: 2004-03-02
Classification: C07C,C07D

Abstract:
A process for preparing quinolonecarboxylic acid derivatives having the formula (I): wherein R1 is H, halogen, or amino,R2 is halogen, R3 is H, halogen, C1-4 alkoxyl, or CN, R4 is selected from the group consisting of C3-6cycloalkyl, C1-4alkyl, C1-4alkoxyC1-4alkyl, and C1-4alkylaminoC1-4alkyl, comprising the steps of:i) reacting a compound of the formula (II) â€ƒwherein R1, R2 and R3 are defined as above, and R7 is a halogen, with an alkyl carbonate to obtain a compound of the formula (III), â€ƒwherein R8 is methyl or ethyl; ii) reacting a compound of the formula (III) successively with an alkyl orthoformate and a compound of the formula (IV) R4NH2 to obtain a compound of the formula (V), iii) cyclizing the compound of the formula (V) in the presence of a base to form a compound of the formula (VI); and iv) hydrolyzing the compound of the formula (VI) to obtain a compound of the formula (I).