| abstract |
A 7-acylamido-3-substituted thio-3-cephem-4-carboxylic ester of general formula (5) can be produced preferentially, readily and efficiently by reacting 7-acylamido-3-acylthio-3- or 2-cephem-4-carboxylic ester of general formula (1) (wherein R¹ represents acyl, R² represents a protective group of the carboxyl group, and R³ represents lower alkyl or (un)substituted aryl) or a mixture thereof with tertiary and secondary amines and further reacting a tertiary amine salt of the reaction product with a compound of general formula (4): R⁴-X, wherein R⁴ represents lower alkyl, cycloalkyl, heterocycle or heterocycle-substituted methyl and X represents a leaving group. |