methanesulfonic acid; sulfuric acid in acetonitrile T=15 - 20°C;

methanesulfonic acid in acetonitrile T=20°C; 3 h;

in tetrahydrofuran; dichloromethane; water T=5 - 10°C; 2.5 h;

1: 4-chloro-2-methoxyimino-3-oxo-butyric acid With phosphorus pentachloride in dichloromethane T=-20 - 0°C; 2: C16H20N2O5S2Si in dichloromethane T=-50 - 0°C; 3: thiourea With sodium hydrogencarbonate; trifluoroacetic acid; sodium 2-ethyl hexanoate Product distribution / selectivity; more than 3 stages;

1: 4-chloro-2-methoxyimino-3-oxo-butyric acid With phosphorus pentachloride in dichloromethane T=-20 - 0°C; 2: (6R,7R)-7-amino-3-(furan-2-carbonylsulfanylmethyl)cephalosporanic acid With ammonia in tetrahydrofuran; dichloromethane; water pH=5.5 - 8.5; 3: thiourea With sodium hydrogencarbonate; trifluoroacetic acid; sodium 2-ethyl hexanoate Product distribution / selectivity; more than 3 stages;