Abstract: An industrially advantageous process for producing 3-chloromethyl-3-cephem derivative crystals. The process for 3-chloromethyl-3-cephem derivative production comprises: a first step in which a thiazolineazetidinone derivative (1) is reacted with a sulfonyl halide (2) in the presence of an acid in a solvent to obtain an azetidinone derivative (3); a second step in which the azetidinone derivative (3) is reacted with a chlorinating agent in an organic solvent to obtain a chlorinated azetidinone derivative (4); and a third step in which the chlorinated azetidinone derivative (4) is reacted with an alcoholate (5) at a pH of 8 or lower in a solvent comprising an alcohol and an ether and a 3-chloromethyl-3-cephem derivative (6) is recovered in the form of crystals.

Abstract: An industrially advantageous process for producing 3-chloromethyl-3-cephem derivative crystals. The process for 3-chloromethyl-3-cephem derivative production comprises: a first step in which a thiazolineazetidinone derivative (1) is reacted with a sulfonyl halide (2) in the presence of an acid in a solvent to obtain an azetidinone derivative (3); a second step in which the azetidinone derivative (3) is reacted with a chlorinating agent in an organic solvent to obtain a chlorinated azetidinone derivative (4); and a third step in which the chlorinated azetidinone derivative (4) is reacted with an alcoholate (5) at a pH of 8 or lower in a solvent comprising an alcohol and an ether and a 3-chloromethyl-3-cephem derivative (6) is recovered in the form of crystals.

Abstract: A chlorinated azetidinone derivative expressed by Formula (1) and an alcoholate are allowed to react in a solvent containing at least one of alcohols and an ether at a pH of 8 or less. Thus a 3-chloromethyl-3-cephem derivative expressed by Formula (2) is prepared. In the formulas, R1 represents a substituted or unsubstituted aryl group or a substituted or unsubstituted heterocyclic residue, and R2 and R3 each represent a substituted or unsubstituted aromatic hydrocarbon group.

Abstract: A chlorinated azetidinone derivative expressed by Formula (1) and an alcoholate are allowed to react in a solvent containing at least one of alcohols and an ether at a pH of 8 or less. Thus a 3-chloromethyl-3-cephem derivative expressed by formula (2) is prepared. In the formulas, R1 represents a substituted or unsubstituted aryl group or a substituted or unsubstituted heterocyclic residue, and R2 and R3 each represent a substituted or unsubstituted aromatic hydrocarbon group.