Process for producing halogenated β-lactam compound

A process for preparing halogenated β-lactam compounds, wherein a β-lactam amino compound of the formula (1)

• wherein
• n is an integer of 0 to 2;
• A is the formula (2) or (3);
• R1 and R2 are the same or different, and are a hydrogen atom, a halogen atom, a C1-C3 alkyl group, a C2-C4 alkenyl group, a C2-C4 alkynyl group, an aliphatic carboxylic acyloxy group having 2 to 4 carbon atoms, an aromatic acyloxy group, a carbamoyloxy group, a hydroxy group, or a mercapto group, or an above group substituted with an alkyl group having 1 to 3 carbon atoms or aliphatic carboxylic acyl group having 1 to 3 carbon atoms, a heterocyclic thio group substituted with an alkyl group having 1 to 3 carbon atoms, or CH2R3;
• and
• R3 is a halogen atom, an aliphatic carboxylic acyloxy group having 2 to 4 carbon atoms, an aromatic acyl group, a carbamoyloxy group, a hydroxy group, a mercapto group, or an above group substituted with an alkyl group having 1 to 3 carbon atoms or an aliphatic carboxylic acyl group having 1 to 3 carbon atoms, or a heterocyclic thio group substituted with an alkyl group having 1 to 3 carbon atoms,
• further wherein the heterocycle of the heterocyclic thio group of R1, R2 and R3 is a five- or six-member ring containing 1 to 4 heteroatoms selected from O, S, or N;
• is reacted with nitrous acid or a salt of a nitrous acid in a slurry dispersion state in water, under acid condition in the presence of halogen molecules, thereby obtaining a halogenated β-lactam compound of the formula (4)
• wherein A is as defined above;
• X1 is a hydrogen atom or a halogen atom;
• and
• X2 is a halogen atom.