To obtain an allenyl β-lactam compound and a 3-halocephem compound in a simple operation and in high purity by using a halogenated β-lactam compound as a starting material and solely changing reaction conditions.
An allenyl β-lactam compound of formula II is obtained by reducing a halogenated β-lactam compound of formula I [R1 is H, an amino or a protected amino; R2 is an aryl which may have a substitution group; (n) is 0-2; R3 is H or a carboxylic acid protecting group; X is a halogen; Y is a halogen or a removed group] with a 0 valent metal. A 3-halocephem compound is obtained by reducing the compound of formula I with the 0 valent metal and carrying out a ring closure reaction by a nucleophilic attack of halogen ion generated in reduction. Both reactions are preferably carried out in the presence of a Lewis acid. The compounds of formulas II and III are, e.g. important intermediates for 3-chlorocepharosporin which is a source material of cefaclor.
TANAKA HIDEO
SASAOKA MICHIO
KAMEYAMA YUTAKA
