METHOD OF PREPARING 2-HALOGENMETHYL PENEMS AND 2-AZITIDINONE DERIVATIVES AS INTERMEDIATE COMPOUNDS Russian patent published in 2001 - IPC

FIELD: chemical industry. SUBSTANCE: described is method of preparing 2-halogenmethyl penems of formula I: wherein R₁ is protective group for alcoholic hydroxy, R₂ is protective group for carboxy and X is halogen. Said method comprises reacting compound of formula III with thio-halogen acetic acid in organic solvent in the presence of organic base and Lewis acid at temperatures from minus 10 to plus 40 C to give compound of formula V which is reacted with oxalyl chloride ether in organic solvent in the presence of organic base at temperatures from minus 60 to plus 20 C, preferably from minus 20 to plus 10 C to give compound of formula VII: which is cyclized in suitable solvent using organic phosphite or phosphonite at temperatures from 20 to 140 C to give intermediate compounds of formula V and formula VII wherein R₁ is tert-butylmethyl silyl, R₂ is alyl and X is chlorine. EFFECT: simplified preparation method and increased yield of the desired product. 7 cl