Patent ID: 6153747
Filing Date: 2000-11-28
Classification: C07D,Y02P

Abstract:
Process for the preparation of 2-halomethyl penems of formula (I) wherein R.sub.1 is an hydroxy-protecting group, R.sub.2 is a carboxyl-protecting group and X is halogen, wherein:a) compounds of formula (III) ##STR4## wherein R.sub.1 is as above defined, are reacted with a 2-halothioacetic acid in an organic solvent in the presence of an organic base and a Lewis acid, at a temperature of -10.degree. C.-+40.degree. C., to give compounds of formula (V) ##STR5## wherein R.sub.1 and X are as above defined; b) the above said compounds of formula (V) are reacted with an oxallyl chloride ester in an organic solvent in the presence of an organic base at a temperature of -60.degree.-+20.degree. C., to give the compounds of formula (VII) ##STR6## wherein R.sub.1, R.sub.2 and X are as above defined; and c) the compounds of formula (VII) are finally cyclized in an appropriate solvent at 20.degree.-140.degree. C. for 1-120 h, under the action of an organic phosphite or phosphonite.