Process for the preparation of 6-alkoxy-substituted penicillins

A process of preparing a 6-substituted penicillin compound of the formula:

• ##STR4## wherein R.sub.1 CO is phenyl lower alkanoyl, phenoxy lower alkanoyl, benzoyl, or benzoyl substituted by nitro, lower alkyl or lower alkoxy in the benzene ring;
• R.sub.2 is lower alkyl, lower alkyl substituted by phenyl, nitro-phenyl, halo-phenyl or lower alkoxy phenyl;
• benzoyl, or benzoyl substituted by nitro, halo, or lower alkoxy;
• R.sub.3 is lower alkyl;
• and m is 1 or 0 which consists essentially of the steps of (a) first adding a halogenating agent to an inert organic solvent solution of a penicillin compound of the formula:
• ##STR5## where R.sub.1, R.sub.2 and m have the same meaning as defined above, under cooling at a temperature of about 0.degree. C. to about -30.degree. C. and then (b) adding to the reaction mixture about one equivalent of an alkali metal alcoholate of the formula
• MOR.sub.3
• wherein R.sub.3 has the same meaning as in the above formula and M represents an alkali metal in the presence of an alcohol corresponding to said alcoholate.