Examinations were made on the mechanism of the reaction of iminoethers derived from benzylpenicillin esters with acid chloride. Slow addition of N-phenylformimino methyl ether (IIIb) to benzoyl chloride (IVb) afforded N-formylbenzanilide (VIb), but N-[1-(N-formyl-N-phenylamino)-1-methoxymethyl] benzanilide (VIIIb) was obtained as a main product when the latter was added to the former. These results suggested the formation of an addition compound (V) of iminoether and acid chloride. Nuclear magnetic resonance (NMR) of the reaction mixture of N-phenylformimino ethyl ether (IIIc) and phenylacetyl chloride (IVc) at-40° also showed the formation of a similar intermediate (V) which was converted to phenylacetanilide (Xc) and orthoformate (IXc) by the action of methanol. The iminoether (XIII) of methyl benzylpenicillinate (XII) was allowed to react with D (-)-α-phenylglycyl chloride hydrochloride (XIV) affording methyl α-aminobenzylpenicillinate (XVI). Follow-up of the reaction by IR and NMR indicated the direct reaction of iminoether (XIII) with acid chloride as is the case with N-phenylformimino ethers (III).
