A suspension of potassium phenoxymethylpenicillanate (I) in CH2Cl2 is treated with bromomethyl methyl ether (II) and DMF to give methoxymethyl ester of penicilline V (phenoxymethylpenicillanic acid) (III), which by treatment with PCl5 and dimethylaniline in CH2Cl2 is converted into methoxymethyl 6-aminopenicillanate (IV). The condensation of (IV) with p-hydroxyphenylglycyl chloride (V) by means of triethylamine in CH2Cl2 affords amoxicilline methoxymethyl ester (VI), which is finally treated with acetone at pH 6.5-9.5.

A suspension of potassium phenoxymethylpenicillanate (I) in CH2Cl2 is treated with bromomethyl methyl ether (II) and DMF to give methoxymethyl ester of penicilline V (phenoxymethylpenicillanic acid) (III), which by treatment with PCl5 and dimethylaniline in CH2Cl2 is converted into methoxymethyl 6-aminopenicillanate (IV). The condensation of (IV) with p-hydroxyphenylglycyl chloride (V) by means of triethylamine in CH2Cl2 affords amoxicilline methoxymethyl ester (VI), which is finally treated with acetone at pH 6.5-9.5.

A suspension of potassium phenoxymethylpenicillanate (I) in CH2Cl2 is treated with bromomethyl methyl ether (II) and DMF to give methoxymethyl ester of penicilline V (phenoxymethylpenicillanic acid) (III), which by treatment with PCl5 and dimethylaniline in CH2Cl2 is converted into methoxymethyl 6-aminopenicillanate (IV). The condensation of (IV) with p-hydroxyphenylglycyl chloride (V) by means of triethylamine in CH2Cl2 affords amoxicilline methoxymethyl ester (VI), which is finally treated with acetone at pH 6.5-9.5.