Abstract: A process for the preparation of [D-.alpha.-amino-p-hydroxyphenylacetamido]-penicillanic acid or cephalosporanic acid compounds comprising reacting a compound having a formula selected from the group consisting of ##STR1## wherein X is selected from the group consisting of hydrogen, acetoxy and five-membered heterocyclic group containing at least one hetero atom of the group consisting of oxygen, sulfur and nitrogen and optionally substituted with e.g. lower alkyl, this residue being attached to the 3-CH.sub.2 group via sulfur atom and wherein a NH radical if present has optionally been silylated with at least one mole equivalent of a silylating agent producing ##STR2## wherein R.sub.1, R.sub.2 and R.sub.

Abstract: A process for the preparation of 6-(D-.alpha.-amino-p-hydroxyphenylacetamido)-penicillanic acid or amoxicillin by reacting 6-aminopenicillanic acid with at least two equivalents of a silylating agent producing trimethylsilyl groups in an anhydrous, inert, water-insoluble organic solvent and reacting the resulting product at a temperature below -25.degree. C with an at least equimolar amount of a compound of the formula ##STR1## wherein R.sub.1 and R.sub.7 are lower alkoxy, R.sub.2 is lower alkyl and R.sub.3 is selected from the group consisting of lower alkyl and hydrogen previously prepared from the corresponding Dane salt and an acid chloride under anhydrous conditions in the presence of a tertiary amine in an inert, water-insoluble organic solvent.