Abstract: Protected amino acid derivatives of general formula (I) and methods for the prepatation of the derivatives are provided.

Abstract: Protected amino acid derivatives of the general formula ##STR1## wherein R.sub.1 represents hydrogen atom, and R.sub.2 represents hydrogen, methyl, isopropyl, 1-methylpropyl, 2-methylpropyl, tert-butoxymethyl, 1-tert-butoxyethyl, 2-methylthioethyl, benzyl, carboxamidomethyl, 2-carboxamidoethyl, tert-butoxycarbonylmethyl, 2-(tert-butoxycarbonyl)ethyl, 4-(tert-butoxycarbamido)butyl, 4-tert-butoxybenzyl, indolyl-3-methyl, S-(triphenylmethyl)thiomethyl, 1-(triphenylmethyl)imidazolyl-4-methyl, 3-(N.sup.G -mesitylenesulfonyl)guanidinopropyl, N-xanthylcarboxamidomethyl, 2-(N-xanthylcarboxamido)ethyl or S-(acetamidomethyl)thiomethyl; or R.sub.1 and R.sub.2 together represent propylene radical. Methods for the preparation of said derivatives are provided, and a process for solid phase peptide synthesis using said derivatives is described.