A method for the synthesis of peptidyl thioacids is described on the basis of the use of the N- [9-(thiomethyl)-9 H-fluoren-2-yl] succinamic acid and cross-linked aminomethyl polystyrene resin. The method employs standard Boc chemistry SPPS techniques in conjunction with 9- fluorenylmethyloxycarbonyl protection of side-chain alcohols and amines and 9- fluorenylmethyl protection of side-chain acids and thiols. Cleavage from the resin is ...