[Synthesis of the human proinsulin sequence 71-86, I: Synthesis of sequence 71-86 as a monomeric cyclic biscystine peptide derivative and as its tetra-S-trityl derivative (author's transl)].

The synthesis of sequence 71-86 of human proinsulin (sequence 6-21 of human insulin A-chain) via its monomeric cyclic dicystine peptide derivative (XXII) and the corresponding tetra-S-trityl-peptide derivative (XVIII) is described. The good solubility of the derivatives (XXII, XVIII) in orgranic solvents makes it possible to purify both the derivatives in their protected form. The S-trityl derivative (XVIII) enables the synthesis of the fragment 71-86 in a scale needed for the planned synthesis of human proinsulin.