Angiotensin II Analogues. Part II. Synthesis and incorporation of the sulfur-containing aromatic amino acids: L-(4′-SH)Phe,L-(4′-SO2NH2)Phe,L-(4′-SO)Phe and L-(4′-S-CH3)Phe

L -Phenylalanine has been treated with chlorosulfonic acid and the product was either hydrolyzed, ammonolyzed or reduced. The resulting sulfonic-acid and aminosulfonyl derivatives have been employed for peptide synthesis with Boc-protection of the N^α-position only. The reduction product L -(4′-SH)Phe has been protected by formation of asymmetric disulfides or with various thiol protecting groups (benzyl-, methyl- and acetamidomethyl groups, the latter being the most suitable for peptide synthesis). With these protected amino acids several analogues of angiotensin II have been synthesized by the solid-phase method. These analogues have been used for structure-activity relationship studies on three different bioassays.