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 Nα‐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.