Synthetische Analoge des Hypertensins. IV. Synthese der kettenhomologen Peptide (des‐Asp¹)‐Val⁵‐Hypertensin II, (des‐Phe⁸)‐Val⁵‐Hypertensin II‐Asp¹‐β‐amid, (homo‐Tyr⁴′)‐Val⁵‐Hypertensin II und (homo‐Tyr⁴′)‐Val⁵‐Hypertensin II‐Asp¹‐β‐amid

The syntheses of the chain‐homologues of hypertensin, H · Arg‐Val‐Tyr‐Val‐His‐Pro‐Phe · OH, H · Asp(NH 2 )‐Arg‐Val‐Tyr‐Val‐His‐Pro · OH, and H · Asp(R)‐Arg‐Val‐Tyr‐Tyr‐Val‐His‐Pro‐Phe · OH (R  −OH and −NH 2 ), are described in detail. A system for the nomenclature of such analogues is proposed. The relative stability of H · Arg‐Val‐Tyr‐Val‐His‐Pro‐Phe · OH, H · Gly‐Arg‐Val‐Tyr‐Val‐His‐Pro‐Phe · OH 2 and H · Asp(R)‐Arg‐Val‐Tyr‐Val‐His‐Pro‐Phe · OH in aqueous solution at 50° over a period of 6 months is discussed: the heptapeptide and Val 5 ‐hypertensin II are very stable under these conditions, but the asparaginyl 1 ‐ and glycyl 1 ‐ compounds lose these residues to an extent of about 10%. A possible mechanism explaining the difference in the behaviour of the aspartyl and the asparaginyl residues is suggested.