Synthesis of an analogue of α‐MSH‐(1–10)‐decapeptide as a substrate for enzymatic Nα‐acetylation

The synthesis of a stable substrate for enzymatic Nα‐acetylation is described. To this end an analogue of α‐MSH‐(1–10)‐decapeptide with norleucine instead of methionine at position 4 is prepared. t‐Butylation of an intermediate Z‐Tyr‐OMe leads only to about 75% conversion in a few hours' reaction time, and cannot be carried to completion. The [Nle4]‐decapeptide is as good a substrate for enzymatic Nα‐acetylation as the original decapeptide containing methionine.