Synthesis of 5- and 7-bromotryptophan and of [5-bromotryptophan9]-β-corticotrophin-(1–24)-tetracosapeptide, a highly potent corticotrophin analogue

Abstract

The synthesis of 5- and 7-bromo-L-tryptophans via Fischer cyclisation of the appropriate bromophenylhydrazone of 4-acetamido-4,4-bis(ethoxycarbonyl)butanal is described. The title tetracosapeptide was synthesised using standard methods of stepwise and fragment condensation. The product was pure as judged by amino-acid analysis after acidic or enzymic hydrolysis and by high pressure liquid chromatography. In an isolated adrenal cell bioassay, the peptide had a steroidogenic potency 2.4 times that of Synacthen.