Studies on Peptides. CXXIX. Application of Nⁱⁿ-Mesitylenesulfonyl-tryptophan for the Syntheses of Neuromedin B and Neuromedin C

Abstract

Two Trp containing peptides, neuromedins B and C, were synthesized using a new Trp derivative, Nⁱⁿ-mesitylenesulfonyltryptophan, [Trp (Mts)]. The thioanisole-mediated deprotection with trifluoromethanesulfonic acid in trifluoroacetic acid was employed at the final steps of these syntheses to remove the Mts group together with the N^α-protecting group. In this deprotecting step, the use of an additional scavenger, ethanedithiol, was recommended to suppress possible indole modification. When smooth-muscle contractile activity in guinea pig ileum was examined, the relative potencies of neuromedins B and C with respect to synthetic substance P (taken as 1) were 0.46 and 0.37, respectively.