Synthesis of Substance P and of Acylated Partial Sequences Substance P undecapeptide has been synthesized by the stepwise procedure and via condensation of the fragments 1–4 and 5–11. Formation of pyrrolidone carboxylic acid‐ and S‐tert. butyl peptides was observed. Gln(Mbh)‐containing sequences have been synthesized but were not useful for fragment condensation due to there low solubility. Additionally, some derivatives have been prepared by acylation of the C‐terminal pentapeptide. Reaction with trifluoracetic acid anhydride resulted in the formation of substituted 5‐amino‐oxazole derivatives as detected by mass spectrometric investigation.