title: The 'azirine/oxazolone method' in peptaibol synthesis: preparation of a derivative of trichotoxin A-50 (G).
abstract: The synthesis of a mixture of epimeric derivatives of the peptaibol trichotoxin A-50 (G) is described. The 'azirine/oxazolone method' has been used as a superior method for the introduction of the Aib as well as the Iva units into the peptide chain. In this protocol, 2,2-disubstituted 2H-azirin-3-amines are the synthons for 2,2-disubstituted glycines, which undergo coupling with N-protected amino or peptide acids in high yield, and without any need of coupling reagents. The problem of the instability of the amide function of the Gln side chain under the conditions of the acid-catalyzed hydrolysis of Z-Gln-(Aib)(n)-N(Me)Ph was solved by using an appropriate protecting group for the amide function of the Gln side chain, e.g., the triphenylmethyl (trityl; Tr) group. The structures of two intermediate peptides, i.e., the segments comprising residues 1-5 and 10-13, resp., were established by X-ray crystallography.
authors.affiliation: Organisch-chemisches Institut der Universität Zürich, Zürich, Switzerland.
authors.forename: Werner
authors.initials: W
authors.lastname: Altherr
authors.forename: Anthony
authors.initials: A
authors.lastname: Linden
authors.forename: Heinz
authors.initials: H
authors.lastname: Heimgartner
mesh_terms: D000900:Anti-Bacterial Agents / Q000138:chemical synthesis*; D023181:Antimicrobial Cationic Peptides; D001389:Azirines / Q000737:chemistry*; D018360:Crystallography, X-Ray; D006868:Hydrolysis; D010081:Oxazolone / Q000737:chemistry*; D010455:Peptides / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D000900:Anti-Bacterial Agents; D023181:Antimicrobial Cationic Peptides; D001389:Azirines; D010455:Peptides; D010081:Oxazolone; C016161:trichotoxin