Synthesis of a Derivative of the Peptaibol-Antibiotic Trichovirin I 1B by means of the 'Azirine/Oxazolone Method'

Abstract

According to the earlier published synthesis of the C-terminal nonapeptide of Trichovirin I 1B, Z-Ser(tBu)-Val-Aib-Pro-Aib-Leu-Aib-Pro-Leuol (5), the complete tetradecapeptide Z-Aib-Asn(Trt)-Leu-Aib-Pro-Ser(t-Bu)-Val-Aib-Pro-Aib-Leu-Aib-Pro-Leuol (11b), a protected Trichovirin I 1B, has now been prepared by means of the 'azirine/oxazolone method'. With the exception of the N-terminal Aib(1), all Aib residues were introduced by the coupling of the corresponding amino or peptide acids with 2,2-dimethyl-2H-azirine-3-(N- methyl-N-phenylamine) (1a) and methyl N-(2,2-dimethyl-2H-azirin-3-yl)-l-prolinate (3a) as the Aib and Aib-Pro synthons, respectively. Single crystals of two segments, i.e., the N-terminal hexapeptide Z-Aib-Asn(Trt)-Leu-Aib-Pro-Ser(tBu)-OMe (23) and the C-terminal octapeptide Z-Val-Aib-Pro-Aib-Leu-Aib-Pro-Leuol (17), were obtained and their structures have been established by X-ray crystallography. Following the same strategy, the C-terminal nonapeptide of Trichovirin I 4A, Z-Ala-Val-Aib-Pro-Aib-Leu-Aib-Pro-Leuol (26), was also synthesized and characterized by X-ray crystallography.