The ‘Azirine/Oxazolone Method’ on Solid Phase: Introduction of Variousα,α-Disubstitutedα-Amino Acids
作者:Simon Stamm、Anthony Linden、Heinz Heimgartner
DOI:10.1002/hlca.200690019
日期:2006.1
been synthesized from the N- to the C-terminus by the ‘azirine/oxazolone method’ under solid-phase conditions. In this convenient method for the synthesis of sterically demanding peptides on solid-phase, 2H-azirin-3-amines are used to introduce the α,α-disubstituted α-amino acids without the need for additional reagents. Furthermore, the synthesis of poly(Aib) sequences has been explored.
By using the 'azirine/oxazolone method', di- and tripeptides containing six-membered heterocyclic 4-amino-4-carboxylic acids with a piperidine, tetrahydropyran or tetrahydrothiopyran ring have been synthesized. It has been shown that the corresponding heterospirocyclic 3-(N-methyl-N-phenylamino)-2H-azirines are suitable synthons for these heterocyclic alpha-amino acids. As expected, the presence of these alpha,alpha-disubstituted alpha-amino acids stabilizes beta-turn conformations in the prepared tripeptides of type Z-Phe-Xaa-Val-OR.
Heterospirocyclic 3-Amino-2H-azirines as Convenient Building Blocks in Peptide Synthesis
作者:Heinz Heimgartner、Christoph Strässler
DOI:10.3987/com-18-s(f)41
日期:——
Novel Heterospirocyclic 3-Amino-2<i>H</i>-azirines as Synthons for Heterocyclic α-Amino Acids
respectively, was demonstrated (Scheme 6). The solid-state conformations of the protected tripeptides 18a-d, as well as that of the corresponding carbocyclic analogue 18e, were determined by X-ray crystallography (Figs. 1-3 and Tables 1-3). All five tripeptides adopt a β-turn conformation of type III or III′. The solvent dependence of the chemical shifts of the NH resonances (Fig. 6) suggests that there is