A-Thiazoline ring

This group comprises condensation products of salicylic acid with cysteine giving a thiazoline ring. For a review, see (570). Some structurally related compounds will also be mentioned here. Salicylic acid isolated from Burkholderia Pseudomonas) cepacia was named azurochelin (555). It was found to act as a siderophore, e.g. for Pseudomonas fluorescens (230) and P. syringae (178) see also Mycobacterium smegmatis (Sect. 2.8). For details on the siderophore activity of salicylic acid, see (559). 

Sansinenea E, Ortiz A (2009) Bacterial Siderophores Containing a Thiazoline Ring. Mini-Rev Org Chem 6 120... 

The resulting thioamide 64 is subjected to cyclodehydratization with the PEG supported Burgess reagent 6225 with the sulfur atom instead of the carbonyl group performing the intramolecular attack on the sulfonate group in a similar way to that described above. The conversion of the oxazoline into a thiazoline ring as the final step yields curacin A (1). 

Gehring AM, Mori I, Perry RD, Walsh CT. The nonribosomal peptide synthetase HMWP2 forms a thiazoline ring during biogenesis of yersiniabactin, an iron-chelating virulence factor of Yersinia pestis. Biochemistry 37 11637-11650, 1998. 

This structure, although consistent with many facts, did not explain the peculiar properties of the A-terminal isoleucine and the negative test for —SH groups. Further experiments led to the conclusion that a thiazoline ring is formed between isoleucine and cysteine this was later proved to be correct. All these results led to the formula for bacitracin A which is now generally accepted - Figure 1.4). 

Ishihara H. Shimura K. Further evidence for the presence of a thiazoline ring in the iso-leucylcysieine dipeptide intermediate in bacitracin biosynthesis. FEBS Lett 1988 226 319-323. 

Spectroscopic evidence for the formation of a thiazoline ring by glutathione under acid conditions is presented by Calvin in the preceding paper (12). It is pertinent to point out that such structures could not account for our results, since such compounds as cysteine, 8-mercaptoethanol and cysteinyl-valine, which show a substantial increase in reactivity in the presence of urea, would be incapable of forming thiazoline rings for obvious structural reasons. ... 

Only compounds of cysteine, in which the amino group is in peptide linkage, possess the necessary sequence of atoms for the formation of a thiazoline ring. 

A -Thiazoline-4-carboxylic acids, metalation 26, 644s32 A -Thiazoline ring opening... 

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