Thiazoles have gained a particular significance in the field of organic chemistry. Amino acid derived thiazoles comprise a common motif in biologically active substances such as the thiopeptide antibiotics. Hence, the preparation and reactions of thiazoles are important for the synthesis of pharmaceuticals and fine chemicals. A sequential procedure for the preparation of 2,5-disubstituted thiazoles from sulfonyl azides, terminal alkynes and thionoesters, by the elimination of the sulfonyl group, was reported. Cyclization reactions of thiosemicarbazide derivatives yielding thiazoles have also been explored. In particular, we may note the production of thiazole esters from the cyclization reaction of 4-substituted benzenenitriles and L-cysteine, followed by the esterification with selected alcohols and oxidation of thiazoline esters mediated by BrCCl3/ DBU. Thiazole and its derivatives were efficiently prepared through a gold-catalyzed oxidation at room temperature. Besides, the reaction of 11-bromo-10-oxoundecanoic acid with acetamide and thiourea yielded the terminally located thiazole derivatives. Several methods for the synthesis of thiazoles have been reported as follows: (i) thiazolecontaining amino acids were synthesized by condensation-cyclization, (ii) Ling and his group prepared 1,2,4-triazole-linked thiazole derivatives from the reaction of a-bromo substituted acetophenones and thiourea, (iii) Wardakhan and his co-workers synthesized several thiazole derivatives from pyridazin-3-hydrazidic acids, and (iv) Khazi et al., have reported a preparation of thiazole-fused diazepinones by the application of intramolecular hydrazinolysis. Thiazoles were also synthesized by an alternative substitution method using MnO2. 18 Notwithstanding the ground that has been broken by these methods, some disadvantages remain. In this context, we have developed a simple, well-ordered and practical method of synthesis of terminal thiazoles in good isolated yields. In our work, we proceeded with the elaboration of Fmoc/Cbz-amino acids to yield the required terminal thiazoles. The necessary thioamides were prepared by the reaction of Nprotected a-amino acid amides with the thionating agent P2S5 through an ultrasonication mediated protocol. The thioamides were then refluxed with chloroacetaldehyde to obtain the thiazole-linked molecules. N-Protected amino acid 1 was dissolved in tetrahydrofuran (THF), followed by the addition of N-methyl morpholine (NMM) and ethyl chloroformate (ECF) at -15 C. The reaction mixture was stirred for 15minutes at the same temperature

中文翻译：

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N-保护氨基酸合成末端噻唑及其抗菌活性研究

噻唑在有机化学领域具有特殊意义。氨基酸衍生的噻唑在生物活性物质（如硫肽抗生素）中包含一个共同的基序。因此，噻唑的制备和反应对于药物和精细化学品的合成具有重要意义。报道了从磺酰叠氮化物、末端炔烃和硫羰酯通过消除磺酰基制备 2,5-二取代噻唑的顺序程序。氨基硫脲衍生物产生噻唑的环化反应也已被探索。特别是，我们可以注意到 4-取代苯腈和 L-半胱氨酸的环化反应生成了噻唑酯，然后用选定的醇酯化和由 BrCCl3/DBU 介导的噻唑啉酯的氧化。在室温下通过金催化氧化有效地制备了噻唑及其衍生物。此外，11-溴-10-氧代十一烷酸与乙酰胺和硫脲反应生成位于末端的噻唑衍生物。已经报道了几种合成噻唑的方法如下：（i）通过缩合环化合成含噻唑的氨基酸，（ii）Ling 和他的团队从 a 的反应制备了 1,2,4-三唑连接的噻唑衍生物。 -溴取代的苯乙酮和硫脲，(iii) Wardakhan 和他的同事从哒嗪-3-肼酸合成了几种噻唑衍生物，以及 (iv) Khazi 等人，已经报道了通过应用分子内肼解制备噻唑稠合的二氮杂酮。噻唑类化合物也通过使用 MnO2 的替代替代方法合成。18 尽管这些方法已经打破了基础，但仍然存在一些缺点。在此背景下，我们开发了一种简单、有序且实用的末端噻唑合成方法，分离收率良好。在我们的工作中，我们继续研究 Fmoc/Cbz-氨基酸以产生所需的末端噻唑。必要的硫代酰胺是通过 N 保护的α-氨基酸酰胺与硫化剂 P2S5 通过超声介导的协议反应制备的。然后将硫代酰胺与氯乙醛回流以获得噻唑连接的分子。