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|Section2= |Section3= }} Oxazole is the parent compound for a vast class of heterocyclic aromatic organic compounds. These are azoles with an oxygen and a nitrogen separated by one carbon.〔Heterocyclic Chemistry TL Gilchrist, The Bath press 1985 ISBN 0-582-01421-2〕 Oxazoles are aromatic compounds but less so than the thiazoles. Oxazole is a weak base; its conjugate acid has a pKa of 0.8, compared to 7 for imidazole. ==Preparation== Classical oxazole synthetic methods in organic chemistry are * the Robinson–Gabriel synthesis by dehydration of 2-acylaminoketones * the Fischer oxazole synthesis from cyanohydrins and aldehydes * the Bredereck reaction with α-haloketones and formamide * the Van Leusen reaction with aldehydes and TosMIC Other methods are reported in literature. * Oxazolines can also be obtained from cycloisomerization of certain propargyl amides. In one study〔''A new consecutive three-component oxazole synthesis by an amidation–coupling–cycloisomerization (ACCI) sequence'' Eugen Merkul and Thomas J. J. Müller Chem. Commun., 2006, 4817 - 4819, 〕 oxazoles were prepared via a one-pot synthesis consisting of the condensation of propargyl amine and benzoyl chloride to the amide, followed by a Sonogashira coupling of the terminal alkyne end with another equivalent of benzoylchloride, and concluding with ''p''-toluenesulfonic acid catalyzed cycloisomerization: : *In one reported oxazole synthesis the reactants are a nitro-substituted benzoyl chloride and an isonitrile:〔''Fully Automated Continuous Flow Synthesis of 4,5-Disubstituted Oxazoles'' Marcus Baumann, Ian R. Baxendale, Steven V. Ley, Christoper D. Smith, and Geoffrey K. Tranmer Org. Lett.; 2006; 8(23) pp 5231 - 5234; (Letter) 〕〔They react together in the first phase in a continuous flow reactor to the intermediate enol and then in the second phase in a phosphazene base (PS-BEMP) induced cyclization by solid-phase synthesis.〕 : 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「oxazole」の詳細全文を読む スポンサード リンク
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