Synthesis of 2-Phenyl-4,5-Substituted Oxazoles by Copper-Catalyzed Intramolecular Cyclization of Functionalized Enamides
作者:S. Vijay Kumar、B. Saraiah、N. C. Misra、H. Ila
DOI:10.1021/jo3021192
日期:2012.12.7
An efficient two-step synthesis of 2-phenyl-4,5-substituted oxazoles involving intramolecular copper-catalyzed cyclization of highly functionalized novel β-(methylthio)enamides as the key step has been reported. These enamides are obtained by nucleophilic ring-opening of newly synthesized 4-[(methylthio)hetero(aryl)methylene]-2-phenyl-5-oxazolone precursors by alkoxides, amines, amino acid esters and
已经报道了2-苯基-4,5-取代的恶唑的有效两步合成,其中涉及高度功能化的新型β-(甲硫基)烯酰胺的分子内铜催化的环化作为关键步骤。这些酰胺是通过新合成的4-[((甲硫基)杂(芳基)亚甲基] -2-苯基-5-恶唑烷酮前体的亲核开环反应,通过醇盐,胺,氨基酸酯和芳基/烷基格氏试剂进行亲核开环而获得的。在产物恶唑的4-位引入酯,N-取代的羧酰胺或酰基官能团。还描述了通过相应的2,5-二芳基恶唑-4-羧酸酯的两步水解-脱羧反应合成两种天然存在的2,5-二芳基恶唑,即texamine和uguenenazole。相似地,通过DAST / DBU介导的环脱水-脱卤化氢序列,将三种丝氨酸衍生的oxazole-4-carboxamides精制为新型三取代的4,2'-bisoxazoles。本协议是对我们先前报道的碳酸银诱导的β-双(甲硫基)烯酰胺成2-苯基-5-(甲硫基)-4-取代的恶唑环化的补充和改进。