Rhodium Carbene Routes to Oxazoles and Thiazoles. Catalyst Effects in the Synthesis of Oxazole and Thiazole Carboxylates, Phosphonates, and Sulfones
作者:Baolu Shi、Alexander J. Blake、William Lewis、Ian B. Campbell、Brian D. Judkins、Christopher J. Moody
DOI:10.1021/jo902256r
日期:2010.1.1
Dirhodium tetraacetate catalyzed reaction of α-diazo-β-keto-carboxylates and -phosphonates with arenecarboxamides gives 2-aryloxazole-4-carboxylates and 4-phosphonates by carbene N−H insertion and cyclodehydration. In stark contrast, dirhodium tetrakis(heptafluorobutyramide) catalysis results in a dramatic change of regioselectivity to give oxazole-5-carboxylates and 5-phosphonates. α-Diazo-β-ketosulfones
四乙酸二丁酯催化α-重氮-β-酮基羧酸酯和-膦酸酯与芳烃酰胺的反应,通过卡宾NH插入和环脱水作用,制得2-芳基恶唑-4-羧酸酯和4-膦酸酯。与之形成鲜明对比的是,四(七氟丁酰胺)四氢吡啶鎓催化作用会导致区域选择性的显着变化,从而产生5-羧酸恶唑酯和5-膦酸酯。α-重氮-β-酮砜的行为相似,在四(七氟丁酰胺)四氢吡啶鎓与羧酰胺的催化反应下生成5-磺酰基恶唑。硫代羧酰胺的类似反应得到相应的噻唑-5-羧酸盐,-膦酸酯和-砜。