Regioselective synthesis of pyrazole and pyridazine esters from chalcones and α-diazo-β-ketoesters
作者:Deepa Nair、Prashant Pavashe、Savita Katiyar、Irishi N.N. Namboothiri
DOI:10.1016/j.tetlet.2016.06.020
日期:2016.7
generates diazoester anion, a reactive 1,3-dipole, which undergoes [3+2] annulation with chalcones to afford pyrazole ketoesters. Under similar conditions, the 1,3-dipole takes part in a [3+3] annulation with chalcone epoxides to provide pyridazine esters. Despite moderate yields, high regioselectivity, mild conditions, and functional group diversity are the salient features of this novel methodology.
碱介导的α-重氮-β-酮酸酯的脱酰作用可生成重氮酸酯阴离子,一种反应性的1,3-偶极离子,可与查耳酮进行[3 + 2]环合反应,得到吡唑酮酸酯。在相似的条件下,1,3-偶极子与查尔酮环氧化物参与[3 + 3]环化反应,从而提供哒嗪酯。尽管产量中等,但这种区域性方法的突出特点是具有较高的区域选择性,温和的条件和功能基团的多样性。