α-Pyranones; I. Reaction of 4-Ethoxy- and 4-Chloromethylene-2-phenyl-5(4<i>H</i>)-oxazolone with Ethyl 3-Oxo-4-(triphenylphosphoranylidene)butyrate: A New Synthesis of 2<i>H</i>-pyran-2-one Compounds
作者:M. L. Gelmi、D. Pocar
DOI:10.1055/s-1992-26133
日期:——
The reaction of 4-ethoxymethylene-5(4H)-oxazolone (2a) with ethyl 3-oxo-4-(triphenylphosphoranylidene)butyrate (1) affords ethyl 3-benzoylamino-2-oxo-6-triphenylphosphoranylidenemethyl-2H-pyran-5-carboxylate (3). Starting from the corresponding 4-chloromethylene compound 2b and 1, besides 3, ethyl 3-benzoylamino-6-[2-(4,5-dihydro-5-oxo-2-phenyl -4-oxazolylidene)-1-(triphenylphosphoranylidene)ethyl]-2-oxo-2H-pyran-5-carboxylate (5) is formed. The phosphorane 3 is a reactive synthetic intermediate for the preparation of ethyl 6-(1-alkenyl)-3-benzoylamino-2-oxo-2H-pyran-5-carboxylates 7 through reaction with aldehydes.
4- 乙氧基亚甲基-5(4H)-恶唑酮(2a)与 3-氧代-4-(三苯基膦亚基)丁酸乙酯(1)反应生成 3-苯甲酰基氨基-2-氧代-6-三苯基膦亚甲基-2H-吡喃-5-甲酸乙酯(3)。除了 3 之外,从相应的 4-氯亚甲基化合物 2b 和 1 开始,生成 3-苯甲酰基氨基-6-[2-(4,5-二氢-5-氧代-2-苯基-4-恶唑亚基)-1-(三苯基膦亚基)乙基]-2-氧代-2H-吡喃-5-羧酸乙酯(5)。磷烷 3 是一种活性合成中间体,通过与醛反应制备 6-(1-烯基)-3-苯甲酰氨基-2-氧代-2H-吡喃-5-羧酸乙酯 7。