The chemistry of 5-oxodihydroisoxazoles. Part 22.1 The synthesis of 1,3-oxazin-6-ones from N-thioacylisoxazol-5(2H )-ones
作者:David S. Millan、Rolf H. Prager
DOI:10.1039/a804527e
日期:——
N-Thioacylisoxazol-5(2H)-ones, prepared by the reaction of thiocarbonyl chlorides with isoxazol-5(2H)-ones in the presence of base, are reduced by triphenylphosphine to afford 1,3-oxazin-6-ones and triphenylphosphine sulfide. If the thioacylation is carried out with phenyl chlorodithioformate, the thermal rearrangement of the intermediate, to again form the oxazin-6-one and sulfur, is so rapid that the use of the phosphine is not required. The presence of an ethoxycarbonyl group at C-3, or of a bromine atom at C-4 of the isoxazolone results in the formation of thiazoles.
通过在碱的存在下,用硫代羰基氯与异噁唑-5(2H)-酮反应制备的N-硫代乙酰异噁唑-5(2H)-酮,经三苯基膦还原得到1,3-氧杂嗪-6-酮和三苯基膦硫化物。如果使用苯基二硫代甲酸氯进行硫代乙酰化反应,中间体的热重排反应迅速,再次生成氧杂嗪-6-酮和硫,因此不需要使用膦。异噁唑酮的C-3位存在乙氧羰基或C-4位存在溴原子时,会导致形成噻唑。