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。