In a novel approach starting from O-trimethylsilyl protected or unprotected cyanohydrins and oxalyl chloride or bromide, a series of unknown 6-substituted 3,5-dihalo-2H-1,4-oxazin-2-ones were prepared. The method was shown to be efficient for various types of cyanohydrins; however cyclization was not obtained with cyanohydrins containing bulky substituents, electron-rich aryl or heteroaryl groups. A mechanism is proposed.
从O-三甲基
硅烷保护或未保护的
氰醇以及
草酰氯或
溴开始,采用一种新颖的方法合成了一系列未知的6-取代-3,5-二卤代-
2H-1,4-恶嗪-2-酮。该方法对各种类型的
氰醇都显示出高效性;然而,对于含有大体积取代基、富电子芳基或杂芳基的
氰醇,未能实现环化反应。提出了一个可能的反应机理。