The oxidation of 3-acylbenzothiazolines (IV) with m-chloroperbenzoic acid gave 3-acylbenzothiazoline sulfoxides (V) and sulfone (VI) in high yield. The stereochemistry of the compounds V is discussed on the basis of nuclear magnetic resonance spectroscopic studies. Reaction of the compound V with refluxing acetic anhydride resulted in the formation of novel ring expansion products, 4-acylbenzothiazine derivatives. A mechanism involving the sulfenic anhydride as an intermediate is proposed for this ring expansion.
三乙酰
苯并噻唑啉(IV)与间
氯过
苯甲酸氧化反应得到高产率的三
乙酰苯并噻唉
硫氧化物(V)和砜(VI)。化合物V的立体
化学结构基于核磁共振光谱学研究进行讨论。化合物V与回流的
乙酸酐反应导致新型环扩张产物的形成,即4-乙酰
苯并噻唑啉衍
生物。为此环扩张反应,提出了一种涉及亚磺酰酐作为中间体的机理。