Transition-metal-free ring expansion of benzoisothiazol-3-ones has been established to synthesize 2,3-dihydrobenzothiazin-4-ones via single-carbon insertion. A variety of 2,3-dihydrobenzothiazin-4-ones have been prepared with good yields. The use of aldehydes and ketones resulted in the formation of 2-substituted and 2,2-disubstituted 2,3-dihydrobenzothiazin-4-ones using HI and NH₄I as additives. Furthermore, the easily prepared 1-(chloromethyl)-1,4-diazabicyclo[2.2.2]octan-1-ium chloride [DABCO·DCM] was first utilized as the methylene source for the selective synthesis of 2,3-dihydrobenzothiazin-4-ones and bis-2,3-dihydrobenzothiazin-4-ones.

中文翻译：

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通过单碳插入将苯并异噻唑-3-酮转化为 2,3-二氢苯并噻嗪-4-酮的无过渡金属骨架编辑


已经建立了苯并异噻唑-3-酮的无过渡金属扩环，以通过单碳插入合成 2,3-二氢苯并噻嗪-4-酮。已经制备了多种 2,3-二氢苯并噻嗪-4-酮，收率良好。醛和酮的使用导致使用 HI 和 NH₄I 作为添加剂形成 2-取代和 2,2-二取代 2,3-二氢苯并噻嗪-4-酮。此外，易于制备的 1-（氯甲基）-1,4-二氮杂双环[2.2.2]辛烷-1-氯化铵 [DABCO·DCM] 首先被用作亚甲基源，用于选择性合成 2,3-二氢苯并噻嗪-4-酮和双-2,3-二氢苯并噻嗪-4-酮。