A novel protocol for the efficient activation of the Beckmannrearrangement utilizing the readily available sulfuryl fluoride (SO2F2 gas) is reported. The substrate scope of this methodology has been demonstrated by 37 examples with good to nearly quantitative isolated yields in a short time. A tentative mechanism was proposed involving formation and elimination of sulfonyl ester.
报道了一种利用容易获得的硫酰氟(SO 2 F 2气体)有效激活贝克曼重排的新方案。该方法的底物范围已通过37个实例证明,并在短时间内获得了良好至近乎定量的分离产率。提出了一种尝试性的机制,涉及形成和消除磺酰基酯。
CuCl2-catalyzed N O bond cleavage of oxime esters: Approach to imidazoheterocycles and furo[3,2-c]chromenyl fused imidazoles
作者:Santosh K. Gudimella、Amanpreet Kaur、Ram Kumar、Sampak Samanta
DOI:10.1016/j.tetlet.2020.152147
日期:2020.7
An articulate approach to a diverse set of imidazoheterocycles in good to high yields via a copper-catalyzed aza-annulation of several oxime esters with a group of 2-amino-azaarenes was developed. The above cyclization reaction probably proceeds via a single electron transfer process which embodies a new technique for creating two new CN bonds for imidazole ring synthesis. Gratifyingly, the implementation
通过用几种肟酯与一组2-氨基氮杂氮杂铜进行铜催化的氮杂环化反应,开发了一种以良好至高收率的多种咪唑杂环杂环的铰接方法。上述环化反应可能是通过单电子转移过程进行的,这体现了一种新技术,该技术为咪唑环合成生成两个新的C N键。令人欣慰的是,该化学方法的实施可以进一步扩展为通过连续的C N键形成,合成带有呋喃[3,2- c ]亚甲基部分的新型稠合咪唑,随后是C(sp 2)-H功能化/ 5-内切-乙氧基环化(CC和C在铜(II)作为π亲电Lewis酸催化剂的情况下,原位生成带有环状烯酮的稠合咪唑。
Beckmann rearrangement of oximes using pivaloyl chloride/DMF complex
A new complex of pivaloylchloride and DMF was found to be very effective for converting ketoximes into their corresponding amides or lactams with excellent conversion via the Beckmann rearrangement. This method offers significant advantages such as efficiency and mild reaction conditions with shorter reaction time.
The Beckmann Rearrangement Executed by Visible-Light-Driven Generation of Vilsmeier–Haack Reagent
作者:Lal Yadav、Vishnu Srivastava、Arvind Yadav
DOI:10.1055/s-0033-1340623
日期:——
A new and efficient approach for the Beckmannrearrangement is reported. The protocol involves eosin Y catalyzed, visible-light-mediated in situ formation of the Vilsmeier–Haack reagent from CBr4 and a catalytic amount of DMF for activation of ketoximes at room temperature. The method is operationally simple and avoids the need for any corrosive, water-sensitive reagents and elevated temperatures.
报道了一种新的、有效的贝克曼重排方法。该方案涉及伊红 Y 催化、可见光介导的 CBr4 原位形成 Vilsmeier-Haack 试剂和催化量的 DMF,用于在室温下激活酮肟。该方法操作简单,不需要任何腐蚀性、对水敏感的试剂和升高的温度。