A novel protocol for the activation of the Beckmannrearrangement utilizing the readily available and economical geminal dichloroimidazolidinediones (DCIDs) on a substoichiometric scale (10 mol %) has been developed. A unique self-propagating mechanism for the substoichiometric dichloroimidazolidinedione-activated transformation was proposed and validated. The substrate scope of the developed protocol
o-Phthalic Anhydride/Zn(OTf)2 co-catalyzed Beckmann rearrangement under mild conditions
作者:Ze-Feng Xu、Teng Zhang、Wenjun Hong
DOI:10.1016/j.tet.2019.04.056
日期:2019.6
o-Phthalic anhydride/Zn(OTf)2 co-catalyzed Beckmann rearrangement was developed, producing the corresponding amide in up to 99% yield with acid-sensitive functionalities tolerated well, and the scale of the reaction could be enlarged to 77 mmol and the excellent yield was maintained. A successive procedure was developed. Moreover, the reaction was carried out at rt under nearly neutral conditions,
A mild process using a combination of TMSCl and NaI in acetonitrile is used to regenerate carbonyl compounds from a variety of dithiane and dithiolane derivatives. This easy to handle and inexpensive protocol is also efficient to deprotect oxygenated and mixed acetals as 1,3-dioxanes, 1,3-dioxolanes and 1,3-oxathianes quantitatively. As a possible extension of this method, it was also showed that
在乙腈中使用 TMSCl 和 NaI 组合的温和工艺用于从各种二噻烷和二硫戊环衍生物中再生羰基化合物。这种易于操作且价格低廉的方案还可以有效地将含氧和混合缩醛作为 1,3-二氧六环、1,3-二氧戊环和 1,3-氧杂环己烷进行定量脱保护。作为该方法的可能扩展,还表明作为腙、N-甲苯磺酰腙和酮时的氮化底物在这些条件下反应良好,以高产率得到预期的酮。本文提出的方法是现有方法的一个很好的替代方案,因为它不使用金属、氧化剂、还原剂、酸性或碱性介质,并且以高产率获得酮产物。
Beckmann Rearrangement of Ketoxime Catalyzed by N-methyl-imidazolium Hydrosulfate
Beckmannrearrangement of ketoxime catalyzed by acidic ionic liquid-N-methyl-imidazolium hydrosulfate was studied. Rearrangement of benzophenone oxime gave the desirable product with 45% yield at 90 °C. When co-catalyst P₂O₅ was added, the yield could be improved to 91%. The catalyst could be reused three cycles with the same efficiency. Finally, reactions of other ketoximes were also investigated
研究了酸性离子液体-N-甲基咪唑鎓硫酸氢盐催化酮肟的贝克曼重排。二苯甲酮肟的重排得到所需产物,在90℃下产率为45%。当加入助催化剂P 2 O 3时,产率可以提高到91%。该催化剂可以以相同的效率重复使用三个循环。最后,还研究了其他酮肟的反应。
Vanadium-Catalyzed Oxidative C(CO)–C(CO) Bond Cleavage for C–N Bond Formation: One-Pot Domino Transformation of 1,2-Diketones and Amidines into Imides and Amides
作者:Chander Singh Digwal、Upasana Yadav、P. V. Sri Ramya、Sravani Sana、Baijayantimala Swain、Ahmed Kamal
DOI:10.1021/acs.joc.7b00950
日期:2017.7.21
identified that enables their transformation into imides and amides. The reaction proceeds by dual acylation of amidines via oxidative C(CO)–C(CO) bond cleavage of 1,2-diketones to afford N,N′-diaroyl-N-arylbenzamidine intermediates. In the reaction, these intermediates are easily hydrolyzed into imides and amides through vanadium catalysis. This method provides a practical, simple, and mild synthetic