Electrocyclic Ring‐Opening of 1,2,4‐Oxadiazole[4,5‐
<i>a</i>
]piridinium Chloride: a New Route to 1,2,4‐Oxadiazole Dienamino Compounds
作者:Stefano Carella、Misal Giuseppe Memeo、Paolo Quadrelli
DOI:10.1002/open.201900230
日期:2019.9
1,2,4‐Oxadiazole[4,5‐a]piridinium chloride adds nucleophiles to undergo electrocyclic ring opening affording 1,2,4‐oxadiazole dienamino derivatives. These pyridinium salts represent a special class of Zincke salts that are prone to rearrange when treated with primary amines or in the presence of bicarbonate to give the pyridones. The pivotal tuning of the experimental conditions leads to a straightforward
1,2,4-氧杂二唑[4,5- a ]氯化吡啶鎓使亲核试剂发生电环开环,从而得到1,2,4-恶二唑二烯氨基衍生物。这些吡啶鎓盐代表一类特殊的Zincke盐,当用伯胺处理或在碳酸氢盐存在下容易产生吡啶酮时,它们倾向于重排。实验条件的关键调整可直接合成有价值的1,2,4-恶二唑二烯胺衍生物。还根据NMR实验和理论计算对机理进行了讨论。
Hypervalent Iodine–Catalyzed Cycloaddition of Nitrile Oxides to Alkenes
作者:Changbin Xiang、Tingting Li、Jie Yan
DOI:10.1080/00397911.2013.834364
日期:2014.3.4
convenient method for preparation of isoxazolines was developed by a catalytic cycloaddition of nitrileoxides generated in situfrom aldoximes to alkenes in the presence of a catalytic amount of iodobenzene. In this protocol, iodobenzene was first oxidized into the hypervalent iodine intermediate by m-chloroperbenzoic acid, which then transformed aldoximes into nitrileoxides, and a 1,3-dipolar cycloaddition
Oxidation of Oximes to Nitrile Oxides with Hypervalent Iodine Reagents
作者:Brian A. Mendelsohn、Shelley Lee、Simon Kim、Florian Teyssier、Virender S. Aulakh、Marco A. Ciufolini
DOI:10.1021/ol900194v
日期:2009.4.2
catalytic amount of TFA efficiently oxidizes aldoximes to nitrile oxides. The latter may be trapped in situ with olefins in a bimolecular or an intramolecular mode. The new method enables the execution of tandem oxidative dearomatization of phenols/intramolecular nitrile oxide cycloaddition sequences leading to useful synthetic intermediates.
Synthetic aspects of the oxidative amidation of phenols
作者:Huan Liang、Marco A. Ciufolini
DOI:10.1016/j.tet.2010.05.020
日期:2010.7
action of hypervalent iodine reagents. The reagent, (diacetoxyiodo)benzene (‘DIB’) is especially effective in these transformations. This paper focuses on techniques for the desymmetrization of the dienoes thus obtained, leading to the stereocontrolled creation of N-substituted spiro carbons. The methodology creates new opportunities in alkaloid synthesis, as apparent from a number of examples.
Reaction of 2-Isoxazolines with Organolithiums in the Presence of Boron Trifluoride
作者:Hidemitsu Uno、Tetsuya Terakawa、Hitomi Suzuki
DOI:10.1246/bcsj.66.2730
日期:1993.9
In the presence of borontrifluoride, 3,4,5-tri-, 3,5,5-tri and 3,5-disubstituted 2-isoxazolines underwent nucleophilic addition of alkyl- and aryllithiums to give 3,3,4,5-, 3,3,5,5-, and 3,3,5-substituted isoxazolidines in moderate to good yields. On the other hand, in the case of 3,4,5,5-tetrasubstituted isoxazolines, the addition did not proceed at all but proton abstraction took place to afford