Trihaloisocyanuric Acid/Triphenylphosphine: An Efficient System for Regioselective Conversion of Epoxides into Vicinal Halohydrins and Vicinal Dihalides under Mild Conditions
作者:Marcio de Mattos、Vitor de Andrade
DOI:10.1055/s-0035-1560408
日期:——
vicinal chloro-/bromohydrins and vicinal dihalides by reaction with the system trihaloisocyanuric acid/triphenylphosphine in acetonitrile under mild and neutral conditions. The reactions proceed smoothly in high yield at room temperature and at reflux, respectively, over a short time. A new synthetic method has been developed for the regioselective conversion of epoxides to vicinal chloro-/bromohydrins
of the starting aldehydes was involved in this asymmetricfluorination. This paper describes the determination of the absolute stereochemistry of a resulting alpha-chloro-alpha-fluoroaldehyde. Some information about the substrate scope and a possible reaction mechanism are also described which shed more light on the nature of this asymmetricfluorination reaction.
Highly Regio- and Stereoselective Synthesis of β-Halohydrins from Epoxides Catalyzed with Ceric Ammonium Nitrate
作者:N. Iranpoor、F. Kazemi、P. Salehi
DOI:10.1080/00397919708003362
日期:1997.4
ceric ammonium nitrate can effectively catalyze ring opening of epoxides with halides under very mild conditions and easy procedure to give the corresponding β-chloro-and β-bromohydrins in excellent yields. The reactions occur with both substituted and unsubstituted quaternary ammonium halides and with high regio- and stereoselectivity. The reaction of opticallyactive styrene oxide with chloride ion was
摘要 Ce(IV)作为硝酸铈铵可以在非常温和的条件和简单的程序下有效地催化环氧化物与卤化物的开环,以优异的收率得到相应的β-氯代醇和β-溴代醇。该反应同时发生在取代和未取代的季铵卤化物中,并且具有高区域选择性和立体选择性。发现光学活性氧化苯乙烯与氯离子的反应具有高度立体定向性,并以 96% ee 提供相应的 β-卤代醇。
Solvent-free organic reactions on silica gel supports. Facile transformation of epoxides to β-halohydrins with lithium halides
The reaction of epoxides with lithiumhalides was efficiently promoted on the surface of silica gel in the absence of any solvent to give the corresponding β-halohydrins. The reactivity of lithiumhalides was shown to follow the order LiI> LiBr>> LiCl, and the reactivity of LiCl was dramatically increased by adding an equivalent amount of water to this system. On the other hand, a similar reaction