Chemical Oxidation Studies of β-Hydroxy-sulfides withtris(4-Bromophenyl)aminium Hexachloroantimonate: Diastereoselective Sulfoxide Obtaining and Pinacol-Type Rearrangement
摘要:
The chemical oxidation of some beta-hydroxy-sulfides in the presence of tris(4-bromo-phenyl)aminium hexachloroantimonate (TBPA) is reported. The oxidation of 2-ethylsulfanyl-cyclohexan-1-ol (cis- and trans-) resulted the corresponding sulfoxides with good diastereoselectivity (d.e.; approximate to50%) and for 2-methyl-2-ethylsulfanyl-cyclohexan-1-ol and 2-ethylsulfanyl-1,2-diphenyl-ethanol, the corresponding nonsulfanylated ketones (61-75%) and ethyl ethanethiolsulfonate (51-65%) were obtained via oxidative cleavage and pinacol-type rearrangement.
Copper(I)-Catalyzed Addition of Grignard Reagents to in Situ-Derived <i>N</i>-Sulfonyl Azoalkenes: An Umpolung Alkylation Procedure Applicable to the Formation of Up to Three Contiguous Quaternary Centers
作者:John M. Hatcher、Don M. Coltart
DOI:10.1021/ja100932q
日期:2010.4.7
that has considerable potential with regard to catalysis and the direct incorporation of functionality not amenable to the use of enolate chemistry. Herein, we describe the first Cu(I)-catalyzed addition of Grignardreagents to in situ-derived N-sulfonyl azoalkenes. This method is remarkable in its ability to deliver highly sterically hindered compounds that would be difficult or impossible to synthesize
Halogenation of Carbonyl Compounds by an Ionic Liquid, [AcMIm]X, and Ceric Ammonium Nitrate (CAN)
作者:Brindaban C. Ranu、Laksmikanta Adak、Subhash Banerjee
DOI:10.1071/ch07061
日期:——
An ionic liquid, acetylmethylimidazolium halide ([AcMIm]X), in combination with ceric ammoniumnitrate promotes halogenations of a wide variety of ketones and 1,3-keto esters at the α-position. The ionic liquid acts here as reagent as well as reaction medium, and thus the reaction does not require any organic solvent or conventional halogenating agent. The reaction is completely arrested when the radical
离子液体乙酰甲基咪唑鎓卤化物 ([AcMIm]X) 与硝酸铈铵结合可促进多种酮和 1,3-酮酯在 α 位的卤化。离子液体在此既充当试剂又充当反应介质,因此该反应不需要任何有机溶剂或常规卤化剂。当使用自由基猝灭剂 TEMPO 时,反应完全停止。还提出了一种似是而非的激进机制。
Catalytic Effect of Five-Coordinate Organotin Bromide or Tetraphenylstibonium Bromide on the Chemo- and Stereoselective Addition of Tin Enolate to<i>α</i>-Halo Ketone
tetraphenylstibonium bromide, similarly promoted the selective addition of tin enolates to the carbonyl moiety in α-halo ketones. The reaction with 2-chlorocyclohexanones and the enolates gave chlorohydrins bearing chloro- and hydroxyl groups in the cis-conformation. Chemoselective carbonyl addition to acyclic α-halo ketones was followed by effective cyclization to 2-(2-oxoethyl)oxiranes. The structural and bonding
Room temperature ionic liquids (ILs) are used as a green recyclable reaction media for the α-monohalogenation of 1,3-diketones, β-keto-esters and cyclic ketones with N-halosuccinimides in excellent yields in the absence of a catalyst. The recovered ionic liquid was reused five to six times with consistent activity.
The electrochemical oxidation of 2,2-disubstituted cyclicketones was carried out using Et3N-5HF as the electrolyte. The selective cleavage of the carbon-carbon bond between the carbonyl carbon and substituted α-carbon took place and fluorocarboxylicacidesters (2) were obtained in good yields after the esterification of the resulting fluoroacyl fluorides (1).