Asymmetric Schmidt Reaction of Hydroxyalkyl Azides with Ketones
作者:Kiran Sahasrabudhe、Vijaya Gracias、Kelly Furness、Brenton T. Smith、Christopher E. Katz、D. Srinivasa Reddy、Jeffrey Aubé
DOI:10.1021/ja0348896
日期:2003.7.1
asymmetric equivalent of the Schmidtreaction permits stereocontrol in ring expansions of symmetrical cyclohexanones. The procedure involves the reaction of chiral 1,2- and 1,3-hydroxyalkyl azides with ketones under acid catalysis; the initial reaction affords an iminium ether that can be subsequently opened with base. A systematic study of this reaction is reported, in which ketone substrates, chiral hydroxyalkyl
Stereoselective one-pot synthesis of β-alkylsulfide enol esters. Base-triggered rearrangement under mild conditions
作者:Adrián A. Heredia、Silvia M. Soria-Castro、Lydia M. Bouchet、Gabriela Oksdath-Mansilla、Cecilia A. Barrionuevo、Daniel A. Caminos、Fabricio R. Bisogno、Juan E. Argüello、Alicia B. Peñéñory
DOI:10.1039/c4ob01011f
日期:——
A stereoselective one-pot procedure was developed to prepare S-substituted (Z)-enol esters through a base-triggered rearrangement. This transition metal-free multicomponent approach can be performed under an air atmosphere at room temperature, tolerates a wide set of chemical functionalities and generally affords high isolated yields. The (Z)-selectivity arises from the [1,4]-S- to O-acyl migration
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。
A mild and efficient procedure for α-bromination of ketones using N-bromosuccinimide catalysed by ammonium acetate
Cyclic ketones reacted with N-bromosuccinimide (NBS) catalysed by NH4OAc in Et2O at 25 °C to give the corresponding α-brominated ketones in good yields, while acyclic ketones were efficiently brominated in CCl4 at 80 °C.
Directed regioselectivity of bromination of ketones with NBS: solvent-free conditions versus water
作者:Igor Pravst、Marko Zupan、Stojan Stavber
DOI:10.1016/j.tetlet.2006.04.119
日期:2006.7
The reaction conditions employed directed the site of functionalisation of ketones with NBS: under solvent-free conditions α-bromination was the exclusive process, while in water, ring functionalisation occurred in the case of methoxy substituted aromatic ketones.