A new type of allylation: synthesis of β,γ-unsaturated ketones from α-halogenated aryl ketones using an allyltributyltin(IV)–tin(II) dichloride–acetonitrile system
作者:Makoto Yasuda、Makihiro Tsuchida、Akio Baba
DOI:10.1039/a708679b
日期:——
Allylation of α-halogenated aryl ketones with an allyltributyltinâtin dichlorideâacetonitrile system gave β,γ-unsaturated ketones in high yields via selective aryl rearrangement.
Site-Selective Aliphatic C–H Bromination Using <i>N</i>-Bromoamides and Visible Light
作者:Valerie A. Schmidt、Ryan K. Quinn、Andrew T. Brusoe、Erik J. Alexanian
DOI:10.1021/ja508469u
日期:2014.10.15
Transformations that selectively functionalize aliphatic C-H bonds hold significant promise to streamline complex molecule synthesis. Despite the potential for site-selective C-H functionalization, few intermolecular processes of preparative value exist. Herein, we report an approach to unactivated, aliphatic C-H bromination using readily available N-bromoamide reagents and visible light. These halogenations
Free-radical addition reaction of organoboranes to α, β-unsaturatedketones forms corresponding vinyloxyboranes (3) as the intermediate. Methanolysis of the dibromoderivatives which should be obtained by bromination of the initially formed vinyloxyboranes provides a convenient one-step synthetic procedure of α-bromoketones from organoboranes in good yields.
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.
Variation in the regioselectivity of levulinic acid bromination in ionic liquids
作者:Alexander G. Zavozin、Natalya E. Kravchenko、Nikolay V. Ignat’ev、Sergei G. Zlotin
DOI:10.1016/j.tetlet.2009.11.097
日期:2010.1
The reaction of levulinicacid and its esters with bromine in ionic liquids results in the formation of 3-bromo derivatives as the major products and not the 5-bromo substituted isomers, which are typically formed in organic solvents. The bromination of levulinicacid in ionic liquids in the presence of urea leads to the formation of 5-bromolevulinic acid.