Synthesis of Substituted Phenyl Ketones via Pd-Catalysed hydrodechlorination of Their Polychlorinated Derivatives
作者:Andrea Bomben、Carlos A. Marques、Maurizio Selva、Pietro Tundo
DOI:10.1055/s-1996-4344
日期:1996.9
The following compounds, 2- and 3-methylacetophenones, 2- and 3-methylbenzophenones, and 2,2’-, 2,3’- and 3,3’-dimethylbenzophenones have been synthesized through a Pd-catalysed hydrodechlorination of the corresponding dichlorinated derivatives. The reaction has been carried out under multiphase conditions at 30-50°C, by bubbling H2 at atmospheric pressure into a biphasic system constituted by an organic substrate solution (isooctane solvent) and an aqueous alkaline solution (50% aq KOH), in the presence of Pd/C (5% wt) and Aliquat 336 (triaprylylmethylammonium chloride). Likewise, fluorinated aceto- and benzophenones (4-fluoro-3-methylacetophenone and 4-fluoro-3-methylbenzo-, 4-fluoro-2’,3-dimethylbenzo-, 4-fluoro-3,3’-dimethylbenzophenones) have been prepared starting from the corresponding chlorinated methylfluoro- and dimethylfluoro ketones. Under such conditions, the presence of the onium salt allows the reaction to proceed with a high chemoselectivity: chlorine is removed while both the reduction of the carbonyl group and/or fluorine removal are prevented.
通过钯催化的相应二氯化合物的氢脱氯反应,合成了以下化合物:2-和3-甲基乙酰苯酮、2-和3-甲基苯甲酮,以及2,2’-、2,3’-和3,3’-二甲基苯甲酮。反应在30-50°C的多相条件下进行,通过将氢气在常压下鼓泡通入由有机底物溶液(异辛烷溶剂)和水性碱性溶液(50% aq KOH)组成的双相系统中,在Pd/C(5% wt)和Aliquat 336(三吡啶基甲基氯化铵)的存在下进行。同样,氟化乙酰苯酮和苯甲酮(4-氟-3-甲基乙酰苯酮和4-氟-3-甲基苯甲酮、4-氟-2’,3-二甲基苯甲酮、4-氟-3,3’-二甲基苯甲酮)从相应的氯化甲基氟和二甲基氟酮出发制备。在这些条件下,季铵盐的存在使得反应具有高度的化学选择性:氯被移除,同时羰基的还原和/或氟的去除被阻止。