Han Xiaoqing, Wang Xiang, Pei Tao, Widenhoefer Ross A
P. M. Gross Chemical Laboratory, Duke University, Durham, North Carolina 27708-0346, USA.
Chemistry. 2004 Dec 3;10(24):6333-42. doi: 10.1002/chem.200400459.
Reaction of 3-butenyl beta-keto esters or 3-butenyl alpha-aryl ketones with a catalytic amount of [PdCl2(CH3CN)2] (2) and a stoichiometric amount of Me3SiCl or Me3SiCl/CuCl2 in dioxane at 25-70 degrees C formed 2-substituted cyclohexanones in good yield with high regioselectivity. This protocol tolerated a number of ester and aryl groups and tolerated substitution at the allylic, enolic, and cis and trans terminal olefinic positions. In situ NMR experiments indicated that the chlorosilane was not directly involved in palladium-catalyzed hydroalkylation, but rather served as a source of HCl, which presumably catalyzes enolization of the ketone. Identification of HCl as the active promoter of palladium-catalyzed hydroalkylation led to the development of an effective protocol for the hydroalkylation of alkyl 3-butenyl ketones that employed sub-stoichiometric amounts of 2, HCl, and CuCl2 in a sealed tube at 70 degrees C.
3-丁烯基β-酮酯或3-丁烯基α-芳基酮与催化量的[PdCl2(CH3CN)2] (2)以及化学计量的Me3SiCl或Me3SiCl/CuCl2在二氧六环中于25至70摄氏度反应，以良好的产率和高区域选择性生成2-取代环己酮。该方法耐受多种酯基和芳基，并且耐受烯丙基、烯醇式以及顺式和反式末端烯烃位置的取代。原位核磁共振实验表明氯硅烷不直接参与钯催化的氢烷基化反应，而是作为HCl的来源，HCl大概催化了酮的烯醇化。将HCl鉴定为钯催化氢烷基化反应的活性促进剂，从而开发出一种有效的方法，用于在密封管中于70摄氏度使用亚化学计量的2、HCl和CuCl2对烷基3-丁烯基酮进行氢烷基化反应。
