Palladium-Catalyzed Cross-Coupling Reactions of Potassium Alkenyltrifluoroborates with Organic Halides in Aqueous Media
Palladium-Catalyzed Cross-Coupling Reactions of Potassium Alkenyltrifluoroborates with Organic Halides in Aqueous Media
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DOI：
10.1021/jo802356n
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发表时间：
2009-03-20
影响因子：
3.6
通讯作者：
Najera, Carmen
中科院分区：
文献类型：
--
作者：
Alacid, Emilio;Najera, Carmen
以Pd(OAc)(2)为预催化剂，K2CO3为碱，四丁基溴化铵(TBAB)为添加剂，在常规或微波加热条件下，将乙烯基钾和烯基三氟硼酸钾与芳基和杂芳基溴化物发生交叉偶联反应，得到苯乙烯类、二苯乙烯类和烯基苯类化合物。在50℃、0.1mol%Pd负载量的丙酮-水(3：2)中，以氢氧化钾为碱，这些硼酸盐可以与烯丙基和苄基氯化物交叉对映选择性偶联，分别得到相应的1，4-二烯和烯丙基芳烃。这些简单的不含磷化氢的反应条件允许通过萃取分离含58-105ppm钯的产物，在长达五次的运行中从水相中回收钯。
Potassium vinyl and alkenyltrifluoroborates are cross-coupled with aryl and heteroaryl bromides using 1 mol % Pd loading of 4-hydroxyacetophenone oxime derived palladacycle or Pd(OAc)(2) as precatalysts, K2CO3 as base, and TBAB as additive and water reflux under conventional or microwave heating to afford styrenes, stilbenoids, and alkenyl benzenes. These borates can be cross-coupled diastereoselectively with allyl and benzyl chlorides using KOH as base in acetone-water (3:2) at 50 degrees C and 0.1 mol % Pd loading, giving the corresponding 1,4-dienes and allylarenes, respectively. These simple phosphine-free reaction conditions allow the palladium recycling from the aqueous phase during up to five runs by extractive separation of the products, which contain 58-105 ppm of Pd.