Microwave-promoted palladium-catalyzed coupling reactions
Microwave-promoted palladium-catalyzed coupling reactions
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DOI：
10.1021/jo9612990
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发表时间：
1996-12-27
影响因子：
3.6
通讯作者：
Hallberg, A
中科院分区：
文献类型：
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作者：
Larhed, M;Hallberg, A
芳基卤化物或芳基三氟甲磺酸酯与烯烃的分子间Heck反应在有机合成中是极其重要的。1除了少数例外，2-4大多数用于偶联的底物需要70-100 ℃的反应温度和数小时至数天的反应时间才能完全转化。由于催化体系的崩溃，通过提高温度来减少反应时间的尝试很少有效。1d，5，6因此，获得允许快速偶联反应的替代和通用合成程序将是有价值的，特别是关于这些程序在组合化学中的明显应用。7.已经报道了微波辐射益处的许多实例，包括减少反应时间和电费。8所进行的转化包括双键的反应，包括由拉尼或Pd/C催化的氢化，9在CuCl和TMEDA存在下的氢化硅烷化，10以及由Cu（I）络合物催化的氯化烃的加成。11此外，通过Baylis-Hillman反应的乙烯基取代可以在显著减少反应时间的情况下实现。12本研究致力于研究微波辐射对Heck芳基化反应的影响，并简要研究了相关的Suzuki 13和Stille 14反应，其中不稳定的有机过渡金属中间体在催化循环中起着关键作用。我们在此报告，这些钯催化的偶联反应可以完成的反应时间范围从2.8至7.0分钟，并在大多数情况下观察到良好的产率。
The intermolecular Heck reaction of aryl halides or aryl triflates with olefins is of the utmost importance in organic synthesis. 1 With a few exceptions, 2-4 most substrates for coupling require reaction temperatures of 70-100 C1e and reaction times ranging from hours to days for full conversion. Attempts to reduce the reaction time by enhancing the temperature are seldom effective due to collapse of the catalytic system. 1d, 5, 6 Therefore, access to alternative and general synthetic procedures that permit fast coupling reactions would be valuable, in particular with respect to the obvious applications of such procedures to combinatorial chemistry. 7 Many examples of the benefits of microwave irradiation, including reduction of reaction times and electricity costs, have been reported. 8 Among the transformations performed are reactions of double bonds, including hydrogenation, catalyzed by RaNi or Pd/C, 9 hydrosilylation, in the presence of CuCl and TMEDA, 10 and addition of chlorinated hydrocarbons, catalyzed by a Cu (I) complex. 11 Furthermore, vinylic substitution by the Baylis-Hillman reaction can be achieved with substantial reduction of reaction times. 12 The present investigation has been devoted to a study of the effect of microwave irradiation on the Heck arylation and briefly on the related Suzuki13 and Stille14 reactions, in which labile organotransition metal intermediates play a pivotal role in the catalytic cycle. We herein report that these palladium-catalyzed coupling reactions can be accomplished with reaction times ranging from 2.8 to 7.0 min and that good yields were observed in most cases.