Cross-Coupling between Hydrazine and Aryl Halides with Hydroxide Base at Low Loadings of Palladium by Rate-Determining Deprotonation of Bound Hydrazine.
Cross-Coupling between Hydrazine and Aryl Halides with Hydroxide Base at Low Loadings of Palladium by Rate-Determining Deprotonation of Bound Hydrazine.
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DOI：
10.1002/anie.202011161
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发表时间：
2021-01-04
期刊：
影响因子：
--
通讯作者：
Hartwig JF
中科院分区：
文献类型：
--
作者：
Wang JY;Choi K;Zuend SJ;Borate K;Shinde H;Goetz R;Hartwig JF
我们报道了Pd催化的肼与（杂）芳基氯化物和溴化物的C-N偶联，以形成芳基肼，催化剂负载量低至100 ppm的Pd和KOH。机理研究揭示了两种催化剂的静止状态：芳基氢氧化钯（II）和芳基氯化钯（II）。这些化合物存在于两个相互连接的催化循环中，并与肼和碱或单独的肼反应得到产物。氢氧化物与肼形成芳基的选择性低于二芳基肼，催化反应也低于氯络合物。相反，氯络合物的选择性与催化反应的选择性紧密匹配，表明芳基肼是由该络合物衍生的。动力学研究表明，偶联过程发生由限速脱质子化的肼结合的芳基氯化钯（II）配合物，得到芳基钯（II）酰肼配合物。本文报道了一种以氢氧化钾为碱，钯催化剂负载量低至100 ppm时，（杂）芳基卤与肼偶联生成（杂）芳基肼的方法，并沿着了详细的机理数据，揭示了控制反应速率和选择性的因素。两种催化剂的静止状态进行观察，但一个主要的途径涉及限速脱质子肼绑定到芳基氯化钯（II）络合物发生。
We report the Pd-catalyzed C–N coupling of hydrazine with (hetero)aryl chlorides and bromides to form aryl hydrazines with catalyst loadings as low as 100 ppm of Pd and KOH. Mechanistic studies revealed two catalyst resting states: an arylpalladium(II) hydroxide and arylpalladium(II) chloride. These compounds are present in two interconnected catalytic cycles and react with hydrazine and base or hydrazine alone to give the product. The selectivity of the hydroxide complex with hydrazine to form aryl over diaryl hydrazine was lower than that of the chloride complex, as well as the catalytic reaction. In contrast, the selectivity of the chloride complex closely matches that of the catalytic reaction, indicating that the aryl hydrazine is derived from this complex. Kinetic studies show that the coupling process occurs by rate-limiting deprotonation of a hydrazine-bound arylpalladium(II) chloride complex to give an arylpalladium(II) hydrazido complex. A practical coupling of (hetero)aryl halides with hydrazine to form (hetero)aryl hydrazines with loadings down to 100 ppm of a Pd catalyst and KOH as base is reported, along with detailed mechanistic data revealing the factors that control the rate and selectivity. Two catalyst resting states are observed, but one major pathway involving rate-limiting deprotonation of hydrazine bound to an arylpalladium(II) chloride complex occurs.
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影响因子：
4.3
作者：
Crawford, Sarah M.;Lavery, Christopher B.;Stradiotto, Mark
通讯作者：
Stradiotto, Mark
影响因子：
4.9
作者：
Alsabeh, Pamela G.;Lundgren, Rylan J.;Stradiotto, Mark
通讯作者：
Stradiotto, Mark
影响因子：
15
作者：
Alvaro E;Hartwig JF
通讯作者：
Hartwig JF
影响因子：
64.8
作者：
Hartwig, John F.
通讯作者：
Hartwig, John F.
影响因子：
5.2
作者：
Green RA;Hartwig JF
通讯作者：
Hartwig JF