Epoxide Hydrogenolysis Catalyzed by Ruthenium PNN and PNP Pincer Complexes
Epoxide Hydrogenolysis Catalyzed by Ruthenium PNN and PNP Pincer Complexes
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DOI：
10.1021/acs.organomet.2c00068
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发表时间：
2022-04-25
期刊：
影响因子：
2.8
通讯作者：
Chianese, Anthony R.
中科院分区：
文献类型：
--
作者：
Kirlin, Fallyn L.;Borden, Olivia J.;Chianese, Anthony R.
在过去的几年里，金属催化环氧化物氢解生成醇的研究进展很快，一些催化剂选择性地提供线状(反Markovnikov)产物，另一些催化剂提供支化(Markovnikov)产物。目前已知的支化选择性催化剂体系需要1%或更高的催化剂负载量，并且通常需要强碱添加剂。本文报道了含N-H官能团的PNN-和PNP-Ru钳形配合物对环氧化物的支化选择性氢解反应具有很高的活性。以异丙醇为溶剂，催化剂用量低至0.03%，无强碱性添加剂，支化醇产品收率高。具有直接连接的二次碳的环氧化物对支化产物具有非常高的选择性(>；99：1)。芳基取代的环氧化物给出支化：线性比率从2.7到19.0。对于芳基环氧化物，PNP-Ru催化剂比PNN-Ru催化剂表现出更大的对支化产物的偏好，而具有丰富电子取代基的底物对支化产物的偏好较低
The metal-catalyzed hydrogenolysis of epoxides to give alcohols has advanced rapidly in the past several years, with some catalysts selectively giving linear (anti-Markovnikov) products and other catalysts providing branched (Markovnikov) products. The currently known branched-selective catalyst systems require catalyst loadings of 1% or higher and typically require a strong base additive. We report herein that PNN- and PNP-ruthenium pincer complexes containing N-H functional groups are highly active for branched-selective hydrogenolysis of epoxides. When isopropyl alcohol is used as the solvent, excellent yields of the branched alcohol products are obtained without strongly basic additives, using catalyst loadings as low as 0.03%. Epoxides with a directly attached secondary carbon give a very high (>99:1) selectivity for the branched products. Aryl-substituted epoxides give branched:linear ratios ranging from 2.7 to 19.0. For aryl epoxides, a PNP-Ru catalyst showed a greater preference for the branched product than a PNN-Ru catalyst, and substrates with electron-rich aryl substituents showed a lower preference for the branched product