Department of Chemical Sciences, Tezpur University, Napaam, Assam, 784028, India.
Inorganic Materials and Catalysis Division, CSIR-Central Salt and Marine Chemical Research Institute, G. B. Marg, Bhavnagar, Gujarat, 364002, India.
Chem Asian J. 2020 Mar 16;15(6):926-932. doi: 10.1002/asia.201901760. Epub 2020 Feb 27.
Herein we disclosed the use of a remote 'imidazole'-based precatalyst [(para-cymene)Ru (L)Cl] , C-1 where L=2-(4-substituted-phenyl)-1H-imidazo[4,5-f] phenanthroline) for the selective oxidation of a variety of alkyl arenes/heteroarenes and alcohols to their corresponding aldehydes or ketones in presence of tert-butyl hydroperoxide (TBHP). The remote 'imidazole' moiety present in the complex facilitates the activation of oxidant and subsequent generation of active species via the release of para-cymene from C-1, which in-turn was less effective without the 'imidazole' moiety. The mechanistic features of C-1 promoted oxidation of alkyl arenes were also assessed from spectroscopic, kinetic, and few control experiments. The substrate scope for C-1 promoted oxidation reaction was assessed based on the selective oxidation of 27-different alkyl arenes/heteroarenes and 25 different alcohols to their corresponding aldehydes/ketones in moderate to good yields.
在此，我们披露了一种远程“咪唑”基前催化剂[(对伞花烃)Ru(L)Cl]，C-1，其中 L=2-(4-取代苯基)-1H-咪唑[4,5-f]菲咯啉），用于在叔丁基过氧化氢（TBHP）存在下，选择性氧化各种烷基芳烃/杂芳烃和醇类为相应的醛或酮。配合物中存在的远程“咪唑”部分通过从 C-1 中释放对伞花烃来促进氧化剂的活化，并随后生成活性物种，而没有“咪唑”部分时则效果较差。还通过光谱、动力学和一些对照实验评估了 C-1 促进的芳基烷基氧化的反应机理特征。根据 27 种不同的烷基芳烃/杂芳烃和 25 种不同的醇类在中等至良好收率下选择性氧化为相应的醛/酮，评估了 C-1 促进的氧化反应的底物范围。
