Ruthenium(III)-Catalyzed β-Alkylation of Secondary Alcohols with Primary Alcohols

Abstract

A Ru­(III)-NNN complex bearing a pyridyl-supported pyrazolyl-imidazolyl ligand was synthesized and utilized as the catalyst for the direct β-alkylation of secondary alcohols with primary alcohols. β-Alkylated secondary alcohols were obtained in moderate to high yields with water formed as the byproduct through a hydrogen borrowing pathway. The present protocol provides a concise atom-economical and environmentally benign method for C–C bond formation.

Phosphine Ligand‐Free Ruthenium Complexes as Efficient Catalysts for the Synthesis of Quinolines and Pyridines by Acceptorless Dehydrogenative Coupling Reactions

“…In the presence of KOtBu, the condensation of aminobenzaldehyde Taken previous reports [40][41][42][43][44]82,88] into account, we propose a possible mechanism for Ru catalyzed ADC reaction as depicted in…”

“…Complexes 1 b and 2 b showed similar catalytic activity for the same ADC reactions, indicating that a Ru(II) species is the true catalytically active species, consistent with previous reports. [82,88] The precatalyst Ru(III) complex 1 is reduced in situ to an active Ru(II) species in the presence of KOtBu and alcohol under the reaction conditions, that was further confirmed by electrospray ionization mass spectrometry (ESI-MS), see following. Only 4 a as a substrate under standard reaction conditions generated the dehydrogenative product acetophenone (4 a') and homo-coupling product 1,3-diphenylbutan-1-one (4 a'') (Scheme S1 in the Supporting Information).…”

“…The air-and moisture-stable phosphine-free Ru(III) complexes are easily prepared in a large scale via reaction [ of RuCl 3 with pincer ligands, but have been paid much less attention for ADC or auto-transfer-hydrogen (ATH) reactions. [82] Recently, we have been interested in ADC and ATH reactions catalyzed by Cu(I)/Ni(II) N-heterocycle thiolate clusters via ligand-metal cooperative catalysis. [59,72,83] In this work, we have chosen and prepared a family of NH functionalized N^N^N pincer ligands (L1 = 6-(1H-pyrazol-1-yl)-N-(pyridin-2-yl)pyridin-2amine; L2 = 6-(3,5-dimethyl-1H-pyrazol-1-yl)-N-(pyridin-2-yl)pyridin-2-amine; [84] L3 = N-(pyridin-2-yl)-6-(3-(trifluoromethyl)-1Hpyrazol-1-yl)pyridin-2-amine; L4 = 6-(3-phenyl-1H-pyrazol-1-yl)-N-(pyridin-2-yl)pyridin-2-amine) and the methyl-substituted derivative 6-(3,5-dimethyl-1H-pyrazol-1-yl)-N-methyl-N-(pyridin-2yl)pyridin-2-amine (L2 Me ) [84] for the catalytic performance comparison.…”

Advances in One-Pot Synthesis through Borrowing Hydrogen Catalysis

“…A second recent example on Ru(III) catalyzed β-alkylation of secondary alcohols with primary alcohols was reported by Wang et al In this case, the catalyst was prepared by mixing RuCl 3 and the ligand 28 in refluxing ethanol to give the catalyst 29 (Scheme 11). 85 The complex was characterized by HRMS, elemental analysis, and IR. Indeed the HRMS analysis showed a peak assigned to the fragment ([M − Cl] + ), whereas the IR spectrum showed a stretching vibration that shifted from 1580 cm −1 from the original ligand to 1609 cm −1 due to the coordination effect with the metal cation.…”

Progress in Ruthenium-Catalyzed Dehydrogenation C—C/C—N Bonds Coupling Reactions from Alcohols

“…Synthesis of alcohols via C-C bond coupling catalyzed by ruthenium from alcohols 等反应, 最后得到 2-芳基丙醇.2016 年 Yu 等[77] 研究了以伯醇作为烷基化试剂与仲 醇在钌催化剂 24 作用下发生 C-C 偶联制备 β 烷基取 代的仲级醇, 收率 52%～91%, 该反应催化剂 TOF＝15 h -1 , 原子利用率高, 条件温和, 适用范围广(Eq. 39).…”