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Treatment of Ru3(CO)12 with one equivalent of 2‐indolyl‐6‐pyridinyl‐alcohol ligands 2‐(C8H6N)‐6‐(CR1R2OH)C5H3N (R1 = R2 = Me (L1H); R1 = R2 = C2H5 (L2H); R1, R2 = −(CH2)4‐ (L3H);& R1, R2 = −(CH2)5‐ (L4H)) in refluxing THF afforded the corresponding trinuclear ruthenium clusters L(μ2‐H)Ru3(CO)9 (1a–1d), respectively. All the novel Ru complexes were well characterized by NMR, elemental analyses and IR spectra. Structures of complexes 1a, 1c, and 1d were further determined by X‐ray crystallographic studies. Complexes 1a–1d were applied to catalytic Oppenauer‐type oxidation of secondary alcohols with acetone as oxidant, and complex 1a was found to be the most efficient catalyst. [ABSTRACT FROM AUTHOR]

In recent years, there has been an increasing interest in using alcohols as alkylating agents for C−C and C−N bond‐forming processes employing mainly TM‐catalysts. Although BH‐catalysis looks like a green atom economy process since water is the only by‐product, it often suffers from one or more drawbacks, such as the use of expensive noble metal complexes, capricious ligands, and toxic organic solvents. Therefore, straightforward, efficient, atom economy and environmentally benign alternative protocols are desirable. This review aims to summarize the current knowledge within the published literature about dehydrative processes developed without TM‐catalysts. The most recent contributions to this topic have been reviewed keeping into account the new findings reported in this area. The features, strengths, and limitations of these alcohol‐based C−C and C−N bond‐forming processes has also been taken into account. [ABSTRACT FROM AUTHOR]

Although zinc catalysis is widely used in organic synthesis, very few studies on the dinuclear zinc mechanism have been reported. Here, a dinuclear zinc pathway is proposed for the Zn(OTf)2-catalyzed oxidative coupling of aldehydes with terminal alkynes. DFT calculations revealed that the deprotonation of the terminal alkyne would preferentially lead to the formation of a dinuclear zinc intermediate. The nucleophilic addition of this intermediate to an aldehyde, followed by an Oppenauer-type oxidation was investigated theoretically according to the mono- and dinuclear pathways. The formation of a dinuclear zinc intermediate from a mononuclear alkynyl zinc complex was exergonic, favoring the dinuclear zinc pathway. The subsequent protonation and regeneration of the active dinuclear catalyst were also evaluated by DFT calculations. The oxidizabilities of various aldehydes and ketones were evaluated to determine the best oxidant for this step. Trifluoroacetaldehyde was predicted to be a better oxidant for this reaction because its calculated energy barrier for the Oppenauer-type oxidation step was much lower than that of the other carbonyl complexes. [ABSTRACT FROM AUTHOR]

• 1,2-Dihydropyrimidine is introduced as an N-donor into a pincer ligand. • Ruthenium(II) complexes Ru1-Ru3 were produced from this ligand and RuCl 2 (DMSO) 4. • The structure of Ru2 was confirmed by single-crystal X-ray diffraction. • All complexes exhibit catalysis in Oppenauer-type oxidation of secondary alcohols. Treatment of the (diethylaminomethyl-picolyl)pyrazolium (A3) with NaOH in dichloromethane affords the pincer ligand (L) bearing a 1,2-dihydropyrimidine unit. Reaction of [RuCl 2 (DMSO) 4 ] and the ligand (L) affords the complex [RuCl 2 (L)(DMSO)] (Ru1). Removal of the chlorides from Ru1 with either NaBF 4 or KPF 6 in CH 3 CN produces the complexes [Ru(L)(CH 3 CN) 3 ](BF 4) 2 (Ru2) and [Ru(L)(CH 3 CN) 3 ](PF 6) 2 (Ru3), respectively. Ru2 has been characterized with X-ray crystallography. All of the new ruthenium complexes (Ru1 - Ru3) are catalytically active in the Oppenauer-type oxidation of secondary alcohols. Among them, the complex Ru1 is the most active. Steric effects were observed from the outcome of substituted acetophenones. [Display omitted] [ABSTRACT FROM AUTHOR]