Terpyridine Ruthenium-Catalyzed One-Pot Conversion of Aldehydes into Amides

Amide-Assisted Rearrangement of Hydroxyarylformimidoyl Chloride to Diarylurea

A novel amide-assisted rearrangement reaction of hydroxybenzimidoyl chloride has been established for the efficient synthesis of 1,3-diphenylurea derivatives. A variety of electronically and sterically different 1,3-diphenylurea derivatives can be obtained in good to excellent yields, and a proposed reaction mechanism is also presented.

Half-Sandwich Iridium Complexes Based on β-Ketoamino Ligands: Preparation, Structure, and Catalytic Activity in Amide Synthesis

A series of β-ketoamino-based N,O-chelate half-sandwich iridium complexes with the general formula [Cp*IrClL] have been prepared in good yields. These air-insensitive iridium complexes showed desirable catalytic activity in an amide preparation under mild conditions. A number of amides with diverse substituted groups were furnished in a one-pot reaction with good-to-excellent yields through an amidation reaction of NH₂OH·HCl with aldehydes in the presence of these iridium(III) precursors. The excellent catalytic activity, mild reaction conditions, and broad substrate scope gave this type of iridium catalyst potential for use in industry. All of the obtained iridium complexes were well characterized by different spectroscopy techniques. The exact molecular structure of complex 3 has been confirmed by single-crystal X-ray analysis.

Rhodium-terpyridine Catalyzed Transfer Hydrogenation of Aromatic Nitro Compounds in Water

A rhodium terpyridine complex catalyzed transfer hydrogenation of nitroarenes to anilines with i-PrOH as hydrogen source and water as solvent has been developed. The catalytic system can work at a substrate/catalyst (S/C) ratio of 2000, with a turnover frequency (TOF) up to 3360 h^-1 , which represents one of the most active catalytic transfer hydrogenation systems for nitroarene reduction. The catalytic system is operationally simple and the protocol could be scaled up to 20 gram scale. The water-soluble catalyst bearing a carboxyl group could be recycled 15 times without significant loss of activity.

(Ar-tpy)RuII(ACN)3: A Water-Soluble Catalyst for Aldehyde Amidation, Olefin Oxo-Scissoring, and Alkyne Oxygenation

The synthetic chemists always look for developing new catalysts, sustainable catalysis, and their applications in various organic transformations. Herein, we report a new class of water-soluble complexes, (Ar-tpy)Ru^II(ACN)₃, utilizing designed terpyridines possessing electron-donating and -withdrawing aromatic residues for tuning the catalytic activity of the Ru(II) complex. These complexes displayed excellent catalytic activity for several oxidative organic transformations including late-stage C-H functionalization of aldehydes with NH₂OR to valuable primary amides in nonconventional aqueous media with excellent yield. Its diverse catalytic power was established for direct oxo-scissoring of a wide range of alkenes to furnish aldehydes and/or ketones in high yield using a low catalyst loading in the water. Its smart catalytic activity under mild conditions was validated for dioxygenation of alkynes to highly demanding labile synthons, 1,2-diketones, and/or acids. This general and sustainable catalysis was successfully employed on sugar-based substrates to obtain the chiral amides, aldehydes, and labile 1,2-diketones. The catalyst is recovered and reused with a moderate turnover. The proposed mechanistic pathway is supported by isolation of the intermediates and their characterization. This multifaceted sustainable catalysis is a unique tool, especially for late-stage functionalization, to furnish the targeted compounds through frequently used amidation and oxygenation processes in the academia and industry.

Facile Fabrication of Ordered Component-Tunable Heterobimetallic Self-Assembly Nanosheet for Catalyzing "Click" Reaction

How to maximize the number of desirable active sites on the surface of the catalyst and minimize the number of sites promoting undesirable side reactions is currently an important research topic. In this study, a new way based on the synergism to achieve the successful fabrication of an ordered heterobimetallic self-assembled monolayer (denoted as BMSAM) with a controlled composition and an excellent orientation of metals in the monolayer was developed. BMSAM consisting of phenanthroline and Schiff-base groups was prepared, and its novel heterobimetallic (Cu and Pd) self-assembled monolayer anchored in silicon (denoted as Si-Fmp-Cu-Pd BMSAM) with a controlled composition and a fixed position was fabricated and characterized by UV, cyclic voltammetry, Raman, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), X-ray diffraction (XRD), inductively coupled plasma atomic emission spectroscopy (ICP-AES), and water-drop contact angle (WDCA) analyses. The effects of Si-Fmp-Cu-Pd BMSAM on its catalytic properties were also systematically investigated using "click" reaction as a template by WDCA, XPS, SEM, XRD, ICP-AES and in situ Fourier transform infrared analyses in a heterogeneous system. The results showed that the excellent catalytic characteristic could be attributed to the partial (ordered or proper distance) isolation of active sites displaying high densities of specific atomic ensembles. The catalytic reaction mechanism of the click reaction interpreted that the catalytic process mainly occurred on the surface of the monolayer, internal active site (Pd) and rationalized that the Cu(I) species and Pd(0) reduced from the Cu(II) and Pd(II) catalyst were active species, which had a proper distance between two different metals. The cuprate-triazole intermediate and the palladium intermediate, whose production is the key step, should lie in a proper position between the copper and active palladium sites, with which the reaction rate of transmetalation would be improved to increase the amount of the undesired Sonogashira coupling product.

Hexagonal Mesoporous Silica-Supported Copper Oxide (CuO/HMS) Catalyst: Synthesis of Primary Amides from Aldehydes in Aqueous Medium

Hexagonal mesoporous silica (HMS)-supported copper oxides (CuO/HMS) have been prepared by a sol-gel method and characterized by X-ray diffraction, FTIR spectroscopy, transmission electron microscopy, N₂ sorption, inductively coupled plasma (ICP), X-ray photoelectron spectroscopy (XPS), H₂ temperature-programed reduction (TPR), NH₃ temperature-programed desorption (TPD), and high-resolution (HR)-TEM techniques. An analysis of these results revealed a mesoporous material system with a high surface area (974 m²  g^-1 ) and uniform pore-size distribution. The catalytic efficacy of CuO on the HMS support with varying Cu loadings (1, 3, 5, 10, and 15 wt %) was investigated for the transformation of aldehydes to primary amides; 3 wt % CuO/HMS exhibited good catalytic performance with good to excellent yields of amides (60-92 %) in benign aqueous medium. The intrinsically heterogeneous catalyst could be recovered after the reaction and reused without any noticeable loss in activity.

Copper(II) Acetate-Catalysed Conversion of Aldoximes to Amides under Mild Conditions

A mild method for the metal-catalysed conversion of aldoximes to amides has been achieved by the combined use of copper(II) acetate and MeCN in EtOH under reflux. The presence of a catalytic amount of MeCN (0.05 equiv.) accelerated the reaction and improved the yield. Aryl, heteroaryl and alkyl aldoximes were transformed into the corresponding amides in moderate to good yield. 2-Furyl and 2-thiophenyl aldoximes, which possess a heteroatom lone pair positioned ortho to the oximido group, showed enhanced reactivity, and the corresponding amides were obtained in excellent yield.

Chemoselective dehydrogenative esterification of aldehydes and alcohols with a dimeric rhodium(ii) catalyst

A dimeric rhodium(ii) complex catalyses the chemoselective dehydrogenative esterification of aldehydes and alcohols.

Dehydrogenative cross-coupling of aldehydes with alcohols as well as dehydrogentive cross-coupling of primary alcohols to produce esters have been developed using a Rh-terpyridine catalyst. The catalyst demonstrates broad substrate scope and good functional group tolerance, affording esters highly selectively. The high chemoselectivity of the catalyst stems from its preference for dehydrogenation of benzylic alcohols over aliphatic ones. Preliminary mechanistic studies suggest that the active catalyst is a dimeric Rh(ii) species, operating via a mechanism involving metal–base–metal cooperativity.

Highly efficient synthesis of primary amides via aldoximes rearrangement in water under air atmosphere catalyzed by an ionic ruthenium pincer complex

An ionic Ru pincer complex was demonstrated to be highly efficient catalyst for conversion of aldoximes and aldehydes into corresponding primary amides with environmental benignity, operational convenience and catalytic loading as low as 0.5 mol%.

Catalytic synthesis of amides via aldoximes rearrangement

This Feature article provides a comprehensive overview of the developments achieved in the catalytic synthesis of amides via rearrangement of aldoximes.

Efficient and selective copper-grafted nanoporous silica in aqueous conversion of aldehydes to amides

The one-pot conversion of aldehydes to their corresponding primary amides has been studied using SBA-15-grafted ethylenediamine copper complexes (En–Cu).

Nitrogen enriched mesoporous organic polymer anchored copper(ii) material: an efficient and reusable catalyst for the synthesis of esters and amides from aromatic systems

New mesoporous polymer anchored copper acetate (Cu-mPMF) has been synthesized and well characterized. The catalytic performance of this complex has been tested for the synthesis of esters and amides.

An efficient magnetic copper ferrite nanoparticle catalysed ligand and solvent free synthesis of N-aryl amide from aldoximes and iodobenzene

A one pot dehydration, hydration and coupling reaction protocol for N-substituted amide formation.

Phosphine-free ruthenium-arene complex for low temperature one-pot catalytic conversion of aldehydes to primary amides in water

A simple and highly efficient catalytic system based on a phosphine-free ruthenium arene complex for aqueous-phase one-pot direct synthesis of primary amides from aldehydes and hydroxylamine hydrochloride, with a high tolerance for other reactive functional groups, is described.

Palladium-catalyzed synthesis of primary benzamides from aryl bromides via a cyanation and hydration sequence

An interesting and effective procedure for the synthesis of primary benzamides from aryl bromides via cyanation and in situ hydration sequence has been developed.

An aerobic oxidative synthesis of aryl nitriles and primary aryl amides from benzylic alcohols catalyzed by a polymer supported Cu(ii) complex

A new polymer anchored Cu(ii) complex has been synthesized and characterized. The catalytic performance of this complex has been tested for the synthesis of nitriles and amides from benzylic alcohols. This catalyst showed excellent catalytic activity, recyclability and could be reused more than five times without appreciable loss of its initial activity.