A catalyst-free protocol for direct oxidative esterification of alcohols and aldehydes

A fast, simple, and efficient protocol for the direct conversion of alcohols and aldehydes to methyl ester has been developed using TsNBr₂ without any catalyst. The one pot reaction proceeds in the presence of a base at room temperature in methanol, to produce the corresponding methyl ester in high yield within a short time.     

Iridium-catalyzed oxidative esterification reaction of aliphatic aldehydes and olefinic alcohols with precoordination of the double bond of alcohols to iridium

A novel iridium-catalyzed oxidative esterification reaction of aliphatic aldehydes and olefinic alcohols in toluene was found under mild conditions of [IrCl(cod)]₂ (5 mol %) in combination with K₂CO₃ (10 mol %) at rt.     

[IrCl(cod)]2-catalyzed direct oxidative esterification of aldehydes with alcohols

[IrCl(cod)]₂ catalyzed the oxidative esterification of a variety of aldehydes with methanol as a solvent in combination with K₂CO₃ under mild conditions (rt, 12 h). The oxidative esterification reaction of aliphatic aldehydes also took place with olefinic alcohols as reagents in toluene under similar conditions.     

Copper-catalyzed oxidative esterification of alcohols with aldehydes activated by Lewis acids

An efficient oxidative esterification of aromatic and aliphatic aldehydes with simple alcohols was accomplished using catalytic amounts of Cu(ClO₄)₂·6H₂O and InBr₃ with tert-hydroperoxide as an oxidant.     

Metal‐free aerobic oxidative esterification of aromatic aldehydes promoted by potassium fluoride (KF)

We investigated the oxidative esterification of aldehydes with alcohols/phenols to produce a range of esters. In this approach, we conducted the reaction under metal‐free conditions at room temperature. The reactions were promoted by potassium fluoride (KF) as the additive, resulting in the desired product in good to high yields. This procedure was found to be effective for the production of aryl esters, which are challenging in most of the available reports. It is vital for this procedure not to exclude air as the source of oxygen.     

nBu4NI-catalyzed oxidative amidation of aldehydes with tertiary amines

An efficient oxidative coupling protocol for amide formation has been developed. Various tertiary amines and aromatic aldehydes were oxidized to their corresponding tertiary amides in moderate to good yields in the presence of a simple nBu₄NI-catalyst.     

非贵金属Co-N-C/MgO高效催化糠醛氧化酯化制糠酸甲酯

设计开发绿色、可持续的生物质资源高效转化制化学品催化过程具有重要的科学与应用研究价值.生物质基平台分子糠醛在分子氧存在下与甲醇发生氧化酯化,提供了一条糠酸甲酯的"非石油基"合成新路线.该反应采用贵金属/非贵金属催化体系,目前通常需要引入K2CO3或CH3ONa等碱性添加剂,以提高催化氧化酯化反应活性和选择性;但是存在活性组分流失、生成副产物及污染环境等问题,阻碍了其进一步应用.探索高性能非贵金属催化剂,实现无碱条件下糠醛高效氧化酯化,对于提高该生物质路线竞争力与推动工业化进程具有重要意义.     

Direct oxidative esterification of toluene with 1,3‐dicarbonyl compounds catalysed by copper complex supported on magnetic nanoparticles

Toluene oxidation is one of the substantial industrial technologies since oxidized products are industrially very important intermediates. A Fe₃O₄@cysteine@Cu‐catalysed reaction that uses tert ‐butyl hydroperoxide as oxidant to produce esters from toluene and β‐diketones or β‐keto esters, enolate precursors, has been developed. Oxidative esterification of toluene with 1,3‐dicarbonyl derivatives led to C─O bond formation and direct C─H functionalization.     

甲苯和一氧化碳氧化用介孔LaFeO3催化剂（英文）

以KIT-6和二氧化硅纳米球为硬模板制备了比表面积分别为138和65 m2/g的正交相蠕虫状介孔LaFeO3催化剂LFO-1和LFO-2.在空速为20000 mL/(g劒h)的条件下,LFO-1样品显示出最高的催化活性:对于CO氧化反应,T50%和T90%分别为155和180 oC;对于甲苯氧化反应,T50%和T90%分别为200和253 oC.该样品优异的催化性能与它具有较大的比表面积、较高的氧吸附物种浓度、较好的低温还原性以及良好的蠕虫状介孔结构有关.     

Copper‐mediated simple and direct aerobic oxidative esterification of arylacetonitriles with alcohols/phenols

A simple and direct aerobic oxidative esterification reaction of arylacetonitriles with alcohols/phenols is achieved in the presence of a copper salt and molecular oxygen, which produces a broad range of aryl carboxylic acid esters in good to high yields. Copper salt plays multiple roles in the transformation, which allows the oxygenation of C? H bond, cleavage of inert C? C bond, and formation of C? O bond in one pot without the assistance of any of the acids, bases, ligands, and so on. The reaction provides a simple, direct, and efficient protocol towards functionalized esters, especially aryl benzoates, from readily available starting materials.     

Mild and selective deprotection of carbamates with Bu4NF

A new mild method allowing the removal of carbamates using TBAF in THF is reported. Reactions were performed on indole, indoline, N-methyl aniline, aniline and tryptamine derivatives. The observed selectivity according to the carbamates or the substrates is discussed. A mechanism is postulated.     

Synthesis of 3-keto-quinolines from enaminones,anilines and DMSO: Transition metal free one pot cascade

An efficient and transition metal-free approach for the synthesis of functionalized 3-ketoquinolines from readily available anilines, enaminones and DMSO in the presence of K₂S₂O₈ has been conducted. This one pot tandem reaction proceeds through [3+2+1] cycloaddition reaction involving DMSO, enaminones and amines. In this environmental benign approach, DMSO acts as both a one carbon source and the solvent. A broad range of variously substituted amines and enaminones are successfully employed in this one pot tandem process to access a broad range of substituted 3-ketoquinolines.     

Transition metal promoted carboxylation of unsaturated substrates with carbon dioxide

The use of CO₂ as a C1 building block for the synthesis of useful chemicals is of great significance, and has attracted increasing attention in recent years. The transition metal catalyzed or mediated addition of CO₂ to unsaturated chemical bonds has proved to be a powerful and versatile protocol for the incorporation of CO₂ into various unsaturated organic substrates such as alkynes, alkenes, allenes, aldehydes, and 1,3-dienes. The hydrogenative, alkylative and arylative carboxylation, heterocarboxylation, and carboxylative cyclization with CO₂ have led to efficient and selective formation of various functionalized carboxylic acids and derivatives. This review focuses on recent advances in this area with emphasis on conceptual reaction design.     

A simple and efficient approach for the synthesis of 2-aminated quinazoline derivatives via metal free oxidative annulation

A simple and efficient approach for the synthesis of 2-aminoquinazoline derivatives in moderate to good yields. This reaction employs mild reaction conditions, is metal-free and utilizes readily available starting materials making it a more viable reaction for scale up synthesis and ligand diversity. Notably, this methodology allows for the synthesis of 2-aminoquinazolines using a free amine or cyclic amine enabling structural diversity and good atom economy.     

Synergetic effect of FeVO4 and α-Fe2O3 in Fe-V-O catalysts for liquid phase oxidation of toluene to benzaldehyde

Synergistic effect of FeVO₄ withα-Fe₂O₃ was found in Fe-V-O catalyst,which was responsible for the high apparent formation rate（A.F.R.） of benzaldehyde in liquid phase oxidation of toluene by hydrogen peroxide.The synergistic effect might create VO_πspecies as active sites;moreover,it improved the reducibility and the reactivity of Fe-V-O catalyst.In order to gain the high A.F.R. of benzaldehyde,the catalyst should have the moderate reducibihty.     

Ion-pair extraction of transition metal cations from aqueous media using novel N2O2-macrocyclic crown ligands

Three new macrocyclic crown ether ligands containing nitrogen–oxygen donor atoms were designed and synthesized from 1,4-bis(2′-formylphenyl)-1,4-dioxabutane and 4-nitro-o-phenylenediamine. Ion-pair extraction of metal picrates such as Ag⁺, Hg²⁺, Cd²⁺, Zn²⁺, Cu²⁺, Ni²⁺, Mn²⁺, Co²⁺, and Pb²⁺ from aqueous phase to the organic phase was carried out using the novel ligands. The solvent effect over the metal picrate extractions was investigated at 25 ± 0.1 °C by using UV–visible spectrometry. The extractability and the values of the extraction constants (log K_ex) were determined for the extracted complexes.     

Transition metal free one pot synthesis of aryl carboxylic acids via dehomologative oxidation of styrenes

Iodine/NaOH-catalyzed one-pot dehomologative oxidation of styrenes to aryl carboxylic acids has been reported. A wide range of carboxylic acids are obtained using iodine (I₂) as a catalyst, tert-butyl hydroperoxide (TBHP) as an oxidant and sodium hydroxide (NaOH) as a base. This reliable conversion involves dehomologation of styrene to aromatic aldehyde which on subsequent oxidation affords aryl carboxylic acid. This protocol was used for gram-scale synthesis as it is free from chromatographic purification. This is the first report for the oxidative transformation of styrenes into aryl carboxylic acids under transition metal-free conditions.