Designed pincer ligands supported Co(II)-based catalysts for dehydrogenative activation of alcohols: Studies on N-alkylation of amines, -alkylation of ketones and synthesis of quinolines

Base-metal catalysts Co1, Co2 and Co3 were synthesized from designed pincer ligands L1, L2 and L3 having NNN donor atoms respectively. Co1, Co2 and Co3 were characterized by IR, UV–Vis....

Pyridine mediated transition-metal-free direct alkylation of anilines using alcohols via borrowing hydrogen conditions

Herein, we report aza-aromatics based organic mediators as a readily accessible alternative to the traditional approach of using transition metal catalyst systems for the activation of alcohols in borrowing hydrogen reactions.

Gold(III)/Sodium Diphenylphosphinobenzene-3-sulfonate (TPPMS) Catalyzed Dehydrative N-Benzylation of Electron-Deficient Anilines in Water

A strategy for the dehydrative N-benzylation of electron-deficient anilines in water has been developed. The gold(III)/sodium diphenylphosphinobenzene-3-sulfonate (TPPMS) catalyst is highly effective as a Lewis acid for the activation of alcohols and tolerates aerobic conditions. A Hammett study in the reaction of para-substituted benzhydryl alcohols shows negative σ values, indicating a build-up of cationic charge during the rate-determining sp3 C–O bond-cleavage step. The inverse kinetic solvent isotope effect (KSIE = 0.6) is consistent with a specific acid catalysis mechanism. This simple protocol can be performed under mild conditions in an atom-economic process without the need for base or other additives, furnishing the electron-deficient N-benzylic anilines in moderate to excellent yields along with water as a sole coproduct.

H2-Generation from Alcohols by the MOF-Based Noble Metal-Free Photocatalyst Ni/CdS/TiO2@MIL-101

The synthesis of important classes of chemical compounds from alcohols helps to conserve Earth’s fossil carbon resources, since alcohols can be obtained from indigestible and abundantly available biomass. The utilisation of visible light for the activation of alcohols permits alcohol-based C–N and C–C bond formation under mild conditions inaccessible with thermally operating hydrogen liberation catalysts. Herein, we report on a noble metal-free photocatalyst able to split alcohols into hydrogen and carbonyl compounds under inert gas atmosphere without the requirement of electron donors, additives, or aqueous reaction media. The reusable photocatalyst mediates C–N multiple bond formation using the oxidation of alcohols and subsequent coupling with amines. The photocatalyst consists of a CdS/TiO2 heterojunction decorated with co-catalytic Ni nanoparticles and is prepared on size-optimised colloidal metal–organic framework (MOF) crystallites.

A Bench-Stable Vilsmeier Reagent for in situ Alcohol Activation: Synthetic Application in the Synthesis of 2-Amino-2-Thiazolines

A robust, chemoselective direct condensation/cyclization of thioureas and amino alcohols is described. Employing a bench-stable Vilsmeier reagent, methoxymethylene-N,N-dimethyliminium methyl sulfate, the selective in situ activation of alcohols is achieved with high efficiency and broad functional-group tolerance. The reversible interaction of the Vilsmeier reagent with substrate was key to the success of this activation strategy.