Cobalt(II)/TPPMS-Catalyzed Dehydrative Nucleophilic Substitution of Alcohols in Water

Dehydrative amination of benzhydrols with electron-withdrawing group-substituted 2-aminopyridines utilizing Au(III)/TPPMS catalyst system in water

We report a method for gold(III)/sodium diphenylphosphinobenzene-3-sulfonate (TPPMS)-catalyzed direct amination of benzhydrols using 2-aminopyridines with poor nucleophilic character in water. Various functional groups such as electron-withdrawing nitro, cyano and halogen groups were tolerated well to form the desired N-benzylated 2-aminopyridine compounds. On the basis of mechanistic studies including kinetic profiles, Hammett study and isotope effects, we propose a pathway in which a Lewis acidic gold cation species activates the sp³ C-O bond of the alcohol in the rate-determining step.

pH-Mediated Selective Synthesis of N-Allylic Alkylation or N-Alkylation Amines with Allylic Alcohols via an Iridium Catalyst in Water

Amination of allylic alcohols is an effective approach in the facile synthesis of N-allylic alkylation or N-alkylation amines. Recently, a series of catalysts were devised to push forward this transformation. However, current synthetic methods are typically limited to achieve either N-allylic alkylation or N-alkylation products via a certain catalyst. In this article, a pH-mediated selective synthesis of N-allylic alkylation or N-alkylation amines with allylic alcohols via an iridium catalyst with water as the environmental benign solvent is revealed, enabling the miscellaneous synthesis of N-allylic alkylation and N-alkylation products in outstanding yields. Furthermore, a gram-scale experiment with low catalyst loading offers the potential to access a distinct entry for the synthesis of the antifungal drug naftifine.

Pd/TiO2-Photocatalyzed Self-Condensation of Primary Amines To Afford Secondary Amines at Ambient Temperature

Symmetric secondary amines were synthesized by the self-condensation of primary amines over a palladium-loaded titanium dioxide (Pd/TiO₂) photocatalyst. The reactions afforded a series of secondary amines in moderate to excellent isolated yields at ambient temperature (30 °C, in cyclopentyl methyl ether). Applicability for one-pot pharmaceutical synthesis was demonstrated by a photocatalytic reaction sequence of self-condensation of an amine followed by N-alkylation of the resulting secondary amine with an alcohol.

N-Alkylation of functionalized amines with alcohols using a copper-gold mixed photocatalytic system

Direct functionalization of amino groups in complex organic molecules is one of the most important key technologies in modern organic synthesis, especially in the synthesis of bio-active chemicals and pharmaceuticals. Whereas numerous chemical reactions of amines have been developed to date, a selective, practical method for functionalizing complex amines is still highly demanded. Here we report the first late-stage N-alkylation of pharmaceutically relevant amines with alcohols at ambient temperature. This reaction was achieved by devising a mixed heterogeneous photocatalyst in situ prepared from Cu/TiO₂ and Au/TiO₂. The mixed photocatalytic system enabled the rapid N-alkylation of pharmaceutically relevant molecules, the selective mono- and di-alkylation of primary amines, and the non-symmetrical dialkylation of primary amines to hetero-substituted tertiary amines.