Experimental Evidence for Zerovalent Pd(NHC) as a Competent Catalyst in C-N Cross-Coupling (NHC = DiMeIHept).

Use of the branched N-heterocyclic carbene (NHC) ligand 1,3-bis(2,6-bis(3-methyl-1-(2-methylpropyl)butyl)phenyl)-4,5-dichloro-1,3-dihydro-2-imidazole-2-ylidene (DiMeIHept) facilitated the stabilization of several relevant intermediates for Pd(NHC)-catalyzed C-N cross-coupling reactions. Complexes [Pd(DiMeIHept)](μ-N), [Pd(DiMeIHept)](μ-η-1,2-η-4,5-CH), and Pd(DiMeIHept)(pyridine), representing zerovalent Pd(NHC) bearing labile ligands, were isolated and structurally characterized, along with divalent PdCl(Ph)(DiMeIHept) and PdCl(Ph)(DiMeIHept)(-propylamine). The former is a 14-electron Pd complex, which is stable under air and chromatography on silica gel or neutral alumina.

Ultrasmall Cu Nanoparticles Stabilized on Surface of HPMC: An Efficient Catalyst for Fast and Organic Solvent-Free Tandem Click Chemistry in Water.

A simple and environmentally benign technology for synthesizing ultrasmall Cu nanoparticles (NPs) on the surface of the food additive hydroxypropyl methylcellulose (HPMC) and their application in completely organic solvent-free tandem alkyne-azide cycloaddition reactions were reported. The NP catalyst was thoroughly characterized by high-angle annular dark-field scanning transmission electron microscopy, high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy analysis for its morphology, particle size distribution, chemical composition, and oxidation state analyses. The NP catalyst was highly efficient, affording products in 10-45 min.

Enabling Metallophotoredox Catalysis in Parallel Solution-Phase Synthesis Using Disintegrating Reagent Tablets.

Compressed tablets containing a mixture of a photocatalyst, a nickel catalyst, an inorganic base, and an inert excipient are employed as a fast, safe, and user-friendly chemical delivery system for two different metallophotoredox-catalyzed reactions. This delivery method simplifies the preparation of compound libraries using photoredox chemistry in a parallel setting. The reagent tablets were successfully applied to late-stage functionalization of drug-like intermediates.

(DiMeIHept)Pd: A Low-Load Catalyst for Solvent-Free (Melt) Amination.

, a hyper-branched N-aryl Pd NHC catalyst, has been shown to be efficient at performing amine arylation reactions in solvent-free ("melt") conditions. The highly lipophilic environment of the alkyl chains flanking the Pd center serves as lubricant to allow the complex to navigate through the paste-like environment of these mixtures. The protocol can be used on a multi-gram scale to make a variety of aniline derivatives, including substrates containing alcohol moieties.

Sodium Butylated Hydroxytoluene: A Functional Group Tolerant, Eco-Friendly Base for Solvent-Free, Pd-Catalysed Amination.

NaBHT (sodium 2,6-di-tert-butyl-4-methylphenolate), a strong, but hindered and lipophilic base, has been effectively paired with similarly lipophilic, high-reactivity Pd-NHC (N-heterocyclic carbene) catalysts to produce an ideal combination for performing solvent-free (melt) cross-coupling amination. The mild nucleophilicity of NaBHT, coupled with the anti-oxidant properties of its conjugate acid byproduct, BHT means the process seems to have no functional group incompatibilities. Highly effective coupling of base-sensitive and redox-active functional groups was observed in all cases with only 0.