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With electricity as green oxidant, a catalytic amount of benzoquinone (BQ) was used as an electron-transfer mediator (ETM) in palladium-based electrocatalysis to provide highly efficient access to γ-lactones and spirolactone skeletons in an undivided cell. This represents the first successful example of an electrochemical oxidative palladium-catalyzed reaction of allenes.

Abstract

Herein, we report an electrochemical oxidative palladium-catalyzed carbonylation-carbocyclization of enallenols to afford γ-lactones and spirolactones, which proceeds with excellent chemoselectivity. Interestingly, electrocatalysis was found to have an accelerating effect on the rate of the tandem process, leading to a more efficient reaction than that under chemical redox conditions.

Nature Chemistry, Published online: 01 September 2022; doi:10.1038/s41557-022-01023-x

Given the importance of amine compounds, methods for their synthesis continue to be in high demand. Now, a palladium-catalysed strategy has been developed for the selective oxidative amination of unactivated olefins with Lewis basic amines, via C(sp3)–H activation, forming architecturally versatile and functionally diverse allylamines in a single step.

Nature Chemistry, Published online: 01 September 2022; doi:10.1038/s41557-022-01029-5

Amines with free N–H groups have long posed a tremendous challenge in transition metal-catalysed amination reactions. Now, use of a bidentate phosphorus ligand enables the palladium-catalysed oxidative amination of simple olefins with Lewis basic amines, with no prefunctionalization, forming both alkyl and aryl allylamines.

Low coordination number yet stable: The synthesis and characterisation of new low-valent palladium (0) complexes are reported, and provide simple access to known and novel complexes, the instrinsic reactivity of which prevented their isolation using existing methods. One complex performs exceptionally well as a catalyst in the hydrosilylation reaction.

Abstract

The synthesis and isolation of [Pd(NHC)(PhC≡CPh)] complexes are reported. These new 14-electron Pd(0)-complexes are key synthons leading to known palladium(0) and palladium(II) species, as well as permitting access to unprecedented mixed NHC-phosphite palladium(0) complexes. This motif permits the facile catalytic hydrosilylation of allenes. DFT calculations have allowed the characterization of the relatively weak interaction between the metal and the diphenylacetylene ligand, with a comparison with a series of ligands with more or less coordinating power, bearing varied structural and electronic properties.

A highly enantioselective nickel-catalyzed electrochemical radical allylation reaction was developed in high yields with excellent enantiomeric ratios (up to 93 % ee). The single-electron transfer-based enantioselective electrocatalytic routes would be applied as an alternative approach for the development of a wide range of useful stereocontrolled reactions.

Abstract

A simplified and appealing strategy via a chiral catalyst to facilitate the electrochemical process and provide asymmetric induction of radical reactions is particularly desirable and would have potential applications in electrosynthesis, organic chemistry, and drug discovery. Here, we introduced a novel electrolytic system that diverts the standard ionic reactivity to new catalytic functions, enabling mechanistically distinct single-electron transfer-based enantioselective routes to exhibit a brand-new pattern of reactivity—electricity-driven asymmetric catalysis as a privileged chiral platform for enantioselective radical allylation. The nickel-catalyzed activation of nucleophiles triggered a single-electron transfer process to provide a chiral catalyst-bound radical cation intermediate, which could be applied as an alternative strategy for the development of stereocontrolled radical reactions.

Herein, a general and practical protocol to aziridines and cyclopropanes using free XH₂ (X=C or N) with alkenes by thianthrenation is presented under mild conditions. Free sulfonamides, amides, carbamates, amines, and acidic methylene with protons, are good precursors for three-membered ring formation, providing an attractive alternative for straightforward synthesis of aziridines and cyclopropanes from easily available starting materials.

Abstract

Three-membered cyclic structures are widely existing in natural products and serve as enabling intermediates in organic synthesis. However, the efficient and straightforward access to such structures with diversity remains a formidable challenge. Herein, a general and practical protocol to aziridines and cyclopropanes synthesis using free XH₂ (X=C or N) with alkenes by thianthrenation is presented. This metal-free protocol features the direct aziridination and cyclopropanation with unprotected XH₂. Free sulfonamides, amides, carbamates, amines, and methylene with acidic protons, are good precursors, providing an attractive alternative for straightforward synthesis of aziridines and cyclopropanes from easily available starting materials.

Nature Communications, Published online: 30 July 2022; doi:10.1038/s41467-022-32084-8

1,2-Aminoxygenation of alkenes without extra oxidant is a practical yet challenging way to prepare β-amino alcohols. Here, the authors report an electro-oxidative route achieving such a goal with H2 evolution, exhibiting broad scope and application potential.

This review highlights transition-metal-free synthesis of heterocyclic organoboron compounds by following dehalogenative, dehydrogenative borylation, alkyne activation and intramolecular cyclization pathways

We report α-thianthrenium carbonyl species as α-carbonyl carbocation equivalents, generated in situ by radical conjugate addition of trifluoromethyl radical to Michael acceptors. The method can obtain C^α-tetrasubstituted amino acids in 90 seconds.

Abstract

Here we report an α-thianthrenium carbonyl species, as the equivalent of an α-carbonyl carbocation, which is generated by the radical conjugate addition of a trifluoromethyl thianthrenium salt to Michael acceptors. The reactivity allows for the synthesis of C^α-tetrasubstituted α- and β-amino acid analogues via a Ritter reaction by addition of acetonitrile. Addition of hydroxide, methoxide, and even fluoride can afford α-heteroatom substituted α-phenylpropanoates.