Vicinal diamines are a common structural motif in bioactive natural products, therapeutic agents, and molecular catalysts, motivating the continuing development of efficient, selective, and sustainable technologies for their preparation. We report an operationally simple and environmentally friendly protocol that converts alkenes and sodium azide-both readily available feedstocks-to 1,2-diazides. Powered by electricity and catalyzed by Earth-abundant manganese, this transformation proceeds under mild conditions and exhibits exceptional substrate generality and functional group compatibility. Using standard protocols, the resultant 1,2-diazides can be smoothly reduced to vicinal diamines in a single step, with high chemoselectivity. Mechanistic studies are consistent with metal-mediated azidyl radical transfer as the predominant pathway, enabling dual carbon-nitrogen bond formation.
Electrochemistry has been used as a tool to drive chemical reactions for over two centuries. With the help of an electrode and a power source, chemists are bestowed with an imaginary reagent whose potential can be precisely dialed in. The theoretically infinite redox range renders electrochemistry capable of oxidizing or reducing some of the most tenacious compounds (e.g., F − to F 2 and Li + to Li 0). Meanwhile, a granular level of control over the electrode potential allows for the chemoselective differentiation of functional groups with minute differences in potential. These features make electrochemistry an attractive technique for the discovery of new modes of reactivity and transformations that are not readily accessible with chemical reagents alone. Furthermore, the use of an electrical current in place of chemical redox agents improves the costefficiency of chemical processes and reduces byproduct generation. Therefore, electrochemistry represents an attractive approach to meet the prevailing trends in organic synthesis and has seen increasingly broad use in the synthetic community over the past several years.
Chiral nitriles and their derivatives are prevalent in pharmaceuticals and bioactive compounds. Enantioselective alkene hydrocyanation represents a convenient and efficient approach for synthesizing these molecules. However, a generally applicable method featuring a broad substrate scope and high functional group tolerance remains elusive. Here, we address this long-standing synthetic problem using an electrocatalytic strategy. Electrochemistry allows for the seamless combination of two classic radical reactions-cobalt-mediated hydrogen-atom transfer and copper-promoted radical cyanation-to accomplish highly enantioselective hydrocyanation without the need for stoichiometric oxidant. We harness electrochemistry's unique feature of precise potential control to optimize the chemoselectivity of challenging substrates. Computational analysis sheds light on the origin of enantioinduction, for which the chiral catalyst imparts a combination of attractive and repulsive non-covalent interactions that direct the enantio-determining C-CN bond formation. This discovery demonstrates the power of electrochemistry in accessing new chemical space and providing solutions to pertinent challenges in synthetic chemistry. File list (2) download file view on ChemRxiv 01_Lin_MS.pdf (1.70 MiB) download file view on ChemRxiv 00_Lin_TOC.png (333.52 KiB)
We report a Mn-catalyzed electrochemical dichlorination of alkenes with MgCl as the chlorine source. This method provides operationally simple, sustainable, and efficient access to a variety of vicinally dichlorinated compounds. In particular, alkenes with oxidatively labile functional groups, such as alcohols, aldehydes, sulfides, and amines, were transformed into the desired vicinal dichlorides with high chemoselectivity. Mechanistic data are consistent with metal-mediated Cl atom transfer as the predominant pathway enabling dual C-Cl bond formation and contradict an alternative pathway involving electrochemical evolution of chlorine gas followed by Cl-mediated electrophilic dichlorination.
We report a mild and efficient electrochemical protocol to access a variety of vicinally C–O and C–N difunctionalized compounds from simple alkenes. Detailed mechanistic studies revealed a distinct reaction pathway from those previously reported for TEMPO-mediated reactions. In this mechanism, electrochemically generated oxoammonium ion facilitates the formation of azidyl radical via a charge-transfer complex with azide, TEMPO–N3. DFT calculations together with spectroscopic characterization provided a tentative structural assignment of this charge-transfer complex. Kinetic and kinetic isotopic effect studies revealed that reversible dissociation of TEMPO–N3 into TEMPO• and azidyl precedes the addition of these radicals across the alkene in the rate-determining step. The resulting azidooxygenated product could then be easily manipulated for further synthetic elaborations. The discovery of this new reaction pathway mediated by the TEMPO+/TEMPO• redox couple may expand the scope of aminoxyl radical chemistry in synthetic contexts.
The emergence of new catalytic strategies that cleverly adopt concepts and techniques frequently used in areas such as photochemistry and electrochemistry has yielded a myriad of new organic reactions that would be challenging to achieve using orthodox methods. Herein, we discuss the strategic use of anodically coupled electrolysis, an electrochemical process that combines two parallel oxidative events, as a complementary approach to existing methods for redox organic transformations. Specifically, we demonstrate anodically coupled electrolysis in the regio- and chemoselective chlorotrifluoromethylation of alkenes.
In contrast to the rapid growth of synthetic electrochemistry in recent years, enantioselective catalytic methods powered by electricity remain rare. In this work, we report the development of a highly enantioselective method for the electrochemical cyanophosphinoylation of vinylarenes. A new family of serine-derived chiral bisoxazolines with ancillary coordination sites were identified as optimal ligands.
Catalytic asymmetric electrochemical C-H functionalization of simple ketones has been developed. The transformation is realized by the combination of electrochemical oxidation and chiral primary amine catalysis. This metal- and oxidant-free method furnishes diverse C1-alkylated tetrahydroisoquinolines in high yields and with excellent enantioselectivities under very mild conditions.
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