Electrochemical Dearomative Spirocyclization of N-Acyl Thiophene-2-sulfonamides

Radical Cyclization-Initiated Difunctionalization Reactions of Alkenes and Alkynes

Radical reactions are powerful in the synthesis of diverse molecular scaffolds bearing functional groups. In previous review articles, we have presented 1,2-difunctionalizations, remote 1,3-, 1,4-, 1,5-, 1,6- and 1,7-difunctionalizations, and addition followed by cyclization reactions. Presented in this paper is radical cyclization followed by the second functionalization reaction. The second functionalization could be realized by atom transfer reactions, radical or transition metal-assisted coupling reactions, and reactions with neutral molecules, cationic and anionic species.

Scalable Diastereoselective Electrosynthesis of Spiro[benzofuran-2,2'-furan]-3-ones

Spirobenzofuran scaffolds, because of their three-dimensional structure, are incorporated into several valuable natural products and drug candidate molecules. Herein, with the assistance of electrosynthesis, we introduce a novel electrochemical approach for achieving spirobenzofurans in a user-friendly and operationally simple undivided cell setup under constant current. This metal-catalyst-free electrochemical procedure afforded spiro[benzofuran-2,2'-furan]-3-ones with high diastereoselectivity. Compatibility with gram-scale synthesis along with the convenient accessibility of reaction instruments and starting materials collectively raised the importance of this protocol compared to previous challenging methods. Furthermore, mechanistic cognizance of this reaction is obtained by the investigation of the cyclic voltammetry spectra of reactants.

Total Synthesis of Aleutianamine

Aleutianamine is a recently isolated pyrroloiminoquinone natural product that displays potent and selective biological activity toward human pancreatic cancer cells with an IC50 of 25 nM against PANC-1, making it a potential candidate for therapeutic development. We report a synthetic approach to aleutianamine wherein the unique [3.3.1] ring system and tertiary sulfide of this alkaloid were constructed via a novel palladium-catalyzed dearomative thiophene functionalization. Other highlights of the synthesis include a palladium-catalyzed decarboxylative pinacol-type rearrangement of an allylic carbonate to install a ketone and a late-stage oxidative amination. This concise and convergent strategy will enable access to analogues of aleutianamine and further investigation of the biological activity of this unique natural product.

Electrochemical N-Aroylation of Sulfoximines by Using Benzoyl Hydrazines with H2 Generation

Developed here is a robust electrochemical cross-coupling reaction between aroyl hydrazine and NH-sulfoximine via concomitant cleavage and formation of C(sp2 )-N bonds with the evolution of H2 and N2 as innocuous by-products. This sustainable protocol avoids the use of toxic reagents and occurs at room temperature. The reaction proceeds via the generation of an aroyl and a sulfoximidoyl radical via anodic oxidation under constant current electrolysis (CCE), affording N-aroylated sulfoximine. The strategy is applied to late-stage sulfoximidation of L-menthol, (-)-borneol, D-glucose, vitamin-E derivatives, and marketed drugs such as probenecid, ibuprofen, flurbiprofen, ciprofibrate, and sulindac. In addition, the present methodology is mild, high functional group tolerance with broad substrate scope and scalable.