5122-81-6Relevant articles and documents
Catalyst-Free Decarbonylative Trifluoromethylthiolation Enabled by Electron Donor-Acceptor Complex Photoactivation
Lipp, Alexander,Badir, Shorouk O.,Dykstra, Ryan,Gutierrez, Osvaldo,Molander, Gary A.
supporting information, p. 3507 - 3520 (2021/06/11)
A catalyst- and additive-free decarbonylative trifluoromethylthiolation of aldehyde feedstocks has been developed. This operationally simple, scalable, and open-to-air transformation is driven by the selective photoexcitation of electron donor-acceptor (EDA) complexes, stemming from the association of 1,4-dihydropyridines (donor) with N-(trifluoromethylthio)phthalimide (acceptor), to trigger intermolecular single-electron transfer events under ambient- and visible light-promoted conditions. Extension to other electron acceptors enables the synthesis of thiocyanates and thioesters, as well as the difunctionalization of [1.1.1]propellane. The mechanistic intricacies of this photochemical paradigm are elucidated through a combination of experimental efforts and high-level quantum mechanical calculations [dispersion-corrected (U)DFT, DLPNO-CCSD(T), and TD-DFT]. This comprehensive study highlights the necessity for EDA complexation for efficient alkyl radical generation. Computation of subsequent ground state pathways reveals that SH2 addition of the alkyl radical to the intermediate radical EDA complex is extremely exergonic and results in a charge transfer event from the dihydropyridine donor to the N-(trifluoromethylthio)phthalimide acceptor of the EDA complex. Experimental and computational results further suggest that product formation also occurs via SH2 reaction of alkyl radicals with 1,2-bis(trifluoromethyl)disulfane, generated in-situ through combination of thiyl radicals. (Figure presented.).
Nature of the Nucleophilic Oxygenation Reagent Is Key to Acid-Free Gold-Catalyzed Conversion of Terminal and Internal Alkynes to 1,2-Dicarbonyls
Dubovtsev, Alexey Yu.,Shcherbakov, Nikolay V.,Dar'in, Dmitry V.,Kukushkin, Vadim Yu.
, p. 745 - 757 (2020/02/04)
2,3-Dichloropyridine N-oxide, a novel oxygen transfer reagent, allows the conductance of the gold(I)-catalyzed oxidation of alkynes to 1,2-dicarbonyls in the absence of any acid additives and under mild conditions to furnish the target species, including those derivatized by highly acid-sensitive groups. The developed strategy is effective for a wide range of alkyne substrates such as terminal- and internal alkynes, ynamides, alkynyl ethers/thioethers, and even unsubstituted acetylene (40 examples; yields up to 99%). The oxidation was successfully integrated into the trapping of reactive dicarbonyls by one-pot heterocyclization and into the synthesis of six-membered azaheterocycles. This synthetic acid-free route was also successfully applied for the total synthesis of a natural 1,2-diketone.
Stereocontrolled Synthesis of 1,4-Dicarbonyl Compounds by Photochemical Organocatalytic Acyl Radical Addition to Enals
Goti, Giulio,Bieszczad, Bartosz,Vega-Pe?aloza, Alberto,Melchiorre, Paolo
supporting information, p. 1213 - 1217 (2019/01/04)
We report a visible-light-mediated organocatalytic strategy for the enantioselective acyl radical conjugate addition to enals, leading to valuable 1,4-dicarbonyl compounds. The process capitalizes upon the excited-state reactivity of 4-acyl-1,4-dihydropyridines that, upon visible-light absorption, can trigger the generation of acyl radicals. By means of a chiral amine catalyst, iminium ion activation of enals ensures a stereoselective radical trap. We also demonstrate how the combination of this acylation process with a second catalyst-controlled bond-forming event allows to selectively access the full matrix of all possible stereoisomers of the resulting 2,3-substituted 1,4-dicarbonyl products.
