15212-27-8Relevant academic research and scientific papers
Mechanistic insight into the photoredox catalysis of anti-markovnikov alkene hydrofunctionalization reactions
Romero, Nathan A.,Nicewicz, David A.
, p. 17024 - 17035 (2014)
We describe our efforts to understand the key mechanistic aspects of the previously reported alkene hydrofunctionalization reactions using 9-mesityl-10-methylacridinium (Mes-Acr+) as a photoredox catalyst. Importantly, we are able to detect alk
An Intramolecular Iodine-Catalyzed C(sp3)?H Oxidation as a Versatile Tool for the Synthesis of Tetrahydrofurans
Br?se, Stefan,Koch, Vanessa
supporting information, p. 3478 - 3483 (2021/07/22)
The formation of ubiquitous occurring tetrahydrofuran patterns has been extensively investigated in the 1960s as it was one of the first examples of a non-directed remote C?H activation. These approaches suffer from the use of toxic transition metals in overstoichiometric amounts. An attractive metal-free solution for transforming carbon-hydrogen bonds into carbon-oxygen bonds lies in applying economically and ecologically favorable iodine reagents. The presented method involves an intertwined catalytic cycle of a radical chain reaction and an iodine(I/III) redox couple by selectively activating a remote C(sp3)?H bond under visible-light irradiation. The reaction proceeds under mild reaction conditions, is operationally simple and tolerates many functional groups giving fast and easy access to different substituted tetrahydrofurans.
Copper-Catalyzed Enantioselective Hydroalkoxylation of Alkenols for the Synthesis of Cyclic Ethers
Chen, Dake,Berhane, Ilyas A.,Chemler, Sherry R.
, p. 7409 - 7414 (2020/06/29)
The copper-catalyzed enantioselective intramolecular hydroalkoxylation of unactivated alkenes for the synthesis of tetrahydrofurans, phthalans, isochromans, and morpholines from 4- and 5-alkenols is reported. The substrate scope is complementary to existing enantioselective alkene hydroalkoxylations and is broad with respect to substrate backbone and alkene substitution. The asymmetric induction and isotopic labeling studies support a polar/radical mechanism involving enantioselective oxycupration followed by C-[Cu] homolysis and hydrogen atom transfer. Synthesis of the antifungal insecticide furametpyr was accomplished.
Catalytic Hydroetherification of Unactivated Alkenes Enabled by Proton-Coupled Electron Transfer
Knowles, Robert R.,Metrano, Anthony J.,Tsuchiya, Yuto,Tsui, Elaine
, p. 11845 - 11849 (2020/05/22)
We report a catalytic, light-driven method for the intramolecular hydroetherification of unactivated alkenols to furnish cyclic ether products. These reactions occur under visible-light irradiation in the presence of an IrIII-based photoredox catalyst, a Br?nsted base catalyst, and a hydrogen-atom transfer (HAT) co-catalyst. Reactive alkoxy radicals are proposed as key intermediates, generated by direct homolytic activation of alcohol O?H bonds through a proton-coupled electron-transfer mechanism. This method exhibits a broad substrate scope and high functional-group tolerance, and it accommodates a diverse range of alkene substitution patterns. Results demonstrating the extension of this catalytic system to carboetherification reactions are also presented.
Ligand-enabled gold-catalyzed 1,2-heteroarylation of alkenes
Tathe, Akash G.,Chintawar, Chetan C.,Bhoyare, Vivek W.,Patil, Nitin T.
supporting information, p. 9304 - 9307 (2020/10/02)
By adopting the interplay between ligand-enabled Au(i)/Au(iii) catalysis and the unique π-activation mode of gold complexes, a highly coveted 1,2-heteroarylation of alkenes has been accomplished. The present ligand-enabled approach not only circumvents the requirement for strong sacrificial oxidants or photocatalysts but also operates under mild reaction conditions by utilizing simple and non-prefunctionalized aryl coupling partners. This journal is
Gold(I)/Gold(III) Catalysis that Merges Oxidative Addition and π-Alkene Activation
Amgoune, Abderrahmane,Bourissou, Didier,Rigoulet, Mathilde,Thillaye du Boullay, Olivier
supporting information, p. 16625 - 16630 (2020/07/24)
Heteroarylation of alkenes with aryl iodides was efficiently achieved with a (MeDalphos)AuCl complex through AuI/AuIII catalysis. The possibility to combine oxidative addition of aryl iodides and π-activation of alkenes at gold is demonstrated for the first time. The reaction is robust and general (>30 examples including internal alkenes, 5-, 6-, and 7-membered rings). It is regioselective and leads exclusively to trans addition products. The (P,N) gold complex is most efficient with electron-rich aryl substrates, which are troublesome with alternative photoredox/oxidative approaches. In addition, it provides a very unusual switch in regioselectivity from 5-exo to 6-endo cyclization between the Z and E isomers of internal alkenols.
C(sp3)?C(sp3) Cross-Coupling of Alkyl Bromides and Ethers Mediated by Metal and Visible Light Photoredox Catalysis
Santos, Marilia S.,Corrêa, Arlene G.,Paix?o, Márcio W.,K?nig, Burkhard
supporting information, p. 2367 - 2372 (2020/05/08)
We report a C(sp3)?C(sp3) cross-coupling of alkyl bromides and alkyl chlorides with ethers by dual photoredox-nickel catalysis. The catalytic system comprises of the organic photocatalyst 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene (4-CzIPN) and bench stable nickel (II) acetylacetonate in the presence of visible-light, providing the coupling products in up to 92% yield. Preliminary mechanistic studies suggest two catalytic cycles, as well as the photogeneration of bromine or chlorine radicals from halide atoms that are present in the structures of the coupling partners. The halide radical mediates the hydrogen atom transfer event, avoiding the need of an additional HAT catalyst. (Figure presented.).
Electrophotocatalytic C-H Functionalization of Ethers with High Regioselectivity
Huang, He,Lambert, Tristan H.,Strater, Zack M.
supporting information, (2020/02/04)
The highly regioselective electrophotocatalytic C-H functionalization of ethers is described. These reactions are catalyzed by a trisaminocyclopropenium (TAC) ion at mild electrochemical potential with visible light irradiation. Ethers undergo oxidant-fre
Visible-Light-Induced C-O Bond Formation for the Construction of Five- and Six-Membered Cyclic Ethers and Lactones
Im, Honggu,Kang, Dahye,Choi, Soyeon,Shin, Sanghoon,Hong, Sungwoo
supporting information, p. 7437 - 7441 (2018/11/27)
Visible-light-induced intramolecular C-O bond formation was developed using 2,4,6-triphenylpyrylium tetrafluoroborate (TPT), which allows the regiocontrolled construction of cyclic ethers and lactones. The reaction is likely to proceed through the single-electron oxidation of the phenyl group, followed by the formation of a benzylic radical, thus preventing a competing 1,5-hydrogen abstraction pathway. Detailed mechanistic studies suggest that molecular oxygen is used to trap the radical intermediate to form benzyl alcohol, which undergoes cyclization. This new approach serves as a powerful platform by providing efficient access to valuable five- and six-membered cyclic ethers and lactones with a unified protocol.
Singlet vs Triplet Reactivity of Photogenerated α,n-Didehydrotoluenes
Pedroli, Chiara,Ravelli, Davide,Protti, Stefano,Albini, Angelo,Fagnoni, Maurizio
, p. 6592 - 6603 (2017/07/15)
The reactivity of α,n-didehydrotoluenes (DHTs) in protic media (organic/aqueous mixtures) was explored by means of a combined computational and experimental approach. These intermediates were generated via a photoinduced double elimination process occurring in (chlorobenzyl)trimethylsilanes and led to the formation of a varied products distribution, depending on the isomer tested. Irradiation of ortho- and para-derivatives resulted, respectively, in the formation of triplet α,2- and α,4-DHTs, whose diradical reactivity led to both radical and polar products. On the other hand, irradiation of the meta-precursor led to the singlet α,3-DHT isomer. The latter showed a marked preference for the formation of polar products and this was rationalized, as supported by computational evidence, via the involvement of a zwitterionic species arising through interaction of the nucleophilic solvent with the benzylic position of the DHT.
