RESUMEN
A tunable method for the selective preparation of p-aminophenol and tertiary amines from a secondary amine and cyclohexenone has been described. Nonaromatic cyclohexenones were used as an aryl source. The desired tertiary amine products were generated when using I2 as the catalyst. This approach yields single-site-selective p-aminophenol without using I2, and the 18O labeling experiments demonstrated that hydroxyl oxygen originates from O2.
RESUMEN
Disulfide bonds, especially unsymmetric disulfide bonds, have important applications in bioactivity and drug molecules, but the synthesis of unsymmetric disulfide bonds remains challenging due to efficiency and selectivity issues. Herein, this work utilizes anthraquinone (AQ) and cyclictriphosphonononitrile through a nucleophilic substitution reaction to synthesize an organic polymer (ANTH-AMI) that incorporates an ortho-polyquinone (o-polyquinone) redox center. The anthraquinone molecule functions as a redox center, capable of accepting photoinduced electrons and subsequently transferring them to initiate an electron-coupled hydrogenation reaction (AQ to AQH). Moreover, the proximity of the o-polyquinone redox sites facilitates the catalysis of unsymmetric disulfide bond formation. Consequently, the ANTH-AMI photocatalysts demonstrate exceptional yields (up to 82 %), substrate versatility, cycling stability, and scalable preparation in promoting unsymmetric coupling reactions of thiol. This work offers a solution for designing organic polymer photocatalysts with adjacent multiple redox centers for cross-coupling reactions.
RESUMEN
A novel visible-light-driven photoredox-catalyzed cascade bicyclization of 1,7-enynes with aqueous sulfoxonium ylides is reported. The reaction is highly chemoselective with three new C-C bonds, two new rings, and an all-carbon quaternary stereocenter constructed in a one-pot fashion. This mild protocol features a remarkably broad substrate scope with good functional group tolerance, providing a general and practical approach to access various cyclopenta[c]quinolines.
RESUMEN
The incorporation of gem-difluoromethylene units into organic molecules remains a formidable challenge. Conventional methodologies for constructing aryldifluoromethyl derivatives relied on the use of high-functional fluorinating regents under harsh conditions. Herein, we report general and efficient photoredox catalytic systems for defluoroalkylation of readily available trifluoromethylarenes through selective C-F cleavage to deliver gem-difluoromethyl radicals which proceed through reductive addition to both electron-donating and withdrawing alkenes under transition-metal free conditions. Mechanistic studies reveal that thiol serves as both photocatalyst and HAT reagent under visible light irradiation. This synergistic photocatalysis and HAT catalysis protocol exhibits ample and salient features such as high chemo- and regioselectivity, broad substrate scope, amenable gram-scale synthesis and late-stage modification of bioactive molecules.
RESUMEN
A convenient protocol for synthesis of unsymmetrical 2-methylpyridines from acetyl ketones, ammonium salts and tertiary amines is described. The construction of two C-C bonds and two C-N bonds via [2 + 2 + 1 + 1] four-component domino cyclization reaction is achieved using Cu(OTf) as catalyst in one pot. This cyclization reaction shows good selectivity and produces multisubstituted 2-methylpyridine derivatives in good yields with various functional groups.
RESUMEN
Herein, we have developed a complementary entry to enable hydroheteroarylation of alkenes involving basically photoredox dearomatizative heterocyclic carbon radical formation through acid-coupled electron transfer followed by Giese addition. While protonic solvent and thiophenol additive enabled two molecular hydroheteroarylations of alkenes, the nonproton environment with BF3 altered the chemoselectivity over cascade hydroheteroarylation of alkenes by radical addition of heteroaromatics with two molecular alkenes. This chemoselectivity can be mechanistically attributed to the dynamically favored hydrogen atom transfer via the cyclic transition state.
RESUMEN
A visible-light-induced photoredox three-component carbocyclization reaction of 1,7-enynes with sulfoxonium ylides and water is reported. The protocol provides a facile entry to structurally valuable highly functionalized cyclopenta[c]quinoline scaffolds in a highly chemoselective and stereoselective manner. Salient features of this method include facile redox-neutral conditions, no requirement of base or other additive, and good functional-group tolerance.
RESUMEN
A copper-catalyzed three-component coupling reaction of styrene oxide, aryl iodide, and carbon disulfide for the construction of ß-hydroxysulfides has been developed. In this process, readily available CS2 was used as the sulfur source to construct C-S bonds for the synthesis of phenyl-ß-hydroxysulfides and (benzo[d]thiazol)-ß-hydroxysulfides. This process features mild reaction conditions, simple operation, and wide substrate scope (>50 examples).
RESUMEN
The diversity of catalytic products determines the difficulty of selective product modulation, which usually relies on adjusting the catalyst and reaction conditions to obtain different main products selectively. Herein, we synthesized D-π-A-D conjugated organic polymers (TH-COP) using cyclotriphosphonitrile, alkyne, 2H-benzimidazole, and sulfur units as electron donors, π bridges, electron acceptors, and electron donors, respectively. TH-COP exhibited excellent photoinduced carrier separation and redox ability under different visible light wavelengths, and the main products of its CO2 reduction are CH4 (1000.0 µmol g-1) and CO (837.0 µmol g-1) under 400-420 nm and 420-560 nm, respectively. In addition, TH-COP could completely convert phenylmethyl sulfide to methyl phenyl sulfone at 400-420 nm and diphenyl disulfide at 480-485 nm in yields up to 95 %. This study presents a novel strategy for the targeted fabrication of various main products using conjugated polymers by simply changing the wavelength range of visible light.
RESUMEN
A selective three-component 1,2-sulfonyl etherification of aryl 1,3-dienes enabled by copper catalysis to afford biologically interesting alkenyl 1,2-sulfone ether derivatives through C-S and C-O bond formation is described. The protocol proceeds with the sulfonyl chloride and alcohols under simple, mild, and base-free conditions, providing a straightforward route to sulfonylated allyl ether compounds with broad functional group tolerance and excellent chemo- and regioselectivity. Mechanistic studies indicate that the selective alkene difunctionalization includes a key copper-mediated single-electron transfer process.
RESUMEN
Pyrrolo[1,2-a]indoles are structurally important scaffolds in many natural products and bioactive compounds. Herein, we report a novel synthetic method for pyrrolo[1,2-a]indole derivatives through visible-light-induced cascade dearomatizative cyclization of indoles with external nucleophiles. Moderate yields, good diastereoselectivities, and excellent regioselectivities were generally observed with the resultant indole-fused polycyclic compounds.
RESUMEN
Herein, we introduce a tetralone-mediated photocyclization method of N-arylacrylamides. The protocol proceeds smoothly to deliver a diverse set of 3,4-dihydroquinolinones in moderate to good yields with excellent functional group compatibility and readily allows for late-stage modifications of a number of complex drug molecules. Mechanistic studies reveal that the present systems with ultraviolet light irradiation enable the cyclization via energy transfer and exclusive 1,3-hydrogen shift.
RESUMEN
A three-component 1,4-alkylarylation of 1,3-enynes with organic halides through the combination of nickel and photoredox catalysis has been established, providing a novel and modular approach for the assembly of tetrasubstituted allenes. This reductive cascade cross-electrophile reaction obviates the need for air-sensitive organometallic reagents and stoichiometric metallic reductants. A diverse range of functional groups are very compatible under mild reaction conditions and give satisfactory yields. Moreover, a reasonable mechanism is presented according to a series of control experiments.
RESUMEN
The photoredox/PPh3-mediated cyclization of 2-isocyanobiaryls has been developed. A substantial range of functional-group-rich phenanthridine derivatives were synthesized at room temperature in a highly selective and atom-economic manner. Mechanistic studies suggested that the cyclization process is probably mediated both by Ph3P radical cation with key 1,2-hydride transfer and hydrogen atom generated through O-H bond homolytic cleavage of Ph3P-OH radical intermediate.
RESUMEN
2-Azidoimines are versatile precursors to value-added vicinal unsymmetrical diamines, which are among the most common motifs in biologically active compounds. Herein, we report their operationally simple synthesis through a highly regioselective intermolecular azidoamination of olefins under metal-free conditions. The approach proceeded through azide and iminyl, two differentiated N-centered radicals. The synthetic potential of the protocols was further established via the condensation/amination sequential cascade and chemoselective, orthogonal transformations to access vicinal primary diamines.
RESUMEN
Herein, we have developed an atom- and step-economic three-component cascade reaction that enables a modular platform for the synthesis of pyrrolo[2,3-c]quinoline compounds through ring-expansion/cyclization by way of novel N1-C2 cleavage of indoles. The metal-free catalytic system exhibits a broad functional group tolerance.
RESUMEN
A facile and practical approach for the preparation of substituted pyrimidines from ketones, NH4OAc, and N,N-dimethylformamide dimethyl acetal has been described. This NH4I-promoted three-component tandem reaction affords a broad range of substituted pyrimidines in acceptable yields under metal- and solvent-free conditions. The present methodology features the advantages of simple and easily available starting materials, metal- and solvent-free conditions, a broad substrate scope with good functional group tolerance, and gram-scale synthesis.
RESUMEN
An environmentally benign multicomponent strategy for the amidosulfenylation of alkenes for the synthesis of ß-succinimide sulfides is disclosed. In this process, common disulfides smoothly act as a sulfur-based source, and N-iodosuccinimide (NIS) is used not only as a free radical initiator but also as an N-nucleophile. A broad range of functional groups are tolerated in this reaction system.
RESUMEN
A novel and selective synthesis of polycyclic fused maleimides from easily available raw materials under metal-free conditions is presented. This cascade protocol involves self-condensation of cyclohexanones, followed by Diels-Alder reaction with maleimides, intramolecular dehydration, and selective dehydroaromatization in a one-pot fashion, affording maleimide-fused 9,10-phenanthrenes and their analogues in satisfactory yields. Notably, iodide reagents play a critical role in switching the selectivity toward full or partial dehydrogenation compounds.
RESUMEN
A visible-light-induced cascade arylazidation of activated alkenes with trimethylsilyl azide (TMSN3) has been developed. Mechanistic investigations reveal that the single electron transfer (SET) of TMSN3 with the excited photocatalyst was involved in the initial step, followed by radical addition/aryl migration/desulfonylation to furnish valuable α-aryl-ß-azido amides and azidated oxindoles under mild conditions, which are versatile building blocks in organic synthesis. With simple treatment, the obtained arylazidated products were further converted to valuable ß-amino amide and 1,2,3-triazole derivatives.