RESUMO
An efficient palladium-catalyzed carbonylation of aryl fluorosulfates with aryl formates for the facile synthesis of esters was developed. The cross-coupling reactions proceeded effectively in the presence of a palladium catalyst, phosphine ligand, and triethylamine in DMF to produce the corresponding esters in moderate to good yields. Of note, functionalities or substituents, such as nitro, cyano, methoxycarbonyl, trifluoromethyl, methylsulfonyl, trifluoromethoxy, fluoro, chloro, bromo, methyl, methoxy, N,N-dimethyl, and [1,3]dioxolyl, were well-tolerated in the reactions, which could be kept for late-stage modification. The reactions employing readily available and relatively robust aryl fluorosulfates as coupling electrophiles could potentially serve as an attractive alternative to traditional cross-couplings with the use of aryl halides and pseudohalides as substrates.
RESUMO
Hydroxylation of aryl sulfonium salts could be realized by utilizing acetohydroxamic acid and oxime as hydroxylative agents in the presence of cesium carbonate as a base, leading to a variety of structurally diverse hydroxylated arenes in 47-95% yields. In addition, the reaction exhibited broad functionality tolerance, and a range of important functional groups (e.g., cyano, nitro, sulfonyl, formyl, keto, and ester) could be well amenable to the mild reaction conditions.
RESUMO
A reductive amidation of triazine esters with nitroarenes by using cheap iron as a reducing metal in the presence of TMSCl in DMF was developed. The reactions proceeded efficiently under transition metal-free conditions to give the corresponding amides in moderate to good yields with good functional group compatibility. Preliminary mechanistic investigations indicated that nitrosobenzene, N-phenyl hydroxylamine, azoxybenzene, azobenzene, aniline, and N-arylformamide possibly served as the intermediates of the reaction.
RESUMO
A chemo-, regio-, and stereoselective reaction of trifluoromethyl enones, phenylsilane, and phosphine oxides through a sequential hydrodefluorination and defluorophosphorylation relay is developed for the synthesis of distinctive gem-fluorophosphine alkenes. This multicomponent reaction occurred under transition-metal-free conditions with good functional group tolerance. Moreover, the preinstalled carbonyl auxiliary is important for tuning the reactivity of ß-trifluoromethyl enones, thereby enabling controllable and selective functionalization of two fluorine atoms in trifluoromethylated enones.
RESUMO
A nickel-catalyzed direct cross-coupling of unactivated aryl fluorides with aryl bromides is realized. The one-pot reaction, which avoids the use of preformed and sensitive organometallic reagents, proceeds effectively via C-F bond cleavage at room temperature in THF in the presence of the phosphine ligand and magnesium powder (with or without TMSCl) to produce the desired biaryls in modest to good yields.
RESUMO
An unprecedented defluorocyclization of perfluorobutyl tetralones with Na2S·9H2O was developed for the synthesis of trifluoromethyl 1,2-dithioles, which provided chemists novel access to biologically and pharmaceutically relevant organofluorides. Successive C(sp3)-F bond functionalization at the perfluoroalkyl chain is vital for the formation of four C-H/C-S/S-S bonds and a five-membered S-heterocycle assembly. Cheap, weakly toxic, and odorless inorganic sulfide Na2S·9H2O acts as both a disulfurating precursor and a hydrodefluorinating reagent in this tandem multi-bond-interconverting reaction.
Assuntos
TetralonasRESUMO
The auxiliary function of a carbonyl group in the tunable defluorophosphination and defluorophosphorylation of trifluoromethylated enones with P(O)-containing compounds was demonstrated. Controlled replacement of one or two fluorine atoms in trifluoromethylated enones while maintaining high chemo- and stereoselectivity was achieved under mild conditions, thus enabling diversity-oriented synthesis of skeletally diverse organophosphorus librariesâ(Z)-difluoro-1,3-dien-1-yl phosphinates, (1Z,3E)-4-phosphoryl-4-fluoro-buta-1,3-dien-1-yl phosphinates, and (E)-4-phosphoryl-4-fluoro-1,3-but-3-en-1-onesâin good yields with excellent functional group tolerance.
RESUMO
A straightforward cross-coupling of aryl thioether with aryl bromide with the aid of nickel salt, magnesium, and lithium chloride in tetrahydrofuran at ambient temperature was accomplished. The one-pot reactions proceeded efficiently via C-S bond cleavage to produce the desired biaryls in modest to good yields, avoiding the use of pregenerated or commercial organometallic reagents.
RESUMO
A one-pot, direct cross-coupling of aryl fluorosulfate with aryl bromide, which is step-economical and avoids the use of a preprepared/commercial organometallic reagent, could be accomplished by performing the reaction in THF at room temperature in the presence of nickel catalyst, magnesium turnings, and lithium chloride, giving rise to the corresponding biaryls in moderate to good yields with reasonable functional group compatibility.
RESUMO
A modular multicomponent reaction of readily available fluoroalkyl alkenes, amidines, ammonium carbonate, and water was developed for the facile construction of ß-fluoroalkylated aminovinyl ketones, which provided chemists a novel access to value-added organofluorine compounds. The reaction proceeded regio-/stereoselectively under mild conditions and exhibited good functional group tolerance. Cheap, stable, and low-toxic inorganic salt (NH4)2CO3 was first found to act as both a nitrogen source and a carbonyl equivalent in the multi-bond-forming process.
RESUMO
The direct cross-couplings of diaryl sulfoxides with aryl bromides via C-S bond cleavage could be readily accomplished using nickel(II) as the catalyst, 1,2-bis(diphenylphosphino)ethane (dppe) as the ligand, and magnesium turnings as the reducing metal in THF, leading to the corresponding biaryls in moderate to good yields. The reaction exhibited a broad substrate scope and could be applied to a gram-scale synthesis. The "one-pot" reaction, which avoids the utility of presynthesized and moisture-labile organometallic compounds, is operationally simple and step-economic.
RESUMO
An efficient method for the synthesis of ß,ß-di(hetero)aryl-α,α-difluorinated ketones using readily available organophosphonium salts and difluoroenol silyl ethers has been developed. This mild reaction features a good functional group tolerance, a scaled-up synthesis, and synthetic simplicity. By taking advantage of DMSO as a less-toxic promoter and solvent for the difluoroalkylation and C-P bond functionalization, the use of transition-metal catalysts and sensitive additives could be avoided.
Assuntos
Éteres , Sais , Catálise , Dimetil Sulfóxido , Éteres/química , Cetonas/químicaRESUMO
An efficient Sonogashira coupling of a heterocyclic phosphonium salt with a terminal alkyne via C-P bond cleavage was developed. The reactions proceeded smoothly in the presence of palladium catalyst, copper(I) iodide, and N,N-diisopropylethylamine (DIPEA) in N-methyl-2-pyrrolidone (NMP) at 100 °C for 12 h, producing the corresponding alkynyl-substituted pyridine, quinoline, pyrazine, and quinoxaline in moderate to good yields with wide substrate scope and broad functional group tolerance. In addition, gram-scale synthesis could also be achieved, and the reaction could be applied to the functionalization of alkyne-containing complex molecules derived from sugars and pharmaceutical and naturally occurring products (e.g., estrone, d-galactopyranose, menthol, and ibuprofen).
Assuntos
Alcinos , Paládio , Alcinos/química , Catálise , Cobre , Paládio/químicaRESUMO
The direct cross-couplings of aryl sulfonium salts with aryl halides could be achieved by using nickel as a reaction catalyst. The reactions proceeded efficiently via C-S bond activation in the presence of magnesium turnings and lithium chloride in THF at ambient temperature to afford the corresponding biaryls in moderate to good yields, potentially serving as an attractive alternative to conventional cross-coupling reactions employing preprepared organometallic reagents.
RESUMO
Few methods are known for the synthesis of nitroindole derivatives. A simple and practical Cs2CO3-promoted method for the synthesis of 6-nitroindole derivatives from enaminones and nitroaromatic compounds has been developed. Two new C-C and C-N bonds were formed in a highly regioselective manner under transition metal-free conditions.
RESUMO
A titanium(IV)-mediated ring-opening/dehydroxylative cross-coupling of diaryl-substituted methanols with a cyclopropanol derivative was developed. The reactions proceeded efficiently to provide synthetically useful γ,γ-diaryl esters in moderate to good yields, which could be applied to the functionalization of complex molecules derived from bioactive fenofibrate and isoxepac and the synthesis of a precursor of Zoloft.
Assuntos
Metanol , Titânio , Ésteres , Éteres CíclicosRESUMO
As the "chemical chameleon", sulfonyl-containing compounds and their variants have been merged with various types of reactions for the efficient construction of diverse molecular architectures by taking advantage of their incredible reactive flexibility. Currently, their involvement in radical transformations, in which the sulfonyl group typically acts as a leaving group via selective C-S, N-S, O-S, S-S, and Se-S bond cleavage/functionalization, has facilitated new bond formation strategies which are complementary to classical two-electron cross-couplings via organometallic or ionic intermediates. Considering the great influence and synthetic potential of these novel avenues, we summarize recent advances in this rapidly expanding area by discussing the reaction designs, substrate scopes, mechanistic studies, and their limitations, outlining the state-of-the-art processes involved in radical-mediated desulfonylation and related transformations. With a specific emphasis on their synthetic applications, we believe this review will be useful for medicinal and synthetic organic chemists who are interested in radical chemistry and radical-mediated desulfonylation in particular.
Assuntos
Elétrons , Técnicas de Química SintéticaRESUMO
An unprecedented and expeditious tandem bisannulation of polyfluoroalkylated tetralones with benzamidines to access various fluoroalkyl tetracyclic [1,3]-diazepines through multiple C-N bond formation and C(sp3)-F bond cleavage is reported. The process features high regio-/chemoselectivities, broad substrate scope, good functional group tolerance, procedural simplicity, mild reaction conditions, and scale-up synthesis. Mechanistic studies showed that the distinctive fluorine effect of polyfluoroalkyl tetralone plays a vital role for the aza-tetracycle construction.
Assuntos
FlúorRESUMO
A nickel-catalyzed direct reductive cross-coupling of disubstituted cycloalkyl iodides with aryl iodides was developed. The one-pot reaction, which is simple to operate, was capable of proceeding efficiently in a stereocontrolled manner to afford a variety of cross-coupled products with high diastereoselectivity and wide functional group tolerance.