Seven- and eight-membered heterocyclic biaryl synthesis through a metal-free oxidative coupling reaction

A metal-free intramolecular biaryl coupling mediated by DDQ and BF₃·OEt₂ was developed. The reaction proceeds smoothly at room temperature to give seven- and eight-membered heterocyclic biaryl compounds in up to 95% yields. Only 1 equiv of DDQ sufficed for the reaction, obviating the use of a large excess of oxidants and undesired chlorination pathway in metal-mediated process.     

Synthesis of novel 2,2-disubstituted naphthodioxoles via an unprecedented reaction

A reaction of 2,3-dihydroxynaphthalene with ethyl-2,3-dibromo-3-phenyl-propionate or 1,3-diaryl-2,3-dibromo ketone under basic conditions led to the formation of novel 2,2-disubstituted naphthodioxoles.     

Efficient synthesis of isoflavone analogues via a Suzuki coupling reaction

Analogues of 3-aryl-8-isobutyl-5,6,7-trihydroxy-2-methyl-4H-chromen-4-one were synthesized with high yields via the Suzuki coupling reaction of 3-iodo-8-isobutyl-5,6,7-trimethoxy-2-methyl-4H-chromen-4-one with different aryl boronic acids.     

Expanded scope of heterocyclic biaryl synthesis via a palladium-catalysed thermal decarboxylative cross-coupling reaction

The palladium-catalysed decarboxylative cross-coupling of heterocyclic aromatic carboxylates and aryl halides is described. The cross-coupling proceeds under relatively mild conditions using catalytic Pd(0) and tetrabutylammonium bromide (TBAB). Utilizing a mixed solvent system consisting of N,N-dimethylformamide (DMF) and N-methyl-2-pyrrolidone (NMP), the cross-coupling system operated at temperatures ranging from 80 to 140 °C.     

Palladium-catalyzed synthesis of highly substituted endocyclic enol lactones via a three-component coupling reaction in an ionic liquid

[reaction: see text] A new, efficient ionic liquid based synthetic procedure was developed for the preparation of highly substituted endocyclic enol lactones via the carbonylation coupling reactions of alkynes and 1,3-diketones in ionic liquid. The reactions proceeded in excellent regioselectivity and in reasonably good yields. The catalyst system can be recycled five times with only modest loss of its catalytic activity.     

杂环合成中的氮杂Wittig反应

氮杂Wittig反应是杂环化合物的一个新的合成方法.本文阐述了羰基通过叠氮化物和三价膦形成的亚胺基膦的作用, 以氮杂Wittig反应的方式, 合成含氮杂环化合物的进展.     

Me3SiCl-promoted three-component coupling reaction of a functionalized enamine, an acetal, and an alkyne: an unprecedented approach to the synthesis of tetrasubstituted pyridines via a [3 + 2 + 1] intermolecular cyclization

We have identified a Me3SiCl-mediated three-component coupling reaction of a functionalized enamine, N,N-dimethylformamide diethyl acetal, and an internal alkyne having an electron-withdrawing group that produces 2,3,4,5-tetrasubstituted pyridine derivatives in good to excellent yields via a single-step reaction.     

Stereoselective synthesis of amides possessing a vinylsilicon functionality via a ruthenium catalyzed silylative coupling reaction

An effective stereoselective synthesis of E-N-2-(silyl)vinylamides via silylative coupling of vinyl amides such as N-vinylpyrrolidinone, N-vinylphthalimide, and N-vinylformamide with vinyltrisubstituted silanes catalyzed by [RuH(Cl)(CO)(PCy₃)₂] I is described.     

One-pot synthesis of substituted indolines via a copper-catalyzed sequential multicomponent/C-N coupling reaction

One-pot synthesis of 2-(N-sulfonylimino)indolines has been developed. The procedure combines the copper-catalyzed three-component reaction of sulfonyl azides, o-bromophenylacetylenes, and amines and the copper-catalyzed intramolecular C-N coupling in one sequence, which afforded the products in moderate to good yields. The resulting 2-(N-sulfonylimino)indolines could be easily transformed to pharmaceutically valuable oxindoles (indolin-2-ones).     

Gold(III) Salen complex-catalyzed synthesis of propargylamines via a three-component coupling reaction

[reaction: see text] Propargylamines have been synthesized by a gold(III) salen complex-catalyzed three-component coupling reaction of aldehydes, amines, and alkynes in water in excellent yields at 40 degrees C. With chiral prolinol derivatives as the amine component, excellent diastereoselectivities (up to 99:1) have been attained. This coupling reaction has been applied to the synthesis of propargylamine-modified artemisinin derivatives with the delicate endoperoxide moieties remaining intact. Cytotoxicities with IC(50) values up to 1.1 microM against a human hepatocellular carcinoma cell line (HepG2) were exhibited by these artemisinin derivatives.     

Total synthesis of aristolactams via a one-pot suzuki-miyaura coupling/aldol condensation cascade reaction

A direct one-pot synthesis of phenanthrene lactams, which employs a Suzuki-Miyaura coupling/aldol condensation cascade reaction of isoindolin-1-one with 2-formylphenylboronic acid, has been developed. The approach is used to efficiently produce a number of natural aristolactams, such as aristolactam BII (cepharanone B), aristolactam BIII, aristolactam FI (piperolactam A), N-methyl piperolactam A, and sauristolactam.     

Synthesis of an influenza neuraminidase inhibitor intermediate via a highly diastereoselective coupling reaction

[reaction: see text]. A highly diastereoselective coupling reaction between TBSOP (3) and trityl sulfenimine 4 was developed which provided influenza neuraminidase inhibitor intermediate 7 in 80% yield and >99% de after crystallization. The reaction was shown to be reversible with the high diastereoselectivity resulting from a favorable H-bonding interaction in the major diastereomer.     

Design and synthesis of potential β-sheet nucleators via Suzuki coupling reaction

Three series of compounds characterized by biphenylic structure were synthesized in order to develop new scaffolds able to induce β-sheet folding in the peptides. Microwave flash heating was used in order to shorten reaction times and to enhance the obtained yields. Simulated annealing molecular dynamics simulations demonstrated that some of the compounds were capable of adopting a 15-membered intramolecularly hydrogen-bonded conformation, which supports an antiparallel β-sheet structure.     

Green synthesis of novel chalcone and coumarin derivatives via Suzuki coupling reaction

Chalcones and coumarins are important naturally occurring plant constituents and display a wide range of pharmacological and biological activities. In an environmentally benign approach, synthesis of biphenyl chalcone and coumarin derivatives was successfully accomplished via Suzuki coupling by using PEG-400 as a solvent under microwave irradiation. Salient feature of this methodology includes: short reaction time, good to excellent yields, and prominent tolerance of different functional groups.     

Synthesis of N-(iodophenyl)-amides via an unprecedented Ullmann-Finkelstein tandem reaction

Using a new Ullmann-Finkelstein tandem reaction, N-(iodophenyl)-amides were synthesized from the corresponding amides and iodo-bromobenzenes. The catalyst/ligand couple CuI/N,N′-dimethyl-cyclohexane-1,2-diamine was used for this reaction in dioxane with K₃PO₄ as base.     

Chemical capture of an unprecedented oxatetramethyleneethane radical cation with a through-space electronic coupling

A photoinduced electron-transfer reaction of 2,2-dianisyl-4-isopropylidene-3,3-dimethylcyclobutanone (5) in acetonitrile containing molecular oxygen or water gave 4,4′-dimethoxybenzophenone (7) and 2,2-dianisyl-4-isopropylidene-5,5-dimethylhydrofuran-3-one (8), demonstrating the chemical capture of an unprecedented oxatetramethyleneethane-type radical cation intermediate (6⁺). A density functional theory calculation suggests through-space electronic coupling between the tetramethylallyl and joined dianisylmethyl carbonyl subunits in 6⁺.     

Arylation of halogenated pyrimidines via a Suzuki coupling reaction

The Suzuki coupling reaction has been used extensively for the synthesis of a wide variety of unsymmetrical biaryl compounds. We have extended this reaction to demonstrate the utility of preparing monophenyl-, diphenyl-, or triphenylpyrimidine depending on the reaction conditions. Further, it has been shown that chloropyrimidine substrates are preferable over iodo-, bromo-, or fluoropyrimidines.     

Total synthesis of the alkaloids martinelline and martinellic acid via a hetero Diels-Alder multicomponent coupling reaction

[reaction: see text] A concise synthesis of the guanidine alkaloids, (+/-)-martinelline and (+/-)-martinellic acid, using a protic acid catalyzed 2:1 hetero Diels-Alder coupling reaction between N-Cbz 2-pyrroline and methyl 4-aminobenzoate, is described. Protic acid catalysis, rather than Lewis acid catalysis, was necessary to achieve the desired sense of diastereocontrol in the coupling reaction.