Copper-Catalyzed Oxidative Cross-Dehydrogenative Coupling/Oxidative Cycloaddition: Synthesis of 4-Acyl-1,2,3-Triazoles

Organobase-catalyzed efficient synthesis of 4-acyl-5-aryl tri-substituted triazole linked N-glycosides as glycohybrids

Herein, we report a highly efficient organobase-catalyzed method for the synthesis of fully decorated chiral 4-acyl-5-aryl-trisubstituted-1,2,3-triazole-linked N-glycosidic molecular scaffolds as glycohybrids. This process involves a base-catalyzed 1,3 dipolar cycloaddition reaction, where β-ketoesters react with various glycosyl azides in dimethyl sulfoxide at room temperature, furnishing new glycohybrids in good to excellent yields. This intermolecular reaction is metal-free, exceptionally efficient, versatile, and high-yielding, with a broad substrate scope and remarkable regioselectivity.

HFIP-Mediated Synthesis of 4-Aryl-NH-1,2,3-Triazoles and 1,5-Disubstituted 1,2,3-Triazolyl Glycoconjugates

We herein report a multicomponent reaction for the synthesis of N-unsubstituted-1,2,3-triazoles and N-substituted-1,2,3 triazoles from the reaction of aldehydes, nitroalkanes, and sodium azides/glycosyl azides in the presence of 1,1,1,3,3,3-hexafluoroisopropanol, a hydrogen bond-donating reaction medium. This three-component reaction provides a metal-free strategy for sequentially forming one C-C and two C-N bonds in a one-pot fashion. One-pot mild reaction condition, operational simplicity, wide substrate scope, good functional group tolerance, easy purification, high reaction yields, and altogether excellent regioselectivity are the notable advantages of this 1,2,3-triazole-forming protocol. Moreover, this protocol provides practical access to the gram-scale synthesis of potent inhibitors of indoleamine 2,3-dioxygenase 1.

Ring-Opening α,β-Difunctionalization of Cyclopropanols with Azides Enables 4-Keto-Functionalized 1,2,3-Triazole Synthesis

Selective C-C bond cleavage and transformation of organic small molecules to create products of increased value are one of the central goals in organic chemistry. In this study, we have developed a novel TEMPO-mediated ring-opening α,β-difunctionalization of cyclopropyl alcohols with organic azides to prepare structurally important 4-keto-1,2,3-triazoles under metal- and additive-free conditions. This protocol not only provides a straightforward and efficient method for the synthesis of 4-keto-functionalized 1,2,3-triazoles in one pot but also accomplishes the goal of constructing α,β-double C-N bonds via the ring opening of cyclopropyl alcohols for the first time. Additionally, the application of the skeletons of drugs and natural products and the synthesis of Kv1.5 channel blocker 4u further demonstrate the synthetic potential and practicability of this strategy.

Synthesis of Substituted of Benzo[4,5]imidazo[1,2-a]pyrimidines through (3 + 2+1) Cyclization of 2-Aminobenzimidazole, Acetophenone, and N,N-Dimethylformamide as One-Carbon Synthon

An efficient method for the construction of benzo[4,5]imidazo[1,2-a]pyrimidines using N,N-dimethylformamide as a one-carbon source and 2-aminobenzimidazoles and acetophenone as substrates through a one-pot, three-component cascade reaction is described. Spectra investigations indicated the fluorescent properties of selected products, exhibiting quantum yields 0.07-0.16 with maxima absorption at 266-294 nm and emission at 472-546 nm.

In Situ-Generated Formamidine as a Carbon/Nitrogen Source for Enaminone Formation: One-Pot Synthesis of Functionalized 4-Acyl-1,2,3-triazoles

N,N-Dimethylformamide was reacted with hexamethyldisilazane to generate an N,N-dimethylformimidamide intermediate; thereafter, a reaction with acetophenones/β-diketones was induced to form enaminones. The one-pot synthetic protocol described in this paper can be applied to synthesize 1,4-disubstituted 1,2,3-triazoles and 1,4,5-trisubstituted 1,2,3-triazoles, in which organic azides are used as substrates under optimized conditions. Furthermore, this protocol uses readily available materials, is nearly free of solvent, can be applied to gram-scale operations, and leads to the formation of structurally diverse products with favorable yields.

An FeCl3-catalyzed three-component reaction for the synthesis of β-(1,2,3-triazolyl)-ketones using DMF as a one-carbon source

An FeCl3-catalyzed oxidative condensation of NH-1,2,3-triazoles, aryl methyl ketones (or acetophenones) and DMF (N,N-dimethylformamide) for the synthesis of β-(1,2,3-triazolyl)-ketones was developed. DMF serves as a one-carbon source, and the resulting products display diverse reaction selectivity, highlighting the existence of distinct approaches.

Copper-catalyzed multiple oxidation and cycloaddition of aryl-alkyl ketones (alcohols) for the synthesis of 4-acyl- and 4-diketo-1,2,3-triazoles

A Cu/TEMPO-catalyzed tandem multiple oxidative dehydrogenation and cycloaddition has been developed, which affords 4-acyl-1,2,3-triazoles and 4-diketo-1,2,3-triazoles from readily-available aryl-alkyl ketones (or alcohols) and different organic azides. Moreover, the reaction used environmentally friendly dimethyl carbonate (DMC) as the solvent and air as the oxidant, and H₂O was the only by-product, so it provides a green and practical synthetic method for 1,2,3-triazoles.

Catalytic Direct Cyanomethylenation of C(sp3)-H Bonds via a One-Step Double C-C Bond Formation

An elegant and catalytic procedure for the one-step cyanomethylenation of C(sp³)-H bonds adjacent to benzazoles and ketones is described herein using DMF as a C-1 unit and TMSCN as the cyanide source. The copper-mediated reaction between DMF and TMSCN gives a cyanomethylene radical intermediate that reacts with 2-alkylbenzazoles or alkylketones to furnish desired cyanomethylenated compounds under palladium catalysis. Subsequent interconversion of cyanomethylenated products makes the protocol synthetically attractive.

Two C═C Bond Participation in Annulation to Pyridines Based on DMF as the Nonadjacent N and C Atom Donors

Two C═C bond participation in annulation to pyridines using N,N-dimethylformamide (DMF) as the N1 and C4 synthons has been carried out. In this reaction, DMF contributed one N atom and one C atom to two disconnected positions of pyridine ring, with no need for an additional nitrogen source. Two C═C bonds in two molecules of substituted styrenes offered four carbon atoms in the presence of iodine and persulfate. With the optimized conditions in hand, both symmetric and unsymmetric diaryl-substituted pyridines were obtained in useful yields. On the basis of relevant literature and a series of control experimental results, a possible mechanism was proposed in this work, which may demonstrate how DMF provides both N1 and C4 sources.

Transition Metal-Free Oxidative Cross-Coupling Reaction of Activated Olefins with N-Alkyl Amides

The K₂S₂O₈-mediated transition metal-free oxidative cross-coupling reaction of activated olefins with N-alkyl amides was developed, and the reaction gave N-allylic amides in moderate to good yield. This reaction protocol was suitable for different kinds of activated olefins.

Sequential Cu(II)-promoted oxidation/[3 + 2] cycloaddition/aromatization tandem reaction for the synthesis of 2-substituted benzo[f]isoindole-4,9-dione

An efficient method for the synthesis of 2-substituted benzo[f]isoindole-4,9-dione derivatives from N-substituted iminodiacetates and quinones via a Cu(II)-promoted oxidation/[3 + 2] cycloaddition/aromatization tandem reaction was reported. This tandem reaction uses a wide range of N-substituted iminodiacetate derivatives that contain the chain-alkyl, cycloalkyl, and aryl group on the N-atom. Based on optimized reaction conditions, the desired product of 2-substituted benzo[f]isoindole-4,9-diones was obtained in moderate to excellent yields. Taken together, the promising results of this research would provide an especially efficient strategy to synthesize polysubstituted pyrroles from easy available starting materials and promoted by cheaper Cu(OAc)2.

The crystal structure of 1-benzyl-4-(2-(phenylethynyl)phenyl)-1H-1,2,3-triazole, C23H17N3

C23H17N3, monoclinic, P21 (no. 4), a = 11.7817(14) Å, b = 5.3165(6) Å, c = 14.1747(16) Å, β = 95.731(2)°, V = 883.43(18) Å3, Z = 2, R gt(F) = 0.0663, wR ref(F 2) = 1567, T = 298(2) K.

Metal-Free C-N or C-C Bond Cleavages of α-Azido Ketones: An Oxidative-Amidation Strategy for the Synthesis of α-Ketothioamides and Amides

A novel metal-free oxidative-amidation strategy for the synthesis of α-ketothioamides and amides from α-azido ketones was developed. The C-H bond thionation of α-azido ketones with elemental sulfur could form α-ketothioacyl azide, which was then nucleophilically attacked by amines, causing the cleavage of the C-N bond to afford α-ketothioamides, while amides could be formed with the release of nitrogen gas and cyano anion in the presence of PhI(OAc)₂ by selective C-C bond cleavage.

Facile synthesis of 1,2,3-triazole-fused indolo- and pyrrolo[1,4]diazepines, DNA-binding and evaluation of their anticancer activity

A facile synthetic strategy has been developed for the generation of structurally diverse N-fused heterocycles. The formation of fused 1,2,3-triazole indolo and pyrrolodiazepines proceeds through an initial Knoevenagel condensation followed by intramolecular azide-alkyne cycloaddition reaction at room temperature without recourse to the traditional Cu(I)-catalyzed azide-alkyne cycloadditions. The synthesized compounds were evaluated for their in vitro anti-cancer activity against the NCI 60 cell line panel. Among the tested compounds, 3a and 3h were found to exhibit potent inhibitory activity against many of the cell lines. Cell cycle analysis indicated that the compounds inhibit the cell cycle at sub G1 phase. The DNA- nano drop method, viscosity experiment and docking studies suggested these compounds possess DNA binding affinity.

A cascade oxidation/[4 + 1] annulation of sulfonium salts for synthesis of polyfunctional furans: DMSO as one carbon source

A novel DMSO-involved cascade reaction of stabilized sulfonium salts has been established for direct construction of polyfunctional furans.

Cu(ii)- or Co(ii)-Catalyzed C(SP3)–H oxidation of N,N-dimethylaminoethanol: facile synthesis of methylene-bridged biindoles and 3-formylindoles selectively

Methylene-bridged biindoles and 3-formylindoles were synthesized with high conversion rate and good regioselectivity using a new carbon donor N,N-dimethylethanolamine, catalyzed by CuCl₂ and CoCl₂ respectively.

Potassium Persulfate‐Promoted N‐Nitrosation of Secondary and Tertiary Amines with Nitromethane under Mild Conditions

A simple and efficient route for the N‐nitrosation of various secondary amines with nitromethane is described in the presence of potassium persulfate and DBU. Under optimized condition, tertiary amines underwent a dealkylative N‐nitrosation with good yields. Inexpensive reagents, broad substrate scope and efficient conversion make the current protocol more attractive in organic synthesis.

Recent Uses of N,N-Dimethylformamide and N,N-Dimethylacetamide as Reagents

N,N-Dimethylformamide and N,N-dimethylacetamide are multipurpose reagents which deliver their own H, C, N and O atoms for the synthesis of a variety of compounds under a number of different experimental conditions. The review mainly highlights the corresponding literature published over the last years.

Cu-Catalyzed Cross-Dehydrogenative ortho-Aminomethylation of Phenols

A highly selective Cu^II‐catalyzed cross‐dehydrogenative ortho‐aminomethylation of phenols with aniline derivatives is described. The corresponding C(sp²)−C(sp³) coupling products were obtained in moderate to excellent yields under mild reaction conditions and with a broad substrate scope. A radical mechanism is proposed.

Copper-Catalyzed Syntheses of Pyrene-Pyrazole Pharmacophores and Structure Activity Studies for Tubulin Polymerization

Tubulin polymerization is critical in mitosis process, which regulates uncontrolled cell divisions. Here, we report a new class of pyrene-pyrazole pharmacophore (PPP) for targeting microtubules. Syntheses of seven pyrenyl-substituted pyrazoles with side-chain modification at N-1 and C-3 positions of the pyrazole ring were accomplished from alkenyl hydrazones via C-N dehydrogenative cross-coupling using copper catalyst under aerobic condition. Tubulin polymerization with PPPs was investigated using docking and biological tools to reveal that these ligands are capable of influencing microtubule polymerization and their interaction with α-, β-tubulin active binding sites, which are substituent specific. Furthermore, cytotoxicity response of these PPPs was tested on cancer cells of different origin, such as MCF-7, MDA-MB231, and C32, and also noncancerous normal cells, such as MCF-10A. All newly synthesized PPPs showed excellent anticancer activities. The anticancer activities and half-maximal inhibitory concentration (IC₅₀) values of all PPPs across different cancer cell lines (MCF-7, MDA-MB231, and C32) have been demonstrated. 1,3-Diphenyl-5-(pyren-1-yl)-1H-pyrazole was found to be best among all other PPPs in killing significant population of all of the cancerous cell with IC₅₀ values 1 ± 0.5, 0.5 ± 0.2, and 5.0 ± 2.0 μM in MCF-7, MDA-MB231, and C32 cells, respectively.