Search

The first photo-induced nickel-mediated regioselective radical–radical cross-electrophile coupling process with alkyl NHP esters and EDA complexes for alkylated allenes is described.

An environmentally benign electrochemical decyanative C(sp3)–H oxygenation of N-cyanomethylamines for the synthesis of structurally diverse formamides is described.

C22H22O7, orthorhombic, C2221 (no. 20), a = 8.891(2) Å, b = 17.938(5) Å, c = 25.996(6) Å, V = 4146.0(18) Å3, Z = 8, R gt (F) = 0.0461, wR ref (F 2) = 0.1189, T = 296 K.

C49H52Cl2N10O6, monoclinic, P21 (no. 4), a = 12.2875(14) Å, b = 8.3031(10) Å, c = 13.1242(15) Å, β = 100.0640 ( 10 ) ∘ $100.0640{(10)}^{\circ }$ , V = 1318.4(3) Å3, Z = 1, R g t ${R}_{\mathrm{g}\mathrm{t}}$ (F) = 0.0736, w R r e f $w{R}_{\mathrm{r}\mathrm{e}\mathrm{f}}$ (F 2) = 0.1545, T = 296 K.

Herein, we developed a novel strategy for synthesizing ladder (thio)furan-fused phospholes via intermolecular phosphonation cyclization and a base-promoted phospha-Friedel-Crafts reaction under mild conditions. The starting substrates are readily available phosphinic acids and easy-to-handle alkynes. The details of the reaction mechanism were further rationalized using theoretical calculations. This protocol can be widely applied to synthesize furan- and thiofuran-fused phospholes as well as the corresponding large π-extended derivatives, which are of great interest in the domain of organic functional materials.

This review covers the recent progress in electrochemically enabled radical-mediated aryl/alkenyl C(sp2)–C(sp3) cross-coupling reactions, including synthetic strategies, plausible mechanisms and further research outlook.

Glycals are highly versatile and useful building blocks in the chemistry of carbohydrate and natural products. However, the practical synthesis of glycals remains a long-standing and mostly unsolved problem in synthetic chemistry. Herein, we present an unprecedented approach to make a variety of glycals using phosphonium hydrolysis-induced, P(v) intermediate-mediated E1cB elimination. The method provides a highly efficient, practical and scalable strategy for the synthesis of glycals with good generality and excellent yields. Furthermore, the strategy was successfully applied to late-stage modification of complex drug-like molecules. Additionally, the corresponding 1-deuterium-glycals were produced easily by simple

Rigidly planar polycyclic phosphacycles featuring an internal dioxaphosphorane are promising photofunctional materials. However, the lack of efficient synthetic methods resulted in limited structural diversities which significantly hampered extensive study. Herein, we report a straightforward three-component synthesis of novel dioxaphosphorane-fused diphosphacycles with distinctive photophysical properties. Control experiments and theory calculations were performed to account for a plausible reaction mechanism. We also systematically investigated the structure-property relationships of these unprecedented platforms by combining experiments (X-ray analysis, optical and redox properties) and theoretical computations. Based on their unique structure and properties, a novel fluorescent switch for pH sensing was revealed by a dynamic ring-opening/ring-closing process.

C24H25BrClNO11, monoclinic, C2 (no. 5), a = 28.914(5) Å, b = 7.9349(14) Å, c = 13.062(2) Å, β = 114.867(3)°, V = 2718.9(8) Å3, Z = 4, R gt (F) = 0.0352, wR ref (F 2) = 0.0888, T = 296.15 K.

A series of novel arylamine-substituted phenyl-phosphachromones were constructed via post-functionalization. As a new type of D–π–A functional molecule, their photophysical properties can be well tuned by different amino substituents at different positions with variable Stokes shifts (Δλ = 127–299 nm). Moreover, compounds 4a, 4b, 4f, 4m, and 4n exhibit an unusual dual emission with a large wavelength difference. Strong intermolecular interactions were also observed for these compounds, and therein, a sandwich π(donor)–π(donor) stacking interaction was found in the solid-state structure of 4e. Moreover, (TD-)DFT computations were performed to rationalize the observed electronic properties and intramolecular interactions. Finally, the delayed fluorescence of these D–π–A molecules in the film was observed and further confirmed to be a result of thermally activated delayed fluorescence and mixed room-temperature phosphorescence.

A practical and concise synthesis of 4-methylumbelliferyl α-l-idopyranosiduronic acid, a fluorogenic enzyme substrate diagnostic for α-l-iduronidase, was accomplished. It features successive radical bromination and radical reduction of easily accessible methyl 4-methyl­umbelliferyl-2,3,4-tri-O-acetyl-β-d-glucouronate in four steps with 28% overall yield.

In order to validate the structure of a rarely reported naturally occurring nucleoside isolated from the broth of Penicillium sp. (NO. 64), practical syntheses of 2′-O-methyl-β- l -arabinosyluridine, 2′-O-methyl-α- l -arabinosyluridine, and 2′-O-methyl-β- l -uridine were accomplished. Comparing their nuclear magnetic resonance (NMR) spectra and physical data, its structure was reassigned as 2′-O-methyl-β- l -uridine instead of former reported 2′-O-methyl-β- l -arabinosyluridine.

A metal-free, Bronsted acid-mediated cascade cyclization of 2-propynolphenols for efficient synthesis of various 4-thiocyanated 2H-chromenes is developed by using KSCN as the thiocyanated source. This reaction was characterized by readily prepared starting materials, bearing good functional group tolerance and excellent yields. Moreover, the obtained 4-thiocyanated 2H-chromenes could be further derivated to potential bioactive and pharmaceutical molecules.

The first total synthesis of 5′-O-α-d-glucopyranosyl tubercidin was successfully developed. It is a structurally unique disaccharide 7-deazapurine nucleoside exhibiting fungicidal activity, and was isolated from blue-green algae. The total synthesis was accomplished in eight steps with 27% overall yield from commercially available 1-O-acetyl-2,3,5-tri-O-benzoyl-β-d-ribose. The key step involves stereoselective α-O-glycosylation of the corresponding 7-bromo-6-chloro-2′,3′-O-isopropylidene-β-d-tubercidin with 2,3,4,6-tetra-O-benzyl-glucopyranosyl trichloroacetimidate. All spectra are in accordance with the reported data for natural 5′-O-α-d-glucopyranosyl tubercidin. Meanwhile, 5′-O-β-d-glucopyranosyl tubercidin was also prepared using the same strategy.

A novel, efficient and metal-free cascade sulfonylation/cyclization of 2-propynolphenols with commercially available sodium sulfinates was developed for the synthesis of 4-sulfonyl 2H-chromenes under mild conditions. The reaction occurred by the sodium sulfinates’ nucleophilic addition of the allylene carbocation intermediate followed by a 6-endo-trig pathway. Additionally, this approach avoids the use of an oxidant or a photo-radical inducer and the reaction can tolerate a wide variety of functional groups in good yields.

A novel and efficient p-TsOH-promoted cascade cyclization of 2-propynolphenols is developed to give 4-tosyloxy-2H-chromenes in moderate to efficient yields. It is noted that p-TsOH acts not only as a promoter in this reaction, and also as the sulfonate source. Importantly, the obtained 4-tosyloxy-2H-chromenes can be used as versatile intermediates for the synthesis of various functionalized compounds through diverse metal-catalyzed cross-coupling reactions. Moreover, this method can be enlarged to gram scale.

The [Cu(OTf)]2·C6H6 catalyzed cascade intermolecular addition–intramolecular cyclization reaction of easily prepared 2-propynol phenyl azides and diarylphosphine oxides was developed. This novel reaction leads to simultaneous formation of one C–N and two C–P bonds in a single step to give bisphosphorylated indole derivatives under mild conditions in moderate to good yields.

A glucopyranosyltriazole unit covalently bonded to a uridine nucleoside was synthesized and its gelation properties evaluated in ionic liquids. The ionogels were thermally stable; no melting occurr...

A novel and efficient strategy for the synthesis of 4-chloro quinolines via the TMSCl-mediated cascade cyclization of easily prepared ortho-propynol phenyl azides is developed. This reaction proceeds smoothly in moderate to excellent yields with a wide range of substrate compatibility. TMSCl acted not only as a promoter, but also as a chloro source in this transformation. Moreover, the obtained 4-chloro quinolines could be further derivated in an array of palladium-catalyzed coupling and nucleophilic substitution reactions to construct potential biologically active and pharmaceutical molecules.

A novel copper-catalyzed cascade cyclization of easily prepared 2-propynolphenols with disubstituted phosphine oxide is developed to give 4-phosphorylated 2H-chromenes in moderate to excellent yields. This cascade process involves multiple bond-forming events including C−O and C−P bonds. Moreover, both tertiary and secondary propargylic alcohols with diverse functional groups showed excellent compatibilities under ligand and additive-free conditions.

A convenient strategy is present for easy construction of a series of 4-halo-2 H -chromenes and 1,2-dihydroquinolines through Bronsted acid-mediated cascade cyclization of readily accessible 2-propynolphenols/anilines. Our developed approaches prove have good functional-group applicabilities and could be enlarged to gram quantities in high yields. Moreover, the resulting halides could be further exploited in subsequent palladium-catalyzed coupling reactions.

In order to validate the structure of a rarely reported naturally occurring nucleoside isolated from the broth of Penicillium sp. (NO. 64), practical syntheses of 2'-O-methyl-β-L-arabinosyluridine, 2'-O-methyl-α-L-arabinosyluridine, and 2'-O-methyl-β-L-uridine were accomplished. Comparing their nuclear magnetic resonance (NMR) spectra and physical data, its structure was reassigned as 2'-O-methyl-β-L-uridine instead of former reported 2'-O-methyl-β-L-arabinosyluridine.

The first total synthesis of the marine nucleoside Mycalisine B—a naturally occurring and structurally distinct 4,5-unsaturated 7-deazapurine nucleoside—has been accomplished in 10 linear steps with 27.5% overall yield from commercially available 1,2,3,5-tetra-O-acetyl-ribose and tetracyanoethylene. Key steps of the approach include: (1) I2 catalyzed acetonide formation from 1,2,3,5-tetra-O-acetylribose and acetone at large scale; (2) Vorbrüggen glycosylation using N4-benzoyl-5-cyano-6-bromo-7H-pyrrolo[2,3–d]pyrimidine as a nucleobase to avoid formation of N-3 isomer; (3) mild and scalable reaction conditions.

In the present paper, we report a novel strategy for highly efficient stereoselective synthesis of 2′-modified nucleosides by using ortho-alkynyl benzoate as neighboring participation group. Subsequently, ortho-alkynyl benzoate can be removed smoothly in the presence of 5 mol% Ph3PAuCl–AgOTf in dichloromethane with H2O (1 eq.) and ethanol (6 eq.) to afford 2′-OH nucleosides in high yields and selectivity.

A novel and efficient TMSCl-mediated cyclization reaction of easily prepared 2-propynolphenols/anilines is developed to give 4-chloro-2H-chromenes and 1,2-dihydroquinolines in good to efficient yields. It is noted that TMSCl acts not only as a promoter in this reaction, and also as the chloro source. Both tertiary and secondary propargylic alcohols with diverse functional groups were tolerated under mild conditions. Moreover, this method can be enlarged to gram scale (yield up to 90%). (C) 2016 Elsevier Ltd. All rights reserved.

In present paper, an expeditious total synthesis of naturally occurring 5′-deoxytoyocamycin and 5′-deoxysangivamycin was accomplished. Because of the introduction of a benzoyl group at N-6 of 4-amino-5-cyano-6-bromo-pyrrolo[2,3-d]pyrimidine, a Vorbrüggen glycosylation with 1,2,3-tri-O-acetyl-5-deoxy-β-D-ribofuranose afforded a completely regioselective N-9 glycosylation product, which is unambiguously confirmed by X-ray diffraction analysis. All of the involved intermediates were well characterized by various spectra.

Ultrafine Gd 2 O 3 :Eu 3+ nanocrystals were successfully prepared by a simple reverse microemulsion method and subsequent calcination. Their structural, optical and magnetic properties were investigated using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR), photoluminescence (PL), and magnetic property measurement system (MPMS). The amorphous Gd 2 (CO 3 ) 3 :Eu 3+ colloidal spheres were proved as an intermediate product, and gradually transformed into crystallized Gd 2 O 3 :Eu 3+ with average diameter less than 100 nm. The paramagnetic property of the synthesized Gd 2 O 3 :Eu 3+ nanocrystals were confirmed with its linear hysteresis plot ( M - H ). And Gd 2 O 3 :Eu 3+ nanocrystals showed high contrast T 1 -enhancing modality due to the presence of the Gd 3+ ions onto the particle surface. In addition, the application of the Gd 2 O 3 :Eu 3+ nanocrystals as biotag for cell labeling was reported, red fluorescence from Eu 3+ ions observed by fluorescence microscopy showed that the nanocrystals could permeate the cell membrane. Cytotoxicity studies of the Gd 2 O 3 :Eu 3+ nanocrystals showed no adverse effect on cell viability, evidencing their high biological compatibility. Therefore, the nanoprobe formed from Gd 2 O 3 :Eu 3+ nanocrystals provided the dual modality of optical and magnetic resonance imaging.

An efficient rhodium(II)-catalyzed transannulation method of 1-sulfonyl-1,2,3-triazoles with 2H-azirines has been utilized for the synthesis of phenyl-substituted dihydropyrazines. The dihydropyrazine products can be further converted to pyrazines under basic conditions in excellent yield.