Metal- and Light-Free Decarboxylative Giese Addition Reaction Facilitated by Hantzsch Ester.

We have developed a novel strategy for decarboxylative radical addition reactions that employs ground-state reduced nicotinamide adenine dinucleotide (NADH) analogues under ambient and open-air conditions, facilitating the efficient formation of Csp-Csp bonds in a variety of substrates. This protocol is distinguished by its operational simplicity, mild reaction conditions, high efficiency, and the use of cost-effective starting materials. Furthermore, experimental studies have provided valuable insights into the reaction mechanism, elucidating the light-independent pathways that promote these transformations.

NADH Analogues Enable Metal- and Light-Free Decarboxylative Functionalization.

Here we report a metal- and light-free decarboxylative functionalization approach enabled by reduced nicotinamide adenine dinucleotide (NADH) analogues. The efficient and operationally simple approach, conducted in 5 minutes from in situ preparation of aryliodine (III) dicarboxylates under open-air and ambient conditions, enables diverse bond formation and exhibits a broad substrate scope of over 70 examples. Late-stage functionalization of drug molecules and natural products further demonstrates the synthetic utility of this method.

Copper-Catalyzed Intermolecular Alkynylation and Allylation of Unactivated C(sp)-H Bonds via Hydrogen Atom Transfer.

We describe Cu-catalyzed intermolecular alkynylation and allylation of unactivated C(sp)-H bonds with singly occupied molecular orbital-philes (SOMO-philes) via hydrogen atom transfer (HAT). Employing -fluoro-sulfonamide as a HAT reagent, a set of substituted alkene and alkyne compounds were synthesized in high yields with good regioselectivity and functional-group compatibility. Late-stage functionalization of natural products and drug molecules is also demonstrated.

Core-shell GaP@C nanoparticles with a thin and uniform carbon coating as a promising anode material for rechargeable lithium-ion batteries.

Transition metal phosphides are used as anode materials for lithium-ion batteries because of their high theoretical capacity and low polarization. In this work, a core-shell GaP@C nanocomposite was successfully synthesized by a simple chemical vapor deposition (CVD) method, utilizing commercial GaP as the raw material and xylene as the carbon source. The uniform thin carbon shell could alleviate the volumetric variation and improve the conductivity of the inner GaP.

Bagasse as a carbon structure with high sulfur content for lithium-sulfur batteries.

A bagasse-based 3D carbon matrix (BC) with high specific surface area and high conductivity was obtained by carbonization and pore-forming processes with bagasse as the carbon precursor and KFeO as the pore-former. The microporous structure and nitrogenous functional groups were determined in the prepared carbon matrix, which could allow high sulfur loading and improve the polysulfide absorption capacity during cycling. After sulfur infusion, the S/BC composite with 68.

Photoinduced Copper-Catalyzed Site-Selective C(sp)-C(sp) Cross-Coupling via Aryl Sulfonium Salts.

The classical Sonogashira reaction of aryl electrophiles in the presence of Pd catalysts has been well established as a potent method for arylalkyne synthesis. However, the site-selective C(sp)-C(sp) cross-coupling strategy using a non-noble-metal catalyst is rare. An efficient alternative approach for the synthesis of arylalkynes via a Cu-catalyzed Sonogashira-type reaction promoted by visible light is described.

Highly effective transformation of methyl phenyl carbonate to diphenyl carbonate with recyclable Pb nanocatalyst.

Diphenyl carbonate (DPC) is a type of versatile industrial chemical, and the disproportionation of methyl phenyl carbonate (MPC) is a key step to produce DPC. However, the design and formulation of a catalyst for the efficient synthesis of DPC is a major challenge due to its small equilibrium constant. The support material is a critical factor influencing the performance of Pb nanocatalysts.

Facile synthesis of chiral [2,3]-fused hydrobenzofuran via asymmetric Cu(i)-catalyzed dearomative 1,3-dipolar cycloaddition.

Intermolecular asymmetric dearomative 1,3-dipolar cycloaddition of 2-nitrobenzofurans with azomethine ylides was enabled by using a chiral Cu(i)/(S,Sp)-iPr-Phosferrox catalyst. As a result, a series of highly stereoselective chiral [2,3]-fused hydrobenzofurans possessing four contiguous stereogenic centers were obtained with good to high yields, diastereoselectivities and enantioselectivities. The reaction has broad substrate scope tolerating various functional groups.

Synthesis of Chiral Six-Membered Carbocyclic Purine Nucleosides via Organocatalytic Enantioselective [3 + 3] Annulation.

A direct route to chiral six-membered carbocyclic purine nucleoside analogues with three chiral stereocenters, including a chiral tetrasubstituted carbon center, via a highly enantioselective [3 + 3] annulation has been established. With the application of Takemoto's catalyst, various chiral six-membered carbocyclic purine nucleoside analogues were obtained in high yields (up to 89%) with moderate to good diastereoselectivities (up to 90:10 dr) and excellent enantioselectivities (92-98% ee). Furthermore, diverse chiral six-membered carbocyclic purine nucleoside analogues were generated by simple transformations.

Visible-Light-Mediated Monoselective Ortho C-H Arylation of 6-Arylpurine Nucleosides with Diazonium Salts.

A combined palladium- and photoredox-catalyzed monoselective arylation of 6-arylpurine nucleosides has been developed by employing purine as a directing group via the photoredox reaction, and many functional groups are well tolerated in this direct C-H arylation condition. Various of functionalized purines (nucleosides) which are potentially of great importance in medicinal chemistry could be obtained under visible light irradiation at room temperature within 4 h.

Enantioselective Intermolecular Cyclopropanations for the Synthesis of Chiral Pyrimidine Carbocyclic Nucleosides.

A direct route to chiral cyclopropylpyrimidine carbocyclic nucleoside analogues has been reported via highly enantioselective intermolecular cyclopropanation reactions of N1-vinylpyrimidines with α-diazoesters. With chiral ruthenium(II)-phenyloxazoline complex (2 mol %) as the catalyst, cyclopropyl pyrimidine nucleoside analogues could be obtained in good yields (71-96% yields) with high levels of diastereo- and enantioselectivities (10:1 to >20:1 dr and 96-99% ee) in 1 min.

Diversity-oriented synthesis of acyclic nucleosides via ring-opening of vinyl cyclopropanes with purines.

The diversity-oriented synthesis of acyclic nucleosides has been achieved via ring-opening of vinyl cyclopropanes with purines. With Pd2(dba)3·CHCl3 as a catalyst, the 1,5-ring-opening reaction proceeded well and afforded N9 adducts as the major form, in which the C=C bonds in the side chain were exclusively E-form. In the presence of AlCl3, the 1,3-ring-opening reaction occurred smoothly, giving N9 adducts as the dominate products.

Copper-catalyzed intramolecular cyclization of N-propargyl-adenine: synthesis of purine-fused tricyclics.

A novel protocol to construct fluorescent purine-fused tricyclic products via intramolecular cyclization of N-propargyl-adenine has been developed. With CuBr as the catalyst, a series of purine-fused tricyclic products were obtained in good to excellent yields (19 examples, 75-89% yields). When R2 was a hydrogen atom in N-propargyl-adenines, the reactions only afforded the endocyclic double bond products.

A copper-catalyzed domino route toward purine-fused tricyclic derivatives.

Purine-fused tricyclic derivatives have been synthesized via a copper-catalyzed domino Michael/oxidative cross-coupling reaction between adenines and nitroolefins for the first time. With air as the oxidant, this method has high regioselectivity, which provides a new route for constructing purine-nucleoside-conjugated systems with two newly formed C–N bonds. Meanwhile, purine nucleosides with an exocyclic amino group could be obtained easily by simple reduction, which may lead to potential applications in fluorescence recognition of various bases in vivo.

A new strategy to construct acyclic nucleosides via Ag(I)-catalyzed addition of pronucleophiles to 9-allenyl-9H-purines.

A new strategy to construct acyclic nucleosides with diverse side chains was developed. With Ag(I) salts as catalysts, the hydrocarboxylation, hydroamination, and hydrocarbonation reactions proceeded well, affording acyclic nucleosides in good yields (41 examples, 60-98% yields). Meanwhile, these reactions exhibited high chemoselectivities and E-selectivities.

Radical route for the alkylation of purine nucleosides at C6 via Minisci reaction.

A highly regioselective Minisci reaction with the decarboxylative alkylation of purine nucleosides under mild conditions was developed. With 5 mol % AgNO3 as a catalyst and (NH4)2S2O8 as an oxidant, a series of purine nucleosides including ribosyl, deoxyribosyl, arabinosyl purine nucleosides worked well with primary, secondary, and tertiary aliphatic carboxylic acids.

Highly regioselective three-component domino Heck-Negishi coupling reaction for the functionalization of purines at C6.

A highly regioselective three-component domino Heck-Negishi coupling reaction has been developed. Organozinc reagents are used to trap an alkylpalladium intermediate of olefins for a first example in the domino Heck reaction. This reaction is applicable to acrylates (or acrylamides) and purine compounds, producing a series of novel purine compounds with carbon substituents at the C6 position in moderate to good yields.

One-pot synthesis of 7,9-dialkylpurin-8-one analogues: broad substrate scope.

The one-pot and direct synthesis of 7,9-dialkylpurin-8-one analogues with broad substrate scope has been developed. This copper-catalyzed C-H oxidation reaction could avoid multistep synthesis of quaternary ammonium salts and expand the scope of halogenated alkanes. Moreover, benzimidazole derivatives are also applicable in the catalytic system.

Pd(II)-catalyzed one-pot, three-step route for the synthesis of unsymmetrical acridines.

Unsymmetric acridines are synthesized via a one-pot amination/cyclization/aromatization reaction for the first time. With Pd(OAc)2-X-Phos as the catalyst, a series of unsymmetric acridines are obtained in moderate to excellent yields (up to 99% yield). Meanwhile, the diphenylamine intermediate could be isolated, which is evidence of the domino process.

CuI controlled C-C and C-N bond formation of heteroaromatics through C(sp3)-H activation.

A new method for C-C and C-N bond formation of heteroaromatics and C(sp(3))-H alkanes was developed with high regioselectivity. The reaction occurred on C8 to give 8-cylcoakylpurines by C-C bond formation only promoted by tBuOOtBu, while it occurred on the amino group to give N6-alkylated purines by C-N bond formation when 2 equiv of CuI were added. A reaction mechanism was also proposed based on our preliminary experimental data.

Metal catalyzed C(sp3)-H bond amination of 2-alkyl azaarenes with diethyl azodicarboxylate.

Metal-catalyzed direct C(sp(3))-H bond amination of 2-alkyl azaarenes with N=N double bonds has been developed, which expands the scope of C(sp(3))-H bond activation reactions and provides a new access to medicinally important azaarene derivatives.

Copper-catalyzed synthesis of purine-fused polycyclics.

A novel protocol for a Cu-catalyzed direct C((sp(2)))-H activation/intramolecular amination reaction of 6-anilinopurine nucleosides has been developed. This approach provides a new access to a variety of multiheterocyclic compounds from purine compounds via Cu-catalyzed intramolecular N-H bond tautomerism which are endowed with fluorescence.

Synthesis of fused N-heterocycles via tandem C-H activation.

The synthesis of fused N-heterocycles has been developed using an intramolecular cyclisation of purines or benzimidazoles. A range of medium and large rings were prepared.

Nickel catalyzed alkylation of N-aromatic heterocycles with Grignard reagents through direct C-H bond functionalization.

A novel protocol for nickel-catalyzed direct sp(2) C-H bond alkylation of N-aromatic heterocycles has been developed. This new reaction proceeded efficiently at room temperature using a Grignard reagent as the coupling partner. This approach provides new access to a variety of alkylated N-aromatic heterocycles which are potentially of great importance in medicinal chemistry.