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C-6 phosphonated purine nucleosides were synthesized in good to high yields by Arbuzov reaction between 2,6-dichloropurine nucleosides and phophite ester promoted by microwave. In addition, phosphomonoesterase and phosphate compounds of C-6 phosphonated purine nucleosides were obtained by further reaction. The structures of all compounds are characterized by NMR, HRMS and IR.

The synthesis and fluorescence properties of novel purine analogues linked azacrown ether at C6 position were investigated. These new purine analogues could be prepared from a series of 6-chloropurines and showed selective and efficient signaling behaviors toward micromolar concentration of Ag(+) ion over other common metal ions in an aqueous environment.

A novel and efficient synthetic method has been developed for the preparation of chiral acyclic nucleosides with a chiral amino side chain by Mitsunobu reaction between nucleoside bases and protected L-serine. This method suggests a potentially more efficient and complementary process to acquire chiral acyclic nucleosides.

The synthesis of 3,4-dihydropyrimidin-2-(1H)-ones derivatives via a three-component Biginelli reaction using copper nitrate as a catalyst under solventless conditions is reported, providing a green, rapid, efficient, and convenient method for the preparation of Biginelli compounds in good yields.

A novel approach to the synthesis of purines bearing functionalized carbon substituents or methyl in position 6 was developed. Under different reaction conditions, 6-halopurine derivatives could react with ethyl acetoacetate efficiently to yield 2-(purin-6-yl)acetoacetic acid ethyl esters, (purin-6-yl)acetates and 6-methylpurines respectively. No metal catalyst and ligand were required.

The binding interaction of adenosine with human serum albumin (HSA) was investigated under simulative physiological conditions by fluorescence spectroscopy in combination with a molecular modeling method. A strong fluorescence quenching reaction of adenosine to HSA was observed and the quenching mechanism was suggested as static quenching according to the Stern-Volmer equation. The binding constants (K) at different temperatures as well as thermodynamic parameters, enthalpy change (ΔH) and entropy change (ΔS), were calculated according to relevant fluorescent data and Vant′Hoff equation. The hydrophobic interaction was a predominant intermolecular force in order to stabilize the complex, which was in agreement with the results of molecular modeling study.

An efficient and novel procedure for the preparation of pyrazolo[3,4- b ]pyridine derivatives through multi-component reaction of aldehyde, 5-amino-3-methyl-1-phenylpyrazole and malononitrile or cyanoacetate in [bmim][BF 4 ] is described in this paper. Advantages of the method presented here include mild conditions, high yields together with a green nature and ease of recovery and reuse of the reaction medium.

A simple, efficient and eco-friendly method for the synthesis of bis(acylhydrazones) from hexanediohydrazide aldehydes under microwave irradiation without use solvent catalyst is reported. technique solvent-free condition proved to be quite valuable in organic synthesis.

The mol­ecules of 2,2,2-trichloro-N,N′-diphenyl­ethane-1,1-diamine, C14H13Cl3N2, are linked into (040) sheets by a combination of C—H⋯Cl and C—H⋯π(arene) hydrogen bonds. In 2,2,2-trichloro-N,N′-bis­(4-methyl­phen­yl)ethane-1,1-diamine, C16H17Cl3N2, the mol­ecules are linked into C(7) chains by two independent C—H⋯Cl hydrogen bonds and one Cl⋯Cl contact.

At present work, five new tetrathiafulvalene (TTF) derivatives bearing two or four thiazole groups are prepared, which have been characterized by 1 H NMR, IR, MS spectra, elemental analysis and X-ray analysis for 6 . The preliminary electrochemical properties of them are investigated by cyclic voltammetry (CV) and two one-electron quasi-reversible waves with redox potentials are observed.

A simple, rapid, and regioselective approach for the synthesis of N-(methoxy-carbonylmethyl)- and N-(n-propoxycarbonylmethyl) nucleobases was developed. By using DMF as the solvent and in the presence of K2CO3 as the base, all the desired products were obtained in moderate yields within 8 min under microwave irradiation.

A straightforward entry to chiral carbocyclic nucleoside analogues has been realized via the enantioselective [3+2] cycloaddition of α-nucleobase substituted acrylates to vinyl cyclopropanes for the first time. With Pd2(dba)3-L5 as the catalyst, carbocyclic purine, uracil, and thymine nucleoside analogues with quaternary stereocenters were obtained in excellent yields (up to 99% yield) and good enantioselectivities (up to 92% ee).

A novel protocol for an asymmetric 1,3-dipolar cycloaddition of azomethine ylides with β-nucleobase acrylates gives access to chiral azacyclic nucleosides.

Acyclic nucleosides and their phosphonates possess significantly antiviral and cytostatic activities. For acyclic nucleosides and their phosphonates, the introduction of a chiral group to their side chain or the absolute configuration of the chiral atom could affect their biological activities obviously. Thus, the asymmetric synthesis of chiral acyclic nucleosides and their phosphonates has received continuous attention. The previous reports mainly focus on employing the chiral pool and chiral auxiliary methods for the synthesis of chiral acyclic nucleosides and their phosphonates. In contrast, the asymmetric catalysis methods for the synthesis of acyclic nucleosides and their phosphonates are still in the beginning. This digest paper will serve to highlight the significant progress that has been made in these areas.

A simple, efficient and eco-friendly method for the synthesis of thiosemicarbazones from thiosemicarbazides and aldehyde under microwave irradiation has been reported, and no solvent and catalyst were used. And the technique of microwave irradiation coupled with solvent-free condition proved to be a quite valuable method in the organic synthesis.

Several benzo-[b]-pyran derivatives were prepared via microwave irradiation under solvent-free conditions in the presence of InCl3·4H2O. The advantages of this method include simple operational process, environmental benignancy, and high efficiency. Moreover, the catalyst can be recovered and reused effectively for at least six times.Key words: benzo-[b]-pyran derivatives, indium trichloride, microwave irradiation.

A simple, efficient and eco-friendly method for the synthesis of a series of thiosemicarbazides containing 4-antipyrinyl group under microwave irradiation has been reported, no solvent and catalyst was used. Five of them are new compounds.

Through multi-component condensation of aldehydes, 1,3-dione, Meldrum's acid, and ammonium acetate in an ionic liquid ([bmim][BF4]), a series of 1,4-dihydropyridine derivatives were prepared in excellent yields in the absence of any additional catalysts. In addition, [bmim][BF4] can be recovered and reused effectively for at least six times without obvious decrease of its efficiency. Advantages of this novel protocol include simple operational process, environmental benignancy, and high efficiency. © 2006 Wiley Periodicals, Inc. Heteroatom Chem 17:382–388, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20221

A highly regioselective Pd-catalyzed C(Ar)-H bond activation method was developed for the modification of purines (nucleosides) with different functional groups by using purine as a directing group. This approach provides a new access to a variety of functionalized purines (nucleosides) which are potentially of great importance in medicinal chemistry.

A broad scope of different functionalized purine-fused compounds is obtained in high yields by the presented process.

A rapid and divergent access to chiral azacyclic nucleoside analogues has been established via highly exo-selective and enantioselective 1,3-dipolar cycloaddition of azomethine ylides with β-nucleobase substituted acrylates. Using 1 mol% of a chiral copper complex, various chiral azacyclic nucleoside analogues were obtained in high yields, excellent exo-selectivities and enantioselectivities (98 to >99% ee).

Antiviral drugs nebularine (Ia) and vidarabine (IIa) are readily prepared by a dehydrazination of corresponding precursors (Ib) and (IIb).

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.

Utilizing Ag(I) salts as catalysts, hydrocarboxylation, hydroamination, and hydrocarbonation reactions proceed well affording acyclic nucleosides with good results.

An efficient and mild method has been developed for the preparation of 9-oxiranyl-9 H -purine derivatives. This reaction proceeds smoothly in β - cyclodextrin cavity at room temperature, giving good to excellent yields.

A highly regioselective Minisci reaction for the decarboxylative alkylation of Purine derivatives under mild conditions is presented.

The title Cu-catalyzed synthesis avoids multistep synthesis of quaternary ammonium-salts as precursors and expands the scope of halogenated alkanes.

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. When R2 was an aryl group, the electron-donating groups favored the endocyclic double bond products, while the electron-withdrawing groups favored the exocyclic double bond products.

A one-pot amination/cyclization/aromatization sequence is described to construct substituted acridines from 2-formylphenyl triflates and electron rich anilines in the presence of Pd(II)/XPhos as the catalyst.

A polymer containing 3‘-[trifluoromethyl-4,3‘-dibenzoazo] dyes in the side chains has been synthesized, and a monolayer of this polymer has been transferred onto solid substrate by the Langmuir−Blodgett (LB) technique. The reversible processes of photoisomerization of the LB films induced by light are observed by UV−vis absorption spectra, in situ atomic force microscopy, and friction force microscopy. In addition, the physisorbed monolayers of the monomer of the polymer at liquid/solid interface are investigated by scanning tunneling microscopy. The films of the polymer show the reversible change of morphological and friction force responses under alternate UV (365 ± 10 nm) and visible (436 ± 10 nm) irradiation. The films also undergo reversible wettability changes with UV and visible light irradiation, which are directly confirmed by contact angle measurement. The largest photoinduced change of contact angle is 11 ± 1°. The larger value of the contact angles measured corresponds to films mainly composed...

An azobenzene derivative [4-(6-oxo-hexacarboxylic acid)-3'-trifluoromethyl-azobenzene] was synthesized and transferred onto a solid substrate by the Langmuir-Blodgett (LB) technique. The films undergo reversible wettability changes upon irradiation with ultraviolet (UV, 365 ± 10 nm) and visible (436 ± 10 nm) light. This property of reversible wettability of the LB film is confirmed directly by contact angle measurement, UV-Vis absorption spectroscopy and atomic force microscopy (AFM). The results suggest that the wettability change is due to a photoinduced surface energy change.

Highly functionalized C6-aryl-substituted purine analogues were synthesized through direct arylation of 6-chloropurine with aromatics promoted by anhydrous AlCl(3) in a single step. The reactions, which were conducted using a 3-fold excess of AlCl(3) in refluxing 1,2-dichloroethane, gave moderate to excellent product yields in 0.5 h. This work is complementary to the classical coupling reactions for the synthesis of C6-aryl-substituted purine analogues.

In each of methyl 2-methyl-5-oxo-2-pyrroline-3-carboxylate, C(7)H(9)NO(3), and 3-acetyl-2-methyl-2-pyrrolin-5-one, C(7)H(9)NO(2), the pyrrolinone ring is planar. In each structure, molecules are linked into simple chains by way of a single N-H...O hydrogen bond.

In the title compound, C3H6N2O2S, the five-membered ring has an envelope conformation and the two hydroxyl groups lie on opposite sides of the ring. The crystal structure is stablized by inter­molecular O—H⋯S and N—-H⋯O hydrogen bonds, and also a close O⋯O inter­molecular approach, to form a two-dimensional network parallel to bc.

The crystal packing of the title compound, C21H16N2S9, involves weak inter­molecular C—H⋯S inter­actions and inter­planar π–π stacking, generating a three-dimensional supra­molecular structure.

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 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.

The reaction of the substituted 2-methylquinoline derivatives with various aromatic and heteroaromatic aldehydes affords the target compounds in high yields.

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.

tBu-O-O-tBu-mediated treatment of purines with alkanes provides a new and highly regioselective approach to C-8 alkylated purines.

The synthesis of acylhydrazines by using hydrazine hydrate as the reductant to hydrogenate acyldiazenes is reported. Twelve acylhydrazines have been synthesized from acyldiazenes in excellent yields under mild conditions. This method is rapid, convenient, and efficient.

In the presence of β-cyclodextrin, purine is effectively alkylated at N9 using water as solvent.

Novel metal-catalyzed benzylic amination of 2-alkylquinolines and -pyridines are described.