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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. [ABSTRACT FROM AUTHOR]

A novel one-step method for preparing C-5-substituted O6,5′-cyclopyrimidine nucleoside analogues is reported. This method employs molecular iodine to mediate the cyclization from the 5′-O-hydroxyl group of the sugar ring and C-6 at the position of the nitrogen base in ammonia water under mild conditions without any other aprotic organic solvent. [ABSTRACT FROM AUTHOR]

Novel C6-phosphonated purine nucleosides were obtained in good to excellent isolated yields by the simple and catalyst-free SNAr-Arbuzov reaction of trialkyl phosphite with 6-choloropurine nucleosides, including a series of nonsugar carbon nucleosides. Shorter reaction times were needed, and substantially higher yields were obtained under microwave irradiation conditions compared with conventional heating conditions. [ABSTRACT FROM AUTHOR]

Novel 6-[N,N-bis(2-hydroxyethyl)amino]purine nucleosides were prepared in one step by nucleophilic substitution reaction of 6-choloropurine nucleosides with diethanolamine. Shorter reaction times and higher yields were achieved under microwave irradiation conditions in neat water. [ABSTRACT FROM AUTHOR]

The synthesis of C6-cyclo secondary amine-substituted purine analogues in neat water was achieved with the aid of microwave irradiation, providing a rapid, efficient and convenient method for the preparation of acyclic nucleosides in high yields. [ABSTRACT FROM AUTHOR]

The organocatalytic asymmetric allylic etherification reaction of Morita-Baylis-Hillman carbonates and silanols was reported for the first time. With modified cinchona alkaloid (DHQD)2PYR as the catalyst, a series of aromatic, heterocyclic, or aliphatic Morita-Baylis-Hillman carbonates (25 examples) worked well with triphenylsilanol, affording the corresponding products in moderate to good yields (up to 98%), high regioselectivities (>20:1), and good enantioselectivities (up to 92%). When dimethylphenylsilanol was used as the nucleophile, the product was obtained in 60% yield and 87% ee. [ABSTRACT FROM AUTHOR]

With 9-(2-tosylvinyl)-9H-purines as the dipolarophiles, a series of chiral azacyclic nucleosides with four continuous stereocenters were obtained in 86-99% yields, >20:1 dr, and 94 → 99% ee via the Cu(I)-catalyzed asymmetric [3 + 2] cycloaddition. Both (E)- and (Z)-9-(2-tosylvinyl)-9H-purines were suitable dipolarophiles, enriching the structure diversity of azacyclic nucleosides. Furthermore, when α-methyl imino ester was explored, the corresponding azacyclic nucleoside with a chiral quaternary stereocenter could also be afforded with excellent results. [ABSTRACT FROM AUTHOR]

With 9-(2-tosylvinyl)-9H-purines as the dipolarophiles, a series of chiral azacyclic nucleosides with four continuous stereocenters were obtained in 86-99% yields, >20:1 dr, and 94 ? 99% ee via the Cu(I)-catalyzed asymmetric [3 + 2] cycloaddition. Both (E)- and (Z)-9-(2-tosylvinyl)-9H-purines were suitable dipolarophiles, enriching the structure diversity of azacyclic nucleosides. Furthermore, when α-methyl imino ester was explored, the corresponding azacyclic nucleoside with a chiral quaternary stereocenter could also be afforded with excellent results. [ABSTRACT FROM AUTHOR]

An efficient route to construct chiral acyclic purine nucleosides containing a hemiaminal ester moiety is reported via three-component dynamic kinetic resolution of purines, aldehydes, and acid anhydrides. The procedure provides diverse chiral acyclic purine nucleoside analogues in a regioselective manner with good yields (up to 93% yield) and excellent enantioselectivities (up to 95% ee). Furthermore, the chiral (acyloxyalkyl)-5-fluorouracil could also be generated as a potential prodrug of 5-fluorouracil. [ABSTRACT FROM AUTHOR]

An efficient route to chiral carbocyclic nucleoside analogues containing a quaternary stereocenter and a C-C double bond has been established via a highly enantioselective [3 + 2] annulation of Morita-Baylis-Hillman (MBH) carbonates with a-purine-substituted acrylates. With 20 mol % (S)-SITCP as the catalyst, various chiral carbocyclic nucleoside analogues with a quaternary stereocenter and a C-C double bond were obtained in high yields (up to 92%) with good diastereoselectivities (up to 10:1 dr) and excellent enantioselectivities (up to 96% ee). Furthermore, the corresponding products were subjected to diverse transformations to afford interesting and potentially useful chiral carbocyclic nucleosides. [ABSTRACT FROM AUTHOR]

An efficient route to construct chiral cyclopropyl purine nucleoside analogues has been established via the catalytic asymmetric Michael-initiated ring-closure reactions of a-purine acrylates with a-bromo-carboxylic esters. Using (DHQD)2AQN as the catalyst, various chiral cyclopropyl purine nucleoside analogues with a chiral quaternary stereocenter were obtained in 72-98% yields, excellent diastereoselectivities, and 93-97% ee. Through simple functional group transformations, diverse chiral cyclopropyl purine nucleosides with hydroxymethyl group or carboxyl group were obtained. [ABSTRACT FROM AUTHOR]

A direct route to branched N-allylpyrimidine analogues is herein reported via the highly regio- and enantioselective asymmetric allylation of pyrimidines with racemic allylic carbonates. With [Rh(COD)Cl]2/chiral diphosphine as the catalyst, a range of chiral pyrimidine acyclic nucleosides could be obtained under neutral conditions in good yields (up to 95% yield) with high levels of regio- and enantioselectivities (15:1 to >40:1 B/L and up to 99% ee). Furthermore, chiral pyrimidine acyclic nucleoside bearing two adjacent chiral centers has been successfully synthesized by asymmetric dihydroxylation. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The first asymmetric hydrogenation of α-purine nucleobase-substituted α,β-unsaturated esters, catalyzed by a chiral rhodium (R)-Synphos catalyst, has been developed. A wide range of mono- and disubstituted acrylates were successfully hydrogenated under very mild conditions in high yields with good to excellent enantioselectivities (up to 99% ee). This method provides a convenient approach to the synthesis of a new kind of optically pure acyclic nucleoside and Tenofovir analogues. [ABSTRACT FROM AUTHOR]

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 b-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 499% ee). [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

A simple dehydrazination reaction has been achieved in the presence of a catalytic amount of CuSO4 for the first time. With CuSO4 (2 mol%) as a catalyst and water as a solvent, the dehydrazination products were obtained in good yields (66-95%). Moreover, the drugs nebularine and vidarabine were afforded successfully, and vidarabine could be produced on a 0.923 kg scale, which shows good potential for industrial applications. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Purine is utilized as a new directing group for the Pd-catalyzed monoarylation of 6-arylpurines with simple aryl iodides via C−H bond activation in good yields, providing a complementary tool for the modification of 6-arylpurines (nucleosides). Most importantly, purine can be used as a building block for nucleoside derivatives, and the use of purine as a directing group helps avoid additional synthetic steps. [ABSTRACT FROM AUTHOR]

In the title compound, C17H20O3S, the dihedral angle between the planes of the two aromatic rings is 66.5 (1)°. Weak C—H⋯O inter­actions are observed in the crystal structure. [ABSTRACT FROM AUTHOR]

An efficient method for the synthesis of C6-functionalized purine nucleosides was developed viathe direct nucleophilic substitution reaction of 6-chloropurine derivatives with various mild nucleophiles. The eco-friendly solvent-free process gave good to high isolated yields within a short reaction time (5 min) under microwave irradiated conditions. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

A simple, efficient and eco-friendly method for the synthesis of acylhydrazones from acylhydrazides and aldehydes under microwave (MW) irradiation was reported, no solvent and catalyst was used. The method is combined with a combinatorial approach and fourteen novel acylhydrazones were synthesized in excellent yields (89-96%) and short reaction times (less than 5 min). [ABSTRACT FROM AUTHOR]

Highly functionalized C6-aryl-substituted purine analogues were synthesized through direct arylation of 6-chloro- purine with aromatics promoted by anhydrous AlCl3 in a single step. The reactions, which were conducted using a 3-fold excess of AlCl3 in refluxing 1,2-dichloroethane, gave moderate to excellent product yields in 0.5 h. This work is complementary to the classical coupling re-actions for the synthesis of C6-aryl-substituted purine analogues. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

In 2,2,2-trichloro- N, N′-bis(4-methoxyphenyl)ethane-1,1-diamine, C16H17Cl3N2O2, molecules are linked into helical chains by N—H...O hydrogen bonds. Molecules of 2,2,2-trichloro- N, N′-bis(4-chlorophenyl)ethane-1,1-diamine, C14H11Cl5N2, are connected into a three-dimensional framework by two independent Cl...Cl interactions and one C—H...Cl hydrogen bond. [ABSTRACT FROM AUTHOR]

In each of methyl 2-methyl-5-oxo-2-pyrroline-3-carboxylate, C7H9NO3, and 3-acetyl-2-methyl-2-pyrrolin-5-one, C7H9NO2, the pyrrolinone ring is planar. In each structure, molecules are linked into simple chains by way of a single N—H...O hydrogen bond. [ABSTRACT FROM AUTHOR]

In the title compound, C18H24N2O6, the two pyrrolinone rings are planar and adopt anti conformations. The molecule lies on an inversion centre. The molecules are linked into a three-dimensional framework structure by three independent C—H...O hydrogen bonds. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]