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(sp³)–H alkanes was developed with high regioselectivity. The reaction occurred on C8 to give 8-cylcoakylpurines by C–C bond formation only promoted by <i>t</i>BuOO<i>t</i>Bu, while it occurred on the amino group to give <i>N</i>6-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

A New Strategy To Construct Acyclic Nucleosides via Ag(I)-Catalyzed Addition of Pronucleophiles to 9‑Allenyl‑9<i>H</i>‑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 <i>E</i>-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

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

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

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

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

Copper-Catalyzed Intramolecular Cyclization of <i>N</i>‑Propargyl-Adenine: Synthesis of Purine-Fused Tricyclics

A novel protocol to construct fluorescent purine-fused tricyclic products via intramolecular cyclization of <i>N</i>-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 <i>N</i>-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

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