Selectfluor-Induced Oxidative Amination of N-Heteroaromatics with Purine.

An oxidative coupling reaction between purines and aromatic N-heterocycles was developed to synthesize a series of N-heteroaryl purine derivatives using Selectfluor as an oxidant at room temperature. This process uses a commercial oxidant, uses no base, metal, or other additives, is simple to carry out, and has a broad range of substrates.

Visible light-induced direct alkylation of the purine C8-H bond with ethers.

The one-step visible light-induced direct alkylation of the C8-H bond for purine derivatives by ethers was developed using Eosin Y as the photocatalyst and t-BuOOH as the oxidant at room temperature. This method describes the coupling of the α-C of the ether to the C8 of purine. Of particular interest is that substrates include purines with various functional groups and even unprotected 9H-purines. The protocol provides an effective method for the synthesis of 8-alkylpurine derivatives with high atom economy and high regioselectivity.

One-Step Visible Light Photoredox-Catalyzed Purine C8 Alkoxylation with Alcohol.

A cross-dehydrogenation coupling reaction between purines and alcohols, induced by visible light, using an acridinium photocatalyst and air as the sole oxidant, to synthesize a series of C8-alkoxy purine derivatives was developed. This protocol is a green and novel method to construct the C8-O bond on a purine ring with high step and atom economy.

Iodine-catalyzed oxidative functionalization of purines with (thio)ethers or methylarenes for the synthesis of purin-8-one analogues.

An efficient oxidative functionalization of purine-like substrates with (thio)ethers or methylarenes under mild conditions is described. Using I2 as the catalyst, and TBHP as the oxidant, this protocol provides a valuable synthetic tool for the assembly of a wide range of 9-alkyl(benzyl)purin-8-one derivatives with high atom- and step-economy and exceptional functional group tolerance.

Cu NPs-embedded cross-linked microporous 3D reduced graphene hydrogels as photocatalyst for hydrogen evolution.

Three-dimensionally (3D) structured Cu nanoparticles (NPs)-embedded graphene hydrogels were synthesized from inexpensive graphite and low-cost copper acetate by a novel self-assembly and in-situ slow-release photoreduction method. The cross-linked microporous 3D reduced graphene oxide framework ensures full contact of the photocatalyst with water and promotes electron transfer. The EDA-reduced Cu-rGH hydrogel with an 11.3% Cu NPs mass ratio exhibits the best hydrogen evolution rate (16.92 mmol·g-1·h-1). This rate is almost 17 times faster than pure Cu NPs. EDA played an important role in both forming a hydrogel as the reducing agent and slowly releasing Cu NPs as a ligand in the process of in-situ photoreduction, allowing small sized and uniformly distributed Cu NPs. Therefore, the number of reaction sites in the composite increases and the recombination of photoinduced electron-hole pairs in Cu NPs decreases. Under irradiation, the SPR-excited (surface plasmon resonance) hot electrons from Cu NPs quickly transfer through the rGH channel. 3D rGH was found to be a promising substrate for boosting hydrogen production by Cu NPs.

Direct Sulfenylation of the Purine C8-H Bond with Thiophenols.

The one-step copper-mediated regioselective formation of the C8-S bond for purine derivatives with arylthiols was achieved using air as the green oxidant in the presence of 1.0 equiv of Na2CO3 and stoichiometric CuCl and 1,10-phenanthroline monohydrate. This method provides an economical, easy-to-handle, and effective method for the synthesis of 8-sulfenylpurine derivatives in moderate to excellent yields. The reaction is selective for C8 over C2 and C6. It also tolerates a free amine on the purine, and it has a wide substrate scope.

One-step solvothermal fabrication of Cu@PANI core-shell nanospheres for hydrogen evolution.

Polyaniline(PANI)-decorated Cu nanoparticles were prepared by a facile solvothermal method. Different reaction temperatures resulted in different morphologies of the Cu/PANI composites, which exhibited good photocatalytic activities. When the mass ratio of PANI increased to 2.5 wt%, the H2 evolution rate reached 1.97 mmol g-1 h-1 in lactic acid solution under solar light irradiation, which is about 2 times higher than that of pure Cu nanoparticles (1.06 mmol g-1 h-1). The introduction of PANI can improve the separation efficiency of the photo-generated electron-hole pairs, where PANI acts as a hole reservoir for trapping holes generated by the Cu NPs and hindering the recombination of the electron-hole pairs. A possible mechanism is presented to explain the photocatalytic process using Cu@PANI core-shell nanospheres as the photocatalyst.

A convenient, one-step synthesis of benzyl (Ar) ureas of the type ArCH(2)NHCONHR from Ar and R(1)OCH(2)NHCONHR via ureidoalkylation.

A method for the one-step C-ureidoalkylation of phenol, anisole, or aniline rings furnishing ArCH(2)NHCONHR (Ar = benzyl) products in moderate to good yields is described. With phenol ring systems, higher yields were attained when the reaction was worked up with an acidic ethanethiol addition to cleave any O-ureidoalkylation products that formed during the reaction.