Metal-free direct C-6-H alkylation of purines and purine nucleosides enabled by oxidative homolysis of 4-alkyl-1,4-dihydropyridines at room temperature.

Herein we report the application of 4-alkyl-1,4-dihydropyridines (DHPs), which are easily prepared from inexpensive aldehydes in one step, for the direct site-specific C-H alkylation of purines and purine nucleosides. Despite there being three active C(sp)-H bonds (C-2-H, C-6-H, and C-8-H) in the structure, the reactions still show high regioselectivity at the purinyl C-6-H position. Importantly, the reactions successfully avoid the use of transition metal catalysts and additional acids.

Regiospecificity C(sp)-C(sp) Bond Construction between Purines and Alkenes to Synthesize C-Alkylpurines and Purine Nucleosides Using O as the Oxidant.

A highly site-selective and Markovnikov-type radical C-H alkylation of purines with alkenes is achieved, allowing fast construction of the C(sp)-C(sp) bond at the C-6-position of purines and purine nucleosides using O as a green oxidant and alkenes as cheap alkylation reagents. The route was also a radical route to synthesize C-alkyl-N-substituted purines with potential steric hindrance between C-alkyl groups and N-substituted groups. This reaction is easily scaled up and has excellent functional group compatibility and broad substrate scopes.

Gold-Catalyzed Cyclization/Hydroboration of 1,6-Enynes: Synthesis of Bicyclo[3.1.0]hexane Boranes.

The gold-catalyzed cyclization/hydroboration of 1,6-enynes offers facile, versatile, and atom-economical one-step access to bicyclo[3.1.0]hexane boranes.

Regioselective C-H Hydroxyalkylation of Purines and Purine Nucleosides via α-C-H Functionalization of Alcohols at Room Temperature.

The highly regioselective C-H hydroxylalkylation of purines and purine nucleosides within 10 min via the α-C(sp)-H functionalization of alcohols at room temperature is reported here for the first time. The reaction tolerated various functional groups, which have the potential for further modification to afford other valuable molecules. The reported method avoids metal catalysts, light, and protecting groups, giving a direct strategy to access 6-substitued alkylated purines and nucleosides with pharmaceutical bioactivities.

Copper(I)-catalyzed tandem synthesis of 2-acylquinolines from 2-ethynylanilines and glyoxals.

An efficient one-step synthesis of 2-acylquinolines using a copper-catalyzed tandem reaction of 2-ethynylanilines with glyoxals in the presence of piperidine has been developed. This new protocol successfully avoids multi-step operation and the use of highly toxic cyanides required in traditional methods, and provides a practical tool for synthetic and pharmaceutical chemists. Various 2-acylquinolines are obtained with perfect regioselectivity in moderate to good yields (up to 86%).

One-step synthesis of mixed valence FeO nanoparticles supported on biomass activated carbon for degradation of bisphenol A by activating peroxydisulfate.

A novel FeO nanoparticles supported biomass activated carbon (BAC/FeO) composite was prepared through one-pot calcination method with FeCl and cherry stone powder as precursors. The carbonization of biomass, reduction of Fe, and FeO anchored on carbon substrate could be achieved at the same time. Characterization with transmission electron microscope (TEM) and scanning electron microscope indicated that nanoscale FeO distributed uniformly on carbon substrate, and X-ray photoelectron spectroscopy, X-ray diffraction, and high resolution TEM characterization proved that the loaded FeO was high crystallinity of FeO and α-Fe.

Purinyl N(3)-Directed Palladium-Catalyzed C-H Alkoxylation of N(9)-Arylpurines: A Late-Stage Strategy to Synthesize N(9)-(ortho-Alkoxyl)arylpurines.

A palladium-catalyzed alkoxylation of N(9)-arylpurines with primary or secondary alcohols has been developed successfully, which is a rare C-H activation reaction of polynitrogenated purines and offers a late-stage strategy to synthesize N(9)-(ortho-alkoxyl)arylpurines. Although there are more than four nitrogen atoms present in the purine moiety, the reaction can be effectively conducted by sterically blocking the N(1) site for catalyst coordination and first employing the purinyl N(3) atom as a directing group.

Copper-Catalyzed Intramolecular Alkoxylation of Purine Nucleosides: One-Step Synthesis of 5'-O,8-Cyclopurine Nucleosides.

A novel copper-catalyzed intramolecular dehydrogenative alkoxylation of purine nucleosides has been developed successfully, providing the 5'-O,8-cyclopurine nucleosides in one-step with a yield up to 90%. The method, which utilized an inexpensive CuCl catalyst and a di-tert-butyl peroxide (DTBP) oxidant was suitable in a broad substrate scope and proceeded well even in gram scale.