Ruchun Yang

A highly efficient and selective synthesis of 1,2,3-triazole linked saccharide nucleosides via "click chemistry".

A series of 1,2,3-triazole linked saccharide nucleosides were synthesized in high yield and selectivity via “click chemistry” of the 3′-azido-2′-deoxythymidine and the propargyl carbohydrates.

Synthesis of bifunctional Gd2O3:Eu3+ nanocrystals and their applications in biomedical imaging

Abstract Ultrafine Gd 2 O 3 :Eu 3+ nanocrystals were successfully prepared by a simple reverse microemulsion method and subsequent calcination. Their structural, optical and magnetic properties were investigated using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR), photoluminescence (PL), and magnetic property measurement system (MPMS). The amorphous Gd 2 (CO 3 ) 3 :Eu 3+ colloidal spheres were proved as an intermediate product, and gradually transformed into crystallized Gd 2 O 3 :Eu 3+ with average diameter less than 100 nm. The paramagnetic property of the synthesized Gd 2 O 3 :Eu 3+ nanocrystals were confirmed with its linear hysteresis plot ( M - H ). And Gd 2 O 3 :Eu 3+ nanocrystals showed high contrast T 1 -enhancing modality due to the presence of the Gd 3+ ions onto the particle surface. In addition, the application of the Gd 2 O 3 :Eu 3+ nanocrystals as biotag for cell labeling was reported, red fluorescence from Eu 3+ ions observed by fluorescence microscopy showed that the nanocrystals could permeate the cell membrane. Cytotoxicity studies of the Gd 2 O 3 :Eu 3+ nanocrystals showed no adverse effect on cell viability, evidencing their high biological compatibility. Therefore, the nanoprobe formed from Gd 2 O 3 :Eu 3+ nanocrystals provided the dual modality of optical and magnetic resonance imaging.

Concise total synthesis of two marine natural nucleosides: trachycladines A and B

Summary We report the first total synthesis of trachycladines A (10 steps, 34.2% overall yield) and B (11 steps, 35.0% overall yield) by using 5-deoxy-1,2,3-tri-O-acetyl-β-D-ribofuranose as the starting material. The critical step was the SnCl4 assisted regio- and steroselective deprotection of perbenzylated 1-O-methyl-5-deoxyribofuranose. The enzyme adenylate deaminase (EC 3.5.4.6) was successfully applied to the chemoenzymatic synthesis of trachycladines B.

(2R,3S,4R,5R)-5-(4-Amino-5-iodo-7H-pyrrolo-[2,3-d]pyrimidin-7-yl)-4-fluoro-2-(hy-droxy-meth-yl)tetra-hydro-furan-3-ol.

The title compound, C11H12FIN4O3, is composed of a 7-carbapurine moiety connected via an N atom to 2-deoxy-2-fluoro-β-d-ribose. The conformation about the N-glycosydic bond is −anti with χ = −129.0 (11)°. The glycosydic N—C bond length is 1.435 (14) Å. The sugar ring adopts an Nconformation with an unsymmetrical twist O-endo-C-exo (oT4). The conformation around the C—C bond is +sc, with a torsion angle of 53.0 (12)°. In the crystal, molecules are linked by N—H⋯O hydrogen bonds, forming chains propagating along the a axis. These chains are linked via O—H⋯I and C—H⋯O hydrogen bonds, forming layers lying parallel to the c axis.