Haixin Ding

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.

First Total Synthesis of a Naturally Occurring Iodinated 5′-Deoxyxylofuranosyl Marine Nucleoside

4-Amino-7-(5′-deoxy-β-D-xylofuranosyl)-5-iodo-pyrrolo[2,3-d]pyrimidine 1, an unusual naturally occurring marine nucleoside isolated from an ascidan, Diplosoma sp., was synthesized from D-xylose in seven steps with 28% overall yield on 10 g scale. The key step was Vorbrüggen glycosylation of 5-iodo-pyrrolo[2,3-d]pyrimidine with 5-deoxy-1,2-O-diacetyl-3-O-benzoyl-D-xylofuranose. Its absolute configuration was confirmed.

Total synthesis of a marine alkaloid--rigidin E.

In the present paper, we report an efficient total synthesis of a marine alkaloid, rigidin E. The key tetrasubstituted 2-amino-3-carboxamidepyrrole intermediate was synthesized by cascade Michael addition/intramolecular cyclization between N-(2-(4-(benzyloxy)phenyl)-2-oxoethyl)methanesulfonamide and 3-(4-(benzyloxy)phenyl)-2-cyano-N-methylacrylamide. Subsequent carbonylation with triphosgene catalyzed by I2 and deprotection of benzyl groups afforded rigidin E in 21% overall yield. This strategy has the merits of metal-free reactions, low cost, mild reaction protocols, and easy access to diversity-oriented derivatives for potential structure-activity relationship investigation.

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.

An efficient approach to 4-chloro quinolines via TMSCl-mediated cascade cyclization of ortho-propynol phenyl azides

A novel and efficient strategy for the synthesis of 4-chloro quinolines via the TMSCl-mediated cascade cyclization of easily prepared ortho-propynol phenyl azides is developed. This reaction proceeds smoothly in moderate to excellent yields with a wide range of substrate compatibility. TMSCl acted not only as a promoter, but also as a chloro source in this transformation. Moreover, the obtained 4-chloro quinolines could be further derivated in an array of palladium-catalyzed coupling and nucleophilic substitution reactions to construct potential biologically active and pharmaceutical molecules.

An Expedient Total Synthesis of Triciribine

In the present paper, we report an expedient total synthesis of triciribine, a tricyclic 7-deazapurine nucleoside and protein kinase B (AKT ) inhibitor, in 35% overall yield. Our synthesis route features a highly regioselective substitution of 1-N-Boc-2-methylhydrazine and a trifluoroacetic acid catalyzed one-pot transformation which combined the deprotection of the tert-butylcarbonyl (Boc) group and ring closure reaction together to give a tricyclic nucleobase motif.

First total synthesis of kipukasin A

In this paper, a practical approach for the total synthesis of kipukasin A is presented with 22% overall yield by using tetra-O-acetyl-β-D-ribose as starting material. An improved iodine-promoted acetonide-forming reaction was developed to access 1,2-O-isopropylidene-α-D-ribofuranose. For the first time, ortho-alkynylbenzoate was used as protecting group for the 5-hydoxy group. After subsequent Vorbrüggen glycosylation, the protecting group could be removed smoothly in the presence of 5 mol % Ph3PAuOTf in dichloromethane to provide kipukasin A in high yield and regioselectivity.