One-step synthesis of 5′-azido-nucleosides

Facile Synthesis of Trisaccharide Moiety Corresponding to Antitumor Activity in Triterpenoid Saponins Isolated from Pullsatilla Roots

“…19) Treatment of allyl b-L-arabinopyranoside (13) with 2,2-dimetoxypropane in dry DMF containing p-TsOH at room temperature for 6 h gave the 3,4-isopropylidene derivative (14), which was used without purification in the next step. Lewis acid-catalyzed assembly of 14 with the donor 2,3,4-tri-Obenzoyl-a-L-rhamnopyranosyl tirchloroacetimidate (11) by TMSOTf at a low temperature gave disaccharide 15 (63%) exclusively. The success of the reaction was evident from the down field shift in the (17) monoacetylated on the axial hydroxyl group of arabinose C-4, compound 16 was treated triethyl orthoacetate (CH 3 C(OEt) 3 ) and p-TsOH as acid catalyst in toluene and subsequently cleaved the intermediate cyclic ortho ester under acidic condition (80% aq.…”

“…1. Indeed, glucose has been integrated into anticancer agents as a conjugate for the improvement of their activity since cancer cells have increased rate of glucose metabolism compared with healthy cells and over-expression of 11) This approach has been also applied to pep- A trisaccharide found in triterpenoid saponins isolated from Pullsatilla roots appears as an important promoiety for the enhancement of anticancer activity of their aglycones. Thus a facile synthetic method for a trisaccharide moiety, allyl-2,3,4-tri-O-benzoyl-a a-L-rhamnopyranosyl-(1→ →2)- [2,3,4,6-…”

“…Indeed, glucose has been integrated into anticancer agents as a conjugate for the improvement of their activity since cancer cells have increased rate of glucose metabolism compared with healthy cells and over-expression of GLUT-1. 10,11) This approach has been also applied to pep-tide drugs 12) and cytotoxic agents 13,14) for improvement of delivery into the central nervous system (CNS). Although there are some studies on natural oligosaccharide (i.e., Digitoxin), 15) these attempts have been mainly restricted to conjugation with a monosaccharide.…”

Synthesis of Certain New 1,2,3-Triazole Acyclonucleosides via 1,3-Dipolar Cycloaddition

“…In general, such addition tends to give mainly the isomers with electron withdrawing groups at the 4-position and electron releasing groups at the 5-position. [12][13][14] On the other hand, the sterically less hindred isomers tend to be the major isomer. 15,16 A differentiation between DHPG and iso-NDG isomers analogues was determined on the basis of the chemical shifts of the sugar moiety.…”

5'-Azido-2',5'-dideoxythymidine

“…The synthesis of 5'-azido-2',5'-dideoxythymidine has been reported by Hata, Yamamoto & Sekine (1975) and Yamamoto, Sekine & Hata (1980). It is an important starting material in the synthesis of 5'-amino-2',Ydideoxythymidine (Horwitz, Tomson, Urbanski & Chua, 1962), which is used for the syntheses of some oligonucleotide analogues with modified backbones, such as carbamates (Coull, Carlson & Weith, 1987), amides (Mesmaeker et al, 1994) and phosphoramidates (Mag & Engels, 1989).…”