- A short, flexible route toward 2'-C-branched ribonucleosides
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A five-step synthesis of 2'-C-branched ribonucleosides from commercially obtained 1,3,5-tri-O-benzoyl-α-D-ribofuranose (4) is described. The free hydroxyl group of 4 was oxidized in high yield with Dess-Martin periodane reagent. The resultant 2-ketosugar was treated with MeMgBr/TiCl4, CH2=CHMgBr/CeCl3, or TMSC≡CLi/CeCl3, and in each case addition to the ketone proceeded stereoselectively to provide 2-alkylated ribofuranosides. After conversion to the corresponding tetrabenzoyl derivatives, the 2-alkylribofuranosides were coupled to nucleobases under Vorbruggen persilylation conditions, giving the β-nucleosides with high stereoselectivity. Deprotection with methanolic ammonia provided the title compounds in 17-49% overall yields from 4.
- Harry-O'kuru,Smith,Wolfe
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p. 1754 - 1759
(2007/10/03)
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