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A five-step synthesis of 2′-C-branched ribonucleosides from commercially obtained 1,3,5-tri-Obenzoyl-R-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/TiCl 4 , CH 2 dCHMgBr/CeCl 3 , or TMSCtCLi/CeCl 3 , 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 Vorbru ¨ggen persilylation conditions, giving the β-nucleosides with high stereoselectivity. Deprotection with methanolic ammonia provided the

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