A practical and scalable synthesis of several base modified 3'-O-methyl ribonucleosides.

An easy and efficient large-scale synthesis of 1, 2,-di-O-acetyl-5-O-benzoyl-3-O-methyl-d-ribofuranose (8) was accomplished from commercial 1,2:5,6-di-O-isopropylidene-α-d-allofuranose in 7-steps and 30 % overall yield. The utility of protected 8 was demonstrated via synthesis of 9-(3'-O-methyl-β-d-ribofuranosyl)-6-chloropurine (21) and six other nucleoside analogues in good yields. A library of five novel base modified nucleosides were generated starting from purine nucleoside 21 via functional group manipulations.

-Toluenesulfonic acid adorned on MCM-41: an efficient and mild catalyst for the regio/chemo-selective hydrolysis of terminal isopropylidene acetals.

Regio/chemo-selective hydrolysis of a 5,6-O-isopropylidene group over a 1,2-O-isopropylidene group is accomplished to obtain corresponding diols in good to excellent yields within 4-5 hours using the p-toluenesulfonic acid impregnated MCM-41 (PTSA-MCM-41) catalyst in acetonitrile and water (9:1, v/v) at room temperature. Other sensitive hydroxyl protecting groups such as naphthyl, toluoyl, pivaloyl, benzoyl, and benzyl are compatible with this methodology. The low cost of the PTSA-MCM-41 catalyst and ease of separation of product from the reaction mixture are significant advantages of this method, which makes it useful in the multigram scale operation.