Methyl 2-deoxy-3,5-di-O-p-toluoyl-α-d-ribofuranoside: isolation, crystal structure and conformation

The X-ray crystal structure of methyl 2-deoxy-3,5-di-O-p-toluoyl-α-d-ribofuranoside (5) presented here, is a unique example of an alpha-configured, methyl 2-deoxyribofuranoside with the same protecting group at positions C3 and C5. Methyl 2-deoxy-3,5-di-O-p-toluoyl-α/β-d-ribofuranoside (3), exists as a mixture of alpha and beta anomers from which we isolated a single anomer on recrystallization from acetone. TLC analysis indicated the presence of a single compound with NMR analysis in support of the alpha anomer. SC-XRD analysis showed that methyl glycoside (5) crystallizes from acetone as the alpha anomer in the monoclinic space group I2. Methyl glycoside (5) possesses a glycosidic bond length of 1.408 Å with pseudorotational analysis showing the conformation of the five-membered ring to be ⁰E (O4-endo) with P = 89.9° and φ_m = 64.4°.