Abstract
A series of 2 ′,3 ′-isopropylidene and 5 ′-trityl-protected α-indole and α/β-benzimidazole and imidazole ribonucleosides were deprotected with different acids. Selectivity was achieved for 5 ′-versus 2 ′,3 ′- deprotection by using formic acid in the α-indole ribonucleoside series. Treatment of α-indole ribonucleosides with a mixture of formic acid and ether at room temperature afforded 2 ′,3 ′-deprotected α-ribonucleosides, whereas treatment of the α-benzimidazole ribonucleosides with the same acid afforded the 5 ′-deprotected ribonucleoside without any 2 ′, 3 ′-deprotected products. The structures of these ribonucleosides were elucidated with 2D (NOESY, COSY, and HMQC) NMR spectroscopy.
This research was supported by the National Institute of General Medical Sciences, Grant GM 48858