Chemoselective deprotection of alpha-indole and imidazole ribonucleosides.
A series of 2 ',3 '-isopropylidene and 5 '-trityl-protected alpha-indole and alpha/beta-benzimidazole and imidazole ribonucleosides were deprotected with different acids. Selectivity was achieved for 5 '-versus 2 ',3 '- deprotection by using formic acid in the alpha-indole ribonucleoside series. Treatment of alpha-indole ribonucleosides with a mixture of formic acid and ether at room temperature afforded 2 ',3 '-deprotected alpha-ribonucleosides, whereas treatment of the alpha-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.
Chandra
Tilak
T
Department of Chemistry and Biochemistry, Ohio University, Athens, Ohio 45701-3132, USA.
Brown
Kenneth L
KL
D005561:Formates / Q000737:chemistry; D007093:Imidazoles / Q000737:chemistry*; D007211:Indoles / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D012263:Ribonucleosides / Q000138:chemical synthesis* / Q000737:chemistry; D013696:Temperature
D005561:Formates; D007093:Imidazoles; D007211:Indoles; D012263:Ribonucleosides; C030544:formic acid; C029899:imidazole; C030374:indole