Photochemical Behavior of 2-Azidopurine Tri-O-Acetylribonucleoside in Aqueous Solution: Unprecedented Transformation into 1-(5′-O-Acetyl-β-D-Ribofuranosyl)-5-[(2-Oxo-1,3,5-Oxadiazocan-4-Ylidene)Amino]-1H-Imidazole-4-Carbaldehyde

The photochemical behavior of 2-azidopurine 2′,3′,5′-tri-O-acetylribonucleoside has been investigated in aqueous solution under aerobic and anaerobic conditions. The two major processes under anaerobic irradiation of 2-azidopurine 2′,3′,5′-tri-O-acetylribonucleoside involve unprecedented transformation into 1-(5′-O-acetyl-β-D-ribofuranosyl)-5-[(2-oxo-1,3,5-oxadiazocan-4-ylidene)amino]-1H-imidazole-4-carbaldehyde and photoreduction to respective 2-aminopurine derivative, whereas under aerobic conditions these two processes occur to a much lesser extent and photooxidation to respective 2-nitropurine derivative dominates. The structures of photoproducts formed were confirmed by NMR and high-resolution electrospray ionization mass spectral data.