Purines. LXI. An Attempted Synthesis of 2'-Deoxy-7-methyladenosine : Glycosidic Hydrolyses of the N⁶-Methoxy Derivative and 2'-Deoxy N^x-methyladenosines

Abstract

In an attempt to synthesize 2'-deoxy-7-methyladenosine (5b), 2'-deoxy-N⁶-methoxyadenosine (13b) was treated with MeI in AcNMe₂ at 0°C for 7h to give the 2'-deoxy-N⁶-methoxy-7-methyladenosine salt (14b), which was unstable and easily underwent glycosidic hydrolysis in H₂O at 16-18°C to form N⁶-methoxy-7-methyladenine (15). On account of such instability, hydrogenolysis of 14b in H₂O using hydrogen and Raney Ni catalyst failed to afford the desired nucleoside (5b). 2'-Deoxy-N⁶-methyladenosine (2b), 2'-deoxy-1-methyladenosine (3b), and 14b were found to undergo glycosdic hydrolysis in 0.1 N aqueous HCl at 25°C at rates of 7.92×10^-3 min^-1 (half-life 87.5 min), 5.02×10^-3 min^-1 (half-life 138 min), and 2.31×10^-2 min^-1 (half-life 30.0 min), respectively, while the rate in the case of 5b was roughly estimated to be ca. 2 min^-1 (half-life 0.35 min).