Purines. LXVI. Adenine 7-oxide: Its synthesis, chemical properties, and X-ray molecular structure
A detailed account is given of the first unequivocal synthesis of adenine 7-oxide (8). The synthesis started with peroxycarboxylic acid oxidation of 3-benzyladenine (6), readily obtainable from adenine (1) by benzylation, and proceeded through nonreductive debenzylation of the resulting 3-benzyladenine 7-oxide (7). The location of the oxygen function in 7 and 8 was confirmed by their chemical reactions including deamination and methylation and by X-ray crystallographic analysis. A UV spectroscopic approach suggested that the neutral species of 8 exists in H2O as an equilibrated mixture of the NO-oxide (8) and N(7)-OH (21) tautomers. Treatment of 6 with 30% aqueous H2O2 in MeOH in the presence of MeCN and KHCO3 at 30°C produced the N(7)-oxide 7 and 7-acetamido-3-benzyladenine (15) in 12% and 1% yields, respectively.
SYNTHESIS OF ADENINE 7-OXIDE FROM ADENINE: UTILIZATION OF A BENZYL GROUP AS A CONTROL SYNTHON AT THE 3-POSITION
The first unequivocal synthetic route to adenine 7-oxide (7) has been established.The route started with peroxycarboxylic acid oxidation of 3-benzyladenine (5), readily obtainable from adenine (2) by benzylation, 8nd proceeded through nonreductive debenzylation of the resulting 3-benzyladenine 7-oxide (6).