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 N(7)-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.
Oxidation of 1-benzyladenine (12) with m-chloroperoxybenzoic acid in MeOH or in MeOH-0.5 M phosphate buffer (pH 6.6) has been found to afford 1-benzyladenine 7-oxide (13) as the main product. Nonreductive debenzylation of 13 gave adenine 7-oxide (14) in 63% yield. The structure of 13 was unequivocally established by an X-ray crystallographic analysis.
在 MeOH 或 MeOH-0.5 M 磷酸盐缓冲液(pH 值为 6.6)中,用间氯过氧苯甲酸氧化 1-苄基腺嘌呤(12),得到的主要产物是 1-苄基腺嘌呤 7-氧化物(13)。对 13 进行非还原性脱苄基反应后,得到腺嘌呤 7-氧化物(14),产率为 63%。通过 X 射线晶体分析,13 的结构被明确确定。