Purines. LXVIII. Trifluoroperoxyacetic Acid Oxidation of N6-Benzyladenine: Formation of the N(3)-Oxide and N(7)-Oxide, and Their Cytokinin Activities

Treatment of N6-benzyladenine (2) with 15% aqueous H2O2 in trifluoroacetic acid at 65-70°C for 1 h was found to give the N(3)-oxide (3) and the N(7)-oxide (4) in 4% and 4% yields, respectively. The structure of 3 was established by its identity with a sample prepared from 6-chloropurine 3-oxide (6) and benzylamine, and the structure of 4 by its identity with a sample obtained from 1-benzyladenine 7-oxide (8) by Dimroth rearrangement. The N-oxides 3 and 4, together with previously reported N6-benzyladenine 1-oxide (1), were tested for cytokinin activity in the tobacco callus bioassay. Each of the three N-oxides was active at 4 μM concentration, being less active than the parent base 2 by a factor of 40.