Substituent effect of an at-amino group on the H-D exchange of ring hydrogens of adenines compared with an N-methyl group
Substituent effects of an N-amino group on the H-D exchange of ring hydrogens of adenines were compared with those of N-methyl group by treating N3-, N7-, and N9-substituted adenines in phosphate buffered D2O media at 70°C. N-Aminoadenines underwent H-D exchange in position 8 faster than the corresponding N-methyladenines. Rates of the exchange of C8-hydrogen of N9-substituted adenines were independent of pD of the medium in an ordinary pD range above their pKa. In strongly alkaline media, N9-aminoadenine underwent H-D exchange at position 2, but N9-methyladenine did not.
Electrophilic amination of adenines. Formation and characteristics of N-aminoadenines
Amination of adenine with H2N-O-SO3H in alkaline media afforded 1-, 3-, 7- and 9-aminoadenine isomers at a ratio of about 1:1:3:1. In neutral media, the product ratio of the isomers changed to about 3:1:1:0. These results were different from the regioselectivity obtained by methylation of adenine with dimethyl sulfate under similar conditions. Amination of adenine with dinitrophenoxyamine in DMF gave 1-aminoadenine as the main product and this regioselectivity was also different from that of methylation with CH3I. Chemical characteristics of these N-amino adenines are described.