Heterocyclic ambident nucleophiles. III. The alkylation of sodium adenide

Abstract

The alkylation of sodium adenide in HCONMe2 (30�) with various alkylating agents was analysed by 1H n.m.r. spectroscopy. Widely varying N3 : N7 : N9 alkylation patterns were observed, depending on the alkylating agent. These patterns are interpreted in terms of the electrostatic, thermodynamic and steric factors involved in the different SN2 transition states appropriate to each alkylating agent. Hydrogen bonding association between the 6-amino group and certain carbonyl containing alkylating agents is proposed to explain the enhanced N7-alkylation in some cases. Support for this latter proposal was obtained from a comparison of the adenine alkylation results with the corresponding alkylation patterns of 6-pivaloylamino- and 6-chloro-purine.