Electronic structure, PMR spectra, and alkylating capacity of some 2- and 6-alkoxypurines

Abstract

The simple MO LCAO method was used to calculate the isomeric N,N-dimethylhypoxanthines and the corresponding 2(6)-ethoxy- and 2(6)-ethoxy-8-chloro derivatives, and the PMR spectra of a number of compounds of this type were measured. A qualitative correlation was observed between changes in the π -electron densities and changes in the chemical shifts of the protons of the N-methyl groups. Factors affecting the alkylating capacity of 2(6)-alkoxypurines and the direction of the reaction of these compounds with sodiomalonic ester when the molecules contain two different reaction centers were examined. The use of the π -electron densities and orders and polarizabilities of the heterocycle — substituent bonds as reactivity indexes makes it possible to explain the highest alkylating capacity of 2-ethoxy-3,7-dimethylhypoxanthine and its 8-chloro derivative and the order of other compounds with respect to this capacity.