Studies on Pyrimidine Derivatives. XVI. Site Selectivity in the Homolytic Substitution of Simple Pyrimidines

Abstract

Pyrimidine derivatives in which both the 2- and 4-positions are free exhibited site selectivity in their reactions with radicals generated in redox systems. Namely, 6-phenyl-(I), 6-methylpyrimidine (XV), and 5, 6, 7, 8-tetrahydroquinazoline (XVII) reacted with radicals such as RCO, R₂NCO, EtOCO, and CH₂OH to give predominantly the 4-substituted products. Except in the reaction of I with the N, N-dimethylcarbamoyl radical, the formation of the corresponding 2-substituted isomers was not observed.