The synthesis of pyrrolo[1,2-c]pyrimidines from 4-methyl-6-phenylpyrimidine

Abstract

Four routes for the preparation of pyrrolo[1,2-c]pyrimidines from 4-methyl-6-phenylpyrimidine have been investigated. 3-Acylmethylene-4-methyl-6-phenylpyrimidinium bromides were cyclised by treatment with either sodium hydrogen carbonate or 4-methyl-6-phenylpyrimidine. 4-Benzoylmethylene-3-benzyl-3,4-dihydro-6-phenylpyrimidine was converted into 5-acetyl-3,6,7-triphenylpyrrolo[1,2-c]pyrimidine by the action of acetic anhydride. The failure of two other methods previously used for the synthesis of indolizines is suggested to be due to the low basicity of the pyrimidines used as starting materials. Electrophilic substitution reactions of the pyrrolo-[1,2-c]pyrimidines are shown to occur at position 7.