A Facile Synthesis of 5-Iodo-6-Substituted Pyrimidines from Uracil-6-Carboxylic acid (Orotic acid)

Abstract

2,4-Dichloro-pyrimidine-6-carbonylchloride (2) was synthesized by refluxing orotic acid (1) with
phosphorus oxychloride and phosphorus pentachloride. Compound (2) underwent a smooth Friedel-Craft's reaction
with a number of substituted benzene to yield 2,4-Dichloro-6-aroylpyrimidines 6 and 7 which were converted to the
corresponding dimethoxy pyrimidines (8, 9) on treatment with sodium methoxide in methanol. The iodination
reaction on 2,4-dimethoxy-6-aroylpyrimidines (8, 9) was attempted by several methods but only NIS-TFA-TFAA
method gave the desired products, 2,4-dimethoxy-5-iodo-6-aroylpyrimidine (10, 11) in good yields.