Thermal and Base-Induced Cyclizations of N-Heteroarylamidinopropanoates

Abstract

The potential cyclization of N-heteroarylamidines to annelated pyrimidines by flash vacuum pyrolysis or by treatment with bases has been investigated. The pyrolytic process with the title compounds is complicated by competing formation and rearrangement of an imidoylketene. The major pyrolysis products, the 4-aminopyrimidin-6-ones, were best prepared from the title compounds by reaction with hindered alkoxides, while the pyrolysis byproducts, the 4-alkoxypyrimidin-6-ones, were conveniently prepared from the appropriate isoxazol-5(2H)-one by reaction with the appropriate alkoxide, followed by acidic workup.