Preparation of Pyrimidine-N-oxides by Condensation of Functionalized Enamides with Hydroxylamine Hydrochloride

Abstract

β-Alkoxy-β-ketoenamides and hydroxylamine hydrochloride smoothly provide pyrimidine-N-oxides under very mild conditions. Alkyl, aryl, and heteroaryl substituents are compatible with this new method. By treatment with acetic acid anhydride these pyrimidine-N-oxides undergo a rearrangement furnishing highly functionalized 6-acetoxymethyl-substituted pyrimidine derivatives in good yields. Our method, which is based on a three-component reaction of alkoxyallenes, nitriles, and carboxylic acids, therefore constitutes a highly flexible route to densely substituted pyrimidine derivatives.

Key words

pyrimidines - N-oxides - enamides - hydroxylamine - condensation - 3,3-sigmatropic rearrangement

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