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