Autoxidation of Heterocyclic Aminals

The
autoxidation reactions of 2-acyl-2,3-dihydroquinazolin-4­(1H)-ones 4a and 5a and 2,2′-bis­(dihydroquinazolinone) 6a are described. These reactions generate aminyl radicals
that undergo β-C–C cleavage, and subsequent reactions
of the resulting C-based radicals with O2 lead to diverse
products with good selectivity, depending on the structure of the
substrate. Oxidation of 4a, in which the 2-acyl group
is part of a cyclic acenaphthenone unit, yields a heterocyclic C-hydroperoxylaminal via 1,2-acyl migration. Oxidation of 5a, which contains a 2-acetyl group, yields peracetic acid
and a quinazolinone product. Oxidation of 6a forms a
bis­(quinazolinone) by net dehydrogenation.