Ozone-mediated reaction of aromatic acetals and acylal with nitrogen dioxide: a novel methodology for the nuclear nitration of acid-sensitive aromatic compounds under neutral conditions

Abstract

Cyclic acetals 1c–e and 1g can be nitrated smoothly with nitrogen dioxide in ice-cooled dichloromethane in the presence of ozone and magnesium oxide to give mainly ortho- and para- nitro derivatives in good combined yields, the acetal protective group remaining almost intact; acylal 6 is similarly nitrated on the aromatic ring to give a mixture of isomeric nitro derivatives 7, in which the ortho and meta isomers predominate.