Deoxygenation reactions of as-triazine oxides: unusual reactivity of naphtho[1,2-e][1,2,4]triazin-2(3H)-one 1-oxides and the crystal and molecular structure of 3-methylnaphtho[1,2-e][1,2,4]triazin-2(3H)-one 1-oxide

Abstract

The ease of removal of the N-oxide oxygen from a variety of naphtho[1,2,4]triazine N-oxides has been investigated. Naphtho[1,2-e][1,2,4]triazin-2(3H)-one 1-oxide (Ia) and its 3-methyl derivative (Ib), were found to be unusually reactive, being cleanly deoxygenated by boiling 50% aqueous ethanol, and the molecular geometry of (Ib) was unequivocally defined by a crystal-structure analysis. The lability of these compounds is rationalised in terms of a combination of steric and electronic effects.