Unexpected formation of a substituted furazano-[3,4-d]pyridazine trioxide from α-hydroxylaminoaldoxime and its photochemical conversion to a pyrrolidine nitroxyl radical

Abstract

The discovery of the role of nitric oxide (NO) as an endothelial relaxant [1] and cell mediator with various functions [2] in the past decade has stimulated the search for compounds capable of supplying NO. The therapeutic effect of most vasodilators such as nitroglycerin, sodium nitroprusside, and nitrosothiols has been attributed to the decomposition of these compounds in vivo with the release of NO [3]. N-Oxide derivatives of furazane [4, 5], pyrazole [6] and 3,4-dihydro-l,2-diazete [7, 8] are nitrogen heterocycles, whose biological activity may be related to the release of NO.

α-Organoelement Nitrones: Synthesis, Properties, and IR and 13C NMR Spectral and X-ray Structural Characterization

“…13 C resonances at δ 117.13 and 168.54 ppm fit rather well into the range reported for corresponding signals in furoxane derivatives 21a. The set of vibrations in the IR spectrum of 4 is very similar to that of furoxane derivative 5 (Scheme ) . Specifically, the characteristic feature of both spectra is the presence of the intense vibration band of the CN→O group at 1666 cm -1 …”

“…21a The set of vibrations in the IR spectrum of 4 is very similar to that of furoxane derivative 5 (Scheme 2). 22 Specifically, the characteristic feature of both spectra is the presence of the intense vibration band of the CdNfO group at 1666 cm -1 . 23 As previously reported the azabicyclo[3.2.1]oct-2-ene heterocycle in chloronitrones 6 and 7 (Scheme 2) is stable even when boiling in dilute sulfuric acid.…”