Furoxans ozonolysis

Furoxans, bis[(acetoxyalkyl)carbonyl]-synthesis, 6, 421 Furoxans, bisarylsulfonyl-synthesis, 6, 423 Furoxans, bis(dialkylamino)-synthesis, 6, 414 Furoxans, butylhexynyl-synthesis, 6, 423 Furoxans, decamethylenering cleavage, 6, 405 Furoxans, diacyl-thermolysis, 6, 81 synthesis, 6, 442 Furoxans, diadamant-1-yl-ring cleavage, 6, 404 Furoxans, dialkoxycarbonyl-synthesis, 6, 423 Furoxans, dialkyl-synthesis, 6, 423 Furoxans, diaryl-ozonolysis, 6, 405 Furoxans, diaroyl-isoxazoles from, 6, 82 Furoxans, dibenzoyl-synthesis, 6, 423 Furoxans, diethoxycarbonyl-synthesis, 6, 423... 

Direct oxidation of furazans to furoxans has not been achieved. The resistance of the oxadiazole ring to oxidizing agents is illustrated by the preferential attack of potassium permanganate at alkyl substituents dimethylfurazan is converted into furazandicarboxylic acid via the methylfurazanmonocarboxylic acid (see Section 4.22.3.4.1). Furazans appear to be less susceptible to ozonolysis than furoxans. 

The ozonolysis of diarylfuroxans was studied by Kinney and Harwood. In their earlier paper,272 they found that benzoic acid was formed from diphenylfuroxan, and they interpreted this as evidence for the presence of a C=C bond in the heterocyclic ring, as in structure 4. Later, the isolation of isomeric anisylphenylfuroxans by Meisenheimer et al.22 came to their attention, and Kinney269 subjected the two forms to ozonolysis. Both formed a yellow ozone adduct of unknown composition, which with cold dilute sodium hydroxide gave the salt of the acid derived from the 3-substituent, together with a red residue which on further hydrolysis with hot hydroxide formed the acid of the 4-substituent (Eq. 10). This work provided valuable support for Meisenheimer s contention that his compounds were positional isomers, both based on the furoxan ring structure (1). 

---