Mononuclear heterocyclic rearrangement

Table 5 Heterocyclic Rearrangements Involving Side Chains (Mononuclear Heterocyclic Rearrangements)...

The mononuclear heterocyclic rearrangement (MHR) of isoxazole-3-amidoxime 108 in the presence of a base and hydroxylamine with concomitant removal of the amide moiety affords furazan acetaldoxime 109 (Scheme 56) (91CHE651, 91KGS827). 

Nitroethylfurazan 143 has been synthesized by base-promoted mononuclear heterocyclic rearrangement (MHR) of oxime 142 (Scheme 82) (36G819,82G181). 

The role of substituents X on the mononuclear heterocyclic rearrangement (MHR) of 20 phenylhydrazones 54 of 3-benzoyl-5-phenyl-l,2,4-oxadiazole into the triazoles 55 (Equation 2) has been investigated, allowing the influence of X on the product distribution to be evaluated and first-order rate constants and Hammett correlations to be determined <1999T12885>. 

It was shown that furoxans can be transformed to 1,2,3-triazoles. Thus, 4-acetylamino-3-arylazo-l,2,5-oxadiazole 2-oxides undergo two successive (cascade) mononuclear heterocyclic rearrangements in an aqueous basic medium with the formation of 4-acetylamino-2-aryl-5-nitro-2/7-l,2,3-triazoles (Equation 12) <2001MC230>, or 3,3 -disubsti-tuted 4,4 -azo-l,2,5-oxadiazole 2-oxides were found to undergo a rearrangement into 2-(furoxan-4-yl)-4-nitro-2//-1,2,3-triazole 1-oxides on heating in pertrifluoroacetic or peracetic acids (Equation 13) <2003MC272>. 

M. Ruccia, N. Viviona u. D. Spinelli, Mononuclear Heterocyclic Rearrangements, in Advances in Heterocyclic Chemistry, Vol. 29, S. 141 169, Academic Press, Inc., New York San Francisco London 1981. 

Mononuclear Heterocyclic Rearrangements M. Ruccia, N. Vivona and D. Spinelli, Adv. Heterocycl. Chem., 1981, 29, 141-170. 

Meso-ionic compounds, 19, 1 Metal catalysts, action on pyridines, 2, 179 Monoazaindoles, 9, 27 Monocyclic pyrroles, oxidation, of, 15, 67 Monocyclic sullur-conlaining pyrones, 8, 219 Mononuclear heterocyclic rearrangements, 29, 141... 

Ruccia, M., Vivona, N., Spinelli, D., Mononuclear Heterocyclic Rearrangements, 29, 141. 

Scheme IS General expression for mononuclear heterocyclic rearrangements...

Base-catalyzed isomerization (called mononuclear heterocyclic rearrangement ) was described for the formation of Z-phenylhydrazone of 3-benzoyl-l,2,4-oxadiazole 156 into 4-benzoylamino-1,2,3-triazole 157242,243 (equation 61). 

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