1.4- Naphthoquinone 4-oxime, reaction with

Reaction of 1,2-naphthoquinone 1-oxime (499) with 4-phenylthiosemicarbazide (500) yielded either 2-anilinonaphtho[l,2-e][l,2,4]triazine (501) or the corresponding 1-oxide (502) depending on the reaction conditions (78HC(33)189, p. 727). 

Naphthoquinone 1-oxime 1 reacts with guanidin-2-amine and similar compounds to yieldnaphtho[l,2-e][l,2,4]triazin-2-amine 1-oxides 2.132 Reaction of the oxime 1 with thiosemi-carbazides affords usually 2-anilinonaphtho[l,2-e][l,2,4]triazine 3 as deoxygenation products, and only in basic solution the corresponding 1-oxide 2 may be isolated.132... 

Naphthoquinone 1-oxime (772) reacts with aminoguanidine (773) and similar compounds to give 2-aminonaphtho[ 1,2-e][1,2,4]triazine 1-oxides (774). 1-Hydroxy-naphtho[l,2-e][l,2,4]triazin-2-ones can be prepared in an analogous reaction <78HC(33)189, p. 728). 

Heating o-nitrosophenols with hydroxylamine is reported to give furazans, naphtho[l,2-c]furazan (95) being formed from both l-nitroso-2-naphthol and 2-nitroso-l-naphthol, presumably by oximation of the tautomeric o-naphthoquinone monooximes and subsequent dehydration. Compound (95) has also been prepared by oxidation, using alkaline ferri-cyanide or hypochlorite, of l-amino-2-nitroso- and 2-amino-l-nitroso-naphthalene. This latter approach is suitable for heterocyclic fused furazans thus 4,6-diamino-5-nitrosopyrimidine is converted into the furazanopyrimidine (96) by oxidation with lead tetraacetate (71JOC3211). In a similar reaction alkaline hypochlorite oxidizes o-nitrosoacetaniiide to benzofurazan in quantitative yield. 

Domino [3+2] cycloaddition/annulation reactions of aminophenyl-ynones 23 with nitrile oxides, generated in situ from chloro oximes 22, allowed the synthesis of isoxazolo[4,5-c]quinolines 24, in satisfactory yields <03EJO1423>. Bromine substituents on naphthoquinones activate and orient 1,3-DC with nitrile oxides. Compound 25 reacted with halo oximes 22 to give regioselectively only unsymmetrical naphthoquinones 26, as polyketide building blocks <03TL8901>. 

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