Furazan oxide

Furazane (1,2,5-Oxadiazole) und Furoxane (Furazan-oxide) werden als Anhydride von 1,2-Dioximen bzw. als die entsprechenden N-Oxide durch Lithiumalanat zu 1,2-Diaminen reduziert z. B.8 ... 

Dinitro-3,4-diphenylfuroxan or Bis(nitro-phenyD-furazan Oxide,... 

In an interesting sequence of reactions, Grundmann and co-workers have prepared 5-amino-4-nitroisoxazole (67) from the sodium salt of nitromalonaldehyde and hydroxylamine.59 The initially formed sodium malon-dialdoxime nitronate 65 is diacetylated and cyclized to the furazan oxide 66 acid hydrolysis, followed by rearrangement in alkali gives the 5-amino-4-nitroisoxazole (Scheme 13). The same product has also been detected in the decomposition of mercuric fulminate. 

The oxadiazole ring was added onto 1 on stirring a saturated solution in methanol with sodium nitrite and hydroxylamine hydrochloride to give dioxime 235. On treatment with sodium carbonate it gave furazan oxide... 

A simple, efficient, one-step synthesis of quinoxaline 1,4-dioxides from the reaction of benzo-furazan oxide (171) with activated alkenes such as enamines was named the Beirut reaction in honor of the city of its discovery. Earlier developments to 1981 were surveyed by Porter <84CHEC-I(3)157>, and later progress has been reviewed by Haddadin and Issidorides <93H(35)1503> who first demonstrated this reaction. Dienamines and azadienes (172) also react with benzofurazan oxide to yield... 

Acid catalysis is preferable to base for the condensation of 5a-cholestan-3-one (341) with pentyl nitrite to form the hydroxyimino-ketone (342). The dioxime (343) afforded the [2,3-c]furazan 2-oxide (344) on oxidation with hypochlorite. Nitration of the 3-ketone (341) with ethyl nitrate and base gave the 2-nitro-enol (345) the derived 3-oxime (346) gave the furazan oxide (344) on reaction with acid. Nitration of 5a-cholestan-7-one gave the 6a- and 6)5-nitro-ketones (347), apparently the first epimeric pair of steroidal nitro-ketones to be... 

Azido-2-nitrothiophene undergoes thermal cyclization, with loss of N2, to an equilibrium mixture of thieno[3,2-c]- and thieno[2,3-c]furazan oxides <74JOC2956>. Kinetic and thermodynamic data have now bwn generated on the related cyclization of 2-azido-5-methoxycarbonyl-3-nitro-thiophene (499) and of 3-azido-5-methoxycarbonyl-2-nitrothiophene (500) to the corresponding thieno[3,2-e]- and thieno[2,3-c]furazan oxides (501) and (502) (Scheme 103). The equilibrium between (501) and (502) has bwn studied by dynamic H NMR spectroscopy <89JCS(P2)127>. The isomerization rates are very large compared with the cyclization rates hence the same mixture results from both (499) and (500). The equilibrium between (501) and (502) is fast on the NMR time scale. 

Furan-2-carboxaldehyde see furfural Furan-2-carboxylic acid 78 Furan-2-methanthiol 78 Furazan see 1,2,5-oxadiazole Furazan oxide see furoxane Furfural 77 Furocumarin 325 Furoxan 253... 

A soln. of 3,4-bis-(2-thienoyl)furazan oxide prepared from methyl 2-thienyl ketone with HNOg/NaNOg (Y 72% s. Synlh. Meth. 11, 414) in dioxane-ether added dropwise to a well-stirred suspension of LiAlH4 in dry ether, and the product isolated as the N-benzoyl derivative N-benzoyl-/ -(2-thienyl)-/ -hydroxyethylamine. Y 58%. F. e. s. G. R. Meloy and D. A. Shirley, J. Org. Ghem. 32, 1255 (1967). 

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