Hydrazones oximes

Carbon—nitrogen double bonds in imines, hydrazones, oximes, nitrones, azines, and substituted diazomethanes can be cleaved, yielding mainly ketones, aldehydes and/or carboxyHc acids. Ozonation of acetylene gives primarily glyoxal. With substituted compounds, carboxyHc acids and dicarbonyl compounds are obtained for instance, stearoHc acid yields mainly azelaic acid, and a smaH amount of 9,10-diketostearic acid. 

A different type of rearrangement occurs when suitable side chains are a to a pyridine-like nitrogen atom. In the monocyclic series this can be generalized by Scheme 43. For a given side chain the rate of rearrangement is l,2,4-oxadiazoles>isoxazoles> 1,2,5-oxadiazoles. Typical side chains include hydrazone, oxime and amidine. Some examples are shown in Table 9 (79AHC(25)147). Similar rearrangements for benzazoles are discussed in Section 4.02.3.2.4. 

HCN adds to imines, Schiff bases, hydrazones, oximes, and similar compounds. The CN ion can be added to iminium ions ... 

The other reactions of the aldehydes, which are extraordinarily reactive substances, need only he mentioned here. Such reactions are reduction to alcohols, formation of hydrazones, oximes, semicarbazones, bisulphite compounds, acetals and cyanohydrins (by addition of hydrogen cyanide). 

Diazo esters can also be prepared from glycine esters by treatment with nitrous acid [966] or with alkyl nitrites. Further methods include the oxidation of hydrazones, oximes (Forster reaction), and semicarbazones, the base-induced... 

By Dehydration of a-Diketone Hydrazone Oximes Another general method of synthesis of 2i/-triazoles involves intramolecular elimination of water from adjacent hydrazone and oxime functions (Scheme 32). The usual reagent is acetic anhydride, but others, including phosphorus pentachloride and urea, have been used. 

If the hydrazone is unsubstituted, dehydration with acetic anhydride gives a 2-acetyltriazole, which is readily converted into an unsubstituted triazole.Oxidation of a-diketone hydrazone oximes with cupric sulfate in aqueous pyridine leads to the formation of 2.ff-triazole-1-oxides. ... 

Statt der Bisulfit-Verbindungen der Aldehyde konnen auch ihre Semicarbazone, Hydrazone, Oxime oder Imine eingesetzt werden42c. 

Cleavage of hydrazones, oximes, and semicarbazones. Amberlyst 15, an ion-exchange resin with sulfonic acid groups, is a superior reagent for exchange of nitrogeneous derivatives of carbonyl compounds with acetone. Yields are 85-95% with reactions that proceed at room temperature.1... 

Treatment of dehydro-L-ascorbic acid (72) with phenyl hydrazine followed by hydroxylamine yielded the hydrazone oxime (73a), cyclization of which in refluxing acetic anhydride gave 4-[l-//u< o-2,3-diacetoxy-(l-hydroxypropyl)]-2-phenyl-l,2,3-triazole-5-carboxylic acid lactone (74a) <77CAR(59)141>. Analogous reactions of the derivatives (72) with substituted aryl hydrazines yielded the triazoles (74b-d). Alternatively, the hydrazone oximes (73a-d) may be treated with HBr in... 

The cyclization of compounds containing both hydrazone and oxime moieties is a popular method for the preparation of 1,2,3-triazoles and is exploited in the preparation of 2-substituted 5,6-dihydro-5,6-diphenylpyrrolo[3,4-d]-l,2,3-triazol-4(2//,4//)ones. The isomeric hydrazone oximes (84) and... 

Alternatively, the pyrrolo[3,4-d]-l,2,3-triazolones (86) may be attained by alkylation of the hydrazone oximes (84) and (85), followed by treatment with aqueous NaOH. The routes described are high yielding with only one exception pyrrolo[3,4-J]-1,2,3-triazolone (86c) is unavailable from either compound (87c) or compound (88c) (Scheme 7) <90M67i>. 

As a result of the powerful oxidizing potential of benzeneseleninic anhydride, it is incompatible with the presence of a number of functional groups, although many common moieties are well tolerated. Thus, it has been shown to convert thiocarbonyl compounds such as xanthates, thiocarbonates, thioamides and thiones, and hydrazones, oximes, thiosemicarbazones and hydroxyhttnines, into the corresponding carbonyl compounds under relatively mild conditions. Furthermore, hydrazo derivatives are converted to the azo compounds. ... 

Functional groups containing the C = N bond, such as hydrazones, oximes and diazo compounds, can also be used in the synthesis of fluorinated derivatives and these reactions are the subject of this section. The reaction products in these procedures are usually the corresponding g cw-difluoromethylene compounds. Since oximes and hydrazones arc obtained from aldehydes and ketones, these reactions can be considered as an alternative to the direct transformation of a carbonyl group into the difluoromethylene group. As indicated in Section... 

J2J2j6 -Stannyl Hydrazones, Oximes and Carboxylic Acids... 

Hydrogen cyanide adds to the carbon-nitrogen double bonds present in various aldehyde and ketone derivatives, like those in imines, hydrazones, oximes, and Schiff bases. In each instance, a new carbon-carbon linkage is formed. Thus, the reaction of dry hydrogen cyanide with an imine... 

Anodic oxidation of azomethine, hydrazone, oxime, formazane, and semicarbazone structures has been used to initiate the intramolecular cyclization [119] under formation of heterocycles like triazoles [126,127], oxadiazoles [128,129], triazolinones [129], benzoxa-zoles [130,131], benzimidazoles [130,131], pyrazoles [132], indazoles [133], furoxanes [134], and tetrazolium salts [135] (see Chapter 18). Some of these reactions can be performed advantageously by indirect electrolysis using tris(4-bromophenyl)amin or 2,3-dihydro-2,2-dimethylphenothiazine-6(l/7)-one as mediators [119,136]. Two examples are given in Eqs. (19) and (20). 

Compounds are not always formula-indexed under their own formulas. This is a departure from the ideal, but is reasonable. The interest in a salt of a complex organic acid is likely to be mainly in the acid.. It is more valuable to have the record of the salt under the formula of the acid for the use of searchers looking up the acid. In Chemical Abstracts entries under their own formulas are made for all strictly inorganic and strictly organic compounds, both addition compounds and true reaction derivatives (esters, acetals, hydrazones, oximes, picrates, semi-carbazones, etc.) the diethyl ester of malonic acid is found under C7H]204. 

To synthesize the triazole (71), another approach (63) was used, where dehydration of the mixed hydrazone oxime (70) (61) with acetic anhydride afforded the triazole (71). 

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