Anions nitro alkanes

Various side-reactions may complicate the course of the Nef reaction. Because of the delocalized negative charge, the nitronate anion 2 can react at various positions with an electrophile addition of a proton at the a-carbon reconstitutes the starting nitro alkane. 1. The nitrite anion can act as leaving group, thus leading to elimination products. 

In aqueous alkaline solution of low ionic strength the transformation of a nitro-alkane into the irreducible anion is sufficiently slow to allow cyclic voltammetry of the nitroalkane. It has been shown [14] that the reduction occurs in two steps, the first one leading to the radical ion. 

Salts of nitro alkanes show a considerable deviation from the non-ionized nitroalkanes. Novikov and co-workers [7] give the frequencies of mononitro anion as follows ... 

The alternative disconnection (20) requires the Michael addition of an acyl anion equivalent. Cyanide ion, a reagent for COjH and nitro alkane anions (Chapter 22) are both good at Michael additions, so that addition of cyanide ion to (21) is a route to y-keto acids (22). 

Nitro alkane anions (Chapter 22) will add to enones in Michael reactions and therefore behave as acyl anion equivalents in the synthesis of 1,4-diketones (27). ... 

A number of papers have been dedicated to homolytic degradation of TN under the action of ultraviolet or 7-rays. The reaction of TNM with bases (e. benzidine) beings with the formation of CT complexes [183] yielding radical anions which in turn are split into radicals (NO ) and anions (e.g. nitroformanion Irradiation with 7-rays at 77K yielded radicals N02 and C(N02)3 (184). As most nifro compounds TNT inhibits polymerization induced by radiati-[185, 186] and free radical polymerization [I8O- 191]. This is rationalized f the fact that TNM is a radicals acceptor. The higher the number of nitro groui in nitro alkanes the stronger the inhibition of polymerization (189). 

Other exan5)les are summarized in eqs 31-33. In particular, addition of the a-anion of (V-nitrile imines to reagent 1 led to 2-amino p3Timidines (eq 31). The a-anion of a-phenyl nitromethane could also be added to reagent 1, and subsequent hydrolysis of thioimidate intermediate gave amide-substituted nitro alkanes (eq 32).31-33... 

A number of reactants that can give rise to anionic species have been used. These include esters of phenylacetic acid/ malonic and alkymalonic acids/ " acetoacetic acid/ etc. Also useful are some nitriles and nitro-alkanes. The case of 2-nitropropane 76 is interesting. Kloetzel reported that the nature of the product from diethyl fumarate depends on the amount of diethylamine (DEA) catalyst employed. Thus, using 0.20 mole of catalyst, the simple addition product 77 was formed in a 90% yield. However, with 1.25 moles of base, elimination occurred giving 78 in an 83% yield. 

The reduction of ketoximes with titanium(iu) chloride is noted in a partial synthesis of erythromycylamine in this case, the intermediate imine is stable and can be further reduced, though normally imine hydrolysis is rapid and ketones are obtained in high yield. This observation has been utilized to effect conversion of a nitro-compound into a ketone. In search of a route to 1,4-diketones via conjugate addition of a masked carbonyl anion to an ajS-unsaturated ketone, McMurry considered Michael addition with a nitro-alkane. Treatment of the resulting y-nitroketone with titanium(m) chloride afforded the required 1,4-diketone (148) in excellent yield, presumably by sequential intermediacy of the oxime and the imine this mild conversion avoids the harsh conditions of the alternative Nef procedure (Scheme 69). 

Gem-nitro imidazolyl alkanes undergo Sjy l reactions with the anion of various nitroalkanes, as shown in Eq. 5.36.54 The nitro group is replaced by hydrogen in 80-90% yield on treatment with Bu3SnH (see Chapter 7, which discusses radical denitration). 

I-Nitroalkenes. Anions of nitroalkanes react with benzeneselenenyl bromide in THF to form nitro(phenylseleno)alkanes, which usually are not isolated but rather are converted directly into nilroalkenes by oxidation with 35% aqueous H202 (equation I).1... 

Cathodic reduction consists of electron supply from the cathode, followed by acquisition of protons by anionically charged substrates. Thus, ready accessibility of the reductive electron transfer processes leads to a variety of reactions, including reductive abstraction of halogens [13, 14], reduction of alcohols to alkanes [15], reduction of imines, oximes, and hydrazones to the corresponding amines [16], and conversion of nitro groups to the corresponding nitroso, hydroxy amino, and amino groups [17]. In... 

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