Nitro, acids compounds

Alicyclic hydroxamic acids undergo several specific oxidative cleavage reactions which may be of diagnostic or preparative value. In the pyrrolidine series compounds of type 66 have been oxidized with sodium hypobromite or with periodates to give y-nitroso acids (113). Ozonolysis gives the corresponding y-nitro acids. The related cyclic aldonitrone.s are also oxidized by periodate to nitroso acids, presumably via the hydroxamic acids.This periodate fission was used in the complex degradation of J -nitrones derived from aconitine. 

Tlie condensation of nitromalonic aldehyde (26) with 2,6-diaminopyridine (27) in the presence of phosphoric acid, affording 2-amino-6-nitro-l,8-naphthyridine (28,37%) (77TL2087), is another example of a successful application of a nitro aliphatic compound in the synthesis of nitronaphthy-ridines. 

Many reports deal with the preparation of numerous hydroxynitronaph-thyridones and nitronaphthyridinediones. By the nitration of 4-hydroxy-l,X-naphthyridin-2(lH)-ones (X = 5,6,7, and 8) (51a-51d) using nitric acid in acetic acid, the corresponding 3-nitro substituted compounds (52a-52d) were obtained in reasonable-to-good yield (75JMC726 77MI1 96MI1). 

A. number of rutro compounds used m ndturdl product synthesis have been prepared by the n of alkyl halides Some recent examples are summarized m Table 2 4 fi-Nitro carbonyl compounds are important for synthesis of natural products The reaction of alkyl vinyl ketones with sodium nitrite and acetic acid in THF gives thecorrespondmgfi-nitro carbonyl compounds in42-82% ""rhis method is better for the preparation of fi-nitro carbonyl compounds than the nitration of the corresponclmg halides... 

Explosive decomposition occurred during attempted vacuum distillation, attributed either to the presence of some trinitro compound in the unpurified dinitrophenylacetic acid used, or to the known instability of o-nitro acid chlorides. A previous publication (ibid., 407) erroneously described the decomposition of 2,4-dinitrobenzoyl chloride. 

As mentioned earlier, when NO concentration exceeds that of superoxide, nitric oxide mostly exhibits an inhibitory effect on lipid peroxidation, reacting with lipid peroxyl radicals. These reactions are now well studied [42-44]. The simplest suggestion could be the participation of NO in termination reaction with peroxyl radicals. However, it was found that NO reacts with at least two radicals during inhibition of lipid peroxidation [50]. On these grounds it was proposed that LOONO, a product of the NO recombination with peroxyl radical LOO is rapidly decomposed to LO and N02 and the second NO reacts with LO to form nitroso ester of fatty acid (Reaction (7), Figure 25.1). Alkoxyl radical LO may be transformed into a nitro epoxy compound after rearrangement (Reaction (8)). In addition, LOONO may be hydrolyzed to form fatty acid hydroperoxide (Reaction (6)). Various nitrated lipids can also be formed in the reactions of peroxynitrite and other NO metabolites. 

Photolytic. Major products reported from the photooxidation of 2,3-dimethylbutane with nitrogen oxides are carbon monoxide and acetone. Minor products included formaldehyde, acetaldehyde and peroxyacyl nitrates (Altshuller, 1983). Synthetic air containing gaseous nitrous acid and exposed to artificial sunlight (A. = 300-450 nm) photooxidized 2,3-dimethylbutane into acetone, hexyl nitrate, peroxyacetal nitrate, and a nitro aromatic compound tentatively identified as a propyl nitrate (Cox et al., 1980). 

The carbon nucleophiles in amine-catalyzed reaction conditions are usually rather acidic compounds containing two electron-attracting substituents. Malonic esters, cyanoacetic esters, and cyanoacetamide are examples of compounds which undergo condensation reactions under Knoevenagel conditions.115 Nitroalkanes are also effective nucleophilic reactants. The single nitro group sufficiently activates the a hydrogens to permit deprotonation under the weakly basic conditions. Usually, the product that is isolated is... 

Ihmation.—1. By the reduction of the nitro-substitution compounds of the hydrides of the radicals by sulphuretted hydrogen, ammonio sulphide, zinc and sulphurio acid, or iron and acetic acid —... 

Salts have been prepared with optically active camphor sulphonic acids. These also are yellow crystalline bodies, but no resolution of the base has been effected. d-Camphoric acid, d-tartaric acid, and d-nitro-camphor compounds were also prepared, and again no resolution was effected. Hence it is concluded that the hydroxo- and nitroso-groups are probably in the 1-, 0-, or trans-position. 

Here too there is an enol that tautomerizes to the product. The mechanism is illustrated for the case of p-keto acids,475 but it is likely that malonic acids, a-cyano acids, a-nitro acids, and p,y-unsaturated acids476 behave similarly, since similar six-membered transition states can be written for them. Some a,p-unsaturated acids are also decarboxylated by this mechanism by isomerizing to the p,7-isomers before they actually decarboxylate.477 Evidence is that 36 and similar bicyclic p-keto acids resist decarboxylation.47" In such compounds the... 

Reaction LII. (b) Action of Cuprous Chloride on Nitro-diazonium Compounds. (B., 34, 3802 38, 725.)—Ordinarily when cuprous chloride acts on a diazonium salt in acid solution, a chloro-compound is the chief product (Sandmeyer s reaction, p. 345), and only a small quantity of the corresponding diphenyl compound is formed. But if a nitro-diazonium... 

The following are examples of the reduction of nitro-compounds by ferrous sulphate nitro-phenyl propiolic acid1 and nitro-dichlor-benzaldeliyde2 the method has been used to reduce several nitro-acids to the corresponding amino-acids.3... 

Lithium aluminium hydride reduction of 235 followed by mesylation afforded 236. The latter was oxidized with osmium tetroxide and sodium metaperiodate to yield the cyclobutanone 237. Treatment of 237 with acid afforded in 48% yield the ketoacid (238), which was esterified with diazomethane to 239. The latter was converted to the ketal 240 by treatment with ethylene glycol and /7-toluenesulfonic acid. Compound 240 was reduced with lithium aluminium hydride to the alcohol 241. This alcohol had been synthesized previously by Nagata and co-workers (164) by an entirely different route. The azide 242 was prepared in 80% yield by mesylation of 241 and treatment of the product with sodium azide. Lithium aluminium hydride reduction of 242 gave the primary amine, which was converted to the urethane 243 by treatment with ethyl chloroformate. The ketal group of 243 was removed by acidic hydrolysis and the resulting ketone was nitro-sated with N204 and sodium acetate. Decomposition of the nitrosourethane with sodium ethoxide in refluxing ethanol afforded the ketone 244 in 65% yield. The latter had been also synthesized previously by Japanese chemists (165). The ketone 244 was converted to the ketal 246 and the latter to 247... 

Nitration at position 5 of thieno[2,3-d]pyrimidines 90a and 90 (R1 = H, R2 = NMe2, R3 = C02Me) occurs readily with nitric acid in sufuric acid. However, the methoxycarbonylmethylthio group of compound 90a is hydrolyzed in the process (93JHC1065). Nitration of 5,6-dimethylthieno[2,3-d]pyrimidinedione 143 using nitric acid in sulfuric acid gave a mixture of the 5-nitro 144 and 6-nitro 145 compounds. 

Table 13.1 lists the pK values of C,H-acidic compounds with a variety of electron acceptors. It shows that multiple substitution by a given acceptor enhances the acidity of the o -H atom more than monosubstitution. Table 13.1 also shows that the nitro group is the most activating substituent. One nitro group causes the same acidity of an a-H atom as do two carbonyl or two ester groups. 

Pyrimido[5,4-c]-l,2,5-oxadiazinones (417) are suitable starting materials to construct annulated pyrazines. Reaction with carbanions derived from CH-acidic compounds, activated by two different electron-withdrawing functions, proceed in a regioselective manner by initial attack at the N—O bond. Triethyl phosphonoacetate, /f-ketophosphonates, nitro ketones, nitro esters, sulfonylacetates, and JV-acetoacetylglycine have been applied to form 6,7-disubstituted lumazines (418) (Equation (18)) <91H(32)79>. 

The response of the peroxybenzoates to the CIEEL activators depends remarkably on the nature of the substituent. The unsubstituted peroxybenzoate [29a] behaves in a fashion nearly identical to that observed for the peroxyacetate [28]. The p-methoxy-substituted peroxybenzoate [29b] behaves quite like the parent, but the nitro-substituted compounds [29d] and [29e] and the p-dimethylamino-substituted peroxybenzoate [29c] behave quite differently. The properties of these compounds, however, can be understood within the CIEEL mechanism. For example, the nitro-substituted peroxybenzoates [29d] and [29e] with DMAC exhibit a value of k2 approximately ten times greater than for the unsubstituted peroxide. Yet the yield of excited singlet DMAC generated by [29d] and [29e] is 700 times less than from 29a. This seeming inconsistency can be easily understood. In the postulated CIEEL path, the reduction of the peroxide results in its fragmentation to acetophenone and an acid. One of these species must be a radical anion. For the peroxyacetate and all of the substituted peroxybenzoates examined, with the exception of the nitro-substituted examples, the more easily reduced species of this pair is... 

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