Nitro alkyl

The N,]S -dialkyl-/)-PDAs are manufactured by reductively alkylating -PDA with ketones. Alternatively, these compounds can be prepared from the ketone and -lutroaruline with catalytic hydrogenation. The /V-alkyl-/V-aryl- -PDAs are made by reductively alkylating -nitro-, -nitroso-, or /)-aminodipheny1 amine with ketones. The AijAT-dialkyl- PDAs are made by condensing various anilines with hydroquinone in the presence of an acid catalyst (see Amines-aromatic,phenylenediamines). 

The two major methods of preparation are the cycloaddition of nitrile oxides to alkenes and the reaction of a,/3-unsaturated ketones with hydroxylamines. Additional methods include reaction of /3-haloketones and hydroxylamine, the reaction of ylides with nitrile oxides by activation of alkyl nitro compounds from isoxazoline AT-oxides (methoxides, etc.) and miscellaneous syntheses (62HC(i7)i). 

The reaction of alkyl nitro compounds with acetyl chloride in the presence of an alkenic compound produced a 2-isoxazoline. The mechanism is believed to proceed via a nitrile oxide and is illustrated in Scheme 112 (B-79MI41613). 

The unique feature of the SrnI reactions of substituted alkyl nitro compounds is the facility with which carbon-carbon bonds between highly branched centers can be formed. This point is illustrated by several of the examples in Scheme 12.7. 

The combination of silyl enol ethers and fluoride ion provides more reactive anions to give alkylated nitro compounds in good yields after oxidation with DDQ, as shown in Eq. 9.22.36 This process provides a new method for synthesis of indoles and oxyindoles (see Chapter 10, Synthesis of Heterocyclic Compounds). 

Alkyl-, nitro- and chloro-phenols 5-Dimethylaminonaphthalene-l -sulfonyl chloride 94... 

The thermal process has been conducted in hot kerosene/ in w-hexadecane/ in o-dichlorobenzene, in di-n-hexyl ether, and in chlorobenzene. Tetrachlorothiophene has been recommended for similar processes. A low concentration is advantages (<1% was recommended in work that showed kerosene to be the optimal solvent. ) As high a temperature as possible has been recommended. - The process has been conducted with alkyl, nitro, ° bromo, - ° methoxyl, hydroxyl, and even (additional) azido groups... 

CA 48,5836(1954) 9)Sax( 1957),347-8 Benzidine,Alkylated(Nitro Derivatives). See Vol l,p A129-L and Note under 2,5,3,-Trinitrobenzi-dine... 

Biphenyldicarboxylicacids.1 Phenanthrenequinone (1) isoxidized by oxygen in the presence of CuCl in pyridine to 2,2 -biphenyldicarboxylic acid (2) in high yield. Under the same conditions the monoimine 3, prepared in situ, is oxidized to 4. Amino and hydroxyl substituents interfere with this reaction, but alkyl, nitro, and halo groups are well-tolerated. 

Effect of the Atmosphere. The composition of radiolysis products depends substantially on the degree of saturation of the irradiated system with oxygen. In a nitrogen atmosphere, the major radiolysis products of the system TBP-diluent-HN03 were alkyl-nitro and -nitrate compounds. However, in the presence of oxygen, the yields of these compounds were sharply reduced, and an accumulation of carbonyl compounds was measured (11, 25). 

Easton, C. J. Roselt, P. D. Tiekink, E. R. T. Synthesis of side-chain functionalized amino add derivatives through reaction of alkyl nitro-nates with a-bromoglydne derivatives. Tetrahedron 1995, 51, 7809-7822. 

The most conspicuous property of aliphatic amines, apart from their fishy smell, is their high basicity, which usually precludes N-alkylations under acidic reaction conditions (last reaction, Scheme 6.3). Hence, alkylation of amines with tertiary alkyl groups is not usually possible without the use of highly stabilized carbocations which can be formed under basic reaction conditions. Rare exceptions are N-alkyla-tions of amines via radicals (Scheme 4.2), copper-catalyzed propargylations (Scheme 6.3), and the addition of amines to some Michael acceptors and allyl palladium or iridium complexes. Better strategies for the preparation of tert-alkylamines include the addition of Grignard reagents to ketone-derived imines [13] or the reduction of tert-alkyl nitro compounds. 

Reactions of allylic and benzylic Grignard reagents with alkyl nitro compounds can, under the right conditions, provide an acceptable route to nitrones [11]. Lack of regio- and stereoselectivity may be a problem, though the former can be controlled to some extent by varying the acid used for protonation, e.g. 

Reaction of a disubstituted nitronate anion with an allylic or benzylic halide leads not to the expected C-alkylated nitro compound, but rather to the carbonyl product. Presumably this reaction, known by fte names of its discoverers, proceeds by the displacement of the halide ion by nitronate oxygen followed by loss of the oxime (equation 15). 

Sodium nitrite can be used to prepare nitro compounds from primary or secondary alkyl bromides or iodides, but the method is of limited scope. Silver nitrite gives nitro compounds only when RX is a primary bromide or iodide.Nitrite esters are an important side product in all these cases (10-22) and become the major product (by an S l mechanism) when secondary or tertiary halides are treated with silver nitrite. Alkyl nitro compounds can be prepared from the alkyl halide via the corresponding azide, by treatment with HOF in acetonitrile. 

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