2- Alkyl-4,6-dinitrophenols

Riley, J.S. Baer, T. Marbury, G.D. Sequential Ortho Effects Characterization of Novel [M-35] Fragment Ions in the Mass Spectra of 2-Alkyl-4,6-Dinitrophenols. J. Am. Chem. Soc. Mass Spectrom. 1991, 2,69-75. 

Zitko, V., McLeese, D.W., Carson, W.G., Welch, H.E. (1976) Toxicity of alkyl-dinitrophenols to some aquatic organisms. Bull. Environ. Contam. Toxicol. 16, 508-515. 

Researches have investigated the biological action of other alkyl-dinitrophenols as a function of the structure of the compounds (Byrde et al., 1969 Clifford et ai, 1969 and 1972). 

Anthracene and 2,6-dinitrophenol terminate chains in oxidizing PP reacting with alkyl as well as with peroxyl radicals [50]. It is important to note that the last two inhibitors retard the liquid phase oxidation of hydrocarbons and aldehydes only by the reaction with peroxyl... 

This class includes compounds such as nitrobenzene, (di)nitrobenzenes, dinitrophenols, (di)nitrocresols or even (di)nitro(alkyl)phenols or cresols. 

As a typical example, the enol ether of acetoacetic ester 3, when treated with anhydrous crotyl alcohol in hot xylene in the presence of dinitrophenol/potassium hydrogen sulfate (4 1, 2g/100g 3), undergoes transetherification and rearrangement to give a 1 1 mixture of diastereomers of the alkylated /J-oxo ester 4452. 

Orf/jo-nitroaryl-substituted acetonitriles are relatively strong C-H acids, and their C-aUcylation followed by hydrogenation leads to 3-substimted indoles [176]. It has been shown earlier that VNS in 2,4-dinitrophenol proceeds regiospe-cifically at the most hindered position 3 due to electronic configuration of the dinitrophenolate anion [14]. This orientation pattern has been employed for the synthesis of the precursor of damirone B from dinitroguaiacol, in which cyanomethylation proceeds exclusively at position 5 to form upon 0-methylation 3,4-dimethoxy-2,6-dinitrophenylacetonitrile. Further alkylation of the nitrile carb-anion with ethyl bromoacetate and hydrogenation provides the skeleton of damirone tricyclic system (Scheme 66) [183, 184]. 

Another research group has applied this approach to the synthesis of polyfunctional 3-azabicyclo[3.3.1]nonanes from 2,4-dinitrophenol [91]. It has been reported that various alkyl amines and amino acids can be successfully used in these transformations. 

As might be expected, the type of feedstock chemical and industrial process play a key role in determining the presence of phenols in wastewater. For example, the nitration of benzene and toluene to produce nitrobenzene and dinitrotoluene also leads to the incidental formation of nitrophenol, dinitrophenol, and dinitro-o-cresol. Similarly, alkylphenols and methyl-phenols may be produced during alkylation and solvent extraction of toluene, xylene, and Cg-Q alkylphenols. Wise and Fahrenthold (1981) suggested that most industrial processes were not sources of priority pollutants because the processes do not involve critical precursor/process combinations. In addition, synthetic production methods generally lead to an increase in complexity of priority pollutant molecules. These in turn exhibit variable toxicity and persistance, which may be comparable to related priority pollutants. 

Amino acid-derived primary-tertiary diamine catalysts have been used extensively in aldol reactions. Lu and Jiang [34] documented a direct asymmetric aldol reaction between acetone and a-ketoesters catalyzed by an L-serine-derived diamine 17. Sels et al. [35] found that several primary amino acid-based diamines (18) were efficient catalysts for the syn-aldol reaction of linear aliphatic ketones with aromatic aldehydes. Luo and Cheng utilized L-phenylalanine-derived diamine catalyst 15a for the enantioselective syn-aldol reaction of hydroxyl ketones with aromatic aldehydes [36]. Moreover, a highly enantioselective direct cross aldol reaction of alkyl aldehydes and aromatic aldehydes was realized in the presence of 15a (Scheme 3.8) [37]. Very recently, the same group also achieved a highly enantioselective cross-aldol reaction of acetaldehyde [38]. Da and coworkers [39] discovered that catalyst 22, in combination with 2,4-dinitrophenol, provided good activation for the direct asymmetric aldol reaction (Scheme 3.9). 

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