2,4-Dinitrophenyl carbonates

Aminolysis of a series of aryl 2,4-dinitrophenyl carbonates by a series of quinuclidines gave linear Br0nsted-type plots, the magnitudes of their slopes confirming their mechanisms as concerted.40 A comparison41 of the aminolysis, by primary amines, of 4-nitrophenyl phenyl carbonate (31 X = O) with its thiono analogue (31 X = S) is discussed in the section Thioacids, Thioesters, Thiolactones, and Thiocarbonates below. 

Coupling, active ester Bis-(2,4-dinitrophenyl)carbonate. Chloroacetonitrile. Di(p-nitrophenyl)carbonate. 2-Ethoxypyridine-l-oxide. p-Nitrobenzyl tosylate. p-Nitrophenol. p-Nitrophenyl trifluoroacetate. Pentachlorophenol. Phenyltrimethylammonium ethoxide. Phosgene. Pyrazole. Sulfur dioxide-Dimethylformamide. Tetraethyl pyrophosphite. N,N -Thionyldiimidazole. 2,4,S-Trichlorophenol. 

Peptide synthesis /-Amyl chloroformate. Bis-(2,4-dinitrophenyl)carbonate. Bis-o-phenylene pyrophosphite. i-Butyl chloroformate. sec-Butyl chloroformate. /-Butyl chloroformate. /-Butyl 2,4,5-trichlorophenyl carbonate. CopoIy(ethylene-N-hydroxymaleimide). N,N-Diethyl-I-propynylamine. Di-(p-nitrophenyl)sulfate. Ethoxyacetylene. N-Ethoxycarbonyl-2-ethoxy-l,2-dihydroquinoline. N-Ethylbenzisoxazolium fluoroborate. Ethyl chloroformate. N-Ethyl-5-phenylisoxazolium-3 -sulfonate. N-Hydroxysuccinimide trifluoroacetate. Methyl-morpholine. 4-Methylthiophenol. p-Nitrophenol. Oxalylchloride. Pentachlorophenol. Pentamethylbenzyl chloride. /-Pentyl chloroformate. Phenacyl bromide. Polyhexamethylene carbodiimide. Tetraethyl pyrophosphite. 1,2,4-Triazole. 

Mixed anhydride synthesis [1, 366, after citation of ref. 6]. Wicland63 used the reagent for a one-step cyclization of peptides. Thus L-TryGly-L-Leu-L-Ala-D-Thr (1) was treated with 5 equiv. of pyridine hydrochloride in DMF-THF at 15°. The mixed anhydride (2) is formed but not isolated, and addition of triethylamine leads to cyclization to (3) in 30% yield. The yield is significantly lower (8%) in the absence of pyridine hydrochloride. The one-step synthesis with bis-(2,4-dinitrophenyl)-carbonate in place of ethyl chloroformate proceeds in only 13% yield. 

Ethyl chloroformate enables the one-step cyclization of peptides (eq 15), yields generally being superior to those obtained if Bis(2,4-dinitrophenyl) Carbonate is used. However, Isobutyl Ch/oro/ormafc/A -methylmorpholine is now the reagent of choice for many solution-phase anhydride couplings. " ... 

Of the carboxylic acid esters the most important are isopropyl 2-i-butyl-4,6-dinitrophenyl carbonate (dinobuton, 8), methyl 2,4-dinitro-6-(l-ethylhexyl)phenyl carbonate (9a) and methyl 2,4-dinitro-6-(l-propylpentyl)phenyl carbonate (9b). The mixture of the two latter compounds has been introduced under the name dinocton-6 (9) (Pianka and Polton, 1963 Pianka and Smith, 1965). 

Liu et al. report that 6,6 -teUuroxy-bis(6-deoxy-j8-cyclodextrin) (26) acts as an enhancer for the hydrolysis of 4,4 -dinitrophenyl carbonate (28) with a significant rate acceleration. The proposed mechanism is shown in Scheme 7.6 but appears to be unlikely as the substrate is suggested to enter the cyclodextrin at the narrow end twice [24]. 

Scheme 7.6 Telluroxy bis-(p-cyclodextrine) 26 catalyzes the hydrolysis of 4,4"-dinitrophenyl carbonate...

The dinitrophenyl group has been used to protect the imidazole — NH group in histidines (45% yield)" by reaction with 2,4-dinitrofluorobenzene and potassium carbonate. Imidazole —NH groups, but not a-amino acid groups, are quantitatively regenerated by reaction with 2-mercaptoethanol (22°, pH 8, 1 h)." The 2,4-... 

However, in some cases azines can be converted to hydrazones by treatment with excess hydrazine and NaOH. Arylhydrazines, especially phenyl, p-nitrophenyl, and 2,4-dinitrophenyl, are used much more often and give the corresponding hydrazones with most aldehydes and ketones.Since these are usually solids, they make excellent derivatives and are commonly employed for this purpose. Cyclic hydrazones are also known, ° as are conjugated hydrazones. a-Hydroxy aldehydes and ketones and ot-dicarbonyl compounds give osazones, in which two adjacent carbons have carbon-nitrogen double bonds ... 

Dinitrobenzenesulfenyl bromide may be similarly prepared by refluxing 2,4-dinitrophenyl benzyl sulfide with the equivalent amount of bromine in 5 parts of dry carbon tetrachloride. As it is less stable than the chloride, losing bromine if overheated, it should be concentrated on a 40° water bath under vacuum. When worked up in the same manner as the chloride, the product usually contains some is-(2,4r-dinitrophenyl) disulfide. Because the disulfide is insoluble in carbon tetrachloride, the sulfenyl bromide may be readily purified by recrystallization yield 75-80%, m.p. 102-104°. 

In this group of readily oxidised materials, individually indexed compounds are Arsenic trisulfide, 0108 Bis(2,4-dinitrophenyl) disulfide, 3449 Bis(2-nitrophenyl) disulfide, 3465 Boron trisulfide, 0172 f Carbon disulfide, 0560 Carbon sulfide, 0559 f Carbonyl sulfide, 0556... 

This LSR-CSA technique (discussed in detail in ref. 76) has also been appUed to a series of sulfoxides. Nitroarylsulfoxides are also capable of a strong three-point interaction with fluoroalcohols 1, an ability that is responsible for a considerable difference in stability between the solvates. Mixtures of Id and 2,4-dinitrophenyl methyl sulfoxide are red, and the intensity of this color is inversely proportional to temperature, consistent with formation of tt-tt complexes. Crystallization of the racemic sulfoxide from carbon tetrachloride solutions of (/ )- d leaves mother liquor enriched in the (i )-sulfoxide enantiomer, that predicted by the usual solvation model (41), to form the more stable solvate. With this compound it is also apparent that the (/ , iS )-solvate may differ considerably from the predicted conformation, by population of 42. This additional interaction. 

Fig. 7 Mobility-shift assay for the determination of dissociation constant of the complex between anti-DNP rat monoclonal IgG21) antibody and charged ligands that contained the A-dinitrophenyl group. Mesityl oxide (MO) served as EOF marker, bovine carbonic anhydrase (CAB) and bovine a-lactalbumin (LA) as internal references. The DNP ligands with a charge of —1 (A) und —9 (B), respectively, were used as additives to the running buffer. (Reprinted with permission from Ref. 30. Copyright 1995 American Chemical Society.)...

A Bronsted fl]t value of 0.5 and occh value of 1.31 have been calculated for deprotonation reactions of (3,5-dinitrophenyl)nitromethane promoted by substituted benzoate ions and of substituted (3-nitro-, 4-nitro- and 3,5-dinitro-)phenyhiitro-methanes promoted by benzoate ion, respectively, in methanol.146 The intrinsic rate constants are (2.0-6.3)x 104 tunes lower than for the same reactions in acetonitrile solution, and this has been attributed to commensurate reduction of strength of the hydrogen bond between the carbon acid and benzoate ion in the imbalanced transition state. The transfer activity coefficient (logMyAN) from methanol to acetonitrile solution have been calculated for (// -nitrophenyl)nitromcthyl anion (3.6) and (m-nitrophenyl)-nitromethane (—1.0). 

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