2,4-Dinitrophenyl methyl carbonate

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. 

In 1965, Raban and Mislow [90] postulated that nuclei placed in an asymmetric magnetic field should show NMR nonequivalence. In 1966, Pirkle [91] first reported the validity of the prediction when it was shown that (5)-l-phenylmethylamine caused F-NMR nonequivalency of 2,2,2-trifluoro-1-phenylethanol in a carbon tetrachloride solution. In later studies, 2,2,2-trifluoro-l-(9-anthryl)ethanol, an NMR shift reagent, was used as a mobile-phase additive to separate 2,4-dinitrophenyl methyl sulfoxide on a silica gel column [92]. Later, one enantiomer of this fluoroalcohol was covalently attached to silica gel and used for resolution of a large number of solutes including sulfoxides, lactones, derivatives of alcohols, amines, amino acids, hydroxy acids, and mercaptans [93]. 

The incorporation of [2-14C]pyruvate and [l-14C]acetate into sugars 17 and 18 was investigated.27 Oxidation of the methyl glycosides of sugar 17 with periodate yielded acetaldehyde from the 1-hydroxyethyl branch. The acetaldehyde (2,4-dinitrophenyl)hydrazone was further oxidized by Kuhn-Roth oxidation to acetic acid, which was degraded by the Schmidt reaction to methylamine and carbon dioxide. Periodate oxidation of the methyl glycosides of sugar 18 produced acetic acid from the C-acetyl branch. The acetic acid was isolated, and purified as 1-acetamidonaphthalene. 

P-O bond fission is the usual mode of attack by nucleophiles on phosphodiesters, although there are exceptions. The labile diester methyl-2,4-dinitrophenyl phosphate shows significant amounts of attack at aromatic carbon (nucleophilic aromatic substitution, with loss of methyl phosphate) in competition with attack at phosphorus, most notably with hydroxide and with primary amines.46 Due to the small size of the methyl group it is sterically susceptible to nucleophilic attack in phosphate esters the hydrolysis of the dimethyl phosphate anion occurs almost exclusively by C-O bond fission.4 With larger or less labile leaving groups, even... 

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. 

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). 

Carbobenzoxy-L-phenylalanine dissolved in ethyl acetate with addition of pyridine, treated with di(p-nitrophenyl) carbonate, refluxed 3hrs., L-proline methyl ester hydrochloride in chloroform and triethylamine added, allowed to stand overnight at room temp., then the volatiles removed by distillation in vacuo crude carbobenzoxy-L-phenylalanyl-L-proline methyl ester. Y 87%. F. e. s. T. Wieland et al., A. 655, 189 (1962) cf. P. G. Katsoyannis et al., Am. Soc. 85, 1679, 1681 (1963) also reactions with 2,4-dinitrophenyl esters s. R. Glatthard and M. Matter, Helv. 46, 795 (1963). 

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