2-HYDROXY-5-NITROBENZYL chlorid

The 2-hydroxy-5-nitrobenzyl chloride begins to separate as a solid about one hour after the beginning of the reaction. At the end the mixture is cooled in ice for one hour whereby more crystals separate, after which the acid liquors are either filtered or decanted from the crystals (Note 6). The 2-hydroxy-s-nitro-benzyl chloride is purified by recrystallization from 125 cc. of hot benzene (Note 7). The yield is 46 g. (69 per cent of the theoretical amount based on />-nitrophenol) of a white product melting at 129-130°. 

Hydroxy-5-nitrobenzyl chloride can also be prepared from 2-hydroxy-s-nitrobenzyl alcohol by passing hydrogen chloride into an alcoholic solution at 70 20 for two hours. In this case the yield of chloride is almost quantitative. The foregoing detailed procedure has been arrived at from that given in German Patent 13 2,4 7 5.3... 

HYDROXY-5-NITROBENZYL CHLORIDE (Toluene, a-Chloro-2-hydroxy-5-nitro-)... 

The polar 1,4-cycloaddition of alkenes with 2-hydroxy-5-nitrobenzyl chloride in the presence of tin(IV) chloride yields 6-nitrochromans (69TL5279). The quinone methide, which is protonated under these conditions, undergoes stereospecific syn addition of the alkene. Although in most cases the reaction is regiospecific, ds-pent-2-ene yields a mixture of isomers. 

Other o-nitrophenol-containing resins have been prepared with the aim of increasing the distance between the reactive center and the macromolecular backbone, which should accelerate the active ester formation by achieving an easier approach of the reagents. Thus, the Friedel-Crafts alkylation of styrene-divinyl-benzene copolymer with 4-hydroxy-3-nitrobenzyl chloride promoted by aluminium trichloride gave 4-hydroxy-3-nitrobenzylated polystyrene (70) (approximately 30% of the aromatic rings of the polymer were substituted according to elemental... 

Supplementary to the syntheses of 28 by Spath et al. in the 1940s, several other preparations have been recorded. Southwick and Casanova (83) prepared 28 in a six-step sequence starting from o-nitrobenzylamine (Scheme 5). The intermediate l-(o-aminobenzyl)-3-hydroxy-2-oxopyrrolidone evidently underwent cyclization rapidly and spontaneously to give the 3,4-dihydroquinazoline system. This synthetic scheme was applied readily to the synthesis of 7-hydroxy-vasicine. The Schopf-Oechler scheme (84) for the synthesis of 28 from o-aminobenzaldehyde and "y-amino-a-hydroxybutyraldehyde under physiological conditions has been realized, and 28 was isolated in 39% overall yield (S5). A facile synthesis of 28 was developed by Mohrle and Gundlach (86) condensation of < -nitrobenzyl chloride with 3-hydroxypyrrolidine and reduction of the... 

A soln of a (—)-4-nitrobenzyl [cyclohexyl(Fmoc-amino)methyl]phosphonic add (57 40.0 mg, 0.073 mmol) in CH2C12 (2mL) was cooled to 0°C, and dry DMF (6pL, 0.01 mmol) and oxalyl chloride (13 pL, 0.147 mmol) were added. The mixture was stirred for 0.5 h at 0°C, diluted with benzene (5mL), and concentrated. The phosphonochloridate was redissolved in benzene (2mL), and treated with TEA (20 pL, 0.147 mmol) followed by AgCN (29 mg, 0.217 mmol). After 5 min at rt, D-2-hydroxy-3-(l//-indol-3-yl)propanamide (22.4mg, 0.011 mmol) was introduced, and the mixture was heated at reflux for 2h, cooled to rt, filtered, and concentrated. The phosphonate diester was purified via flash chromatography (2% MeOH/CH2Cl2) to give a mixture of diastereomers (19.8mg, 37%), which were separated by RP-HPLC. For the minor diastereomer (4.5 mg, amorphous solid) [a]D +15 (c 0.47, EtOH). 

A chromogenic crown ether (AA -bis-(2-hydroxy-5-nitrobenzyl)4,13-diazadibenzo-18-crown-6) in a mixed micellar medium was proposed for the determination of Cd in water (the detection limit was 6 ppb) [1]. The preconcentration of Cd on a chelating resin prepared by coupling Pyrocatechol Violet to Amberlite XAD-2 was studied [2]. Quantitative adsorption was achieved at pH 5-7. Nitric acid (4 M) was used as elluent. The effects of various anions (fluoride, chloride, nitrate, sulfate and phosphate) on the adsorption of Cd (Zn, Pb(Il) and Ni) were investigated. 

The modification of tryptophan in proteins has been shown by a number of authors using various modifying agents. In our studies on the tryptophan modification of TK, we have used dimethyl-(2-hydroxy-5-nitrobenzyl)-sulfonium chloride, recently introduced by Horton and Tucker. These authors have shown that the degree of labelling of proteins by HNB depends on the reagent to protein ratio and on the pH of the reaction mixture [14]. 

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