4- nitrobenzyl chloride, reaction + base

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°. 

The reactions of sodium dimethyl and diisopropyl phosphite with 4-nitrobenzyl chloride, 9-chlorofluorene, and diphenylchloromethane provided information that supported the proposed reaction mechanism. The RaPO anion acts towards an arylmethyl chloride as a base and abstracts a proton to form a carbanion, which can then participate in single-electron transfer processes to produce carbon-centred radicals. ... 

Benzylic electrophiles bearing electron-withdrawing groups at the arene do not always yield the expected products of nucleophilic substitution on treatment with a nucleophile. One important side reaction is the dimerization of these compounds to yield 1,2-diarylethenes (stilbenes). This dimerization does not require such highly activated systems as the example sketched in Scheme 4.28, but can even occur with, for example, 2- or 4-nitrobenzyl chloride [120, 121]. The latter compounds are converted into the corresponding stilbenes by treatment with KOH in ethanol [120]. Di-arylmethyl halides behave similarly and can yield tetraarylethenes on treatment with a base. These reactions presumably proceed via the mechanism sketched in Scheme 4.27, in which the amphiphilic character of the nitro group plays a decisive role (metalated nitroalkanes or 4-nitrobenzyl derivatives can act as nucleophiles and as electrophiles). 

Unlike all the other substituted 9-bromofluorenes, the highly acidic 3-nitro-9-bromo isomer is converted extensively into its conjugate base by bases in /-butyl alcohol . The rate of elimination can thus be followed by monitoring the absorption of the blue carbanion rather than the red olefinic product, as is otherwise employed. Extensive carbanion formation is also observed with 4-nitrobenzyl chloride and 4-nitrodiphenylmethyl chloride. For all three of these substrates, the rate of elimination shows a complex dependence on the substrate concentration, but an inverse dependence on the medium basicity. This observation is not consistent with a carbene mechanism but accords with the displacement scheme if the substrate is always more than half-ionised under the reaction conditions. To achieve a rapid successful preparative conversion to the dimeric olefin, it is necessary to keep the substrate in an excess of the base in order to maximise the concentration of unionised substrate on which the carbanion can exert a displacement. 

A solution of N-(2-aminobenzvl)-1-phenyl-2-metKylaminoethanol-1 was prepared by the reaction of a-bromo-acetophenone and (2-nitrobenzyl)methylamine, followed by hydrogenation of the nitro group by means of nickei on diatomaceous earth at room temperature and reduction of the CO group by means of sodium borohydride. The intermediate thus produced was dissolved in 100 ml of methylene chloride and introduced dropwise into 125 ml of sulfuric acid at 10° to 15°C. After a short standing, the reaction mixture was poured onto ice and rendered alkaline by means of a sodium hydroxide solution. Dy extraction with ether, there was obtained 1,2,3,4-tetrahydro-2-methyl-4-phenyl-8-amino-iso-quinoline. The base is reacted with maleic acid to give the maleate melting point of the maleate 199° to 201°C (from ethanol). 

Whereas the results summarized in Scheme 4.32 were achieved under homogeneous reaction conditions, Colonna et al. reported the use of chiral phase-transfer catalysts for asymmetric addition of benzyl mercaptan and thiophenols to cyclohexenone and derivatives [55b], The best result was 85% yield and 36% enantiomeric excess in the addition of thiophenol to cyclohexenone, catalyzed by ca 0.4 mol% N-(o-nitrobenzyl)quininium chloride at 25 °C. In this experiment, CCI4 served as solvent and solid KF as the base. Finally, Aida et al. reported in 1996 that chiral... 

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