Amines 2-nitrobenzyl

Photolytic cleavage reactions (e.g., of o-nitrobenzyl, phenacyl, nitrophenylsul-fenyl derivatives) take place in high yield on irradiation of the protected compound for a few hours at 254-350 nm. For example, the o-nitrobenzyl group, used to protect alcohols, amines, and carboxylic acids,has been removed by irradiation. Protective groups that have been removed by photolysis are described at the appropriate places in this book in addition, the reader may wish to consult five review articles. 

The chemistry of indium metal is the subject of current investigation, especially since the reactions induced by it can be performed in aqueous solution.15 The selective reductions of ethyl 4-nitrobenzoate (entry 1), 2-nitrobenzyl alcohol (entry 2), l-bromo-4-nitrobenzene (entry 3), 4-nitrocinnamyl alcohol (entry 4), 4-nitrobenzonitrile (entry 5), 4-nitrobenzamide (entry 6), 4-nitroanisole (entry 7), and 2-nitrofluorenone (entry 8) with indium metal in the presence of ammonium chloride using aqueous ethanol were performed and the corresponding amines were produced in good yield. These results indicate a useful selectivity in the reduction procedure. For example, ester, nitrile, bromo, amide, benzylic ketone, benzylic alcohol, aromatic ether, and unsaturated bonds remained unaffected during this transformation. Many of the previous methods produce a mixture of compounds. Other metals like zinc, tin, and iron usually require acid-catalysts for the activation process, with resultant problems of waste disposal. 

This approach offers unique opportunities for the generation of multi-functionalized cyclic 2-azadiene systems. A wide variation of the substitution pattern at the positions N-1 and C-6 can be determined by an appropriate choice of the aldehyde and amine. Various substituents can easily be introduced at the C-3 position via addition/elimination reactions on the sensitive imidoyl chloride moiety [24]. Upon reaction with bi-functional reagent, an adequately AT-protected 2(lH)-pyrazinone was elaborated into C-nucleoside analogues (Scheme 8). The desired skeleton and functionalities were obtained by oxidation-cyclization reaction followed by photochemical removal of the protective o-nitrobenzyl group [25]. 

Molecular imprinting is not limited to organic polymer matrices, but can also be applied to silica-based materials and even proteins. Proteins freeze-dried in the presence of a transition state analogue as template have been used successfully as catalysts, e.g., for the dehydrofluorination of a fluorobutanone. For instance, lyophilized 3-lactoglobulin imprinted in this manner with N-isopropyl-N-ni-trobenzyl-amine could accelerate the dehydrofluorination by a factor of 3.27 compared to the non-imprinted protein see Table 5 [62]. In a similar procedure, BSA was imprinted with N-methyl-N-(4-nitrobenzyl)-S-aminovaleric acid and showed an enhancement of the catalytic effect by a factor of 3.3 compared to the control protein for the same reaction see Table 5 [113]. 

This new type of photoredox reaction of p- and m-nitro-substitutcd aromatic derivatives is not observed in organic solvents, and is99,100 extended to m-nitrobenzyl derivatives 162 containing alcohol, alkyl ether, ester or amine functions these compounds undergo photooxidation to produce m-nitrobenzaldehyde (or m-nitroacetophenone) as the major isolable product100 (equation 79). 

Whereas diborane in tetrahydrofuran reduces oximes only at 105-110 , oxime ethers and oxime esters are reduced to amines and alcohols at room temperature in good yields. For example the p-nitrobenzoyl ester of cyclohexanone oxime gave a 67% yield of cyclohexylamine and 81% yield of p-nitrobenzyl alcohol [948]. 

Kinetics and Mechanism of Reactions of Bis (methyl-2,2 -dimercaptodiethyl-amine) dinickel(II) with Alkyl Halides. The rates of reaction of [Ni2 CH3N-(CH2CH2S)2 2], structure III, with methyl iodide, benzyl bromide, benzyl chloride, p-chlorobenzyl chloride, and p-nitrobenzyl chloride have been studied as functions of temperature and concentration in chloroform (3). Absorbance measurements were utilized to determine the rates. All experiments were conducted with excess alkyl halide (20 to 1000 times the initial concentration of complex). Jicha and Busch (18) were able to isolate alkylated complexes of the composition... 

Nitroben2yl-2,4,6-trinitroaniline, 02N.C6H4- CH2.NH.C6H2(N02)3, red-brn solid, mp 191° easily sol in acet less sol in chlf, benz or warm AcOH si sol in ale v diffc sol in eth or petr eth. Was prepd by mixing ale solns of 4-nitrobenzyl-amine and picrylehloride and boiling the mixt for 15 mins on a water bath. Its expl props were not detd... 

Nitrobenzyl-2,4,6-trimUo-nitranilinj 4 -Nitro-benzyl-2,4,6-trimtrophenyl-nitramine or Picryl-(4 -nitrobenzyl)-nitr amine nearly col crysts, mp 141 -2° (with evoln of gas) was first prepd by Blank-sma(Ref 2) by heating N-(4-nitrobenzyl)-4-nitro-aniline with nitric acid(d 1.52) and then later by van den Berg(Ref 3), who showed that this compd can also be obtd by nitration of 4 -nitrobenzyl-2 -ni tro aniline, benzyl-2,4-dinitroaniline, benzyl-2, 4,6-trinitroaniline, 4 -nitrobenzyl-2,4-dinitroani-line or 4 -nitrobenzyl-2,4,6-trinitroaniline. 

The aldehydes 3 were synthesized either by Vilsmeyer formyladon of 2 or by reaction of 4-fluorobenzaldehyde with a secondary amine (20). The stilbenes 4 were formed from the corresponding 4-dialkylamino-benzaldehydes either by the Homer-Emmons reaction with 4-nitrobenzyl-(diethyl)phosphonate (prepared by the Arbuzov reaction of a-bromo-4-nitrotoluene) or with 4-methylsulfonylbenzyl(diethyl)phosphonate (prepared in three steps from 4-methylthiobenzylaicohol) (21). A few nitrostilbene compounds were synthesized by heating aldehyde 3 with 4-nitrophenylacetic acid in the presence of piperidine. 

If the arenes are very electron-deficient direct attack of the nucleophile at the arene might also compete with displacement of the benzylic leaving group, to yield complex structures such as that shown in Scheme 4.28. 2-Nitrobenzyl halides can also react with amines to yield, instead of simple products of nucleophilic substitution, 2fi-indazoles [122] (Scheme4.28). 4-Nitrobenzyl halides, however, yield the expected benzyl amines on treatment with amines [123]. 

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