Amines, conversion

Dichloronitrobenzene has been prepared by deamination of 3,5-dichloro-4-nitroaniline and of 2,4-dichloro-3-nitroaniline. This procedure is an example of the rather general oxidation of anilines to nitrobenzenes with peroxytrifluoroacetic acid. Use of this reagent is frequently the method of choice for carrying out this transformation, and it is particularly suitable for oxidation of negatively substituted aromatic amines. Conversely, those aromatic amines, such as />-anisidine and j8-naphthylamine, whose aromatic nuclei are unusually sensitive to electrophilic attack give intractable mixtures with this reagent. This is not... 

Benzene and its homologs can be converted to the corresponding cyclo-hexadienes and cyclohexenes, and even cyclohexanes, by treatment with dissolving metals lithium, sodium, potassium or calcium in liquid ammonia or amines. Conversions are not complete, and the ratio of cyclohexadienes to cyclohexenes depends on the metal used, on the solvent, and on the presence of hydrogen donors (alcohols) added to the ammonia or amine [392, 393, 394]. 

Access to this type of compound is illustrated in Scheme 30 by the preparation of retro-sulfonamide tripeptide Boc-Pro-Leuijt[NH—S02]Gly-NH2(78). The two false termini used are the prochiral gem-diamino analogue of Leu and sulfoacetic acid. Amide to amine conversion according to Hofmann, carried out on the dipeptide Boc-Pro-Leu-NH2 (76) with iodobenzene l,l-bis(trifluoroacetate) gave the gem-diamino derivative 77. Coupling of the resulting gem-diamino derivative with methyl (chlorosulfonyl)acetate, followed by amida-tion of the intermediate methyl ester, afforded the desired pseudopeptide 78J1341 Full experimental details have not yet been reported. 

Reductive amination. Conversion of ketones or aldehydes to amines is usually accomplished by reduction of the carbonyl compound with sodium cyanoborohydride in the presence of an amine (Borch reduction, 4, 448-449). However, yields are generally poor in reactions of hindered or acid-sensitive ketones, aromatic amines, or trifluoromethyl ketones. Yields can be improved markedly by treatment of the ketone and amine first with TiCl4 or Ti(0-i -Pr)42 in CH2C12 or benzene to form the imine or enamine and then with NaCNBH3 in CH3OH to effect reduction. Note that primary amines can be obtained by use of hexamethyldisilazane as a substitute for ammonia (last example). 

Formylation was also observed when the amine conversion was carried to high conversion. Secondary amines are obtained from primary amines, and diamines can be cyclized photoelectrochemically. 

The isocyanates (9) were transformed into amino derivatives by standard reactions. Acid-sensitive aminocyclopropanes were obtained preferentially from benzyr ) -naphthyl or trifluorethyl-urethanes which were cleaved by hydrogen, EtSNa/DMF or alkaline hydrolysis. The hydrazinolysis of phthalimido compounds obtained from the urethane and phthalic anhydride also was useful Trimethylsilylethanol proved to be advantageous for the isocyanate-amine conversion the resulting urethanes gave amines upon addition of Bu4N p- 161 (e.g. synthesis of amine (21) from truns-crysanthemic acid via isocyanate (20) S equation 3). Contrarily to... 

The benzyl-spaced aminosilica was also used as a scaffold on which to anchor CGC-inspired catalysts [19]. As in the trityl-spaced study, the aminosilica was first reacted with Cp -silane. For the benzyl-spaced materials, complete conversion of the amine groups through reaction with the Cp -silane did not occur however, the amine conversion for this material was twice the amine conversion for the traditionally grafted material (63% reacted amines vs. 29% reacted amines) [19]. When the grafted, metallated catalyst was tested for polymerization of ethylene, the benzyl-spaced catalyst again outperformed the traditionally grafted material, although it was somewhat less active than the trityl-spaced immobilized catalyst. 

The amine conversions obtained correspond to TONs of 1-3 mol amine/(mol metal) per h, indicating very low activity of the catalyst systems. 

The reaction of peracid radicals with >N-H seems, according to Figure 5, indeed to be quite fast. The rate of initiation applied in this experiment was comparatively high. It can t be excluded that under these rather extreme conditions, a certain amount of self termination of peracid radicals has, as a competitive reaction, also occurred. According to Figure 5, the relation between peracid radical production and amine conversion is... 

Cleavage at the secondary amine, conversion of the acid into ketone (Synthetic surface water)... 

Synthesis of the /3-amino methyl esters was accomplished by Grignard addition to aldehydes or epoxides to deliver the ho-moallylic alcohols. After conversion to the homoamino derivative as prescribed in the allylic alcohol to allylic amine conversion, ozonolysis delivered the targets in good yield, without loss of optical activity or nitrogen protection (eq 49). Numerous additional examples as well as synthetic possibilities exist for the synthesis of natural product fragments utilizing this methodology. 

Where agei and Pgd are epoxy and amine conversions at the gel point and fe and fa are the functionality of the epoxy and amine components respectively (fe = 2 and fa = 4l typically, so under stoichiometric conditions, gel point appears at age i= figei = 0.57). Gelation usually has no effect on the curing kinetics. 

Assuming that the reactivity ratio between primary and secondary amines (R) is independent of the reaction path, the kinetic equations for the epxrxy and paimary amine conversion are ... 

Non-linear method Rate equations (2) and (3) may be solved numerically using a computer program. This ap>proach has been used for several epoxy/aUphatic diamine and good fits of epoxy and primary amine conversions were obtained (Figure 11) (M. Gonzalez et al., 2003). 

Appliactions Alcohol into amine conversion via azides... 

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