Hydrogenation benzylic amines

Dibenzjiamine, [103-49-17, CgH CH2NHCH2CgH (bp, 300°C at 101.3 kPa) is produced by reaction of benzyl amine with benzaldehyde and hydrogenation of the Schiffs base. It is used in mbber and tire compounding, as a corrosion inhibitor, and as an intermediate in the production of mbber compounds and pharmaceutical products. 

The strategy for the asymmetric reductive acylation of ketones was extended to ketoximes (Scheme 9). The asymmetric reactions of ketoximes were performed with CALB and Pd/C in the presence of hydrogen, diisopropylethylamine, and ethyl acetate in toluene at 60° C for 5 days (Table 20) In comparison to the direct DKR of amines, the yields of chiral amides increased significantly. Diisopropylethylamine was responsible for the increase in yields. However, the major factor would be the slow generation of amines, which maintains the amine concentration low enough to suppress side reactions including the reductive aminafion. Disappointingly, this process is limited to benzylic amines. Additionally, low turnover frequencies also need to be overcome. 

The benzylic hydrogen atom of alkylarenes is replaced by the azido group on treatment with trimethylsilyl azide in the presence of 2,3-dichloro-5,6-dicyano-l,4-benzoquinone subsequent hydrogenation yields amines (e.g. equation 5)31. 

A variety of ligands were used to hydrogenate 73a, 74a-b, 75a-b, and 76a with moderate results. Steric interactions were magnified and that may explain why nearly all of the substrates in Scheme 15 give less than optimal results. A-methyl-A-phenyl-amine derived enamines 74a and 75a were resistant to hydrogenation where the analogous A-methyl-W-benzyl-amine-based enamines were completely converted with SimplePHOX ligand 77 with moderate enantioselectivity. 

Reductive amination of benzaldehyde with (R)-81 provided the corresponding benzyl amine, which was reductively alkylated with formaldehyde to give 82 (Scheme H) " Compound 82 was debenzylated by hydrogenation in the presence of Pearlman s catalyst to afford frovatriptan ((/J)-6). Alternatively, monomethylation of amine (/ )-81 was affected by treatment with carbon disulfide and dicyclohexylcarbodiimide in pyridine to provide isothiocyanate 83, which was reduced with sodium borohydride to give (l )-6. 

Miscellaneous Derivatives. Other derivatives of toluene, none of which is estimated to consume more than ca 3000 t (106 gal) of toluene annually, are mono- and dinitrotoluene hydrogenated to amines benzotnchloride and chlorotoluene, both used as dye intermediates / rf-butylbenzoic acid from /m-butyltoluene, used as a resin modifier, dodecyltoluene converted to a benzyl quaternary ammonium salt for use as a germidde and biphenyl, obtained as by-product during demelhylation, used in specialty chemicals. Toluene is also used as a denaturant in specially denatured alcohol (SDA) formulas 2-B and 12-A. 

Less optimistic conclusions about the performance of the DFT/PCM scheme were drawn in a study of solvent effect on the optical rotation of (.S )- -mclhy I benzyl amine [67]. The authors compared the optical rotation of this amine measured in 39 different solvents (whenever possible extrapolated to infinite dilusion) with the results obtained by means of IEF-PCM with the B3LYP functional and the aug-cc-pVDZ basis set. They observed substantial discrepancies for many of the hydrogen-bond forming solvents (which is not... 

We put mechanism in inverted commas because this isn t really a proper chemical mechanism, more a scheme with a suggested sequence of events. The key points are that the benzyl amine coordinates to the metal catalyst via the electron-rich aromatic ring. The C-N bond is now in close proximity to the palladium-bound hydrogen atoms, and is reduced. 

Benzylic amines react with hydrogen peroxide to yield benzaldehydes. For example, 4-bromobenzyl-dimethylamine gives a 60% yield of 4-teomobenzaldehyde. Only six cases were reported, with both di-methylamino and diethylamino groups undergoing the reaction. 

Reductive alkylation of ammonia has been proved an effective and highly versatile method for obtaining primary amines. The most satisfactory conditions have been catalytic hydrogenation (Raney nickel) of the carbonyl compound in an ethanolic solution of ammonia under pressure ranging from 20 to 150 atm. and at temperatures in the range of 40° to 150°. Typical amines prepared in this manner include benzyl-amine and 2-aminoheptane (80%). With liquid ammonia and no... 

Whereas metal hydride is eliminated from the o--complex intermediates (cf. 309) in Chichibabin aminations, which results in the subsequent reaction of the metal hydride with ammonia or amines and the evolution of hydrogen, the o--complex intermediates can also be oxidized to the corresponding amino-N-heterocycles. Thus, 5-azacinnoline (320) can be aminated with primary and secondary aliphatic or benzyl amines in the presence of potassium hydroxide/potassium ferricyanide to give the corresponding amino derivatives 321 in up to 65% yield. The... 

Asymmetric synthesis of amino aeUs. Optically active amino acids can be prepared by addition of hydrogen cyanide to SchifT bases prepared from aliphatic aldehydes (representing the R group) and optically active benzylic amines (representing the... 

The catalytic hydrogenation of the benzoylformic acid amides of optically active amino acid esters was carried out. When the (5)-amino acid ester was used, the resulting mandelic acid had the (R)-con-figuration. When pyruvic acid amides of optically active benzylic amines were hydrogenated over palladium, optically active lactic acid was obtained in relatively high enantiomeric excess (ee 60%). The... 

In the hydrogenolytic asymmetric transamination between a benzylic amine and oxalacetic acid the Schiff s base was hydrogenated in ethanol over palladium, but alanine rather than aspartic acid was the... 

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