Homologization amines

Goncalves, M.H., Martinez, A., Grass, S., Bulman-Page, PC. and Lacour. J. Enantioselective Olefin Epoxidation using Homologous Amine and Iminium Catalysts—a Direct Comparison. Tetrahedron Lett. 2006, 47, 5297-5301. 

The results described in the following, part of which have been presented as a preliminary communication, are collected in a full paper. A. Dondoni, S. Franco, F. Junquera, F. L. Merch n, P. Merino, T. Tejero, and V. Bertolasi, Stereoselective homologation-amination of aldehydes by addition of their nitrones to C-2 metalated thiazoles. A general entry to a-amino aldehydes and amino sugars, Chem. Eur. J. 1 505 (1995). 

Enamidines (2). Lithiation of 1 followed by treatment with aldehydes or ketones results in Peterson olefination to give a mixture of isomeric enamidines (2) in good yield. These enamidines can be used to convert the carbonyl compounds used in (heir preparation to homologated amines, aldehydes, and ketones. Conversion to a mclhylaminc involves reduction with sodium borohydride (pH 6) to an aminal, which is then hydrolyzed by dilute acid. The sequence can be carried out from 1 without isolation of any intermediates (equation I). 

Homologous Amines. Toluidines.—The amino derivatives of the homologues of benzene are formed by the same kind of reactions as those for preparing aniline, viz., the reduction of the homologous mono-nitro compounds. The- amino toluenes in which the amino group is substituted in the benzene ring are known as toluidines, and there are, of course, three isomeric compounds, orthoj meta and para. In the ordinary nitration of toluene the ortho and para compounds are formed. By indirect methods (p. 532) the meta-nitro toluene may also be prepared. These nitro compounds by reduction yield the corresponding toluidines. 

M.-H. Goncalves, A. Martinez, S. Grass, P.C.B. Page, J. Lacour, Enantioselective olefin epoxidation using homologous amine and iminium catalysts—a direct comparison. Tetrahedron Lett. 47 (2006) 5297. 

Primary amines are not usually made by reduction of amides (15) but by other reductive processes which are minor variations on this scheme. For unbranched amines (16) we can reduce cyanides. This method is especially suitable for benzylic amines since aryl cyanides (17) can be made from diazonium salts (see Chapter 2), and for the homologous amines (18) since cyanide ion reacts easily with benzyl halides. 

N-Formyl-o-toluidine from o-toluidine and formic acid (s. Synth. Meth. 3, 724) passed at 470-540° in a Ng-stream over a silica gel catalyst (previously treated with a little ale. titanium tetrachloride, hydrolyzed, and heated in a NHg-stream) o-tolunitrile. Y 99%. — By hydrogenation of the products, homologous amines can be obtained. F. e. s. F. Becke et al., Ghemiker-Ztg. 89, 807 (1965). 

The formamidine derivatives of secondary amines stabilize carbanions a to the nitrogen, and are readily alkylated to the homologous amine (c/. Vol. 5, p. 

Formamidine derivatives of secondary amines stabilise carbanions a- to nitrogen, and are readily sdkylated to homologous amines (cf. Vol. 5, p. 188, and Vol. 6 p. 198). In an extension of this approach, formamidine (6) gives rise to eneformamidines (7) via a Peterson olefination of the intermediate a-trimethylsilyl derivatives. Further transformation (Scheme 13) leads to N-methylamines as well as other JV-alkylamines. 

Conversion of a Haloalkane into the Homologous Amine by Cyanide Displacement-Reduction... 

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