Side-chain aromatic amine-substituted

Hydroxy, alkoxy, and amino aldehydes can, like phenols and aromatic amines, be halogenated under mild conditions. The possibility of loss of the aldehyde group has already been mentioned (page 163), and so will be (page 194) the competition between nuclear and side-chain halogenation in substituted alkyl-aromatic ketones. 

The aromatic bromides which contain bromine in the benzene nucleus are either colourless liquids or crystals, which in contrast with the side-chain substituted isomers in part possess an aromatic odour, and their vapours do not attack the eyes and nostrils. The bromine is held very firmly in them, more firmly than in the aliphatic bromides, and cannot he detected by stiver nitrate. While the aliphatic bromides, as mentioned under bromethyl, decompose with ammonia, alcohol, alkalies, etc., to form amines, ethers, alcohols, etc., respectively, these reagents do not act on the aromatic bromides. The bromides containing the bromine in the side-chain, behave like their aliphatic analogues. 

It can be used for reaction with aryl ethers and acylated aromatic amines.764 Various alkylated aromatic compounds can be substituted in the ring by C1SCN in the dark, but in the side chain under UV-irradiation.765... 

The unit - thiophene linked to a carbon - is termed thenyl, hence thenyl chloride is the product of chloromethylation (section 14.1.1.7) thenyl bromides are usually made by side-chain radical substitution. Relatively straightforward benzene-analogue reactivity is found with thenyl halides, alcohols (conveniently preparable by reducing aldehydes) and amines, from, for example, reduction of oximes. One exception is that 2-thenyl Grignard reagents usually react to give 3-substituted derivatives, presumably via a non-aromatic intermediate. ... 

Substituted side-chain amines may also be prepared by aminolysis of substituted haloalkyl pyridines. ° ° Thus, 2-bromomethyl-3-nitropyridine yields the expected 2-arylaminomethyl-3-nitropyridines when treated with aromatic amines at room temperature. At higher reaction temperatures, however, 2/f-pyrazolo[4,3-ft]pyridines (IX-224) result. ... 

The Povarov reaction is related to the previous examples in that it can be defined as the formal imino Diels-Alder reaction between aromatic imines and electron-rich olefins. It is one of the most popular methods for the synthesis of tetrahydro-quinolines [40], and two examples of Povarov reactions in water are summarized in Scheme 1.27. In an eaily example of the use of ceric ammonium nitrate as a catalyst in synthesis [41], Perumal reported a few examples of a CAN-catalyzed Povarov reaction of aldehydes, amines and N-viitylpyrroUdin-2-ones as the olefin component in water for the synthesis of heteroaiyl-substituted tetrahydroquinolines 54 [42]. Using a different approach, Vaultier later described an onium salt-supported Povarov three-component reaction in water at room temperature affording tricyclic compounds 55. In this study, either the aldehyde or the amine components were linked to a side chain containing an onium salt, which confers solubility to the reactant [43]. 

In the aromatic amines, an amino group substituted on the side chain results in a marked ammoniacal odor nuance whereas direct substitution of the amino group onto the nucleus results in a very weak and undefined odor character (e.g., anthranihc acid is odorless whereas methyl anthranilate has a strong orange-flower-hke profile). The amines are of very limited use in flavorings as most of them have an objectionable odor but they do play an important part in some foods [27]. 

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