Bromoamines

In 1890, Gabriel and Lauer (92) established that a-bromoamines react with CS2 to give 2-mercaptothiazolines (61). In the same laboratory, Hirsch (93) reacted /x-mercapto -methylthiazoline (61) with various alkyl iodides and obtained the corresponding S-alkyl derivatives. 

The Hofmann-Loeffler-Freytag reaction has been described with A-chloro-as well as A-bromoamines—the former however usually give better yields. A-chlorinated primary amines react well in the presence of Fe-(II) ions. Just like the Barton reaction, the Hofmann-Loeffler-Freytag reaction has been applied mainly in steroid chemistry. An interesting example from alkaloid chemistry is the synthesis of nicotine 12 by Loeffler ... 

As described above, it was shown that A,iV-dibromomethylamine was effective for orr/io-dibromination of phenol (ref. 7). We also carried out a bromination using NBB as A-bromoamine analogue. One molar amount of NBB did not give 2-bromophenol selectively, but gave a mixture of o/t/io-monobromophenol and 2,6-dibromophenol, and a considerable amount of phenol was recovered. On the other hand, 2,6-dibromophenol was obtained in an 81.7 % yield when two molar amounts of NBB were used. These results suggested that 7V-bromoamines were the best reagents for orf/io-bromination of phenol. However N-bromoamines were very unstable and decomposed explosively in less than a day at room temperature. 

We considered A-bromoamines which generated in situ from the reaction of NBS and various amines, should promote the o/t/io-dibromination of phenol. The results of the bromination with NBS in the presence of amines are summarized in Table 2. 

Particularly, diisopropylamine and dibutylamine showed high o/t/io-selectivity. Addition of tertiary amines, such as triethylamine, tripropylamine, and tripentylamine was ineffective in the"ortAo-selectivity. In this system A-bromoamine never generates. 

The mechanism of the orf/to-dibromination of phenol with NBS in the presence of amines is considered as follows. The hydrogen bonding between phenol and N-bromoamine which are generated from the reaction of NBS and amines (ref. 14), is the driving force, and causes the bromination at one o/t/io-position of phenol and regeneration of the amines. A catalytic amount of the amines is enough because of the regeneration of the amines. The repetition of the above process causes one more substitution at the other orf/io-position of 2-bromophenol. In the cases of 2-substituted phenols the orf/io-bromination can occur only once (Scheme 5). 

Because the tertiary amines cannot be brominated by NBS, they do not influence the o/tAo-bromination of phenols. Though the hydrogen bonding between the phenolic OH and NBS will be formed, the bonding is inferred to be weaker than that between the OH and the (V-bromoamines. The nucleophilicity (or basicity) of the nitrogen atom of A -bromoamines is stronger than that of NBS. This is why traces of A -bromoamines can react with phenols continuously. 

Cyclohexanones have been converted to 8-chloroquinolines through a series of reactions involving imination, a-alkylation with Af,N-disilyl protected oa-bromoamines, transimination, a-chlorination of the resulting bicyclic imines, dehydrochlorination and dehydrogenation <96T(52)3705>. A short, high yielding one-pot synthesis of acenaptho(l,2-b)benzoquinolines... 

Bromine had been mixed with DMF in an autoclave. A very exothermic reaction took place the temperature reached 100°C and the pressure 135 bar, and then the autoclave detonated. The following interpretation was suggested an unsaturated ammonium salt was formed and decomposed violently in N-bromoamine that is unstable ... 

Aziridination of alkenes can be carried out using N-(p- to I ucncsu I I o n y I i m i n o) phenyliodinane and copper triflate or other copper salts.257 These reactions are mechanistically analogous to metal-catalyzed cyclopropanation. Rhodium acetate also acts as a catalyst.258 Other arenesulfonyliminoiodinanes can be used,259 as can chloroamine T260 and bromoamine T.261 The range of substituted alkenes that react includes acrylate esters.262... 

Sphingomonas herbicidovorans Anthraquinone dyes The bacterium was capable of decolorizing bromoamine acid dye (1,000 mg L-1) more than 98% within 24 h [87]... 

Bromoamine acid contaminated soil Bromoamine acid (an intermediate of anthroquinone dye) Sphingomonas herbicidovorans [87]... 

Qu Y, Zhou J, Wang J, Xiang F, Xing L (2005) Microbial community dynamics in bioaugmented sequencing batch reactors for bromoamine acid removal. Microbiol Lett... 

Guo J, Zhou J, Wang D et al (2008) The new incorporation bio-treatment technology of bromoamine acid and azo dyes wastewater under high salt conditions. Biodegr 19 93-98... 

The decomposition of alkyl azides, N-alkylhydroxylamines, and iV-chloro or iV-bromoamines often requires more drastic conditions than the reactions discussed heretofore, and the resemblance to carbonium ion rearrangements is less pronounced. 

The action of chloroamine and bromoamine on organometallic reagents has been reviewed102 and a comprehensive review of electrophilic aminations of carbanions has appeared103. Alkyl, alkenyl and aryllithium compounds are converted into tertiary amines 84 by reaction with the mesityl compounds 83 (R2 = Me or Et Ar = 2,4, 6-MesCeHj)104. 

In a three-component reaction, a cationic platinum isocyanide complex [(Ph3P)2Pt(CNR)Cl][BF4] is reacted with a /3-bromoamine and butyl lithium to give an imidazoldin-2-ylidene complex.This transformation can be a two-component reaction if the isocyanide ligand contains already the necessary amine functionality. This was shown for chromium, molybdenum, tungsten, and rhenium carbonyls. 

Carbon-nitrogen multiple bonds in fluorinated imines and nitriles react with halogen fluoride reagents Imines provideiV-chloroammes on reaction with chlo rine fluonde [62, 121,122,123] (equations 23 and 24) or with cesium fluoride and chlorine [124] and /V-bromoamines on reaction with cesium fluoride and bromine (equation 24)... 

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