Bromination amide

Also cyclization of a six-membered chain has been reported. By brominating nonconjugated allylic amides, McManus et a/.165-166 obtained 5,6-dihydro- 1,3-oxazine derivative in addition to two other compounds (a five-membered ring and the brominated amide) [Eq. (32)]. 

In cases where stabilisation of the newly formed organolithium is available, multiply lithiated species may be formed from polybrominated starting materials. For example, treatment of 59 or 61 with four equivalents of J-BuLi generates dilithio species 60 and 62.69 Lithiation of the non-brominated amides forms only the mono-lithiated product. 

All of the Amathia brominated amides are presumably biosynthesised from amino acids by similar pathways in the related bryozoans. The amathamides are amides derived formally by reaction of 2-(2,4-dlbromo-5-methoxyphenyl)ethanamlne, 68, with proline followed variously by introduction of a double bond, or methyl, methoxy or bromine substituents. The A. convoluta metabolites 70-74, and 75 from A. alternata are all also derived formally from 2-(2,4-dibromo-5-methoxy-phenyDethanamlne, 68—either by direct amide formation with tyrosine, or by having an additional aminopropyl group which is then... 

A remarkably efficient FeCl2-catalyzed intermolecular amination of simple benzylic substrates has been described (Fig. 15) [76]. These same authors have also noted the ability of CuBr to operate in a similar capacity [77]. iV-Bromosucci-mide (NBS) is used as the oxidant together with either a carboxamide or sulfonamide starting material. The /V-brominated amide purportedly reacts with FeCF to generate an Fe nitrene species that is capable of oxidizing benzylic C-H bonds, though evidence for such a mechanism is absent from the discussion. If a nitrenoid pathway is indeed operative, one might expect isocyanate formation to compete... 

N-Bromination. Amides are brominated with AcOBr in CCU at room temperature. 

Motualevic adds A-E are unusual brominated amides of glycine and glydne derivatives isolated from a Fijian Siliquariapongia sp. (Keflfer, Plaza, and Bewley, 2009). Motualevic acids A, B, and F with a carboxylic add function are antimicrobial against Staphylococcus aureus and methidllin-resistant S. aureus (MRSA). 

The reaction is applicable to the preparation of amines from amides of aliphatic aromatic, aryl-aliphatic and heterocyclic acids. A further example is given in Section IV,170 in connexion with the preparation of anthranilic acid from phthal-imide. It may be mentioned that for aliphatic monoamides containing more than eight carbon atoms aqueous alkaline hypohalite gives poor yields of the amines. Good results are obtained by treatment of the amide (C > 8) in methanol with sodium methoxide and bromine, followed by hydrolysis of the resulting N-alkyl methyl carbamate ... 

Poly(phenylene oxide)s undergo many substitution reactions (25). Reactions involving the aromatic rings and the methyl groups of DMPPO include bromination (26), displacement of the resultant bromine with phosphoms or amines (27), lithiation (28), and maleic anhydride grafting (29). Additional reactions at the open 3-position on the ring include nitration, alkylation (30), and amidation with isocyanates (31). 

Amides and imides can be N-brominated in the cold by alkah hypobromites (24). 

This vinylogous amide has been prepared in 70% yield to protect amino acid esters. It is cleaved by treatment with either aqueous bromine or nitrous acid (90% yield). ... 

The bromination of 4,5-j -dihydrocortisone acetate in buffered acetic acid does not proceed very cleanly (<70%) and, in an attempt to improve this step in the cortisone synthesis, Holysz ° investigated the use of dimethylformamide (DMF) as a solvent for bromination. Improved yields were obtained (although in retrospect the homogeneity and structural assignments of some products seem questionable.) It was also observed that the combination of certain metal halides, particularly lithium chloride and bromide in hot DMF was specially effective in dehydrobromination of 4-bromodihydrocortisone acetate. Other amide solvents such as dimethylacetamide (DMA) and A-formylpiperidine can be used in place of DMF. It became apparent later that this method of dehydrobromination is also prone to produce isomeric unsaturated ketones. When applied to 2,4-dibromo-3-ketones, a substantial amount of the A -isomer is formed. 

Bromination of the methyl group of (249) with A -bromosuccinimide, followed by reaction with excess secondary amine gave (250) which shows combined analgesic and antitussive properties. The Reformatsky reaction has also been used for the preparation of 2-amino-ethyl 3,3-diaryl-3-hydroxypropanates (251) as well as their dehydration products. The propene amides (252) have also been prepared for pharmacological evaluation. In l-methyl-3-bis (2-thienyl)-... 

The influence of other groups in a pyridine or similar ring system is more difficult to assess because no kinetic data are available. The deactivating effect of the bromine atom in the 2-position is greater than that in the 3-position, while 2,6-dibromopyridine is very slow to react with dimethyl sulfate. Esters, amides, and nitriles of nicotinic and isonicotinic acids undergo fairly easy quaternization at about... 

The rx bromination of carbonyl compounds by Br2 in acetic acid is limited tc aldehydes and ketones because acids, esters, and amides don t enolize to a suffi cient extent. Carboxylic acids, however, can be a brominaled by a mixture of Br and PBr3 in the HeJI-Volhard-Zelinskii (HVZ) reaction. 

The bromodihydrodibenz[/>,/]az.epine-5-carbonyl chloride 41, prepared by radical bromination of the 10,11-dihydro compound, on heating under pressure with ammonia undergoes dehydrobromination and amidation to yield Carbamazepine (42).122... 

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