Bromine azide addition reactions

Just as bromine chloride is a more reactive electrophile than iodine chloride so one would expect bromine azide acting as an electrophile to be more reactive than iodine azide. In fact in solvents suitable for heterolytic reaction, bromine azide adds to chalcone less readily than iodine azide ° and this further indicates an Adj mechanism. The evidence is strengthened by the occurrence of acid catalysis of the bromine azide addition. 

A better method for the preparation of the terminal isomers has resulted from the observations that bromine azide, unlike iodine azide, may be induced to add to olefins by a free-radical mechanism . Thus, when styrene was subjected to the addition of bromine azide in pentane a quantitative yield of the precursor 23 for the terminal azide was obtained, while reaction in a more polar solvent gave a very high yield of the opposite regioisomer 24. 

The chemistry of l-methyl-truns-cyclo-octene has been studied. In particular it reacts with acidic methanol to give 1-methoxy-l-methylcyclo-octane, with bromine to give a complex mixture, and with peracid to give its epoxide. On warming in acetic acid it is isomerized to 1-methyl-cis-cyclo-octene, and it reacts with diazomethane and phenyl azide to give cycloaddition products. With 4-phenyl-1,2,4-triazine-3,5-dione, the ene product (121) is obtained. The major difference in reactivity between trans-cyclo-octene and its 1-methyl analogue was found for electrophilic addition reactions where the stability of the incipient 3° cation made the 1-methyl compound more reactive.Transannular products were obtained from the reaction between trans-... 

Lifetimes of the ionic intermediates of nucleophilic substitution are generally correlated to the pathways followed under given reaction conditions. Information on the lifetimes of ionic intermediates formed by bromine addition to olefins in methanol, as determined by the azide clock method, do not allow the different reaction pathways to be distin-... 

Bromination of 1114 gave l-(3-bromo-2-oxopropyl)pyridazin-6-ones (1116) as a major product in addition to 1115 (91JHC385). Reaction of 1116 with sodium azide gave the corresponding l-(3-azido-2-oxopropyl)-pyridazin-6-ones 1117, which was reduced to 1118. 4,5-Dichloro-l-(2,3-dihydroxypropyl)pyridazin-6-one 1121 was also prepared from 1116 via 1119 and the corresponding 2,3-epoxypropyl derivative 1120 (91JHC1235). 

The research team of J. Tadanier prepared a series of C8-modified 3-deoxy-P-D-manno-2-octulosonic acid analogues as potential inhibitors of CMP-Kdo synthetase. One of the derivatives was prepared from a functionalized olefinic carbohydrate substrate by means of the Wohl-Ziegler bromination. The stereochemistry of the double bond was (Z), however, under the reaction conditions a cis-trans isomerization took place in addition to the bromination at the allylic position (no yield was reported for this step). It is worth noting that the authors did not use a radical initiator for this transformation, the reaction mixture was simply irradiated with a 150W flood lamp. Subsequently the allylic bromide was converted to an allylic azide, which was then subjected to the Staudinger reaction to obtain the corresponding allylic amine. 

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