Brominations alkynes, copper bromide

Bromination of Alkenes and Alkynes. Heating copper(II) bromide in methanol with compounds containing nonaromatic carbon-carbon multiple bonds leads to di- or tribromination. For example, under these conditions allyl alcohol is converted to 1,2-dibromo-3-hydroxypropane in 99% yield (eq 7), while propar-gyl alcohol produces a mixture of trans di- and tribromoallyl... 

For bromination, this chemistry has been developed using copper bromide in acetonitrile [217], Preparation of the iodinated version was trivial and entailed simply stirring the alkyne with elemental iodine [219]. It should be noted that treating an alkynyl bromide with KI and acetie anhydride afforded the Z-l-iodo-2-hromoalkene [220]... 

Scheme 203 provides a methodology for the conversion of aryl bromides onto 4-aryl-l,2,3-triazoles. In the given example, palladium-copper catalyzed substitution of the bromine atom in indole 1226 by trimethylsilylacetylene provides intermediate 1227. Hydrolysis of the trimethylsilyl protecting group releases terminal alkyne 1228, isolated... 

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