Halogen-metal interconversion

Many organic halides do not react satisfactorily with lithium to form RLi ecMnpounds or with metallic magnesium to form Grignard reagents. The desired organolithium compound can often be prepared by a halogen-metal interconversion reaction ... 

Halogen-metal interconversion between bromothiophenes and n-butyllithium, leading to thienyllithium derivatives and n-butyl bromide, occurs almost instantaneously and in very high yield even at... 

When the bromothiophenes and n-butyllithium are reacted at room temperature, halogen-metal interconversion and metalation occur concurrently to different degrees, and mixtures are obtained. ... 

Thiophenedithiol (170) has been prepared by halogen-metal interconversion between the lithium salt of 4-bromo-3-thiophenethiol and n-butyllithium at —70°C, followed by reaction with sulfur/ IR, NMR, and UV spectra showed that this compound exists in the dithiol form (170). The compound obtained as a by-product in the... 

Some unexpected reactions are observed during the interaction of cyclo-hepta[c]thien-6-one (231) or its 1,3-dibromo derivative and organometallic compounds (74YZ1429) These reactions are halogen-metal interconversion and subsequent dimerization, partial debromination, and simultaneous 1,2- and 1,4-addition of phenyllithium onto tropone 231 to yield tropylium salts 232 and 233, respectively (Scheme 56). 

Bromo- and iodoarenes are the oldest and most typical substrates for permutational halogen/metal interconversions. Butyllithium is routinely used for this purpose (Table 16). Hetero-substituents such as dialkylamino or bis(trialkylsilyl)amino, cyano or nitro (Table 17), alkoxy and 2-tetrahydropyranyloxy (Table 18), lithiooxy or lithiooxycarbonyl (Table 19) and fluoro or trifluoromethyl (Table 20) and chloro, bromo or iodo (Table 21) are well tolerated. 

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