Halogen-metal interconversion reactions

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 ... 

Halocyclopropanes, reactions of, 13, 2 Halogen-metal interconversion reactions,... 

R. G. Jones, H. Gilman, The Halogen-Metal Interconversion Reaction with Organolithium Compounds, ... 

The halogen-metal interconversion reaction with organolithium compounds... 

The Halogen-Metal Interconversion Reaction with Organolithium Compounds ... 

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). 

Halogen-Metal Interconversions with Halo-geneted Anilines. A highly explosive compound which appears to be p-N,N-Trilithioani-line is formed as a by-product in the reaction of BuLi and p-Br-aniline but not o-Br-aniline (Ref 1). More recently this reaction was repeated but no by-product is mentioned (Ref... 

Halogen-metal interconversion between bromothiophenes and n -butyllithium occurs almost instantaneously and in very high yield. The reaction with 3-bromothiophene is usually carried out at -70 °C to avoid any (rans-lithiation. When bromine-lithium exchange takes place, steric crowding in the molecule decreases. As a consequence the percentage of 2-lithio derivative in relation to the 5-lithio isomer formed from 3-alkyl-2,5-... 

Halogen-metal interconversion sometimes occurs prior to the coupling reaction. " Thus, phenyllithium and benzyl bromide react to give bromo-benzene and bibenzyl rather than diphenylmethane. ... 

In this section, we will rather focus, on one hand, on the recent successful work on the discovery or development of transformations considered thus far as side reactions or inefficient processes and, on the other hand, on the preparation of biaryls by coupling of an aryllithium or arylmagnesium and an aryne, especially the so-called ARYNE coupling, which involves 3 successive halogen/metal interconversions in one step. 

The halogen-metal exchange or interconversion reaction was independently discovered by us and by G. Wittig. In one of our initial reactions we observed that o-bromoanisole reacted with n-butyllithium to yield o-anisyllithium and -butyI bromide. 

---