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48.1.2.2.4 Variation 4: Couplings of Other Alkyl Organometallic Compounds

DOI: 10.1055/sos-SD-048-00012

Kantchev, E. A. B.; Organ, M. G.Science of Synthesis, (20094876.

Alkylalkyl couplings of organometallic derivatives other than those described in Sections 48.1.2.2.148.1.2.2.3 are almost unknown. An early study has shown that 1-iododecane does not couple with tetrabutylstannane or butylmercury(II) chloride (<8% yield) with either tetrakis(triphenylphosphine)palladium(0) or [1,2-bis(diphenylphosphino)ferrocene]dichloropalladium(II) in dioxane at 60°C.[‌64‌] The coupling of alkylmanganese reagents prepared from the corresponding alkyl Grignard species and lithium tetrachloromanganate(II) to give alkanes 47 has been investigated. The reaction is catalyzed by Kochi's catalyst, lithium tetrachlorocuprate(II), and takes place in tetrahydrofuran/1-methylpyrrolidin-2-one at room temperature (Scheme 16).[‌98‌] The reaction is suitable for primary alkyl bromides, iodides, and sulfonates, but not for chlorides and secondary alkyl halides. On the other hand, primary, secondary, and tertiary alkylmanganese reagents all react in high yield. The manganese organometallic reagents are more chemoselective than the Grignard reagents and tolerate ketone and ester substituents in the alkyl halide coupling partner. Furthermore, 2-(acyloxy)ethyl bromides couple in high yields without elimination.

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