Coupling of alkyl halides

Coupling of alkyl halides with Na, supplanted by the coupling ol alkyl halides or sulfonates with Gngnard reagents or RLi in the presence of CufI) salts... 

The coupling of alkyl halides 1 upon treatment with a metal, e.g. elemental sodium, to yield symmetrical alkanes 2, is called the Wurtz reaction. Aryl alkanes can be prepared by the Wurtz-Fittig reaction, i.e. the coupling of aryl halides with alkyl halides. 

Coupling of alkyl halides with groups I and II organometallic... 

Helvenston MC, CE Castro (1992) Nickel(l) octaethylisobacteriochlorin anion. An exceptional nucleophile. Reduction and coupling of alkyl halides by anionic and radical processes. A model for factor F-430. JAm Chem Soc 114 8490-8496. 

These results were significantly improved by the same authors using the well-defined pre-catalyst 16 (PEPPSl-lPr), that is able to promote the coupling of alkyl halides, aryl halides or alkyl sulphonates with alkylzinc chlorides or bromides [83,84]. 

This homologation of an oxime ether may have wider application for coupling of alkyl halides to other substrates such as acrylic esters (equation II). 

Tabk 1. Ni- or Co-catalyzed electroreductive coupling of alkyl halides... 

From the practical point of view //-hydride elimination might also be an obstacle. In reactions that involve metal-alkyl complexes as early intermediates one has to block //-elimination to increase the lifetime of the intermediate and enable subsequent transformations on the complex. A reaction, which proved elusive partially for this very reason, is the coupling of alkyl halides. A set of conditions, which allowed for the Negishi coupling of primary alkyl halides and even tosylates with alkyzinc halides is shown in Equation 1.5.20 The recent work of Fu and others showed that the careful... 

Coupling of Alkyl Halides. The Wurtz Reaction De-halogen-coupling... 

Reduction of the C—N bond 0-86 Coupling of alkyl halides (Wurtz) 0-87 Coupling of alkyl halides with or-ganometallic reagents 0-89 Reaction between organometallic reagents and alkyl sulfates or sulfonates... 

An alternative to produce H-H arranged PIB is the coupling via the Wurtz-Fittig reaction. This is the coupling of alkyl halides by the treatment with metallic sodium or other metals such as lithium and zinc. However, this type of reaction results in substantially branched polymers with a comparatively low molecular weight (19). 

From cross coupling of alkyl halides and related compounds with organome-tallic reagents Butyllithium, 56... 

Coupling of alkyl halides (cf. 8,111).1 (-Alkyl, benzylic, and allylic halides form symmetrical dimers in about 85-95% yield when treated with CrCI,.5 The dimerization involves monoalkylchromium(lll) complexes followed by a radical reaction. Crosscoupling of these same halides is also possible, but yields are lower (40-90%). 

Unsymmetrical ketones can be synthesized by the formal double alkylation of carbon monoxide [21] in which the three-component coupling of alkyl halides, carbon monoxide, and electron-deficient alkenes is carried out using tributyltin hydride as a radical chain mediator (Scheme 6.13) [22], The use of a slower radical mediator such as (TMS)3SiH [23] has subsequently proven to be superior to tribu-... 

Kumada-type couplings of alkyl halides 98 with aryl Grignard reagents 99 yielding alkylarenes 100 recently received much attention (see Part 2, Sects. 2.1 and 5.1, Part 3, Sect. 2.1). A vanadium-based method was developed by Oshima and coworkers (Fig. 30) [189]. Primary and secondary alkyl bromides, iodides, and also chlorides were coupled to phenylmagnesium bromide catalyzed by 10 mol%... 

Fig. 1 Iron-catalyzed cross-coupling of alkyl halides with organometallic compounds...

Leigh and coworkers developed in parallel a Ni-catalyzed reductive homocoupling of alkyl halides 93 toward an efficient synthesis of rotaxanes (Fig. 22) [122]. In model studies 5-12 mol% of the Ni(II) precatalyst and terpy 8a or (/LA i-Ph-PyBOX 5g sufficed for the coupling of alkyl halides under normal conditions, under which 78-99% of dimers 94 were obtained. A macrocyclic Ni(PyBOX) complex, which has to be present stoichiometrically due to its function as the wheel, serves as the precatalyst in the rotaxane synthesis. Initial reduction of... 

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