Halides, aryl, arylation alkyl groups

The organocopper compounds react mainly with halides and they also react with aryl compounds, acetals, tosylates (R-0S02-C6H4CH3(-/7)) and tolyflates (R-OSO2CF3). The reactions with halides are first order to each of the concentrations and they are Sn2 reactions. The order of reactivity of alkyl halides regarding the alkyl group is as follows ... 

Indoles with carbocyclic halogen or triflate substituents are potential starting materials for vinylation, arylation and acylation via palladium-catalysed pro-cesses[l]. Indolylstannanes. indolylzinc halides and indolylboronic acids are also potential reactants. The principal type of substitution which is excluded from such coupling reactions is alkylation, since saturated alkyl groups tend to give elimination products in Pd-catalysed processes. 

Preparation of alkanes using lithium di alkylcuprates (Section 14 11) Two alkyl groups may be coupled together to form an alkane by the reaction of an alkyl hal ide with a lithium dialkylcuprate Both alkyl groups must be primary (or meth yl) Aryl and vinyl halides may be used in place of alkyl halides... 

Alkylation reactions are subject to the same constraints that affect all Sn2 reactions (Section 11.3). Thus, the leaving group X in the alkylating agent R—X can be chloride, bromide, iodide, or tosylate. The alkyl group R should be primary or methyl, and preferably should be allylic or benzylic. Secondary halides react poorly, and tertiary halides don t react at all because a competing E2 elimination of HX occurs instead. Vinylic and aryl halides are also unreactive because backside approach is sterically prevented. 

The position of the equilibrium depends upon the solvent and the identity of the specific organic group, but in ether lies well to the left for simple aryl-, alkyl-, and alkenylmagnesium halides.21 Solutions of organomagnesium compounds in diethyl ether contain aggregated species.22 Dimers predominate in ether solutions of alkylmagnesium chlorides. 

Alkyl substituents on boron in 9-BBN derivatives can be coupled with either vinyl or aryl halides through Pd catalysts.22413 This is an especially interesting reaction because of its ability to effect coupling of saturated alkyl groups. Palladium-catalyzed couplings of alkyl groups by most other methods often fail because of the tendency for (3-elimination... 

Coupling of aryl or alkenyl halides with trialkylboranes.1 This reaction can be carried out in refluxing THF with a base (NaOH or NaOCH3,1 equiv.) catalyzed by PdCl2(dppf). A B-alkyl-9-BBN is more useful than a trialkylborane, since only one alkyl group is utilized. 

The catalyst component consists of halides of IV-VIII group elements having transition valence and the cocatalysts are organometallic compounds like alkyls, aryls and hydrides of group I-IV metals. Although there are hundreds of such catalyst cocatalyst systems listed in table below. Systems based on the organoaluminium compounds such as triethyl aluminium (AlEt3) or diethyl aluminium chloride... 

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