Halides dimetallic

Bidentate boranes with an o-phenylene backbone constitute some of the simplest examples of polydentate Lewis acids with rigid backbones. They can be prepared by the reaction of boron halides with a 1,2-dimetallated benzene derivative. Thus, the reaction of 1,2-bis(chloromercurio)benzene (5) with boron trichloride affords 1,2-bis(dichloroboryl)benzene (6, Scheme 3). ... 

Three transmetallation reactions are known. The reaction starts by the oxidative addition of halides to transition metal complexes to form 206. (In this scheme, all ligands are omitted.) (i) The C—C bonds 208 are formed by transmetallation of 206 with 207 and reductive elimination. Mainly Pd and Ni complexes are used as efficient catalysts. Aryl aryl, aryl alkenyl, alkenyl-alkenyl bonds, and some alkenyl alkyl and aryl-alkyl bonds, are formed by the cross-coupling, (ii) Metal hydrides 209 are another partner of the transmetallation, and hydrogenolysis of halides occurs to give 210. This reaction is discussed in Section 3.8. (iii) C—M bonds 212 are formed by the reaction of dimetallic compounds 211 with 206. These reactions are summarized in Schemes 3.3-3.6. 

Palladium-catalysed reactions of dimetallic compounds 358 such as X2B—BX2, R3Sn—SnR3, R3S11—SiR3 or R3Si—SiR3 with halides via oxidative addition and transmetallation are useful for the preparation of carbon main group metal bonds 359. 

The alkenylindium compounds, obtained by the addition of benzyl- and allylindium to alkynes, couple with organic halides in the presence of a palladium catalyst to give the three-component coupling products (Scheme 99).286 1,3-Dibromopropene or 3-bromo-l-iodopropene reacts with indium to give diindiopropene 87a,b.147,148 This dimetallic reagent reacts with two different electrophiles successively carbonyl compounds and imines are allowed to react with 87 as the first electrophile to give vinylic indium intermediates 88, which react with... 

This method has also been a general method for the synthesis of triorganoantimony and -bismuth compounds. The antimony or bismuth anion (RjM", M = Sb, Bi) reacts with organic halides, which can be either aryl halides such as 18 in equation 21 , or alkyl halides (equations 22 and 23 ), Dimetallated triorganometallic compounds such as 19 which are useful as ligands for transition metals are available from this method (equation 24). ... 

Bertini, F., Grasselli, P., Zubiani, G., Cainelli, G. Geminal dimetallic compounds. Reactivity of methylene magnesium halides and related compounds. General carbonyl olefination reaction. Tetrahedron 9 0, 26,1281-1290. 

The yield and ratio of the two Stevens rearrangement products are dependent on both the base and the solvent however, the ortho-rearrangement product was only detected when butyllithium was used in hexane. Variation of the halide ion had only a small effect on the ratio of rearrangement products. Several mechanisms were considered 93) as routes to the formation of the rearrangement products, 1) ion-pairs, 2) cationic rearrangement, 3) carbenoid, 4) dimetallated intermediates, 5) free-radical, 6) predissociation of the ammonium salt and, 7) sigmatropic shift. 

Other mixed g e/H-dimetallic compounds containing zinc and either zirconium, aluminum, or titanium have been successfully prepared from alkynylzinc halide compounds via hydrozirconation by H(Cl)ZrCp2 (the Schwartz s reagent) or carbometalation by a combination of Me3Al/Cp2TiCl2 (Scheme 15). 

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