Lead compounds halide-coordinated products

Excellent yields can be obtained when the mixture of RC=CLi and the epoxide in ammonia is allowed to stand for 12 to 24 hours [2]. With sodium acetylides, there is some risk of subsequent attack of the acetylenic alcoholate on the epoxide, especially when the latter compound is used in excess. The reaction of acetylenic magnesium halides, RCsCMgX, with epoxides also leads to homopropargylic alcohols, but this is generally not recommended as a satisfactory method, as impure products are often obtained [62], Coordination of the epoxide-oxygen atom with the Lewis acid may give rise to a Sjql-like attack of RCaC on... 

The 1,2-insertion of alkenes into transition metal-carbon o-bond leads to C-C bond formation under mild conditions, as described in Chapter 6. This reaction is considered to be a crucial step in the coordination polymerization and carbometalation of alkenes catalyzed by transition metal complexes. A common and important carbometalation is the Heck-type arylation or vinylation of alkene catalyzed by Pd complexes [118], The arylation of alkene, most typically, involves the formation of arylpalladium species and insertion of alkene into the Pd-aryl bond as shown in Scheme 5.20. The arylpalladium species is formed by the oxidative addition of aryl halides to Pd(0) complexes or the transmetalation of aryl compounds of main group metals with Pd(II) complexes. Insertion of alkene into the Pd-aryl bond produces 2-arylalkylpalladium species whose y6-hydrogen elimination leads to the arylalkene. Oxidative chlorination of the 2-arylalkylpalladium intermediate forms chloroalkanes as the product. 

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