Grignard reagents zirconium compounds

Addition of the Grignard reagent to the carbon-carbon double bond requires severe reaction conditions.508 513 Zirconium-based compounds, in contrast, catalyze carbomagnesation of 1-alkenes to occur selectively under mild conditions. [NiCl2(PPh3)2] is the best catalyst to promote syn addition to disubstituted acetylenes, although usually in low yields 514... 

In the addition reaction of Grignard reagents to a carbon-carbon unsaturated bond, the yields and selectivities become higher by using transition metal catalysts, and so these reactions came to public notice. Metal compounds of Ti, Ni, Cu and Zr are used for the catalysts [55,56,99]. For example, the adduct is obtained in a high yield by a carbometalation reaction with zirconium catalysts as shown in eq. (4.36) [100]. On the other hand, cyclization proceeds in a high yield by using a diene as shown in eq. (4.37) [101]. 

Whilst Grignard and organolithium reagents are most widely employed, they are by no means exclusive. Organo-zirconium, silicon, tin, copper, zinc, cadmium, and mercury compounds have... 

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