Alkenyl halides with Grignard reagents

Oxidative addition of the carbon-halogen bond is a well-documented reaction for Group 10 transition metal complexes, but it is relatively limited for ruthenium. The example given here involves the reversible oxidative addition of allyl halide to RuCp(CO)2X to produce RuCp(p -allyl)X2 [78]. Oxidative addition of allyl halide to a Ru(0) complex Ru(l,5-COD)(l,3,5-COT) is also reported, but the product yield was poor [79]. Nevertheless, a catalytic Heck-type alkenylation of bromostyrene with methyl acrylate by Ru(l,5-COD)(l,3,5-COT) proceeded smoothly [80]. A cross-coupling reaction of alkenyl halide with Grignard reagents or alkyl lithium also pro-... 

Tetrakis(triphenylphosphine)palladium catalyzes coupling of alkenyl halides with Grignard reagents and organolithium reagents. 

B. Iron Catalysis in the Cross Coupling of Alkenyl Halides and Grignard Reagents Grignard reagents are cross coupled stereospecifically with alkenyl halides such as 1-bromopropene in the presence of catalytic amounts of iron complexes.(27)... 

In the mid-1970s it was discovered that phosphine-Ni complexes (e.g., (Ph3P)2NiCl2) catalyzed the substitution of aryl halides with Grignard reagents at room temperature. The Ni catalysts were mostly phosphine complexes of NiCla. Alkyl (1°, 2°, or 3°), aryl, or alkenyl Grignard reagents could be used. 

In 2002, Furstner and coworkers reported that aryl halides react with Grignard reagents under the conditions previously used for the coupling of alkenyl halides. They proposed that the active iron species is Fe(MgX)2, a complex described by Bogdanovic and coworkers ° a few years earlier (Scheme 30). This iron(-II) species is formed by addition of four equivalents of the Grignard compounds to FeCl2. 

Alkenylation. Grignard reagents or organozinc halides couple with alkenyl halides with Co(acac)2 as catalyst. The configuration of the double bond is retained. 

Urushiol analogues with Ci8 alkenyl side chains have been synthesised from 3-bromobenzene and 2,3-acetonylidenebromobenzene by cross coupling with Grignard reagents derived from Cig unsaturated halides [217,243],... 

Alkenyl halides couple readily with Grignard reagents in the presence of iron. -E n-Hexylmagnesium bromide allowed to react at 0° with vinyl bromide in tetrahydrofuran in the presence of FeClg 1-octene. Y 83%. F. e. s. M. Tamura and J. Kochi, Am. Soc. 93, 1487 (1971) also coupling with satd. halides in the presence of Ag - and Cu -catalysts s. Synthesis 1971, 303. 

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