Halides, alkenyl Grignard reagents

Reaction of fluorinated alkenyl Grignard reagents or lithium reagents with organotin halides has been utilized for the preparation of fluorinated alkenyl tin reagents [111, 182-184]. Recently, a novel, general and convenient method has been developed for the preparation of a variety of fluorinated alkenylstannanes... 

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)... 

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-... 

Pd- or Ni-catalyzed Kumada cross-coupling Cross-coupling of alkenyl- or aryl halides and Grignard reagents or organolithium species. 258... 

Tamao, K., Sumitani, K., Kiso, Y., Zembayashi, M., Fujioka, A., Kodama, S., Nakajima, I., Minato, A., Kumada, M. Nickel-phosphine complex-catalyzed Grignard coupling. I. Cross-coupling of alkyl, aryl, and alkenyl Grignard reagents with aryl and alkenyl halides general scope and limitations. Bull. Chem. Soc. Jpn. 1976, 49, 1958-1969. 

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

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. 

Cross coupling of alkenyl halides and Grignard reagents. This iron(III) complex is more effective than ferric chloride from the standpoint of both rate and deactivation of the catalyst. The active catalyst is actually a reduced iron(I) species. 

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

In Summary Alkenyl halides are unreactive in nucleophilic substitutions. However, they can participate in carbon-carbon bond-forming reactions after conversion to alkenyllithium or alkenyl Grignard reagents, or in the presence of transition-metal catalysts such as Ni and Pd. 

Cross-coupling between alkyl halides and alkenyl Grignard reagents has also been succeeded using iron catalysis. Catalytically active systems are tris(acetylacetonato)iron with TMEDA and hexamethylenetetramine (HMTAy or iron(IIl) chloride as a precatalyst in combination with TMEDA as a ligand (Scheme 4—233). ... 

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