Grignard reagents copper halide-catalysed

Reactions of organomagnesium compounds with dialkyl sulfates or alkyl sulfonates often give satisfactory yields of the products of displacement of sulfate or sulfonate. Side-reactions have been observed, but they can often be avoided for example, an excess of the sulfate or sulfonate should be used with Grignard reagents, as some is consumed by nucleophilic attack by halide ion [A]. The dialkyl sulfates are reactive, but hazardous. Toluenesulfonates (tosylates) are less reactive, but their reactions are catalysed by copper complexes the reactions of trifluoromethanesulfonates (triflates) are catalysed by nickel complexes. Reactions of Grignard reagents with secondary tosylates appear to follow an Sn2 mechanism, with inversion of configuration [43],... 

CROSS-COUPLING REACTION OF ALKYL HALIDES WITH GRIGNARD REAGENTS IN THE PRESENCE OF 1,3-BUTADIENE CATALYSED BY NICKEL, PALLADIUM, OR COPPER... 

The Syj2 alkylation of acyclic allyl halides by a Grignard reagent catalysed by copper (I) thiophene carboxylate and a phosphoramidite ligand forms a 50 50 mixture of the (Z) and (E) allylic product in high yields (85 to >99%) with 74-94% ee The actual substitution is thought to be a stereospecific anti-Sf 2 mechanism on the Si enantiotopic face of the a- and/or jr-allyl-copper complex(es). 

Harutyunyan et al. investigated the formation of the chiral Cu(I)-diphosphine complexes, as part of a comprehensive mechanistic study on the Cu(I)-catalysed ACA of Grignard reagents to a,p-unsaturated carbonyl compounds [127]. Based on NMR, ESI-MS, IR, electrochemistry and X-ray ciystaUography measurements, they concluded that halide-bridged dinuclear copper complexes Cl (Scheme 30) are formed and persist in the solvents typically used for the ACA (Et20, tBuOMe and CH2CI2). 

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