Halides palladium-catalyzed reactions with organozinc

Sample Solution (a) Palladium-catalyzed reactions of organozinc compounds with alkenyl halides give cross-coupling in which bond formation occurs between the carbon attached to zinc and the carbon attached to the halogen. The stereochemistry at the double bond of the iodoalkene is retained. The product is (f)-6-methyl-l,5-decadiene. 

Organozinc compounds are also useful in palladium-catalyzed coupling with aryl and alkenyl halides. Procedures for arylzinc,156 alkenylzinc,157 and alkylzinc158 reagents have been developed. The ferrocenyldiphosphine dppf has been found to be an especially good Pd ligand for these reactions.159... 

The Negishi cross-coupling reaction is the nickel- or palladium-catalyzed coupling of organozinc compounds with various halides or triflates (aryl, alkenyl, alkynyl,... 

The past decade has seen extensive development of cross-coupling reactions of organozinc compounds and organic halides catalyzed by nickel or palladium catalysts. Although nickel-based catalysts are more reactive with respect to the organic halide partner, the number of failures with these catalysts and the greater selectivity realized with palladium-based catalysts have resulted in the almost exclusive use of the latter group of catalysts for these reactions. 

The Negishi palladium-catalyzed cross-coupling reaction of alkenyl, aryl, and alkynyl halides with unsaturated organozinc reagents provides a versatile method for preparing stereodefined arylalkenes, arylalkynes, conjugated dienes, and conjugated... 

Reaction of the lithiocyclopropene 1 with 0.5 mole equivalent of zinc(II) chloride gave a solution of the organozinc species 2 which was stable even at ambient temperature. This underwent efficient palladium-catalyzed coupling to aryl and vinyl halides giving 1-alkyl- or 1-arylcyclo-propenes 3. ... 

Palladium-catalyzed coupling reactions of organozinc compounds with acyl halides are the fastest and mildest among the known methods using a variety of organometallic compounds. 

Palladium-catalyzed cross-coupling reaction of organozinc reagents with organic halides, triflates, etc. For the catalytic cycle, see the Kumada coupling on page 234. 

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