Organozinc reagents, Negishi cross-coupling reactions

In the frame of a medicinal chemistry program at Merck Sharp Dohme Ltd, Collins and co-workers reported successful Negishi cross-coupling reaction of 3-aryl-7-bromo-6-[( 1 -methyl-1/7-1,2,4-triazol-5-yl)methoxy][ 1,2,4]triazolo[4,3-/ pyridazines (63) with aliphatic organozinc reagents [35]. 

Organozinc compounds have been extremely useful reagents in the Negishi cross-coupling reactions with alkyl and aryl halides creating a new C—C bond (Scheme 13.28). The Negishi Ni, Pd, or Fe mediated cross-coupling reactions have proved to be powerful tools in vast areas of synthesis. 

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... 

In addition to organozinc, -silyl, -magnesium, and -borane reagents employed respectively in Negishi, Hiyama, Kumada, and Suzuki cross-coupling reactions with various electrophiles, organozirconium reagents were... 

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