Preparation and reaction of triorganozincates

A novel approach to allenylzinc reagents, reported by Oku and coworkers, employs propargylic mesylates as starting materials12. Treatment with triorganozincates, prepared in situ by the reaction of dialkylzinc compounds with organolithium reagents, affords transient allenyl dialkylzinc intermediates. These intermediates were found to react with various... 

Lithium triorganozincates are best prepared by the reaction of an alkyllithium (3 equiv.) with zinc chloride or by the addition of an alkyllithium to a dialkylzinc in an ethereal solvent.304,3042-3043 Lithium and magnesium trialkylzinc-ates are more reactive compared to dialkylzincs or alkylzinc halides due to the excess of negative charge at the metallic zinc center, which confers a higher nucleophilicity to the organic substituents. 

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