Organozinc reagents, allylic synthesis

The total synthesis of fluvirucinine A1 127 provides a powerful illustration of the utility of Fu s methodology in natural product synthesis (Scheme 13.34). The asymmetric Negishi reaction of racemic allylic chloride 122 with alkylzinc bromide 123 in the presence of Ni/Pybox catalyst system provided ester 124 in 93% yield and 96% ee. After few steps, the organozinc reagent of bromide 125 was subjected to a second Negishi reaction with chloride 122 under identical coupling conditions to furnish derivative 126 in 80% yield and excellent enantioselectivity. 

Organocopper reagents prepared from the more readily available organozincs have found much use in the synthesis of highly functionalized molecules. For example, Ni-catalyzed hydrozincation of allylic alcohols initiates the preparation of a-(4-hydroxyalkyl)acrylates when the cuprate intermediates are used in the coupling with the a-bromomethylacrylic esters." ... 

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