Triorganozincates

Scheme 2.43 Formation of allenes from propargyl mesylates and lithium triorganozincates.

Reaction of (Me3SiCH2)2Zn with an alkali (K) or alkali earth metal (Ba, Sr or Ca) in a suitable solvent affords the corresponding triorganozincates 12-16 (Scheme 2). 

Mixing a diorganozinc compound with an organometallic reagent in an appropriate solvent is another approach to the synthesis of triorganozincates (Scheme 3). 

FIGURE 14. Molecular geometries of the heteroleptic triorganozincate anions present in 28 and 29... 

FIGURE 15. Molecular geometry of the heteroleptic triorganozincate anion 31... 

Further applications of Negishi s cross-coupling reactions for the synthesis of new chiral ferrocenyl Ugands have been reported. Interestingly, cross-coupUng reactions can also be performed using triorganozincates, such as 454. Chloroenyne 455 reacts with various... 

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... 

Shortly after Negishi s original work, Oku and coworkers described reactions of triorganozincates with 1,1-dibromoalkenes 9, which gave different products upon protonolysis depending on the reaction temperature (equations 4 and 5)3. 

TABLE 1. Reactions of 1,1-dibromoalkenes with triorganozincates (equation 5)... 

Following the report on reactions of 1,1-dibromoalkenes 9 with triorganozincates, the same group reported reactions of 1,1-dibromocyclopropanes 14 (equation if. 

Triorganozincates are prepared by the reaction of diorganozincs with organolithium... 

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