Organozinc reagents synthesis

E. Erdik, in Organozinc Reagents in Organic Synthesis, CRC Press, Boca Raton, 1996. 

Feringa and co-workers described the tandem addition-aldol cyclization protocol leading to the formation of 6,6-, 6,7-, and 6,8-annulated bicyclic systems (Scheme 68).39 Using Cu(n)-29 as catalyst and functionalized organozinc reagents as nucleophiles, the conjugate addition reaction followed by aldol cyclization can offer highly enantioselec-tive annulation products (up to 98% ee). This method can be used in the synthesis of carbocyclic compounds, such as steroids, terpenes, and other natural products. 

In a synthesis of polyketides, Kocienski crafted indole 78 from 2-iodo-l-methylindole and the appropriate organozinc reagent 77 derived from the corresponding stannane (76), which itself was reluctant to undergo a Stille coupling [106],... 

Scheme 2.42. Synthesis of 2-substituted indoles by acylation of functionalized organozinc reagents.

Tandem 1,4-addition to cycloalkenones constitutes an extremely versatile and elegant methodology for the synthesis of 2,3-disubstituted cycloalkanones, as is evident from its application in areas such as prostaglandin synthesis. Noyori et al. have reported the use of organozinc reagents in copper-catalyzed tandem additions [64]. The zinc enolate resulting from the catalytic enantioselective 1,4-addition of Et2Zn to cyclohexenone reacts readily with an aldehyde in a subsequent aldol condensation. 

In 1997, Dunn and Jackson reported on a new approach to the synthesis of di- and tripeptides with unnatural amino acids by converting di- and tripeptides into organozinc reagents and coupling them with aryl iodides or acyl chlorides in the presence of Pd2(dba)3 and either PPhs or P(o-tol)3 under mild reaction conditions, with no loss of optical purity. " The synthesis of jS- and y-amino acids in an analogous fashion was reported shortly after (Scheme 12). " ... 

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