Organozinc reagents functionalized

In the presence of Lil, TMS-C1, and a catalytic amount of (CH3)2CuCNLi2, conjugate addition of functionalized organozinc reagents occurs in good yield. 

Inspired by the well-established nickel-catalyzed co-oligomerization of 1,3-dienes with CO2, which proceeds via bis-TT-allyl intermediate, Mori has developed a powerful intramolecular version of this process (Scheme 103). After insertion of C02 into the bis-vr-allyl complex, a transmetallation with an organozinc reagent takes place to generate the Ni(0) catalyst. Highly functionalized carbo- and heterocyclic compounds with complete stereocontrol can372 be synthesized by this method. 

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. 

Evans et al. prepared organozinc reagent 16 from quantitative metalation of iodide 15 by using an activated Zn/Cu couple in the presence of an ester functionality. Treating 2-iodoimidazole 17 with three equivalents of 16 in the presence of PdCl2(Ph3P)2 afforded adduct 18, which was then transformed into diphthine (19) in five additional steps [17]. 

The related zinc cuprates formed from diorganozinc reagents and copper(I) cyanide also undergo smooth SN2 substitution reactions with propargyl oxiranes in the presence of phosphines or phosphites (Scheme 2.12). These transformations can also be performed with catalytic amounts of the copper salt since no direct reaction between the organozinc reagent and the substrate interferes [31, 34], and therefore should also be applicable to functionalized organozinc compounds. 

Copper-Catalyzed Conjugate Addition of Functionalized Organozinc Reagents to a,p-Unsaturated Ketones Preparation of Ethyl 5-(3-Oxocyclohexyljpentanoate. 

Trcmsmetalation of Functionalized Organozinc Reagents 63, NHBoc 1.CuCN-2LiCI... 

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

Scheme 7.7. Alkenes as starting materials in 1,4-additions involving (functionalized) organozinc reagents.

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