Organocuprates, addition transmetallation

Heterocycles. A route to 2,3-disubstituted furans takes advantage of the Cu-Zn-transmetallation (with ZnCl2) from enolates derived from conjugate organocuprate addition to enones, and aldol reaction of zinc enolates to an alkoxyacetaldehyde. ... 

INT2, Scheme 10.7) undergoes further reaction (Li/Cu transmetalation) and generates a new organocuprate compound. (Note however that this difference could become more subtle since the product of conjugate addition (PD) might behave more like an a-cuprio(I) ketone complexed with a lithium cation [52] than a lithium enolate complexed with copper(I)). In neither reaction was any evidence of radical intermediates (i.e., SET) found by theoretical calculations [79]. 

The addition of functionalized copper-zinc species, obtained after a transmetallation step between an organozinc halide and an organocuprate, to 1-methylthioalkynes produces... 

Organocuprates add at the p position of a,p-unsaturated aldehydes, ketones, esters, and A,A-dialkylamides using trimethylchlorosilane as an activator [24]. The example shown in Equation 7.13 uses transmetallation of the initially formed organozinc to generate an organocuprate that contains an ester moiety. The enolate anion formed by addition to the P carbon is trapped with trimethylchlorosilane, which is then removed with tetrabutylammonium fluoride [25]. 

---