The preparation and chemistry of active copper, nickel, and zinc

Highly reactive copper was prepared by the lithium naphthalide reductions of various copper(I) salt/ligand complexes. In particular, the reductions of copper(I) halide/phosphine complexes resulted in the production of active copper which reacted with a variety of organic halides to form highly functionalized, stable organocopper species. The nature and reactivity of the active copper was found to be highly dependent upon the choice of copper(I) salt and particularly upon the choice of ligand (phosphine). Organocopper species containing ester, nitrile, chloride, and even remote ketone and epoxide groups were prepared directly from the corresponding organic iodides or bromides. These highly functionalized copper reagents were utilized in a variety of reactions including conjugate additions to unsaturated carbonyl systems, epoxide-opening reactions, reactions with acid chlorides to form ketones, and cross-coupling reactions with other organic halides. Additionally, the copper was used to effect homocoupling of various organic halides under very mild conditions. Active nickel was used effectively for the room temperature generation of o-xylylene intermediates from the corresponding $\alpha$,$\alpha\sp\prime$-dihalo-o-xylene species. These highly reactive intermediates were efficiently trapped in situ with electron-deficient olefins, yielding substituted 1,2,3,4-tetrahydronaphthalene cycloadducts in moderate to good yields. Isoindene and 2,3-dihydronaphthalene intermediates were generated and trapped in an analogous fashion to give the one- or two-carbon bridged cycloadducts, respectively. Active zinc was used for preparing organozinc halide species directly from organic halides. The organic halides could contain considerable functionality such as ester, nitrile, and chloride groups. The organozinc halides were prepared readily from organic iodides and even bromides at room temperature. Significantly, functionalized arylzinc halides were prepared directly from the corresponding aryl halides. The organozinc halides underwent facile transmetallation with copper(I) cyanide complexes, generating highly functionalized cuprate species. These cuprates were found to be effective for conjugate additions to unsaturated carbonyl compounds, and for the formation of ketones from the coupling reaction with acid chlorides