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Two new methods of preparation of functionalized diorganomercurials have been developed. The first method involves a substitution reaction of (ICH,),Hg with zinc-copper reagents FG-RCu(CN)ZnI in THF/DMF at-60°C. Functional groups such as an ester, nitrile, ketone, phosphonate, halide, and boronic ester are tolerated in this reaction. The second method involves a reductive transmetallation between poly-functional organozinc halides and mercurous chloride (Hg,CI,). This very convenient procedure provides a rapid route to various functionalized diorganomercurials in good yields (61-89% yield). The synthetic utility of these mercury organometallics is demonstrated. Their transmetallation with zinc dust (toluene, 8o"C, 3-5 h) affords dialkylzincs which add enantioselectively to aldehydes in the presence of a catalytic amount 120 mol%) of the norephedrine derivative 13. This transmetallation can also be used to prepare stereoselectively (E)-alkenylzinc halides (> 98% El. Addition of CI(H)ZrCp, to (E)-S-chloropentenylzinc bromide in CH,Cl, (2S"C, 1 min) affords a l,l-bimetallic of zinc and zirconium CI(CH,),CH(ZnBr)ZrCp,(CI) which reacts stereoselectively with an aldehyde providing the (Ebdisubstituted olefin (49% yield; 100% El.

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