Journal of the American Chemical Society, Vol.120, No.20, 4934-4946, 1998
New formulas for organozincate chemistry
As a new type of zincate, we designed various new organozinc derivatives, Me3Zn(R)Li-2 (R = Me, CN, SCN), which could be prepared in situ from lithium trimethylzincate and anion species such as methyllithium, lithium cyanide, and lithium thiocyanate. We investigated the reactivities of these zincates toward the halogen (or tellurium)-zinc exchange, Michael addition, carbozincation, and epoxide ring opening reactions. On the basis of their excellent chemical yields and chemoselectivities, these species were considered to be differentiated from ordinary triorganozincates, R3ZnLi. We also discuss the structure of the newly designed zincates using H-1 NMR/Raman/in situ FTIR-extended X-ray absorption fine structure (EXAFS) spectroscopic and the density-functional theory (DFT) theoretical studies. All results strongly support the fact that these newly designed zincates are a new category of zincate species. This observation is also identical with the fact that newly designed zincates have a higher and unique reactivity compared to the conventional triorganozincates.
Keywords:METAL-HALOGEN EXCHANGE;HIGHER-ORDER;STRUCTURAL CHARACTERIZATION;OXIDATIVE ADDITION;CYANO LIGAND;ACTIVE ZINC;LITHIUM;REAGENTS;COMPLEXES;DERIVATIVES