Novel synthesis of (E)- gem-dimetalloalkenes containing boron and germanium

ORGN 131

Narayan G. Bhat, Chemistry, Chemistry, University of Texas-Pan American, 1201 West University Drive, Edinburg, TX 78541
A convenient, novel synthesis of (E)-gem-dimetalloakenes containing boron and germanium from the Z-1-bromo-1-alkenylboronate esters is developed. Alpha-bromo- (Z)-1-alkenylboronate esters readily prepared from the literature procedures smoothly undergo a reaction with freshly generated trimethylgermyllithium in hexamethylphosphoramide (HMPA) at -78oC to provide the corresponding tetracoordinated boron complexes. These tetracoordinated boron complexes undergo intramolecular nucleophilic substitution reaction to provide the corresponding (E)-1-alkenylboronate esters containing trimethylgermyl moiety. These intermediates are isolated in good yields (72%-81%) and are characterized by the spectral data (PMR and CMR).