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

ORGN 75

Narayan G. Bhat and Nisha Varghese. Chemistry, University of Texas-Pan American, 1201 West University Drive, Edinburg, TX 78541
A convenient, novel synthesis of (E)-gem-dimetalloakenes containing boron and tin based on the Z-1-bromo-1-alkenylboronate esters is developed. Alpha-bromo-(Z)-1-alkenylboronate esters readily available from literature procedures smoothly undergo a reaction with freshly generated trimethylstannyllithium in hexamethylphosphoramide (HMPA) at -78°C to provide the corresponding tetra coordinated boron complexes. These boron complexes undergo intramolecular nucleophilic substitution reaction to provide the corresponding (E)-1-alkenylboronate esters containing trimethylstannyl moiety. These intermediates are isolated in good yields (70%-82%) and are characterized by the spectral data (PMR and CMR).