CATALYTIC EFFECT OF 5-COORDINATE ORGANOTIN BROMIDE OR TETRAPHENYLSTIBONIUM BROMIDE ON THE CHEMOSELECTIVE AND STEREOSELECTIVE ADDITION OF TIN ENOLATE TO ALPHA-HALO KETONE

Two types of catalysts, five-coordinate organotin bromides and tetraph enylstibonium bromide, similarly promoted the selective addition of ti n enolates to the carbonyl moiety in ct-halo ketones. The reaction wit h 2-chlorocyclohexanones and the enolates gave chlorohydrins bearing c hloro- and hydroxyl groups in the cis-conformation. Chemoselective car bonyl addition to acyclic cu-halo ketones was followed by effective cy clization to 2-(2-oxoethyl)oxiranes. The structural and bonding analog y of both catalysts may be responsible for the similar catalytic activ ities which induced the chemo- and stereoselective addition.