Previously, reagents such as sodium borohydride-boron trifluoride were shown to be capable of reducing typical aliphatic esters and lactones to the corresponding ether derivatives. Under the same reaction conditions, a variety of benzoate esters (I b, II b, III, and V) were essentially unaffected. Resistance to attack was illustrated by conversion, with sodium borohydride-boron trifluoride, of 3-oxo-17β-benzoyloxy-5α-androstane (III) into 3β- ...
