Requirements for Selective Hydrophobic Acceleration in the Reduction of Ketones

Reductions of various quaternized hydrophobic beta-keto amines were performed in water and in methanol using borohydride anions carrying hydrophobic groups. The most important requirement of the substrate to permit hydrophobically accelerated selective reductions is the ability of the hydrophobic group of the substrate and its attached keto group to attain a coplanar relationship. Some derivatives of naturally occurring steroid diones have also been employed as substrates to probe the mechanism and utility of these hydrophobically accelerated selective reductions further.