Hydrophobically directed selective reduction of ketones using amine boranes

Amine boranes bearing hydrophobic substituents were used to reduce aryl ketones in competition with a methyl ketone in a study of hydrophobically directed selective reductions. Several characteristics of the reducing agent were found to be important in determining the reaction selectivity, including available hydrocarbon surface area, degree of fluorination, and proximity of the hydrophobic group to the active hydrides.