The effect of nitrogen atoms in the enantioselective oxidation of aryl or heteroaryl benzyl sulfides

Some aminophenyl benzyl sulfides or benzyl pyridyl sulfides were asymmetrically oxidized with tert-butyl hydroperoxide in the presence of a complex between titanium i-propoxide and (S, S)-hydrobenzoin, an oxidation system that works particularly well with a vast set of aryl benzyl sulfides. Notwithstanding the presence of nitrogen-containing moieties that, in principle, could interfere with the correct co-ordination of the sulfide to the metal center, satisfactory levels of enantioselectivity (up to 78%) were measured for this oxidation process.