The asymmetric oxidation of prochiral 2-(arylsulfenyl)pyrroles has been investigated. A marked electronic effect within the substrate significantly influenced the degree of enantioselectivity obtained, with very high enantio selectivity being obtained for 5-(nitrobenzensulfenyl)pyrrole-2-carboxaldehydes using Ti(i-PrO)4/(+)-(R,R)-DET/H2O/CHP. This result bodes well for optimizing the asymmetric oxidation of other diaryl sulfides, substrates that have previously given only low enantiomeric excesses.Key words: asymmetric oxidation, sulfide, sulfoxide, pyrrole.
研究了手性 2-(芳基亚磺酰基)吡咯的不对称氧化。底物中明显的电子效应极大地影响了所获得的对映体选择性,使用 Ti(i-PrO)4/(+)-(R,R)-DET/H2O/CHP 对 5-(硝基苯磺酰基)吡咯-2-甲醛获得了极高的对映体选择性。这一结果预示着可以优化其他二芳基硫化物的不对称氧化,这些底物以前只给出较低的对映体过量。