Transition metal catalyzed asymmetric oxidation of sulfides

In the past two decades, chiral sulfoxides have been finding increasing use, reflecting growing interest both in convenient auxiliaries in asymmetric synthesis and products with biological properties containing a chiral sulfinyl group. In 1984, groups of Kagan and Modena discovered that titanium(IV) isopropoxide - diethyltartrate based systems (also known as modified Katsuki-Sharpless reagents) are capable of asymmetric oxidizing of prochiral sulfides by alkylhydroperoxides. Later, catalytic versions of the titanium tartrate systems were developed (with up to 90 % yield and 90 % ee for certain sulfides) that remain the most applied systems for asymmetric sulfoxidations. However, the low turnover numbers (5-20), complexity and expensiveness of such systems stimulated the search for other transition metal based catalytic systems. This review will cover the progress in transition metal catalyzed asymmetric sulfides oxidations achieved since the discoveries of early 1980s to the present days.