Asymmetric sulfoxidation of thioethers with hydrogen peroxide in water mediated by platinum chiral catalyst

Easy stereoselective oxidation of prochiral aryl alkyl sulfides 2 to the corresponding sulfoxides can be achieved in water-surfactant medium with inexpensive hydrogen peroxide mediated by the chiral platinum diphosphine complex {[(R)-BINAP]Pt(mu-OH)}(2)(BF4)(2) (1). Remarkable key features of general interest are (i) easy isolation of the products from catalyst by simple diethyl ether/water-surfactant two phase separation, (ii) catalyst loading as low as 1% mol, (iii) good yields, sulfoxide 3 to sulfone 4 ratio up to 200:1 and enantioselectivities up to 88%, (iv) mild experimental conditions.