Catalytic asymmetric oxidation of sulfides to sulfoxides using (R)-6,6$$^{\prime }$$-Diphenyl-BINOL as a chiral ligand

Abstract

The chiral metal complex produced in situ from (R)-6,6 $$^{\prime }$$ -Diphenyl-BINOL and $$\mathrm{Ti}(\mathrm{O}-{} { i}-\mathrm{Pr})_{4}$$ as a catalytic system for asymmetric sulfoxidation of aryl methyl and aryl benzyl sulfides in the presence of 70% aqueous TBHP as the oxidant has been investigated. The influence of variation of reagents mole ratios, temperature, solvent and oxidant was examined, and the optimized conditions were then used to oxidize a number of aryl methyl and aryl benzyl sulfides, producing sulfoxides in high enantiopurities (up to 90% ee) and good yields (up to 81%). (R)-6,6’-Diphenyl Binol in combination with $$\hbox {Ti(O-i-Pr)}_{4}$$ has been developed as an efficient chiral ligand for the asymmetric oxidation of aryl methyl and aryl benzyl sulfides by using 70% aqueous TBHP as an oxidant. High enantioselectivity and good chemical yield have been achieved for various aryl methyl and aryl benzyl sulfides.