Asymmetric oxidation of sulfides catalyzed by (R)-6,6'-dibromo-BINOL derived titanium complex

Abstract

An efficient asymmetric oxidation of sulfides was achieved using (R)-6,6'-dibromo-BINOL as chiral ligand in combination with Ti(OⁱPr)₄ using 70% aqueous tertiary butyl hydroperoxide as oxidant. The resulting sulfoxides had high enantiopurities and good yields. A range of aryl alkyl and aryl benzyl sulfides were oxidized to the corresponding sulfoxides with 78–95% ee in 72–80% yields.

Graphical Abstract

Keywords:

• (R)-6,6'-dibromo-BINOL
• chiral sulfoxides
• kinetic resolution
• asymmetric oxidation

Acknowledgments

The authors are thankful to the M/S Lupin Limited and the authorities of Manipal Academy of Higher Education for the research program. We also acknowledge the valuable guidance, support and suggestions from Dr. P. R. Upadhyay, Dr. Milind Sindkhedkar and Dr. Vijaya Desai.

Supporting informations

Full experimental details, ¹H & ¹³C NMR spectra of the chiral ligand [(R)-2] and sulfoxides (1a–1f), HPLC traces of sulfoxides (1a–1f) can be found via the “Supplementary Content” section of this article’s webpage.