Asymmetric and Sustainable Synthesis of Cyclic Sulfoxides with Low Loading of Bisguanidinium Peroxomolybdate Ion-Pairing Catalyst

Chiral cyclic sulfoxides are valuable heterocyclic building blocks in natural products and pharmaceutically active molecules as well as optoelectronics materials. In view of their manifold applications but limited number of available synthetic methodologies to obtain them, highly enantioselective catalytic approaches to access chiral cyclic sulfoxides are therefore desired. Here, a sustainable and enantioselective oxidation of cyclic sulfides has been developed by employing in situ-generated bisguanidinium peroxomolybdate ion-pairing catalysis. Chiral cyclic sulfoxides bearing different ring sizes and functional groups have been achieved under mild and green conditions with low catalyst loading (0.05-0.5 mol %). The synthetic potentials based on chiral cyclic sulfoxide products have also been demonstrated in preparation of medicinally relevant molecules such as BI 1015550, a candidate drug for the treatment of idiopathic pulmonary fibrosis.