Asymmetric Synthesis of β-Aryl β-Imido Sulfones Using Rhodium Catalysts with Chiral Diene Ligands: Synthesis of Apremilast.

A chiral rhodium(I)-diene catalyst enabled the one-step synthesis of β-aryl β-imido sulfones under mild reaction conditions. By selection of the chiral diene ligand L1a or L2, each enantiomer of the chiral β-aryl β-imido sulfone target can be accessed with high stereoselectivity. Demonstration of the scope of the reaction, which includes the synthesis of an N-protected chiral β-amino β-phenyl sulfone, culminated with the efficient synthesis of the heteroatom-rich active pharmaceutical ingredient apremilast.