Enantioselective α-Chlorination of β-Dicarbonyl Compounds by Isosteviol-Derived Sulfonamide Catalysts

In this paper, a series of isosteviol-derived sulfonamide catalysts were easily synthesized and applied in the enantioselective α-chlorination of β-keto esters and β-keto amides (24 examples) using inexpensive commercially available <b>NCP</b> as the chlorine source in excellent yields (up to 98%) and high enantioselectivities (up to 92% ee). We found that the unique structures of the catalyst (hydrogen bond donors of the sulfonamide group and the chiral pocket of the isosteviol) were important for good enantioselectivity. With a simple operational protocol, this transformation provides a practical method for the preparation of chiral chlorine-containing compounds.