C3-Symmetric Cinchonine-Squaramide-Catalyzed Asymmetric Chlorolactonization of Styrene-Type Carboxylic Acids with 1,3-Dichloro-5,5-dimethylhydantoin: An Efficient Method to Chiral Isochroman-1-ones

A more practical and efficient catalytic asymmetric chlorolactonization of styrene‐type carboxylic acids with 1,3‐dichloro‐5,5‐dimethylhydantoin (DCDMH) using C3‐symmetric cinchonine‐squaramide (CSCS) as organocatalyst has been developed. A series of chiral chloro‐substituted isochroman‐1‐ones was obtained in excellent yields (up to 95%) and enantioselectivities (up to 99% ee), whwereby the results for chloro‐substituted isochroman‐1‐ones are the best ever achieved. The catalyst can be recovered and reused for six cycles. Moreover, the chlorolactonization product 3b was further transformed to optically active bicyclic isochroman‐1‐one derivatives in high yield without losing the enantioselectivity. Furthermore, compounds 3e and 2n proved to be highly potent inhibitors of the HIV‐1 in TZM‐bl cells.