Atroposelective Synthesis of Isoriccardin C through a C−H Activated Heck Type Macrocyclization

Macrocyclization is typically the key step in syntheses of cyclophane-type natural products. Considering compounds with axially chiral biaryl moieties, control atroposelectivity essential for biological activity and synthetically challenging. Herein we report on atroposelective macrocyclization involving an oxidative Heck type process enabling first atropo-enantiopure synthesis isoriccardin C. A sulfinyl auxiliary ortho-position a axis (still flexible) was used to induce C−H activated atropodiastereoselective coupling (>98 % de). The traceless character enables introduction hydroxy group give target molecule >98 ee as well.