Asymmetric Synthesis of Nortropanes via Rh-Catalyzed Allylic Arylation

Tropane derivatives are extensively used in medicine, but catalytic asymmetric methods for their synthesis are underexplored. Here, we report Rh-catalyzed asymmetric Suzuki-Miyaura-type cross-coupling reactions between a racemic N-Boc-nortropane-derived allylic chloride and (hetero)aryl boronic esters. The reaction proceeds via an unexpected kinetic resolution, and the resolved enantiopure allyl chloride can undergo highly enantiospecific reactions with N-, O-, and S-containing nucleophiles. The method was applied in a highly stereoselective formal synthesis of YZJ-1139(1), a potential insomnia treatment that recently completed Phase II clinical trials. Our report represents an asymmetric catalytic method for the synthesis of YZJ-1139(1) and related compounds.