Enantioselective Synthesis of Tropanes: Brønsted Acid Catalyzed Pseudotransannular Desymmetrization

Abstract The enantioselective synthesis of tropanols has been accomplished through chiral phosphoric acid catalyzed pseudotransannular ring opening of 1‐aminocyclohept‐4‐ene‐derived epoxides. The reaction proceeds together with the desymmetrization of the starting material and leads to the direct formation of the 8‐azabicyclo[3.2.1]octane scaffold with excellent stereoselectivity. The synthetic applicability of the reaction was demonstrated by the enantioselective synthesis of the two natural products (−)‐α‐tropanol and (+)‐ferruginine.