Enantioselective approach to tropane skeleton: Synthesis of (1S,5S,6R)-6-Hydroxy-8-methyl-8-azabicyclo[3.2.1]octan-3-one

The original and classical Mannich-type construct for the tropane skeleton, developed over half a century ago by Willstatter, Robinson and Schopf as the first biomimetic synthesis, has been employed for the enantioselective construction of 6-beta-hydroxytropinone. The component compounds of this novel one-step Mannich-type condensation sequence are acetonedicarboxylic acid, methylamine hydrochloride and (2R)-hydroxy-1,4-butanedial, in turn prepared from tert-butyl (R)-3-hydroxy-4-pentenoate as the starting chiral synthon