Syntheses of (−)-hygrine and (−)-norhygrine via Wacker oxidation

Hygrine is an important biosynthetic intermediate for tropane alkaloids. A synthesis of (−)-hygrine starting from l-proline is described. The acetonyl side chain of hygrine was fashioned through the Wittig reaction followed by regioselective Wacker oxidation. In addition, this Letter provides the first synthesis of (−)-norhygrine.