An Improved Synthesis of (+)-2-Tropinone

Abstract

The tropane ring system (8-methyl-8-azabicyclo[3.2.1]octane) is an important substructure in a number of natural products and synthetic compounds of biological and medicinal importance. As a result of the significance of the tropane ring system, the development of new synthetic methodology for the preparation of useful tropane precursors for the construction of more complex molecules continues to be an important field of study.1-11 (+)-2-Tropinone (1) has long been recognized as a useful precursor in the preparation of many compounds of potential and actual biological interest.12,13 Unfortunately, 1 is not as readily available as themeso-derivative 3-tropinone (2).10,14-17 (+)-2-Tropinone (1) has classically been prepared by the degradation of (-)-cocaine.15 However, the degradation process can be tedious and only affords a moderate overall yield of 1. Alternatively, multigram quantities of the racemic compound ((-1) can be prepared by a variety of methods.9,10,15,16