Synthesis of 5‐,6‐, and 7‐deutero sparteines

Abstract

AbstractKinetically controlled 1H/2H exchange at carbon atom 5 of (‐)‐1,6‐dehydrosparteinium monoperchlorate (3a) followed by sodium borohydride or sodium borodeuteride reduction of the iminium double bond gave optically active 5,5‐(2H2)‐sparteine (1b) and 5,5,6‐(2H3)‐sparteine (1c), respectively. Under thermodynamic control a third deuterium atom was incorporated into 3 at carbon atom 7. Borohydride reduction or rapid re‐exchange followed by reduction lead to the novel sparteine analogues 5,5,7‐(2H3)‐sparteine (1d) and 7‐(2H)‐sparteine (1e). The title compounds have been prepared in 76 to 83 % yield and 89 to 97 % isotopic purity.