Application of a Raney-cobalt-mediated tandem reductive cyclization protocol to total syntheses of the Aspidosperma alkaloids (±)-limaspermidine and (±)-1-acetylaspidoalbidine.

The racemic modification of the Aspidosperma alkaloid limaspermidine (1) has been prepared in ten steps including one involving a Raney-cobalt-mediated tandem reductive cyclization of nitrile 8 to give the tetracyclic system 9b. Compound (±)-1 has been converted over two steps into (±)-1-acetylaspidoalbidine [(±)-13].