Studies on the stereochemistry of nucleophilic additions to tetrahydropyridinium salts. Expeditious stereospecific total syntheses of (+)-makomakine, (+)-aristoteline, and (±)-hobartine

The Aristotelia alkaloids (+)-makomakine (+)-aristoteline, and (±)-hobartine have been synthesised stereospecifically via reduction of the corresponding tetrahydropyridines formed in the mercury(II) nitrate-mediated Ritter coupling of 3-β-ylacetonitrile with (+)-β-pinene and (+)-α-pinene, respectively.