Synthetic approaches to coniine and other 2-alkyl piperidines

The first synthesis of coniine, a neurotoxic piperidine alkaloid found in poison hemlock (Conium maculatum L.), was performed back in 1886 by Ladenburg. Since that time, numerous different approaches to the synthesis of this and related alkaloids (2-alkylpiperidines) have been developed. Nowadays, the enantioselective/specific synthesis of coniine is taken as a paradigm of the usefulness of new chiral synthetic methodologies. This review aims to summarize and systematize recent progress in the synthesis of coniine and related compounds.