A Short Synthesis of Ergot Alkaloids and Evaluation of the 5-HT1/2 Receptor Selectivity of Lysergols and Isolysergols

Key transformations in a four-step synthesis of the ergot alkaloid scaffold include a novel cesium carbonate-mediated hydrogen autotransfer alkylation to generate the C(3)-C(4) bond and an intramolecular Heck reaction that directly establishes the C(9)-C(10) alkene of methyl lysergate. An ester reduction and a streamlined experimental procedure establish a readily scalable, expedient total synthesis of all four stereoisomers of lysergol and isolysergol, including the previously unknown (-)-lysergol, for pharmacological evaluation at 5-HT1A and 5HT(2A,B,C) receptors. A bicyclic scaffold is also characterized for the first time in the intramolecular Heck coupling.

Automated summary

This study describes the total synthesis of ergot alkaloids, including the previously unknown stereoisomers, using key transformations and streamlined experimental procedures. The synthesized compounds can be used for pharmacological evaluation.