Syntheses and stereochemical assignment of toxic C₁₇-polyacetylenic alcohols, virols A, B, and C, isolated from water hemlock (Cicuta virosa)

In the course of our study on neurotoxic C₁₇-polyacetylenic alcohols of the toxic plant, Cicuta virosa, virols A (1), B (2), and C (3) were synthesized by stereoselective routes to confirm their stereochemistry and to obtain supply of these compounds for pharmacological study. The syntheses used chiral 3-hydroxy-1-alkyne building blocks, Pd(0)CuI(I)-catalyzed coupling of acetylene with vinyl chloride, and heterocoupling reaction of acetylene mediated by CuI. As a result, the absolute configuration of the stereogenic center of virols A (1), B (2), and C (3) was confirmed as S, S, and S, respectively.