Synthesis of 3-hexahelicenol and its transformation to 3-hexahelicenylamines, diphenylphosphine, methyl carboxylate, and dimethylthiocarbamate

A nonphotochemical synthetic route to 3-hexahelicenol is reported. It involves a key [2+2+2] cycloisomerization of CH3O-substituted triyne that is readily available from 1-methoxy-3-methylbenzene and 1-bromo-2-(bromomethyl)naphthalene. Further functional group transformations led to 3-CO2CH3, 3-NH2, 3-PPh2, and 3-SC(O)N(CH3)(2) substituted hexahelicenes.