Mercuric triflate-catalyzed tandem cyclization leading to polycarbocycles.

[reaction: see text] We developed Hg(OTf)2-catalyzed cyclization of (E)-1,3-dimethoxy-5-(4-methyl-3-nonen-7-ynyl)benzene leading to the formation of (4aS,10aS)-3,4,4a,9,10,10a-hexahydro-5,7-dimethoxy-1,4a-dimethylphenanthrene in 98% yield with up to 100 catalytic turnovers. This is the first mercuric salt-catalyzed biomimetic tandem cyclization.