Construction of Functionalized ortho-Naphthoquinone Methides via Site-Selective Ring Opening of 1-Siloxy-1,4-epoxy-1,4-dihydronaphthalenes

1-Siloxy-4-(benzyloxy)methyl-1,4-epoxy-1,4-dihydronaphthalenes, generated from benzynes and furans, underwent automatic site-selective ring opening because of the synergetic effect of the steric strain of the 1,4-epoxy moiety and the electron-donating ability of the siloxy group on the acetal structure to afford the precursors of ortho-naphthoquinone methides (o-NQMs). Subsequent Lewis acid-facilitated o-NQM formation and annulation with olefins afforded multi-fused heterocycles. Notably, the consecutive hexacyclic skeleton of rubioncolin B was constructed via solvent-dependent regioselective annulation of naphthofuran derivatives.

Automated summary

In this study, it was found that Siloxy-4-(benzyloxy)methyl-1,4-epoxy-1,4-dihydronaphthalenes can undergo automatic site-selective ring opening and subsequent annulation with olefins to form multi-fused heterocycles. The study also revealed the solvent-dependent regioselectivity in certain reactions.