Synthesis of pyranonaphthoquinone antibiotics involving the ring closing metathesis of a vinyl ether

The synthesis of two antibiotic pyranonaphthoquinones was performed by a straightforward synthetic route utilizing ring closing metathesis. Vinylation of 3-(1-propenyl)-2-hydroxymethyl-1,4-dimethoxynaphthalene under iridium catalysis and subsequent ring closing metathesis of 3-(1-propenyl)-2-vinyloxymethyl-1,4-dimethoxynaphthalene with Grubbsʹ catalyst paved the way to the natural antibiotics pentalongin and psychorubrin.