3-Vinyl-2,5-dihydrothiophene 1,1-dioxide: a novel, easily accessible, high-yielding precursor to [3]dendralene, the simplest representative of the diene-transmissive polyenes

Abstract

Cheleotropic extrusion of SO₂ from readily prepared 3-vinyl-2,5-dihydrothiophene 1,1-dioxide 2 provides a clean and efficient route to [3]dendralene (3-methylenepenta-1,4-diene 1), the simplest member of the diene-transmissive polyenes, which contrary to previous reports is a stable, easily handled compound that shows unexpected selectivity in Diels–Alder cycloadditions, thus enhancing its utility as a tandem annelating reagent.