A new access to ring-fused cyclopropanols through samarium diiodide-induced 3-exo-trig-cyclisations

Benzobicyclic δ-oxo-α,β-unsaturated esters easily prepared from tetralones or benzosuberone, readily cyclise in the presence of samarium diiodide and tert-butanol according to a totally syn mode, leading selectively to ‘cis’ ring-fused cyclopropanols that spontaneously lactonise to tetracyclic compounds.