A general method for iterative cyclopentannulation: sequential use of Claisen rearrangement and radical enyne closure
Abstract
Cycloalkenyl acetylenes 4, which are easily prepared from allylic alcohols 1, undergo radical cyclization (4→5) on treatment with stannyl radicals; the products 5 are themselves convertible into allylic alcohols, so that the annulation sequence can be repeated.