Intramolecular Diels–Alder reaction of 1-ethoxycarbonyl-4-alkenylcyclopentadienes
Abstract
4-(But-3-enyl)- and 4-(pent-4-enyl)-1-ethoxycarbonyl-2-ethoxycyclopentadiene, prepared from allylidenetriphenylphosphorane and α-haloketones, underwent a regioselective intramolecular Diels–Alder reaction to give two types of the functionalized tricyclic products depending on the linking carbon-chain length.