[reaction: see text] Substituted cyclopentadienone acetals (CPDAs) were synthesized by a thermal or palladium-catalyzed [3 + 2] cycloadditionreaction of a substituted cyclopropenone acetal to an electron-deficientacetylene. The synthesis afforded di-, tri-, and tetra-substituted CPDAs of considerable structural varieties that undergo Diels-Alder reaction to produce bicyclo[2.2.1]heptenes.
Diels-Alderreactions of a cyclopentadienone acetal with aromatic heterocycles, such as pyrrole or indole, took place with the latter acting as a 2π dienophile. The reaction gave a polycyclic heterocycle in good yield regioselectively. Analysis of the frontier molecular orbitals showed that inverseelectrondemand interactions control the regioselectivity.
regioselective synthesis of polysubstituted benzenederivatives was achieved via multicomponent reaction of a substituted cyclopropenone acetal and two alkyne molecules. The synthesis utilizes cyclopentadienone acetal as an intermediate and enables regioselective [2+2+2] assembly of the three-components into a benzene ring. A variety of polysubstituted benzenederivatives of synthetic and structural interest