High, Exoselective Diels–Alder Reaction in 5.0 M Lithium Perchlorate in Diethyl Ether Medium: Efficient Synthesis of Novel Heterocyclic Derivatives Containing a Spirobicyclo[2.2.1]heptane System

Exocyclic arylidene derivatives have been used as dienophiles in Diels–Alder reactions with cyclopentadiene. A series of novel heterocyclic derivatives containing the spiro bicyclo[2.2.1]heptane system is the outcome of such reactions. The reactions proceed with high exoselectivity in the presence of 5.0 M LPDE medium.