INTER- AND INTRAMOLECULAR DIELS-ALDER REACTION OF ETHENETRICARBOXYLATE DERIVATIVES

摘要

Inter- and intramolecular [4+2] cycloaddition reactions of highly electron-deficient ethenetricarboxylates have been studied. Intermolecular Diels-Alder reaction of ethenetricarboxylate esters and cyclopentadiene proceeded at room temperature or -20 degrees C to give cycloadducts with 1:1.5-1.9 endo:exo ratio. Lewis acids such as EtAlCl2, Zn(OTf)(2) and Cu(OTf)(2) catalyzed reaction at room temperature or -40 degrees C gave cycloadducts with 3.1-5.4:1 endo:exo ratio. Reaction of N-benzYl- or N-allyl-2-furylmethylamine and 1,1-diethyl 2-hydrogen ethenetricarboxylate in the presence of EDCl/HOBt/Et3N at room temperature led directly to an intramolecular Diels-Alder adduct stereoselectively. The observed stereoselectivities were explained by the use of DFT calculations.