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■ Inter- and Intramolecular Diels-Alder Reaction of Ethenetricarboxylate Derivatives

Shoko Yamazaki,* Hirotaka Sugiura, Mamiko Niina, Yuji Mikata, and Akiya Ogawa

*Department of Chemistry, Nara University of Education, Takabatake-cho, Nara 630-8528, Japan

Abstract

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 °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 °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 EDCI/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.