Ck. Mcclure et Kb. Hansen, DIELS-ALDER REACTIVITY OF A KETOVINYLPHOSPHONATE WITH CYCLOPENTADIENEAND FURAN, Tetrahedron letters, 37(13), 1996, pp. 2149-2152
The Diels-Alder reactions between diethyl ketovinylphosphonate 5 and c
yclopentadiene or furan were performed with and without Lewis acid ass
istance. The acetyl group directed endo in all cases, with ratios vary
ing from 1.4:1 - 6.7:1 (acetyl endo).