Diels-Alder cycloadditions of 3-oxobut-1-enyl substituted orthoquinone monoketals with olefinic dienophiles furnished functionalized ortho-endo bicyclo[2.2.2]octenone derivatives with high regio- and stereoselectivities. The competition between self-dimerization and Diels-Alder cycloaddition with an external dienophile usually exists, except in the case of 5-substituted orthoquinone monoketal.

Diels-Alder Cycloadditions of Masked o-Benzoquinones with Alkenes. -Diels-Alder cycloaddition of oxobutenylated orthoquinone monoketals, generated in situ, with olefinic dienophiles yields bicyclo[2.2.2]octenones with high regio-and stereoselectivity. Self-dimerization and intermolecular Diels-Alder cycloaddition compete, except in the case of 5-substituted orthoquinone monoketal. -(GEORGOPANOU, E.; MARTINI, K.-I.; PANTAZIS, P.; PELAGIAS, P.; VOULGARI, P.; HADJIARAPOGLOU*, L. P.; J. Org. Chem. 80 (2015) 19, 9682-9690, http://dx.doi.org/10.1021/acs.joc.5b01755 ; Dep. Chem., Univ. Ioannina, GR-45110 Ioannina, Greece; Eng.) -T. Stabingis 11-082