The First Intramolecular Silene Diels-Alder Reactions. -A derivative of (Ia) with a methyl-substituent at the terminal double bond yields no cycloadduct under the presented conditions. -(CZYZEWSKI, M.; SELLARS, J. D.; GULIASHVILI, T.; TIBBELIN, J.; JOHNSTONE, L.; BOWER, J.; BOX, M.; DAVIES, R. D. M.; OTTOSSON, H.; STEEL*, P. G.; Chem. Commun. (Cambridge) 50 (2014) 22, 2919-2921, http://dx.doi.org/10.1039/c3cc49526d ; Dep. Chem., Univ. Durham, Durham DH1 3LE, UK; Eng.) -M. Tismer 28-189