Diels-Alder reactions of fused pyran-2-ones with maleimides: efficient syntheses of benz[e]isoindoles and related systems.
[reaction: see text] The Diels-Alder reaction of some substituted 5,6,7,8-tetrahydro-2H-1-benzopyran-2-ones (1a-f) with N-substituted maleimides (2a-c) leading to fused isoindole derivatives (5a-n, 7) or, in a few cases, to bridged double cycloadducts (fused bicyclo[2.2.2]octene derivatives) (6a-f) is presented. When X = CO, the first efficient, substituent-driven aromatization of an intermediary-formed cycloadduct was observed, resulting in substituted benz[e]isoindoles (5a-k). The same type of aromatization can also be achieved in an unprecedented catalysis with Rh/C.
Kranjc
Kristof
K
University of Ljubljana, Faculty of Chemistry and Chemical Technology, Askerceva 5, SI-1000 Ljubljana, Slovenia.
Polanc
Slovenko
S
Kocevar
Marijan
M