Macromolecular materials in heterogeneous catalysis: an aluminium silasesquioxane gel as active catalyst in Diels-Alder reactions of enones

A highly active, genuinely heterogeneous catalyst for liquid- phase Diels-Alder reactions of enones results from the silanol centred modification of an incompletely condensed silasesquioxane with trimethylaluminium, the resulting catalytic material being a gel that contains aluminium(III) siloxy functions (Al-O-Si) which are incorporated in a well defined, three-dimensional SiO framework