Abstract
The utility of chiral Lewis acid catalysts in organic synthesis has been increasingly important in recent years. This review describes how we have succeeded to design a new, chiral organoaluminum reagent as a chiral Lewis acid catalyst in the asymmetric hetero-Diels-Alder reaction of siloxydienes and aldehydes. Based on our conceptually new enantioselective activation of carbonyl moieties, exceptionally bulky, chiral organoaluminum reagents of type (R) -4 and (S) -4 can be successfully synthesized in optically pure forms from trimethylaluminium and (R) - (+) - or (S) - (-) -3, 3'-bis (triarylsilyl) binaphthol, respectively.
