Chiral catalysts for the Diels-Alder reaction

TABLE 5-6. List of Chiral Catalysts for the Diel-Alder Reaction... 

Diels-Alder Reactions. It has been demonstrated that the ligand-metal complexes derived from (5,5)-/-Bu-box and a mild Lewis acid such as Cu(OTf)2 are very efficient chiral catalysts for the Diels-Alder reaction with cyclopentadiene and substituted acylimide derivatives. Among various ligands examined, the (5,5)-/-Bu-box ligand consistently provided a very high level of endo/exo selectivity as well as endo enantioselectivity (90-98% ee with 5-10 mol % catalyst) and yield (82-92%) with a number of substituted dienophiles. 

Corey reported an important class of C2-symmetric aluminum-diamine complexes as chiral catalysts for the Diels-Alder reaction [81-83]. Such complexes are particularly suitable for stereochemical control of Diels-Alder reactions with acryloyl and crotonyl imides, as well as maleimides, as dieno-philes. As depicted in Scheme 17.22, enantioselective cycloaddition of malei-... 

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