The asymmetric hetero-Diels–Alder reaction of enamide aldehydes with Danishefsky’s diene and an efficient synthesis of chiral binaphthyl ligands

By varying the substituents on the nitrogen of enamide aldehydes, their reaction mode with Danishefsky’s diene in the presence of Lewis acid catalysts can be controlled and the desired formal hetero-Diels–Alder products obtained. A new and efficient method to synthesize chiral binaphthyl ligands containing sterically bulky 3,3′-substituents has been developed. Lewis acid complexes prepared from these binaphthyl ligands and AlMe3 are used to catalyze the hetero-Diels–Alder reaction of an enamide aldehyde with Danishefsky’s diene with up to 78% ee. This catalytic asymmetric reaction may allow for the efficient synthesis of biologically interesting molecules such as fumonisins.