Quinidine derived organocatalysts for the nucleophile promoted asymmetric [4+2] cycloaddition reaction of salicyl N-tosylimine with allenic esters

Cinchona alkaloid derived catalyst cat. 5 prepared from β-isocupreidine (β-ICD) was found to be a fairly effective organocatalyst for the nucleophilic promoted asymmetric [4+2] cycloaddition reaction of salicyl N-tosylimines and allenic esters to give the corresponding adducts in up to 80% yield, 87% ee.

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6′-N-Methylformamide-β-ICDC21H25N3O2Ee = 100%[α]D20=-50.3 (c 0.54, CHCl3)Source of chirality: chiral poolAbsolute configuration: (S)

6′-N-Phenylformamide-β-ICDC26H27N3O2Ee = 100%[α]D20=-20.4 (c 0.50, CHCl3)Source of chirality: chiral poolAbsolute configuration: (S)

6′-N-Methylethanethioamide-β-ICDC21H26N3OSEe = 100%[α]D20=-75.1 (c 0.55, CHCl3)Source of chirality: chiral poolAbsolute configuration: (S)