Formal [4 + 2] cycloaddition of imines with alkoxyisocoumarins.

ABSTRACT

A new preparation of δ-lactams is reported. In the presence of a Lewis acid promoter, alkoxyisocoumarins engage a range of N-aryl and N-alkyl imines to form δ-lactams with a pendent carboalkoxy substituent. A sulfonamide-thiourea catalyst enables the synthesis of these products in moderate to good enantioselectivities.