Scheme 1.

Diels-Alder-lactamization of furan-based sulfonamide 8a and acryloyl chloride (9) mediated by (R)-(−)-levamisole hydrochloride providing bridged cycloadduct (+)-10.

Diels-Alder-lactamization of furan-based sulfonamide 8a and acryloyl chloride (9) mediated by (R)-(−)-levamisole hydrochloride providing bridged cycloadduct (+)-10.