Organocatalytic enantio- and diastereoselective synthesis of highly substituted δ-lactones via a Michael-cyclization cascade

An organocatalyzed Michael-cyclization cascade approach of readily available alpha,beta-unsaturated aldehydes and pyrazoleamides has been developed to get highly substituted delta-lactones in excellent enantioselectivities (up to 97%) and diastereoselectivities. The delta-lactones so obtained could easily be transformed into benzazepine derivatives with excellent enantio- and diastereoselectivities. Furthermore, the pyrazole moiety from the delta-lactones can be simply cleaved without disturbing the stereoselectivity.