Abstract: Efficient, highly stereoselective approaches have been developed to (+)- actinobolin (1) and (-)-bactobolin (3) from bridged a-keto lactone 11, which can be readily prepared via intramolecular SnCI4 catalyzed ene reaction of cyclohexenol glyoxylate (5). A novel method has been developed for direct, stereoselective reductive sulfonamidation of 11 to simultaneously introduce a protected C-4 amino group of the natural products and ...