Catalytic Asymmetric Henry Reaction of Isatins

Abstract

Wang, Duan and colleagues report a catalytic enantioselective Henry reaction between isatins 1 and nitroalkanes 2 using the simple cinchona alkaloid cupreine (3). The resulting hydroxyoxindole derivatives 4 were isolated with excellent yields and, for the first time, with good to high enantioselectivities. This column-chromatography-free methodology was applied as key step in a concise total synthesis of natural products (+)-dioxibrassinin (5) and (S)-(-)-spirobrassinin (6).