New Schiff bases derived from chiral d-camphor were determined to be effective phosphine ligands for the asymmetric palladium-catalyzed allylic alkylation of activated methylene compounds, the allylic etherification of alcohols, and the allylic amination of primary amines or secondary amines, in which the corresponding products with various functional groups were achieved in good yields with excellent enantioselectivities (up to >99 % ee). Remarkably, the palladium catalyst derived from Schiff base L2 afforded the highest level of enantioselectivity reported to date for allylic substitution reactions, including allylic etherification and allylic amination, which revealed the privileged role of d-camphor-derived Schiff bases in palladium-catalyzed allylic substitution reactions.

The first total synthesis of (±)-latifolin has been accomplished in six steps and 47.8% overall yield. To understand the relative importance of phenolic OH and benzhydryl CH hydrogen on the antioxidant activity of latifolin, 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay and density functional theory (DFT) studies were carried out. On scavenging DPPH radical in ethanol, the activity of latifolin (1) bearing phenolic hydrogen is remarkably higher than analogue 10 bearing no phenolic hydrogen. Therefore, Phenolic hydrogen is responsible for latifolin's antioxidant activity rather than benzhydryl CH hydrogen. Furthermore, the 5-OH BDE is lower than 2′-OH and 7-CH BDEs by a DFT calculation, respectively. Based on theoretical results it is definitely concluded that the phenolic 5-OH plays a major role in the antioxidant activity of latifolin.