Photoexcited Palladium-Catalyzed\nSynthesis of Chiral\nAllenes from Alkynes via Isomerization and Deracemization Sequence

A photoexcited palladium-catalyzed synthesis of chiral\nallenes\nfrom alkynes via a sequence of isomerization and deracemization is\ndisclosed. This method offers an efficient and cost-effective approach\nto produce a wide range of chiral allenes with good enantioselectivities\nand yields (up to 98% yield and 99% ee). The use of readily available\nand stable alkynes as starting materials simplifies experimental procedures\nand broadens the scope of the chiral allene synthesis. DBU plays a\ncrucial dual role in this reaction to effectively facilitate the isomerization\nof alkynes to allenes and enhance the palladium-catalyzed deracemization\nunder visible light excitation, both of which are vital for the success\nof the process.