Palladium-catalyzed [4+3] Cyclization Based On Allyl Carbonate

Transition-metal-catalyzed asymmetric cycloaddition reaction serves as a versatile and reliable tool for the rapid assembly of chiral carbo-and heterocycles,which has been widely employed for the preparation of natural products and bioactive compounds.To date,Enantiodivergent synthesis of both enantiomers of chiral compounds is one of the fundamental tasks in organic synthesis,drug discovery and materials science.In this text,we not only developed a palladium-catalyzed intermolecular asymmetric cycloadditon reaction of isatin-derivedα-(trifluoromethyl)imines,but also realized enantiodivergent synthesis of chiral molecules by tuning achiral amine,which was an unusual phenomenon in asymmetric synthesis.With the catalysis of Pd complex derived from Pd2(dba)3 ·CHCl3 and the chiral phosphoramidite ligand(R,R,R)-L1,the both enantiomers of a series of optically active spirooxindoles were obtained by only varying the reaction pathway of the asymmetric[4+3]cycloaddition reactions between isatin-derivedα-(trifluoromethyl)imines and 2-methylidenetrimethylene carbonate without changing any stereocenter.The salient features of the method included high efficiency,simple operation,mild reaction conditions,and high chemo-and enantioselectivity.The control experiments suggested that the weakly hydrogen-bonding interactions between DBU and isatin-derived α-(trifluoromethyl)imines played a crucial role in determining enantioselectivity reversal.Encouraged by this success,we continued to explore the Pd-catalyzed asymmetric enantiodivergent cycloaddition of other diploes in the future,and we believe that this stereochemical control mode might provide alternative synthetic routes to both enantiomers of diverse chiral molecules in asymmetric catalysis.