Copper-catalyzed enantioselective propargylic [3 + 2] cycloaddition: access to oxygen heterocycles featuring a CF3-substituted quaternary stereocenter†

A Cu(i)-Pybox-diPh catalyzed enantioselective [3 + 2] cycloaddition reaction of CF₃-substituted tertiary propargylic esters as C2-bis-electrophiles with cyclic 1,3-dicarbonyl compounds as C,O-bis-nucleophiles has been reported. The methodology furnishes a variety of optically active oxygen heterocycles containing a CF₃-substituted quaternary stereocenter in good yields and enantioselectivities. Moreover, the scalability of the reaction and transformations of chiral compounds into their derivatives demonstrated the synthetic and practical relevance of the approach.