1,2,3-Triazole Bound Au(I) (TA-Au) as Chemoselective Catalysts in Promoting Asymmetric Synthesis of Substituted Allenes

The triazole-Au (TA-Au) complexes were identified as effective chemoselective catalysts in promoting propargyl ester/ether 3,3-rearrangements. The highly reactive allenes, which could not be isolated by simple cationic gold catalysts, were prepared in excellent yields (1% catalyst loading, >90% yields). Unlike other reported Au catalysts, the TA-Au provided effective chirality transfer without racemization over a long period of time, giving enantioenriched allenes with excellent stereoselectivity (1% catalyst loading, up to 99% ee).