Cyclometallated Gold(III) Complexes as Effective Catalysts for Synthesis of Propargylic Amines, Chiral Allenes and Isoxazoles

Abstract

AbstractA series of cyclometallated gold(III) complexes [Au($\widehat{CN}$)Cl2] 1a–l (H$\widehat{CN}$=arylpyridines) and a PEG‐linked complex 1m were synthesized. Complexes 1a–m are effective in catalyzing the synthesis of propargylic amines, chiral allenes and isoxazoles. Six‐membered ring cyclometallated gold(III) complexes 1f–l exhibited higher catalytic activity than five‐membered ring cyclometallated gold(III) complexes 1a–e. The diastereoselectivity of propargylic amines could be tuned by using chiral aldehyde and/or amine substrates. Excellent enantioselectivities (90–98% ee) were achieved in chiral allene synthesis. Chiral allene racemization could be minimized by using 1f as catalyst. The PEG‐linked catalyst 1m is the most catalytically active towards synthesis of propargylic amines, in which case a product turnover of 900 was achieved. Moreover, 1m could be repeatedly used for 12 reaction cycles, leading to an overall turnover number of 872.