Chiral Tetrafluorobenzobarrelene Ligands for the Rhodium-Catalyzed Asymmetric Cycloisomerization of Oxygen- and Nitrogen-Bridged 1,6-Enynes

摘要

The transition-metal-catalyzed cycloisomerization reaction of 1,n-enynes has emerged as an atom-economical process for the preparation of diverse cyclic compounds. Nitrogen- and oxygen-bridged enynes are useful starting materials for the construction of heterocyclic building blocks. Since Blum et al. reported the PtCl4-catalyzed transformation of allyl propargyl ethers into 3-oxabicyclo[4.1.0]heptenes in 1995, this type of 6-endo-dig cycloisomerization has been developed by the use of π-acidic metal catalysts such as platinum and gold (Scheme 1). The reaction is thought to be promoted by the