Gold(I)-Catalyzed Stereoselective Polycyclizations

Identifier:  TDX:2554

Handle: https://hdl.handle.net/20.500.11797/TDX2554

Authors:  Rong, Zhouting

Abstract:
A gold(I)-catalyzed polyenyne cyclization was developed to allow the formation of up to four carbon-carbon bonds in a single step. The scope of this transformation was explored and was found that 1,5-enynes bearing electron-rich aromatic rings, hydroxyl groups and alkenes are appropriate substrates for this transforamtion. 1-bromo-1,5-enynes were also found to polycyclize under the same conditions as terminal 1,5-enynes to give vinylbromide compounds which can be further transferred into other derivatives. The asymmetric version of this transformation was also investigated. It was found that the best enantioselectivity was given by using (R)-MeO-DTB-BIPHEP as the chiral ligand. The best ee was 54%. While the use of chiral ligands were not successful, a chiral camphorsultam auxiliary was found to be the most efficient auxiliary to promote the asymmetric transformation of this polycyclization. This camphorsultam auxiliary can be easily installed and removed and provide the polycycles in good diastereoselectivity. This is the first example of camphorsultam auxiliary enabled gold catalyzed trransformation and it showed good potential on promoting other gold catalyzed reactions.