Gold(I)-Catalyzed Dearomatization–Allenene Reaction for the Construction of Polycycles with Excellent Diastereoselectivity

Abstract

The synthesis of complex polycycles starting from simple building blocks in just a few reaction steps is usually very challenging. Herein, we present the gold(I)-catalyzed synthesis of various polycycles via dearomatization–allenene reaction of aryl propargyl ethers with different nucleophiles. Depending on the starting material, polycycles can be isolated in yields up to 94% and with an enantiomeric excess of 95%. Quantum chemical calculations show that for all starting materials a Claisen rearrangement to the allenene occurs in the first reaction sequence. The subsequent cyclization and reaction with a nucleophile leads to various polycycles with the formation of up to six new C–C bonds in only one reaction step. All reactions proceed with excellent diastereoselectivity, with a α-quaternary carbonyl carbon present in the products.