Room-Temperature AuI-Catalyzed C-C Bond Formation through a Tandem Friedel-Crafts-Type Addition/Carbocyclization Reaction

摘要

In the past ten years, significant research has been directed towards the development of catalytic reactions for the functionalization of CH bonds.[1] These reactions represent an environmentally friendly and atom-economical concept when performed under mild conditions.[2] Several metals have been recognized as excellent candidates for the functionalization of aromatic or heteroaromatic C-H bonds.[1], [3] As part of our ongoing program towards the development of catalytic tandem and atom-economical reactions,[4] we have been interested in the use of gold for such transformations. Kharash and Isbell were the first to show that AuIII could activate aromatic compounds at room temperature.[5] Following their seminal discovery, homogeneous gold catalysis was forsaken and interest only returned a few years ago.[6] The use of gold for CH functionalization to create CC bonds was recently realized in the presence of various electrophiles such as alkynes or activated alkenes.[1b], [7] To our knowledge, few examples of additions to nonactivated alkenes have been described so far.[8] We anticipated that the unprecedented intermolecular addition of aromatic rings to unactivated alkenes may be feasible in the presence of a second electrophilic moiety such as an alkyne function. We describe herein our preliminary results concerning the novel and diastereoselective tandem gold-catalyzed carbocyclization reaction through Friedel-Crafts-type and cycloisomerization transformations.