Gold-Catalyzed One-Pot Cycloisomerization/Nucleophilic Addition/Rearrangement of Acenaphthylene Carbaldehyde Derivatives

Merging the latest advances in the field of gold catalysis and the efficiency of hexafluoro-2-propanol (HFIP), a gold-catalyzed orthogonal tandem reaction has been developed to access carbocyclic ketone on naphthalene substrates. The methodology involved a cycloisomerization/nucleophilic addition and a C -> O rearrangement. The HFIP solvent most probably acted as a Lewis-acid on isochromene derivatives, through hydrogen donor bond activity. A large range of acenaphthylene carbaldehyde has been engaged in this process coupling gold catalysis and Lewis-acid behavior of HFIP leading to cyclic ketones with a yield ranging from 15 to 91% (27 compounds). The mechanism was investigated, and the reaction most presumably occurred via a classical cyclization process followed by a [Au]-HFIP interaction for the final rearrangement. The interest of such transformation was demonstrated by performing it on a gram-scale. Moreover, a post-functionalization bromination was performed, as well as the isomerization of some functionalized ketones leading to full trans derivatives with a yield ranging from 78 to 90% yields.

Automated summary

A gold-catalyzed orthogonal tandem reaction using HFIP as a Lewis acid has been developed to access carbocyclic ketone on naphthalene substrates. The yield of cyclic ketones ranged from 15% to 91% using a variety of acenaphthylene carbaldehydes. The mechanism involved a cyclization process followed by an [Au]-HFIP interaction for the final rearrangement. The gram-scale transformation and post-functionalization bromination were successfully carried out.