Microporous Polymeric Networks Containing a Long-Term Stable Au^I Catalyst for Enyne Cyclization

Two microporous polymer networks having a confined Au^I carbene catalyst were obtained and tested for the skeletal rearrangement of enynes. These catalysts were obtained from precursor porous organic polymers (POPs), a type of microporous polymer network, synthesized by the reaction of isatin or a mixture of isatin/trifluoroacetophenone (1:1) with triptycene (POP1 and POP2, respectively) through an electrophilic aromatic substitution, EAS, reaction promoted by trifluoromethanesulfonic acid. These precursors could be easily functionalized through the lactam moiety to form Au^I carbene catalysts (POP1-AuCarbene and POP2-AuCarbene). The confined carbenes proved to be very active for the skeletal rearrangement of dimethyl 2-(3-methyl-2-butenyl)-2-propinylmalonate enyne. A large increase in the stability of the Au^I catalysts was observed compared to those of most of the homogeneous catalysts described so far in the bibliography. This long-term stability was associated with the separation of Au^I atoms, induced by their confinement in the microporous networks. In particular, POP2-AuCarbene exhibited outstanding long-term stability, maintaining catalytic activity even after several months.