A significant part of our research work has been focused on the design and synthesis of new chiral catalysts based on Johnphos-type ligands as well as related complexes based on chiral planar ferrocene ligands. These new catalysts have allowed to perform enantioselectively important cyclization reactions and to develop an atroposelective synthesis of aryl-substituted indole derivatives. In addition, new digold complexes derived from cavitands have been design and have been found to catalyze enantioselectively the alkoxycyclization of 1,6-enynes, which has been applied in the first total synthesis of the natural product mafaicheenamine C.
A new family of catalysts with ligands bearing urea, thiourea, and squaramide subunits have been designed for the silver-free gold-catalyzed enantioselective folding of unsaturated substrates. This has led to the development of the new concept of H‑bonded counterion-directed enantioselective gold(I) catalysis.
Small gold(I) and gold(I)-silver(I) clusters have also been synthesized for the activation of alkynes. We have also studied alternative catalysts based on metals different from gold (such as rhodium and zinc). In particular, Rh(II) salts have found to be highly reactive for the generation of the corresponding metal carbenes by decarbenation of substituted cycloheptatrienes.
We have also discovered the activation of acetylene gas catalyzed by gold and have studied the oligomerization of acetylene under mild conditions as well as other metathesis-type reactions with electron-rich alkenes. In these transformations, acetylene behaves as a C2 dicarbene unit leading to double cyclopropanations. This method was applied for the first total synthesis of waitziacuminone, which was remarkably completed in a single step, as well as for the synthesis of chromanes by intermolecular aryloxyvinylation with acetylene gas.
