Enantioselective Catalysis with Pyrrolidinyl Gold(I) Complexes: DFT and NEST Analysis of the Chiral Binding Pocket

Identifier:  imarina:9322152

Handle: https://hdl.handle.net/20.500.11797/imarina9322152

Authors:  Zuccarello, G; Nannini, LJ; Arroyo-Bondía, A; Fincias, N; Arranz, I; Pérez-Jimeno, AH; Peeters, M; Martín-Torres, I; Sadurní, A; García-Vázquez, V; Wang, YF; Kirillova, MS; Montesinos-Magraner, M; Caniparoli, U; Núñez, G; Maseras, F; Besora, M; Escofet, I; Echavarren, AM

Abstract:
A new generation of chiral gold(I) catalysts based on variations of complexes with JohnPhos-type ligands with a remote C2-symmetric 2,5-diarylpyrrolidine have been synthesized with different substitutions at the top and bottom aryl rings: from replacing the phosphine by a N-heterocyclic carbene (NHC) to increasing the steric hindrance with bis- or tris-biphenylphosphine scaffolds, or by directly attaching the C2-chiral pyrrolidine in the ortho-position of the dialkylphenyl phosphine. The new chiral gold(I) catalysts have been tested in the intramolecular [4+2] cycloaddition of arylalkynes with alkenes and in the atroposelective synthesis of 2-arylindoles. Interestingly, simpler catalysts with the C2-chiral pyrrolidine in the ortho-position of the dialkylphenyl phosphine led to the formation of opposite enantiomers. The chiral binding pockets of the new catalysts have been analyzed by DFT calculations. As revealed by non-covalent interaction plots, attractive non-covalent interactions between substrates and catalysts direct specific enantioselective folding. Furthermore, we have introduced the open-source tool NEST, specifically designed to account for steric effects in cylindrical-shaped complexes, which allows predicting experimental enantioselectivities in our systems.© 2023 The Authors. Published by American Chemical Society.