Highly efficient hydroamination of phenylacetylenes with anilines catalysed by gold nanoparticles embedded in nanoporous polymer matrix: Insight into the reaction mechanism by kinetic and DFT investigations

The synthesis of aromatic ketimines via hydroamination phenylacetylenes (PAs) with anilines (ANs) has been accomplished in high yields and excellent regio- stereo-selectivity using gold nanoparticles (AuNPs) embedded crystalline syndiotactic polystyrene-cis-1,4-polybutadiene (sPSB) multiblock copolymer matrix. performances the AuNPs-sPSB catalyst exceed those other commercial catalysts as a result physical chemical properties nanoporous polystyrenic support which allows activity, thermal stability recyclability catalyst. Electron donating (EDGs) electron withdrawing (EWGs) substituents onto group ANs PAs yield, all examined cases, selectivity formation thermodynamic favoured E stereoisomer ketimines. Kinetic investigation reaction mechanism presence AN deuterated analogue, AN-N,N-d2, highlighted new pathway for reaction, was also supported by DFT calculations. Actually, aggregates stabilized hydrogen bonding interactions produces favourable transition state nucleophilic attack to PA, coordinated/activated AuNPs surface. Moreover, an additional molecule cooperatively assists 1,3-hydrogen shuttling from N atom Cβ coordinated enamine intermediate produce kinetically Z-ketimine that turn evolves into thermodynamically stable E-aromatic ketimine. first order kinetics observed AN, along experimental energetic barrier (ΔG‡ = 26.6 ± 0.7 kcal mol−1; ΔH‡ 13.4 1.8 ΔS‡ −0.04 0.04 mol−1 K−1) found good agreement energy calculated shift modelling, strongly latter is rate determining step catalysed PA.