A new library of arsine, stibine-stabilized N-heterocyclic carbene palladium complexes: synthesis, structures and activities in C–C and C–N coupling reactions

Abstract

A series of new N-heterocyclic carbene palladium complexes bearing AsPh₃ and SbPh₃ functions PdCl₂(IMes)(AsPh₃) (1a), PdCl₂(IMes)(SbPh₃) (1b), PdCl₂(IPr)(AsPh₃) (1c), PdCl₂(IPr)(SbPh₃) (1d), PdCl₂(SIMes)(AsPh₃) (2a), PdCl₂(SIMes)(SbPh₃) (2b), PdCl₂(SIPr)(AsPh₃) (2c), and PdCl₂(SIPr)(SbPh₃) (2d) (IMes = N,N′-bis-(2,4,6-trimethylphenyl)imidazol-2-ylidene; IPr = N,N′-bis-(2,6-di(iso-propyl)phenyl)imidazol-2-ylidene; SIMes = N,N′-bis-(2,4,6-trimethylphenyl)imidazolidin-2-ylidene; SIPr = N,N′-bis-(2,6-di(iso-propyl)phenyl)imidazolidin-2-ylidene) was synthesized and fully characterized by ¹H NMR, ¹³C NMR, and FT-IR spectroscopy, elemental analysis and single-crystal X-ray crystallography. The catalytic potential of these arsine and stibine-stabilized carbene palladium complexes for Pd-mediated transformations was investigated with various substrates in the Hiyama cross-coupling reactions and Buchwald–Hartwig aminations. The results demonstrate that these complexes show high catalytic activity and good tolerance to various chemical functions.