Synthesis and characterization of novel chiral NHC–palladium complexes and their application in copper-free Sonogashira reactions

Abstract

A new series of chiral N-heterocyclic carbene (NHC) palladium complexes were synthesized from a relatively inexpensive amino acid, l-phenylalanine. All these compounds were fully characterized by (1)H-NMR, (13)C-NMR and elemental analysis. The X-ray molecular structures of two of the complexes were reported. The catalytic activity of the four palladium complexes was successfully tested in the Sonogashira reaction under copper free conditions in air. The palladium complex 3a provided good activity in the Sonogashira coupling reaction.

Synthesis, Structure, and Reactivity of Dicarbene Dipalladium Complexes

“…The resonance of carbene carbon in these C4–C5 unsaturated palladium complexes is significantly upfield compared to that in those C4–C5 saturated complexes (ca. 183 ppm),13 which means that the carbene in unsaturated complexes is more electron rich than that in their saturated analogues.…”

Efficient synthesis of quinazoline-2,4(1H,3H)-diones from CO2 catalyzed by N-heterocyclic carbene at atmospheric pressure

“…17 Imidazolinium hydroxide i was prepared by modified prodecure. 18 All other chemicals were commercially available and used as received unless otherwise stated.…”

Synthesis of axially chiral biaryl compounds by asymmetric catalytic reactions with transition metals

“…M a n u s c r i p t 74 88 11 CO 2 iPr 141-G3 (0.1) 77 90 Table 7.3 -Enantioselective synthesis of ynamides [238]. [127]. M a n u s c r i p t C(CH 2 OBn) 3 M a n u s c r i p t …”

“…chiral monodentate NHC ligands used in asymmetric Suzuki-Miyaura crosscoupling were reported in 2012 by Cao, Shi et al (Figure 3.16)[127]. Their structure is based on that of commercially available L-phenylalanine and the chiral center is situated on the skeleton of the heterocycle.…”