Palladium-catalysed asymmetric allylic substitution: a ligand design incorporating steric and electronic effects

New Pyridine−Imidazoline Ligands for Palladium-Catalyzed Copolymerization of Carbon Monoxide and Styrene

“…[15,16] Further reaction of 1a with BnBr, TsCl or Tf 2 O, provided the 1-substituted-4,5-dihydro-4,5-diphenyl-2-(2-pyridyl)-imidazoles 1bϪd, respectively, in a racemic manner ( Figure 1). [16] The neutral [PdClMe(N-NЈ)] complexes 2aϪd were isolated from the stoichiometric reaction of [PdClMe(cod)] (cod ϭ 1,5-cyclooctadiene) and the ligands 1aϪd in anhydrous toluene.…”

Enantioselective Nickel-Catalyzed anti-Carbometallative Cyclizations of Alkynyl Electrophiles Enabled by Reversible Alkenylnickel E/Z Isomerization

“…9,10 Xantphos ( L2 ) was inferior to dppe ( L1 ) (entry 3), but the P , N -ligand L3 was much more effective and gave 2a in 87% NMR yield with only a small quantity of 3 (entry 4). Furthermore, by using commercially available chiral phosphinooxazoline ligands 11 L4 – L7 , 2a was obtained in 63–97% ee (entries 5–8). Ligands L5 and L7 gave the highest enantioselectivities but the yields were modest (entries 6 and 8).…”

Multifunctional chiral aminophosphines for enantiodivergent catalysis in a palladium‐catalyzed allylic alkylation reaction

“…The following attack by a nucleophilic species can further contribute to the selectivity because of electronic factors, as the nucleophilic attack tends to prefer the allyl carbon trans to the better π-accepting phosphorous ligating atom ( Figure 3B, Paths a and c preferred over Paths b and d). [76][77][78] Given that the enantioselectivity of the reaction is a complex outcome of multiple factors/pathways, ligands 1-6 were tested in a model AAA reaction in order to ascertain how the rate and enantioselectivity of the reaction may respond to the overall steric and electronic environment provided by these ligands. Using the optimal condition for the model AAA reaction as investigated earlier, the conversion and enantiomeric ratios of the AAA between acetate 8 and dimethyl malonate were monitored for 1 h (Figure 4).…”