Selectivity in palladium catalysed allylic substitution

Bulky Monodentate Phosphoramidites in Palladium‐Catalyzed Allylic Alkylation Reactions: Aspects of Regioselectivity and Enantioselectivity

“…Especially in the last decade, enormous progress has been made in gaining insight in the factors that determine the outcome of the reaction, such as the metal, the structure of the allyl substrate, ligand or nucleophile and the nature of the solvent. [1][2][3][4] The vast majority of the studies reported apply palladium as the metal catalyst of choice. A plethora of ligands has been designed and employed, mainly with phosphorus and/ or nitrogen donor atoms.…”

“…Especially the asymmetric allylic alkylation has received broad attention (Scheme 1). [1][2][3][4][5][6] Excellent enantioselectivities have been obtained when C 2 symmetrical diphosphines were used, as demonstrated by Trost et al [1,6] The observed stereoselectivities for these and other systems can often be explained by the concept of a "chiral pocket". [7][8][9][10] The chiral induction stems from the selective clockwise or anticlockwise rotation of the allyl moiety in this pocket upon nucleophilic attack to form the product h 2 -alkene complex.…”

Highly Enantioselective Copper‐Catalyzed Allylic Alkylation with Phosphoramidite Ligands

“…[1] The allylic alkylation [2] holds a prominent position due to its high versatility as the products can easily be further transformed and functionalized in a variety of ways. Moreover, it is possible to alkylate the substrate by two distinct pathways (Scheme 1).…”

Mechanistic studies of the molybdenum-catalyzed asymmetric alkylation reaction

“…Early work in this area focused on Pd complexes as catalysts, but their utility in organic synthesis was limited because, in general, unsymmetrical substrates afforded the achiral linear product (1)(2)(3)(4)(5). More recently, a limited number of ligands have been designed such that the branched product is now accessible with high enantiomeric excess (ee) by using Pd catalysis (6)(7)(8)(9).…”

“…Faller and Linebarrier (49), Rubio and Liebeskind (50), and Kuhl et al (51) have shown that oxidative addition in stoichiometric reactions of Mo(CO) 3 (MeCN) 3 with cyclic and acyclic allylic acetates proceeds with retention of configuration. On the other hand, Ward et al (52) discovered the stereochemistry of the oxidative addition is influenced by steric factors and experimental conditions, and oxidative addition of a single substrate can follow either an inversion or retention pathway, depending on the solvent and concentration, suggesting both stereochemical avenues may be available to Mo-catalyzed reactions.…”