Palladium-catalyzed site-selective arylation of aliphatic ketones enabled by a transient ligand

Abstract

Transition metal-catalyzed direct C-H bond functionalization enabled by transient ligands has become an attractive topic. Here we report a palladium-catalyzed site-selective arylation of β-C(sp)-H bonds in aliphatic ketones with β-alanine as the transient ligand.

Hexafluoroisopropanol: the magical solvent for Pd-catalyzed C–H activation

“… 71 This result was the outcome of the cooperative effect between the transient directing group and external pyridone ligands in HFIP solvent medium. In addition, other research groups like Jin, 72 Ge and Li, 73 and Chen in collaboration with He, 74 Wei, 75 and Zhang 76 also contributed with their valuable results to enrich this area. However, the exact role of HFIP in the aforementioned reactions is still unknown, presumably due to the lack of computational and mechanistic studies.…”

Transient Ligand‐Enabled Transition Metal‐Catalyzed C−H Functionalization

“…Moreover, our strategy could also be used for the unsymmetric double C−H arylation of ketones. Two different aryl groups were consecutively installed to provide 4‐phenyl‐4‐( p ‐tolyl)butan‐2‐one in 41 % yield (isolated product) by employing a transient ligand β‐alanine (Scheme b) …”

“…Twod ifferent aryl groups were consecutively installed to provide 4-phenyl-4-(p-tolyl)butan-2-one in 41 % yield (isolated product) by employingatransientl igand b-alanine (Scheme 16 b). [32] Lin, Wei, and co-workers also carriedo ut Pd-catalyzed direct inert C(sp 3 )ÀHb ond functionalization of aliphatic ketones by using 2-amino-N-isopropyl-acetamide as an ovel transient ligand via a N,N-bidentatePd-intermediate (Scheme 17). [31a] The formation of ar eversible enamine could also be used in the functionalization of ketones through the transient ligand strategy.I n2 012, Dong and co-workersr eported the regioselective a-CÀHb ond alkylation of ketones with simple olefins by using stoichiometric amounts of 2-aminopyridine (L30)a sa Scheme14.…”

Synthesis and Catalytic Application of Knölker-Type Iron Complexes with a Novel Asymmetric Cyclopentadienone Ligand Design

“…Such dialkyne pre-ligands can be obtained via coupling reactions of enantiopure terminal alkynes (9) with a dihalide (10) [61][62][63][64]. Although syntheses of compounds in accordance with the structure of 6 have been reported [65,66], the acquisition of such diastereopure product in decent yields remains a significant challenge. On the contrary, enantiopure terminal alkynes are easier to synthesize, because they possess only one chiral center, and are readily available from commercial sources.…”