Salicylate‐Directed C−O Bond Cleavage: Iron‐Catalyzed Allylic Substitution with Grignard Reagents

Abstract

Selective CÀOb ond cleavagei so fh igh interest for moderno rganic synthesis. As trategy for selective allylic CÀOb ond cleavage using ethyl salicylate as ad irecting leaving group has been developed. The reactioni si nitiated by the chelation of the ortho-ester phenolic group with iron catalyst. The p-allyl iron intermediate is generated and reacts with Grignardr eagents to give the allylic substitution products. The excellent selectivity of CÀO bond cleavage is achieved in multiple allylic CÀOb ondcontaining substrates with the aid of the salicylate-directed strategy.

Palladium‐Catalyzed Selective Carbofunctionalization of Inert γ‐C(sp3)−O Bonds with 4‐Hydroxypyridin‐2(1H)‐ones and 4‐Hydroxy‐2H‐pyran‐2‐ones

“…Therefore, the development of new strategies to overcome these limitations and realize the functionalization of inert C−O bonds is highly desired. In recent years, the strategy that involves directing group‐assisted regioselective functionalization of C( sp 2 )−O bonds has found great synthetic application value, and great breakthroughs have been achieved in the functionalization of C( sp 2 )−O bonds [6–11] . In contrast, the functionalization of unactivated C( sp 3 )−O bonds is still a particularly difficult challenge owing to their relatively high bond dissociation energy (BDE).…”

“…In recent years, the strategy that involves directing group-assisted regioselective functionalization of C(sp 2 )À O bonds has found great synthetic application value, and great breakthroughs have been achieved in the functionalization of C (sp 2 )À O bonds. [6][7][8][9][10][11] In contrast, the functionalization of unactivated C(sp 3 )À O bonds is still a particularly difficult challenge owing to their relatively high bond dissociation energy (BDE). In a seminal report in 2018, Engle and co-workers explored a new and efficient method to successfully achieve the functionalization of inert C(sp 3 )À O bonds through the cascade of Pd(II)-catalyzed sp 3 CÀ H activation followed by β-O elimination and hydrofunctionalization assisted by the 8-aminoquinolyl directing.…”

Advances in Transition Metal‐Catalyzed Selective Functionalization of Inert C−O Bonds Assisted by Directing Groups

“…Recently, utilizing salicylate as a directing group, Li and co‐workers reported a new strategy to prepare allylic derivatives through Fe‐catalyzed arylation of C−O bonds of phenol allyl ethers with aromatic Grignard reagents (Scheme ) . Both aromatic and alkyl Grignard reagents were compatible in this transformation to react with phenol allyl ethers, giving rise to the corresponding arylated and alkylated products with good chemoselectivity.…”

Cross-Coupling Reaction of Allylic Ethers with Aryl Grignard Reagents Catalyzed by a Nickel Pincer Complex

“…Oshima and Yorimitsu reported a cobalt-catalyzed cross-coupling reaction of allylic ethers with Grignard reagents in a linear manner [8]. Iron catalysts also enable the allylic arylation reaction to be performed [9,10,11,12]. Recently, Ni pincer complexes have been reported as effective catalysts for the coupling reaction of allylic ethers with aryl zinc reagents [13].…”