β-Arylation of Carboxamides via Iron-Catalyzed C(sp³)–H Bond Activation

Abstract

A 2,2-disubstituted propionamide bearing an 8-aminoquinolinyl group as the amide moiety can be arylated at the β-methyl position with an organozinc reagent in the presence of an organic oxidant, a catalytic amount of an iron salt, and a biphosphine ligand at 50 °C. Various features of selectivity and reactivity suggest the formation of an organometallic intermediate via rate-determining C-H bond cleavage rather than a free-radical-type reaction pathway.

Stereoselective Synthesis of Chiral α‐Amino‐β‐Lactams through Palladium(II)‐Catalyzed Sequential Monoarylation/Amidation of C(sp3)H Bonds

“…The asymmetric methods used include the Staudinger ketene-imine [2+2] cycloaddition, Kinugasa alkyne-nitrone cycloaddition, and Gilman-Speeter ester enolate-imine condensation. [1] The seminal work of Daugulis and co-workers on the palladium-catalyzed arylation of secondary C(sp 3 ) À H bonds with an 8-aminoquinoline-derived N,N-bidentate directing group [2] has inspired several research groups to use this type of auxiliary to develop a diverse collection of novel C(sp 3 )ÀH functionalization reactions. [3] Moreover, this chemistry has been applied in the total synthesis of natural products.…”

“…[1] The seminal work of Daugulis and co-workers on the palladium-catalyzed arylation of secondary C(sp 3 ) À H bonds with an 8-aminoquinoline-derived N,N-bidentate directing group [2] has inspired several research groups to use this type of auxiliary to develop a diverse collection of novel C(sp 3 )ÀH functionalization reactions. [3] Moreover, this chemistry has been applied in the total synthesis of natural products. [4] Encouraged by these elegant studies, we recently developed a modified bidentate pyridine-containing directing group derived from 2-(pyridin-2-yl)isopropylamine.…”

“…[4] Encouraged by these elegant studies, we recently developed a modified bidentate pyridine-containing directing group derived from 2-(pyridin-2-yl)isopropylamine. This directing group exhibited superior reactivity in the activation of methylene C(sp 3 ) À H bonds. For example, the use of the 2-(pyridin-2-yl)isopropyl (PIP) directing group was instrumental in the development of a palladium-catalyzed methylene C(sp 3 )ÀH alkoxylation [Eq.…”

The Use of a Rhodium Catalyst/8-Aminoquinoline Directing Group in the C-H Alkylation of Aromatic Amides with Alkenes: Possible Generation of a Carbene Intermediate from an Alkene

“…26 In subsequent studies, we explored the use of Ni(0), 27 Ru(II), 28 Ni(II), 29 and Rh(I) 30 complexes as catalysts in C-H functionalizations using a bidentate-chelation system. Other groups also reported that various metals, including Cu(II), 31 Fe(ate), 32 Co(II) 33 complexes could also be used in C-H functionalizations using a N,N¤-bidentate-chelation system. Combinations of transition metal catalysts and N,N-bidentate directing groups have emerged as powerful methods for the construction of carboncarbon and carbon-heteroatom bonds through C-H bond cleavage.…”

The Development of Ru(II) and Fe(II) Complexes for C-H and H2 Bond Activation

“…37,38 Designing a catalyst to meet these requirements continues to be an insurmountable goal, though significant progress has been made. In the 1970s, Shilov and co-workers developed a system using water soluble Pt II salts to C-H activate and functionalize alkanes (Scheme 4); 35,[38][39][40] for example, this system can transform methane to methanol and chloromethane under mild conditions. This process involves methane coordination to a [Pt(Cl) 4 ] 2-salt followed by C-H activation to result in a Pt-Me species.…”