Oxidative C−H/C−H Cross‐Coupling Reactions between N‐Acylanilines and Benzamides Enabled by a Cp*‐Free RhCl₃/TFA Catalytic System

Abstract

By making use of a dual-chelation-assisted strategy, a completely regiocontrolled oxidative C-H/C-H cross-coupling reaction between an N-acylaniline and a benzamide has been accomplished for the first time. This process constitutes a step-economic and highly efficient pathway to 2-amino-2'-carboxybiaryl scaffolds from readily available substrates. A Cp*-free RhCl /TFA catalytic system was developed to replace the [Cp*RhCl ] /AgSbF system generally used in oxidative C-H/C-H cross-coupling reactions between two (hetero)arenes (Cp*=pentamethylcyclopentadienyl, TFA=trifluoroacetic acid). The RhCl /TFA system avoids the use of the expensive Cp* ligand and AgSbF . As an illustrative example, the procedure developed herein greatly streamlines the total synthesis of the naturally occurring benzo[c]phenanthridine alkaloid oxynitidine, which was accomplished in excellent overall yield.

Recent advances in rhodium-catalysed cross-dehydrogenative-coupling between two C(sp2)–H bonds

“…62 Later, the same group established the first general CDC reaction of N-acylaniline and benzamide by employing a RhCl 3 /TFA catalyst system (Scheme 45a). 63 In particular, the total synthesis of oxynitidine was also illustrated. The RhCl 3catalysed CDC reaction of aniline derivatives for affording 2,2′diaminobiaryls was further shown in 2019 (Scheme 45b).…”

Copper-catalyzed remote C–H arylation of polycyclic aromatic hydrocarbons (PAHs)

“…The direct C7−H arylation of 1-naphthoic acid derivatives is undoubtedly a more effective route for the synthesis of 7-arylnaphthalene derivatives. Although the transition metal-catalyzed C2−H and C8−H arylations of 1-naphthoic acid derivatives have been widely reported, the studies on their C7−H arylation remain rare [18][19][20][21][22][23][24][25]. Our group has recently reported F + reagent-promoted Pd-catalyzed C7-H arylation of 1-naphthamides, but this method still suffers from a few disadvantages (Scheme 1) [26].…”

“…As a component part of our ongoing research on direct C-H bond functionalization [20,[27][28][29], we herein represent a copper-catalyzed remote C-H arylation of PAHs with aryliodonium salts as arylating reagents (Scheme 1). This protocol is compatible with different PAH substrates including 1-naphthamides, phenanthrene-9-carboxamide, pyrene-1-carboxamide and fluoranthene-3-carboxamide, which provides an opportunity for the development of diverse organic photoelectrical materials.…”

Copper-Catalyzed Remote C–H Arylation of Polycyclic Aromatic Hydrocarbons (PAHs)

“…Although the transition metal-catalyzed C2−H and C8−H arylations of 1-naphthoic acid derivatives have been widely reported, the studies on their C7−H arylation remain rare. [18][19][20][21][22][23][24][25] Our group has recently reported F + reagent-promoted Pd-catalyzed C7-H arylation of 1-naphthamides, but this method still suffers from a few disadvantages (Scheme 1). [26] First, precious metal palladium is employed as a catalyst.…”

“…In addition, this protocol is not compatible with other PAHs except naphthalene, such as phenanthrene, pyrene and fluoranthene, and cannot tolerate some special functional groups, such as alkenyl and alkynyl groups. As a component part of our ongoing research on direct C-H bond functionalization, [20,[27][28][29] we herein represent a copper-catalyzed remote C-H arylation of PAHs with aryliodonium salts as arylating reagents (Scheme 1). This protocol is compatible with different PAH substrates including 1-naphthamides, phenanthrene-9-carboxamide, pyrene-1carboxamide and fluoranthene-3-carboxamide, which provides an opportunity for the development of diverse organic photoelectrical materials.…”