Arylations of Arenes

However, given that transition metal catalysis had arguably the strongest impact through the development of efficient methods for bi(hetero)aryl formations, we focus here largely on C—H bond functionalizations for catalytic direct arylations of (hetero) arenes [24]. 

The development of methods for the synthesis of compounds with aryl-aryl or aryl-heteroaryl moieties is of the utmost importance for modern organic synthesis, 

Oxidative direct arylations with organometallic reagents 

Direct arylations with aryl (pseudo)halides 

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Scheme 6.11 Arylation of arenes catalyzed by FeCI3 under microwave irradiation. o m p = 12 3 85.

The first case involves direct arylation of arenes with aryl halides via a Pd(0)/Pd (II) cycle (Scheme 8). After initial oxidative addition of Pd(0) into the aryl halide, the C-H bond activation event takes place at the Ar-Pd(II)-X species 4 and is followed by C-C bond forming reductive elimination and regeneration of Pd(0). 

Abstract A review is presented of synthetic methods for the preparation of biaryls by the rhodium-catalyzed C-H bond arylation of arenes with aryl halides (C-H/ C-X couplings), arylmetal reagents (C-H/C-M couplings) and arenes (C-H/C-H couplings), with an emphasis on postulated mechanisms and their implications on reactivity, selectivity and substrate scope. 

Rh-Catalyzed C-H/C-X Arylation of Arenes Through Electrophilic Metalation. 235... 

Scheme 4 General scheme for C-H/C-X arylation of arenes through electrophilic metalation...

Scheme 13 General catalytic cycle for the C-H arylation of arenes through iV-heterocyclic carbene formation [97-104]...

A number of research groups have developed rhodium-catalyzed methods for the C-H bond arylation of arenes that likely proceed through cyclometalated intermediates. Aryl phosphites and phosphinites undergo facile orthometalation... 

Scheme 25 Rh-catalyzed decarbonylative directed C-H arylation of arenes by Zhao and Yu [118]...

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