Hydroarylations by cobalt-catalyzed C-H activation

Abstract

As an earth-abundant first-row transition metal, cobalt catalysts offer a broad range of economical methods for organic transformations via C-H activation. One of the transformations is the addition of C-H to C-X multiple bonds to afford alkylation, alkenation, amidation, and cyclization products using low- or high-valent cobalt catalysts. This hydroarylation is an efficient approach to build new C-C bonds in a 100% atom-economical manner. In this review, the recent developments of Co-catalyzed hydroarylation reactions and their mechanistic studies are summarized.

Keywords: C–H activation; C−C formation; catalysis; cobalt; hydroarylation.

Scheme 1

Cobalt-catalyzed C–H carbonylation.

Scheme 2

Hydroarylation by C–H activation.

Scheme 3

Pathways for cobalt-catalyzed hydroarylations.

Scheme 4

Co-catalyzed hydroarylation of alkynes with azobenzenes.

Scheme 5

Co-catalyzed hydroarylation of alkynes with 2-arylpyridines.

Scheme 6

Co-catalyzed addition of azoles to alkynes.

Scheme 7

Co-catalyzed addition of indoles to alkynes.

Scheme 8

Co-catalyzed hydroarylation of alkynes with imines.

Scheme 9

A plausible pathway for Co-catalyzed hydroarylation of alkynes.

Scheme 10

Co-catalyzed anti-selective C–H addition to alkynes.

Scheme 11

Co(III)-catalyzed hydroarylation of alkynes with indoles.

Scheme 12

Co(III)-catalyzed branch-selective hydroarylation of alkynes.

Scheme 13

Co(III)-catalyzed hydroarylation of terminal alkynes with arenes.

Scheme 14

Co(III)-catalyzed hydroarylation of alkynes with amides.

Scheme 15

Co(III)-catalyzed C–H alkenylation of arenes.

Scheme 16

Co-catalyzed alkylation of substituted benzamides with alkenes.

Scheme 17

Co-catalyzed switchable hydroarylation of styrenes with 2-aryl pyridines.

Scheme 18

Co-catalyzed linear-selective hydroarylation of alkenes with imines.

Scheme 19

Co-catalyzed linearly-selective hydroarylation of alkenes with N–H imines.

Scheme 20

Co-catalyzed branched-selective hydroarylation of alkenes with imines.

Scheme 21

Mechanism of Co-catalyzed hydroarylation of alkenes.

Scheme 22

Co-catalyzed intramolecular hydroarylation of indoles.

Scheme 23

Co-catalyzed asymmetric hydroarylation of alkenes with indoles.

Scheme 24

Co-catalyzed hydroarylation of alkenes with heteroarenes.

Scheme 25

Co(III)-catalyzed hydroarylation of activated alkenes with 2-phenyl pyridines.

Scheme 26

Co(III)-catalyzed C–H alkylation of arenes.

Scheme 27

Co(III)-catalyzed C2-alkylation of indoles.

Scheme 28

Co(III)-catalyzed switchable hydroarylation of alkyl alkenes with indoles.

Scheme 29

Co(III)-catalyzed C2-allylation of indoles.

Scheme 30

Co(III)-catalyzed ortho C–H alkylation of arenes with maleimides.

Scheme 31

Co(III)-catalyzed hydroarylation of maleimides with arenes.

Scheme 32

Co(III)-catalyzed hydroarylation of allenes with arenes.

Scheme 33

Co-catalyzed hydroarylative cyclization of enynes with carbonyl compounds.

Scheme 34

Mechanism for the Co-catalyzed hydroarylative cyclization of enynes with carbonyl compounds.

Scheme 35

Co-catalyzed addition of 2-arylpyridines to aromatic aldimines.

Scheme 36

Co-catalyzed addition of 2-arylpyridines to aziridines.

Scheme 37

Co(III)-catalyzed hydroarylation of imines with arenes.

Scheme 38

Co(III)-catalyzed addition of arenes to ketenimines.

Scheme 39

Co(III)-catalyzed three-component coupling.

Scheme 40

Co(III)-catalyzed hydroarylation of aldehydes.

Scheme 41

Co(III)-catalyzed addition of arenes to isocyanates.