Palladium-catalyzed phosphination and amination through C–H bond functionalization on biphenyl: Amido-substituent as directing group

Article abstract of DOI:10.1016/j.tet.2018.12.007

The formation of N-(2’-(diphenylphosphoryl)-[1,1′-biphenyl]-2-yl)-2,3,4,5,6-pentafluorobenzamide (3_eaaa) has been achieved through the palladium-catalyzed and Ag(I)-assisted C–H functionalization of N-([1,1′-biphenyl]-2-yl)-2,3,4,5,6-pentafluorobenzamide

Full text of DOI:10.1016/j.tet.2018.12.007

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Palladium-catalyzed phosphination and amination through C-H bond functionalization
on biphenyl: Amido-substituent as directing group
I-Hsiang Kao, Ching-Yu Wang, Yu-Chang Chang, Chu-Lun Wu, Yu-Jen Chiu, Fung-E.
Hong
PII:
S0040-4020(18)31472-8
https://doi.org/10.1016/j.tet.2018.12.007
TET 29993
DOI:
Reference:
To appear in: Tetrahedron
Received Date: 29 September 2018
Revised Date: 9 November 2018
Accepted Date: 4 December 2018
Please cite this article as: Kao I-H, Wang C-Y, Chang Y-C, Wu C-L, Chiu Y-J, Hong F-E, Palladium-
catalyzed phosphination and amination through C-H bond functionalization on biphenyl: Amido-
substituent as directing group, Tetrahedron (2019), doi: https://doi.org/10.1016/j.tet.2018.12.007.
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Graphical Abstract
Palladium-Catalyzed Phosphination and Amination through C-H Bond Functionalization
on Biphenyl: Amido-substituent as Directing Group
I-Hsiang Kao,a Ching-Yu Wang,a Yu-Chang Chang,b Chu-Lun Wu,b Yu-Jen Chiu,a and Fung-E
Honga*
a Department of Chemistry, National Chung Hsing University,
250 Kuo-Kuang Road, Taichung 40227, Taiwan
E-mail: fehong@dragon.nchu.edu.tw
b Department of Applied Chemistry, Providence University,
200, Sec. 7, Taiwan Boulevard, Shalu Dist., Taichung City 43301, Taiwan
E-mail: vickchang@pu.edu.tw
The reaction of amido-substituted biphenyl compound 1 with SPO 2 yields SPO-attached
product 3 or carbazole product 4.

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Palladium-Catalyzed Phosphination and Amination through C-H Bond
Functionalization on Biphenyl: Amido-substituent as Directing Group
I-Hsiang Kao,a Ching-Yu Wang,a Yu-Chang Chang,b Chu-Lun Wu,b Yu-Jen Chiu,a and
Fung-E Honga*
a Department of Chemistry, National Chung Hsing University,
250 Kuo-Kuang Road, Taichung 40227, Taiwan
E-mail: fehong@dragon.nchu.edu.tw
b Department of Applied Chemistry, Providence University,
200, Sec. 7, Taiwan Boulevard, Shalu Dist., Taichung City 43301, Taiwan
E-mail: vickchang@pu.edu.tw
* Author to whom correspondence should be addressed.
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Abstract
The formation of
N-(2'-(diphenylphosphoryl)-[1,1'-biphenyl]-2-yl)-2,3,4,5,6-pentafluorobenzamide
(3_eaaa) has been achieved through the palladium-catalyzed and Ag(I)-assisted C-H
functionalization of N-([1,1'-biphenyl]-2-yl)-2,3,4,5,6-pentafluorobenzamide (1_eaa)
via phosphination and in the presence of diphenylphosphine oxide (2_a). The reaction
was accompanied with small amount of carbazole derivative,
(9H-carbazol-9-yl)(perfluorophenyl)methanone (4_eaa). Crystal structures of 3_eaaa
and 4_eaa were both determined by X-ray crystal diffraction methods. Indeed,
phosphination took place at the ortho-position of inter-annular ring of 1_eaa.
Substituents with various electron-withdrawing/donating capacities on the
amido-fragment of 1 were found to greatly affect the ratio distribution of products 3
and 4. By contrast, substituents on various locations of the biphenyl in 1 do not
influence much on the outcome of the products distribution. A reaction mechanism is
proposed to account for these experimental observations. Computational studies
employing Density Functional Theory methods (DFT) on this proposed mechanism
found that the electron density property of the palladium metal center in the
intermediate II is critical to the formation of either 3 or 4. A relatively electron-poor
palladium metal center favors the pathway of forming 3. On the contrary, the pathway
of producing 4 will be prevailed while the palladium metal center is having fair
amount of electron-density in the proposed intermediate II.
Keywords: C-H activation & functionalization; Directing group; Acetamide;
Secondary phosphine oxide; Carbazole; Palladium; Density Functional Theory
methods.
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