Pd/Cu-Catalyzed aerobic oxidative aromatic C-H bond activation/N-dealkylative carbonylation towards the synthesis of phenanthridinones

Article abstract of DOI:10.1039/c6cc08701a

It is important to achieve diverse functionalization of tertiary anilines due to their importance in biological molecules, pharmaceutical, functional materials, and ligands. A straightforward Pd/Cu-catalyzed oxidative C-H bond activation/N-dealkylative carbonylation of tertiary [1,1′-biphenyl]-2-anilines towards the synthesis of various biologically important phenanthridin-6(5H)-ones has been developed. A wide range of functional groups are well tolerated in this transformation. Moreover, O₂ is utilized as the terminal oxidant to promote the oxidative carbonylation process.

Full text of DOI:10.1039/c6cc08701a

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Marilyn M. Olmstead, Alan L. Balch, Josep M. Poblet, Luis Echegoyenet al.
Reactivity differences of Sc
first methanofullerene derivatives of Sc
3
N@C2n (2n
=
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Pd/Cu-Catalyzed Aerobic Oxidative Aromatic C-H Bond
Activation/N-Dealkylative Carbonylation towards the Synthesis of
Phenanthridinones
Received 00th January 20xx,
Accepted 00th January 20xx
a
a
a
a, b
DOI: 10.1039/x0xx00000x
Renyi Shi, Huiying Niu, Lijun Lu and Aiwen Lei*
www.rsc.org/
It is important to achieve diverse functionalization of tertiary prepared tertiary o-arylanilines and CO.
anilines due to its importance in biological molecules,
Scheme 1.
pharmaceutical, function materials, ligands. A straightforward
O
Pd/Cu-catalyzed oxidative C-H bond activation/N-dealkylative
O
O
O
O
O
carbonylation of tertiary [1, 1'-biphenyl]-2-anilines towards the
synthesis of various biologically important phenanthridin-6(5H)-
ones has been developed. A wide range of functional groups are
N
N
O
O
well tolerated in this transformation. Moreover, O
2
is utilized as
N-methylcrinasiadine
oxysanguinarine
the terminal oxidant to promote the oxidative carbonylation
process.
O
O
Tertiary anilines represent not only core structures in biological
N
N
N
O
1
molecules, pharmaceutical, function materials and ligands, but also
O
readily accessible starting materials and important building blocks in
Fantridone
N-isopentylcrinasiadine
2
3
organic synthesis. Recently, C-N bond activation has attracted
more attention and become a hot research topic which provide us a
novel tool to achieve the modification of tertiary anilines. To the best
of our knowledge, most C-N bond activation of anilines focused on
Our experiment study was initiated by treating N, N-dimethyl-[1,
'-biphenyl]-2-anilines (1a) in the presence of 1 atm CO/O gas
mixture (Table 1). By optimizing various reaction parameters, we
found the best results with the combination of a catalytic amount of
PdCl , Cu(OAc) •H O, AcOH in a mixed solvent of toluene and
1
2
2
the cross-coupling of Csp -N bond with organometallic reagents, and
4
2
2
2
electrophilic cyclization. It still remains a great challenge to achieve
o
2
DMA using O as the terminal oxidant at 110 C. Under the
diverse functionalization of tertiary anilines. According to our
5
optimized conditions, a 80% yield of N-methylphenanthridin-6(5H)-
one (2a) was obtained after 24 h. No product was detected without
the assistance of copper or palladium catalysts (Table 1, entries 2
and 3). Replacing PdCl with PdCl (PPh ) or Pd(OAc) diminished
2 2 3 2 2
the reaction yield (Table 1, entries 4 and 5). Additionally, anhydrous
Cu(OAc) and Cu(OPiv) showed lower efficiency as well (Table 1,
previous work, it is reliable and efficient to combine the C-N bond
activation with C-H oxidative carbonylation to construct important
amide derivatives. As a new protocol on the rise, the C-H
carbonylation is now widely recognized as a very important and
potential tool in organic chemistry, which meets the requirement of
6
2
2
“
atom economy” and “green chemistry”. We envisage that
2
entries 6 and 7). The use of CO/air instead of CO/O afforded much
phenanthridinone scaffold could be readily constructed starting from
o-arylanilines via Pd/Cu-catalyzed aerobic oxidative aromatic C-H
bond activation/N-dealkylative carbonylation.
less desired carbonylation product (Table 1, entry 8). When DMA
was removed, only trace amount of the desired product could be
detected (Table 1, entry 9). The variation of the mixed solvent also
Phenanthridinone is an important scaffold found in many natural led to lower yields (Table 1, entries 10 and 11). Inferior result was
products and synthetic compounds with various biological activities acquired with a decreased reaction temperature (Table 1, entry 12).
7
(
Scheme 1). Consequently, considerable efforts have been made to Without AcOH, only 42% yield of N-methylphenanthridin-6(5H)-
develop efficient methods for the synthesis of phenanthridinone one was obtained (Table 1, entry 13).
derivatives. However, most of these methods involve multistep
8
Table 1. Palladium / copper-catalyzed oxidative intramolecular N-
dealkylative carbonylation of 1a: effects of reaction parameters
procedures under harsh reaction conditions. Through our protocol,
phenanthridinones could be constructed in one step from easily
[
a]
Entry Variation from "standard conditions"
Yield%
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1
2
3
4
5
6
7
8
9
1
1
1
1
none
80(75)
0
2 2
No Cu(OAc) •H O
No PdCl
Pd(OAc)
PdCl (PPh
Cu(OAc)
Cu(OPiv)
CO/air = 3/ 1
2
0
2
instead of PdCl
instead of PdCl
instead of Cu(OAc)
instead of Cu(OAc)
2
17
69
70
69
40
0
2
3
)
2
2
2
2
•H
2
O
2
2
•H
2
O
1.0 mL toluene instead of mixed solvent
0.2 mL DMSO instead of DMA
0.2 mL DMF instead of DMA
0
1
2
3
68
57
52
42
o
o
90 C instead of 110 C
No AcOH
[
a] Standard reaction conditions : 1a (0.2 mmol), PdCl
2 2 2
(10 mol%), Cu(OAc) •H O
o
(
30 mol%), AcOH (40 mol%), CO/O =2/1, toluene/DMA =1.0/0.2, 110 C, 24 h.
2
The yields were determined by GC, and were calibrated using biphenyl as the
internal standard.
Scheme 2. Palladium/copper-catalyzed intramolecular oxidative N-
dealkylative carbonylation of tertiary biphenyl-2-anilines 1.
1
2 2 2 2
(0.2 mmol), PdCl (10 mol%), Cu(OAc) •H O (30 mol%), AcOH (40 mol%), CO/O =
o
a
2
/1, toluene/DMA =1.0/0.2, 110 C, 24 h. Isolated yield. N, N-diethyl-[1, 1'-biphenyl]-
b
2
c
-amine as the substrate. N-methyl-N-ethyl-[1, 1'-biphenyl]-2-amine as the substrate.
N, N-dibenzyl-[1, 1'-biphenyl]-2-amine as the substrate.
Furthermore, this protocol could also be applied to tertiary
biphenyl-2-anilines with substitutes on the other benzene ring
Scheme 3). Halogens like -F, -Cl are well tolerated, which provided
(
the opportunities of further functionalization (2j and 2k). The
reaction underwent smoothly to give the corresponding lactams in
high yields with electron-rich groups (2m and 2n). When electron
deficient N, N-dimethyl-4'-(trifluoromethyl)biphenyl-2-amine was
used, 40% yield of desired product was obtained (2l). The position
of the substituted groups have little influence on this reaction (2o
and 2p). In addition, the carbonylation product was attained in
moderate to good yield by utilizing N, N-dimethyl-2-(naphthalen-1-
yl)aniline (2q).
Scheme 4 Application of palladium/copper-catalyzed intramolecular
oxidative N-dealkylative carbonylation
1
(0.2 mmol), PdCl
2 2 2 2
(10 mol%), Cu(OAc) •H O (30 mol%), AcOH (40 mol%), CO/O =2/1,
o
toluene/DMA =1.0/0.2, 110 C, 24 h. Isolated yield.
With the optimized conditions in hand, the carbonylation of a
variety of tertiary [1, 1'-biphenyl]-2-anilines was tested (Scheme 2).
In general, electron-donating substituents on aniline ring of
biphenyl-2-amine derivatives were well tolerated under the current
conditions (2b, 2c and 2d). The site of methyl has less influence on
the yield. On the other hand, strong electron-withdrawing groups
lowered the yield (2e and 2f). Substrate substituted with halogens
including Cl and Br furnished the corresponding carbonylation
products in good yields (2g, 2h and 2i), which can provide useful
handles for further synthetic transformations.
When N, N-diethyl-[1, 1'-biphenyl]-2-amine 1r was utilized as the
substrate, the desired product could be obtained in 72% yield
(
2
Scheme 3). While the standard reaction of tertiary [1, 1'-biphenyl]-
-anilines 1s gave the mixture of 2r/2a(1.15/1) which indicated that
Scheme 3. Palladium/copper-catalyzed intramolecular oxidative N- methyl group was easier to remove. On the other hand, when we
dealkylative carbonylation of biphenyl-2-amine derivatives 1.
used N, N-dibenzyl-[1, 1'-biphenyl]-2-amine 1t as the substrate, only
5% desired product was obtained. At the meantime, we got 65%
3
benzaldehyde as the by-product which showed that the alkyl group
was transferred to aldehyde after C-N bond activation. After testing
different heteroaryl substituted tertiary anilines N, N-dimethyl-2-
(
thiophen-2-yl)aniline and 2-(furan-2-yl)-N, N-dimethylaniline, we
get 35% and 47% yields respectively.
2
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To demonstrate the utility of this new protocol, we also developed
a short route toward N-methylcrinasiadine, one of the important
alkaloids derived from amaryllidaceae which might have
Notes and references
cytotoxicities. According to the previous works, multistep 1. (a)D. W. Old, J. P. Wolfe and S. L. Buchwald, J. Am. Chem. Soc.
,
procedures under harsh reaction conditions or complex substrates
were involved. Through our protocol, we could achieve this product
in 70% yield form easy-prepared corresponding tertiary aniline
1998, 120, 9722-9723; (b)A. Aranyos, D. W. Old, A. Kiyomori, J. P.
Wolfe, J. P. Sadighi and S. L. Buchwald, J. Am. Chem. Soc., 1999,
9
1
21, 4369-4378; (c)M. C. Harris, O. Geis and S. L. Buchwald, J.
(
Scheme 4).
Org. Chem., 1999, 64, 6019-6022; (d)J. P. Wolfe, R. A. Singer, B.
H. Yang and S. L. Buchwald, J. Am. Chem. Soc., 1999, 121, 9550-
Based on the above observations and previous reports, we
proposed the following catalytic cycle for this intramolecular
oxidative C-H bond activation/N-dealkylative carbonylation reaction
9
561.
(a)Z. Li and C.-J. Li, J. Am. Chem. Soc., 2004, 126, 11810-11811;
b)S.-I. Murahashi, T. Nakae, H. Terai and N. Komiya, J. Am. Chem.
2
.
(
Scheme 5). Taking the reaction of 1a as an example, the Pd-
(
catalyzed aerobic C-N bond activation of 1a slowly releases the
intermediate I(SI). Then, Pd(II) complex I undergoes sequential CO
insertion to generate the key intermediate II, followed by oriented C-
H bond activation to achieve seven-membered palladacycle III.
Finally, reductive elimination occurs to form the product 2a, and
Soc., 2008, 130, 11005-11012; (c)Y.-D. Du, C.-W. Tse, Z.-J. Xu, Y.
Liu and C.-M. Che, Chem. Commun., 2014, 50, 12669-12672; (d)S.
S. Kahandal, S. R. Kale, M. B. Gawande, R. Zboril, R. S. Varma and
R. V. Jayaram, RSC Adv., 2014,
Sedrpoushan, P. Mohammadi, A. R. Faraji and S. Sajjadifar, RSC
Adv., 2014, , 25898-25903; (f)R. K. Kawade, D. B. Huple, R.-J. Lin
and R.-S. Liu, Chem. Commun., 2015, 51, 6625-6628; (g)Y. Tan, W.
Yuan, L. Gong and E. Meggers, Angew. Chem. Int. Ed., 2015, 54
3045-13048; (h)T. Hering, B. Mühldorf, R. Wolf and B. König,
4, 6267-6274; (e)H. Veisi, A.
2
releases the Pd(0) species, which is re-oxidized by O with the
assistance of the copper co-catalyst to regenerate Pd(II) complex.
4
Scheme 5 Proposed mechanism
,
1
Angew. Chem. Int. Ed., 2016, 55, 5342-5345; (i)N. Kennedy, P. Liu
and T. Cohen, Angew. Chem. Int. Ed., 2016, 55, 383-386; (j)N.
Koukabi, S. Otokesh, E. Kolvari and A. Amoozadeh, Dyes Pigments
016, 124, 12-17.
. (a)R. M. Laine, D. W. Thomas and L. W. Cary, J. Am. Chem. Soc.
,
2
3
,
1
982, 104, 1763-1765; (b)E. I. Solomon, U. M. Sundaram and T. E.
Machonkin, Chem. Rev., 1996, 96, 2563-2606; (c)M. Gandelman
and D. Milstein, Chem. Commun. 2000, 1603-1604; (d)T.
,
Hosokawa, T. Kamiike, S.-I. Murahashi, M. Shimada and T.
Sugafuji, Tetrahedron Lett., 2002, 43, 9323-9325; (e)B. Zou, H.-F.
Jiang and Z.-Y. Wang, Eur. J. Org. Chem., 2007, 2007, 4600-4604;
(
f)S. Guo, B. Qian, Y. Xie, C. Xia and H. Huang, Org. Lett., 2010,
, 522-525; (g)J. Luo, M. Wu, F. Xiao and G. Deng, Tetrahedron
1
3
Lett., 2011, 52, 2706-2709; (h)X. Zhao, D. Liu, H. Guo, Y. Liu and
W. Zhang, J. Am. Chem. Soc., 2011, 133, 19354-19357; (i)Y. Xie, J.
Hu, Y. Wang, C. Xia and H. Huang, J. Am. Chem. Soc., 2012, 134
,
,
Conclusions
2
0613-20616; (j)J. Hu, Y. Xie and H. Huang, Angew. Chem. Int. Ed.
In conclusion, we have developed a novel palladium/copper-
catalyzed intramolecular aerobic oxidative C-H bond activation/N-
dealkylative carbonylation reaction of tertiary biphenyl-2-amines.
This transformation provides an effective and straightforward
protocol towards the synthesis of biologically and synthetically
useful phenanthridinones from widely available substrates. Moderate
to good yields were obtained and a variety of functional groups were
2014, 53, 7272-7276; (k)K. Ouyang, W. Hao, W.-X. Zhang and Z.
Xi, Chem. Rev., 2015, 115, 12045-12090; (l)G. Zhang, B. Gao and
H. Huang, Angew. Chem. Int. Ed., 2015, 54, 7657-7661; (m)Q.
Wang, Y. Su, L. Li and H. Huang, Chem. Soc. Rev., 2016, 45, 1257-
1
272; (n)R. Shi, H. Zhang, L. Lu, P. Gan, Y. Sha, H. Zhang, Q. Liu,
M. Beller and A. Lei, Chem. Commun., 2015, 51, 3247-3250.
tolerated as well. Therefore, we anticipate that this work will 4. (a)S. B. Blakey and D. W. C. MacMillan, J. Am. Chem. Soc., 2003,
contribute substantially to the development of next generation
carbonylation of amines.
1
25, 6046-6047; (b)J. Shearer, C. X. Zhang, L. Q. Hatcher and K. D.
Karlin, J. Am. Chem. Soc., 2003, 125, 12670-12671; (c)D. Yue and
R. C. Larock, Org. Lett., 2004, , 1037-1040; (d)S. Ueno, N. Chatani
6
Acknowledgement
and F. Kakiuchi, J. Am. Chem. Soc., 2007, 129, 6098-6099; (e)Y.
Kuninobu, M. Nishi and K. Takai, Chem. Commun., 2010, 46, 8860-
This work was supported by the National Natural Science
Foundation of China (21390400, 21520102003, 21272180,
8
862; (f)L.-G. Xie and Z.-X. Wang, Angew. Chem. Int. Ed., 2011,
, 4901-4904; (g)B. Yao, Q. Wang and J. Zhu, Angew. Chem. Int.
21302148), the Hubei Province Natural Science Foundation of China
5
0
(2013CFA081), the Research Fund for the Doctoral Program of
Higher Education of China (20120141130002), and the Ministry of
Science and Technology of China (2012YQ120060). The Program
of Introducing Talents of Discipline to Universities of China (111
Program) is also appreciated.
Ed., 2012, 51, 12311-12315; (h)B. Yao, Q. Wang and J. Zhu, Angew.
Chem. Int. Ed., 2012, 51, 5170-5174; (i)X.-F. Xia, L.-L. Zhang, X.-
R. Song, Y.-N. Niu, X.-Y. Liu and Y.-M. Liang, Chem. Commun.
013, 49, 1410-1412; (j)B. Yao, Q. Wang and J. Zhu, Angew. Chem.
Int. Ed., 2013, 52, 12992-12996; (k)W. Hao, W. Geng, W.-X. Zhang
,
2
This journal is © The Royal Society of Chemistry 20xx
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Journal Name
and Z. Xi, Chem. Eur. J., 2014, 20, 2605-2612; (l)J. Sheng, S. Li and
J. Wu, Chem. Commun., 2014, 50, 578-580.
Asian J., 2016, 11, 1883-1886; (j)M. Feng, B. Tang, H.-X. Xu and
X. Jiang, Org. Lett., 2016, 18, 4352-4355.
5
6
.
.
R. Shi, L. Lu, H. Zhang, B. Chen, Y. Sha, C. Liu and A. Lei, Angew.
Chem. Int. Ed., 2013, 52, 10582-10585.
(a)Q. Liu, G. Li, J. He, J. Liu, P. Li and A. Lei, Angew. Chem. Int.
Ed., 2010, 49, 3371-3374; (b)H. Zhang, D. Liu, C. Chen, C. Liu and
A. Lei, Chem. Eur. J., 2011, 17, 9581-9585; (c)Q. Liu, H. Zhang and
A. Lei, Angew. Chem. Int. Ed., 2011, 50, 10788-10799; (d)H. Zhang,
R. Shi, P. Gan, C. Liu, A. Ding, Q. Wang and A. Lei, Angew. Chem.
Int. Ed., 2012, 51, 5204-5207; (e)X. Fang, R. Jackstell and M.
Beller, Angew. Chem. Int. Ed., 2013, 52, 14089-14093; (f)X.-F. Wu,
H. Neumann and M. Beller, ChemSusChem, 2013, 6, 229-241; (g)W.
Li, C. Liu, H. Zhang, K. Ye, G. Zhang, W. Zhang, Z. Duan, S. You
and A. Lei, Angew. Chem. Int. Ed., 2014, 53, 2443-2446; (h)L.
Wang, Y. Wang, C. Liu and A. Lei, Angew. Chem. Int. Ed., 2014,
53, 5657-5661; (i)A. McNally, B. Haffemayer, B. S. L. Collins and
M. J. Gaunt, Nature, 2014, 510, 129-133; (j)S. Li, G. Chen, C.-G.
Feng, W. Gong and J.-Q. Yu, J. Am. Chem. Soc., 2014, 136, 5267-
5
270; (k)W. Li, Z. Duan, X. Zhang, H. Zhang, M. Wang, R. Jiang,
H. Zeng, C. Liu and A. Lei, Angew. Chem. Int. Ed., 2015, 54, 1893-
896.
1
7
.
(a)J.-H. Li, L. Serdyuk, D. V. Ferraris, G. Xiao, K. L. Tays, P. W.
Kletzly, W. Li, S. Lautar, J. Zhang and V. J. Kalish, Biorg. Med.
Chem. Lett., 2001, 11, 1687-1690; (b)Z. Tu, W. Chu, J. Zhang, C. S.
Dence, M. J. Welch and R. H. Mach, Nucl. Med. Biol., 2005, 32
37-443; (c)S. Patil, S. Kamath, T. Sanchez, N. Neamati, R. F.
Schinazi and J. K. Buolamwini, Biorg. Med. Chem., 2007, 15, 1212-
228; (d)D. C. Hegan, Y. Lu, G. C. Stachelek, M. E. Crosby, R. S.
Bindra and P. M. Glazer, Proc. Natl. Acad. Sci., 2010, 107, 2201-
206.
(a)Q. J. Zhou, K. Worm and R. E. Dolle, J. Org. Chem., 2004, 69
147-5149; (b)M. A. Yawer, I. Hussain, I. Iqbal, A. Spannenberg
,
4
1
2
8
.
,
5
and P. Langer, Tetrahedron Lett., 2008, 49, 4467-4469; (c)S.
Pimparkar and M. Jeganmohan, Chem. Commun., 2014, 50, 12116-
1
1
2119; (d)S.-M. Lu and H. Alper, J. Am. Chem. Soc., 2005, 127
,
4776-14784; (e)D. Liang, Z. Hu, J. Peng, J. Huang and Q. Zhu,
Chem. Comm., 2013, 49, 173-175; (f)R. G. G. Leenders and H. W.
Scheeren, Tetrahedron Lett., 2000, 41, 9173-9175; (g)T. Harayama,
H. Akamatsu, K. Okamura, T. Miyagoe, T. Akiyama, H. Abe and Y.
Takeuchi, J. Chem. Soc., Perkin Trans. 1, 2001, 523-528; (h)M.
Feng, B. Tang, N. Wang, H.-X. Xu and X. Jiang, Angew. Chem. Int.
Ed., 2015, 54, 14960-14964; (i)T. Cailly, F. Fabis and S. Rault,
Tetrahedron, 2006, 62, 5862-5867; (j)B. O. Ashburn, R. G. Carter
and L. N. Zakharov, J. Org. Chem., 2008, 73, 7305-7309.
9
.
(a)G. Cahiez, C. Chaboche, F. Mahuteau-Betzer and M. Ahr, Org.
Lett., 2005,
T. Sato, T. Miyagoe, H. Abe and Y. Takeuchi, Tetrahedron Lett.
005, 46, 6091-6094; (c)R. Sanz, Y. Fernandez, M. P. Castroviejo,
A. Perez and F. J. Fananas, Eur. J. Org. Chem., 2007, 2007, 62-69;
d)C. S. Yeung, X. Zhao, N. Borduas and V. M. Dong, Chem. Sci.
010, , 331-336; (e)T. Harayama, C. Nagura, T. Miyagoe, Y.
Kawata, H. Abe and Y. Takeuchi, Heterocycles, 2010, 81, 2609-
7, 1943-1946; (b)T. Harayama, Y. Kawata, C. Nagura,
,
2
(
,
2
1
2
2
616; (f)S.-K. Hua, Q.-P. Hu, J. Ren and B.-B. Zeng, Synthesis
,
013, 45, 518-526; (g)S. Pimparkar and M. Jeganmohan, Chem.
Commun., 2014, 50, 12116-12119; (h)M. Feng, B. Tang, N. Wang,
H.-X. Xu and X. Jiang, Angew. Chem., Int. Ed., 2015, 54, 14960-
1
4964; (i)W. Shen, J. Li, C. Zhang, M. Shi and J. Zhang, Chem. -
4
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