Cobalt-Catalyzed Directed sp2 C?H Acetoxylation of Arenes Employing Mn(OAc)3 ? 2H2O as Acetoxy Source

Article abstract of DOI:10.1002/adsc.201800398

A cobalt-catalyzed sp² C?H acetoxylation of amides having 8-aminoquinoline as a directing group has been achieved using manganese(III) acetate both as an oxidant and an acetoxy source. Operational simplicity, broad range of functional group tolerance, use of an earth abundant first row transition metal, and, most importantly, exploitation of an unprecedented acetoxy source are the key features. The method is scalable and does not require any additive. The mechanism of the reaction has been established by conducting a series of experiments. (Figure presented.).

Full text of DOI:10.1002/adsc.201800398

Title: Cobalt-Catalyzed Directed sp2 C-H Acetoxylation of Arenes
Employing Mn(OAc)3.2H2O as Acetoxy Source
Authors: Writhabrata Sarkar, Arup Bhowmik, Aniket Mishra, Tripta
Kumari Vats, and Indubhusan Deb
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To be cited as: Adv. Synth. Catal. 10.1002/adsc.201800398
Link to VoR: http://dx.doi.org/10.1002/adsc.201800398

10.1002/adsc.201800398
Advanced Synthesis & Catalysis
COMMUNICATION
DOI: 10.1002/adsc.201((will be filled in by the editorial staff))
Cobalt-Catalyzed Directed sp2 CH Acetoxylation of Arenes
Employing Mn(OAc)3.2H2O as Acetoxy Source
†
†
Writhabrata Sarkar, Arup Bhowmik, Aniket Mishra, Tripta Kumari Vats and
Indubhusan Deb*
a
Organic & Medicinal Chemistry Division, CSIR-Indian Institute of Chemical Biology, 4-Raja S.C. Mullick Road,
Jadavpur, Kolkata 700032, India. Phone: (+91)-33-24995938; Fax (+91)-33-24735197; e-mail:
indubhusandeb@iicb.res.in & indubhusandeb@gmail.com
†
AB and AM contributed equally.
Received:((will be filled in by the editorial staff))
Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/adsc.201######.
Abstract: A cobalt-catalyzed sp2 CH acetoxylation of
amides having 8-aminoquinoline as a directing group has
been achieved using manganese(III) acetate both as an
oxidant and an acetoxy source. Operational simplicity,
broad range of functional group tolerance, use of an earth
abundant first row transition metal, and, most
importantly, exploitation of an unprecedented acetoxy
source are the key features. The method is scalable and
does not require any additive. The mechanism of the
reaction has been established by conducting a series of
experiments.
Very recently, several transformations have been
reported in synthetic organic chemistry which rely on
CH activation using cobalt catalysts in different
oxidation states.[6] Inspired by the pioneering research
reported by Yoshikai using low valent cobalt and by
Kanai using high valent Co(III), various
methodologies have been designed by different
research groups.[7,8] The major problems associated
with these methods are the use of highly reactive
Grignard reagents or expensive Cp* ligands. As an
advancement, Daugulis et al. demonstrated 8-
aminoquinoline[10]
directed
oxidative
alkyne
Keywords: Cobalt; CH bond activation; 8-
aminoquinoline; manganese(III) acetate; acetoxylation
annulations[9a] using easily affordable cobalt salts in
the presence of stoichiometric amounts of an oxidant.
Most of the seminal works in this field concentrate on
direct alkylation, alkenylation, arylation, alkynylation,
cyanation, amination, and sulfenylation.[6-9] Although
CO bond formation by cobalt catalysis has been
recently developed,[11] direct CH acetoxylation still
remains a challenge.
The acetoxy group acts as a functional group
modifier while imparting polar nature to a molecule.
It is ubiquitous in a plethora of pro-drugs, natural
products, antimicrobial agents, and herbicidal
materials.[1] Newer methods of regiospecifically
introducing this group in organic molecules continues
therefore to be of relevance. In this regard, metal
based protocols depending on a suitable directing
group have emerged as useful propositions for direct
and regioselective acetoxylation of relatively inert
CH bonds in atom and step economic manner. Most
of these methods rely on palladium,[2] ruthenium[3]
and rhodium[4] catalysis. Apart from their expensive
nature, the catalysts also suffer from their low earth
abundance as well as bio-incompatibility. Though a
handful of stoichiometric or sub-stoichiometric
copper-mediated acetoxylation methods have also
been reported[5] in the literature (Scheme 1, eq 1), an
efficient catalytic method relying on the cheaper and
earth-abundant first row transition metal catalysts in
place of the expensive second row ones continues to
be highly solicited in organic synthesis.
Scheme 1. Transition metal catalyzed CH acetoxylation
We have recently reported a rhodium-catalyzed
mild CH acetoxylation reaction[4c] as a part of a
continuing research endeavour in transition metal
catalyzed CH functionalizations.[12] Significant
progress has been made exploiting various acetoxy
sources such as Cu(OAc)2, AgOAc, PhI(OAc)2,
1
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10.1002/adsc.201800398
Advanced Synthesis & Catalysis
AcOH etc. However, there is ample scope for
developing complementary methods using a cheap,
benign and new acetoxy source. In an effort to
harness the potential of cobalt catalysis for this task,
we therefore explored an operationally simple cobalt
catalyzed 8-aminoquinoline directed acetoxylation
process, relying on Mn(OAc)3.2H2O to perform both
as an oxidant and an unprecedented acetoxy source
(Scheme 1, eq 2).
An elevated temperature of 100 °C improved the
yield further to 84% (Table 1, entry 14). But
incorporation of various bases such as Na2CO3,
K2CO3, NaOAc, NaOPiv, or NaHCO3 proved to be
ineffective (see SI, Table S1). The use of other
common additives such as AcOH, Ac2O etc was also
not beneficial (see SI, Table S1). Also on performing
the reaction under the standard conditions under an
air atmosphere a slightly lower yield of 80% was
observed (Table 1, entry 15). Various commonly used
bidentate directing groups either did not participate or
showed poor conversion under the optimized
condition (see SI).
Table 1. Optimization of reaction conditions[a]
With the optimized conditions in hand, the scope
of benzamides 1 was then examined (Table 2). In
general, the reactivity of substrates meta-substituted
with electron-donating or electron-withdrawing
groups was marginally higher than that of para-
substituted ones. Electron-withdrawing groups like
fluoro, chloro or bromo in 3-substituted amides of o-
toluic acid gave the desired products 2b-2d in good to
excellent yields (76-87%). However, the nitro
containing substrate 1e underwent moderate
conversion. Electron-donating groups (Me, OMe) at
this position gave satisfactory yield of desired
products 2f-2g, so did various aryl groups carrying
either electron donating or withdrawing substituents
(1h-1l). When we examined the reactivity of different
substituents at para position of amide, both electron
withdrawing (1m-1o) and electron-donating (1p-1q),
the yields continued to be satisfactory. Substrates
having different aryl groups at this position showed
moderate to good conversion (2r-2v). Even the
presence of various functional groups like chloro,
bromo, iodo, trifluoromethyl and phenyl in place of
the ortho methyl group (substrates 1w-1ac) delivered
desired products in moderate to good yields. But
stronger electron-withdrawing groups such as fluoro
and nitro gave lower yields.
Yield[b] of
Entry
[Co]
Solvent
(0.1 M)
(10 mol %)
2a (%)
1
2
3
4
5
6
7
8
Co(acac)2
Co(OAc)2
Co(OAc)2.4H2O MeCN
Co(C2O4).2H2O MeCN
MeCN
MeCN
60
16
13
10
nr
13
64
17
nr
60
53
nr
CoBr2
MeCN
MeCN
DCE
Co(acac)3
Co(acac)2
Co(acac)2
Co(acac)2
Co(acac)2
Co(acac)2
-
Co(acac)2
Co(acac)2
Co(acac)2
TFE
9
10
11
12
13[c]
14[c,d]
15[c,d,f]
HFIP
Toluene
Dioxane
DCE
DCE
DCE
71
84 (78)[e]
80
DCE
[a]Reaction conditions: Unless otherwise mentioned,
substrate 1a (0.1 mmol), Co(acac)2 (10 mol%),
Mn(OAc)3.2H2O (2.0 equiv), solvent (1.0 mL), 85 °C, N2.
[b]Isolated yield. [c]Mn(OAc)3.2H2O (4.0 equiv). [d]100 °C.
[e]Yield for 0.2 mmol scale. [f]Reaction was performed
under air. nr: no reaction
Table 2. Substrate Scope[a]
We commenced our studies with 2-methyl-N-
(quinolin-8-yl)benzamide 1a as the model substrate
for acetoxylation. To our delight, the desired product
3-methyl-2-(quinolin-8-ylcarbamoyl)phenyl acetate
2a was obtained in 60% yield in presence of 10 mol%
of Co(acac)2 catalyst and 2.0 equiv of
Mn(OAc)3.2H2O in MeCN at 85 C (Table 1, entry 1).
A series of other cobalt catalysts was screened (Table
1, entry 2-6), but all of these had detrimental effect
on the yield; Co(acac)2 was found to be the best
catalyst for the present reaction. Various solvents
were also tested (Table 1, entry 7-11) and DCE was
found to be the solvent of choice which furnished the
desired product 2a in 64% yield (Table 1, entry 7).
Control experiments proved the essentiality of the
cobalt catalyst (Table 1, entry 12) for the
acetoxylation. To enhance the efficacy of the reaction,
the loading of Mn(OAc)3.2H2O was increased to 4.0
equiv which raised the yield of 2a (Table 1, entry 13).
2
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10.1002/adsc.201800398
Advanced Synthesis & Catalysis
[a]Reaction conditions: substrate 1 (0.2 mmol), Co(acac)2
(10 mol%), Mn(OAc)3.2H2O (4.0 equiv), DCE (2.0 mL),
100 °C, N2. [b] 0.1 mmol scale.
between 1ao and 1ao-d5, and kinetic isotope effect
(KIE) values of 2.6 and 2.7 were observed
respectively (Scheme 3b, 3c and SI). These results
implied that the CH bond cleavage step may be
involved in the turn over limiting step of the
mechanism. Also, no significant substituent effect
was observed in the competitive experiment of the
substrates 1q and 1n (Scheme 3d). When we
performed the reaction in the presence of the catalyst
C1,[9d] the desired product 2a was obtained in 80%
yield, comparable to that achieved with Co(acac)2
(Scheme 3e).
Based on the above experimental results and
previous reports,[11,13] a plausible reaction pathway is
proposed as depicted in Scheme 4. Initially CoII
undergoes coordination with both the N atoms of the
bidentate 8-aminoquinoline directing group of the
substrate 1a to give the intermediate A, which is
oxidized by Mn(OAc)3.2H2O to the Co(III) species
Various di-substituted amides 1ad-1aj also
furnished the corresponding products 2ad-2aj in
good to moderate yields. Meta-substituted amides
1ak and 1al gave the mono acetoxylated products
2ak and 2al in comparatively lower yields of 24%
and 29% respectively. The naphthyl substrate 1am
successfully reacted to deliver the acetoxylated
product 2am in 62% yield. Interestingly, the current
protocol also tolerated the heterocyclic substrate 1am
and produced the desired product 2an in 40% yield.
However, the unsubstituted benzamide 1ao produced
both mono and bis acetoxylated products, 2ao and
2ap, in 22% and 14% yields, respectively. Neither
increasing the loading of Mn(OAc)3.2H2O nor
increasing the time of the reaction led to increased
yields of 2ap. Also when the ortho-substituted O-
acetyl substrate 2ao was tried as the substrate, bis-
acetoxy product 2ap was obtained in a comparatively
lower yield of 27%.
In order to broaden the synthetic utility of the
methodology, a gram scale reaction was conducted
under standard conditions and the desired product 2a
was obtained in 64% yield (Scheme 2a). The
acetoxylated product could be hydrolysed smoothly,
furnishing the hydroxylated product 3 in 95% yield
(Scheme 2b).
Scheme 2. Gram scale reaction and hydrolysis
Scheme 3. Mechanistic experiments
In order to get an insight into the reaction
mechanism, few control experiments were performed
(Scheme 3 and SI). When the reaction was performed
with 1ao under standard conditions and quenching
was done with excess CD3OD, deuterium-proton
exchange was observed in the recovered starting
material as well as in the mono acetoxy product. The
result illustrated that the CH bond cleavage step was
reversible in nature. But when performed in absence
of Mn(OAc)3.2H2O, no H/D exchange was observed
in the recovered starting material (Scheme 3a). This
result proved that Mn(OAc)3.2H2O is responsible in
oxidising Co(II) to Co(III), formation of which is
essential for the CH bond activation to occur (see SI
for more details). In addition, both intermolecular
competitive and parallel experiments were conducted
(intermediate B). Ortho Csp2H activation then affords a
bis-chelated metallacyclic complex C (via a concerted
metalation-deprotonation process), which undergoes
reductive elimination to yield the corresponding
acetoxylated product 2a and generates the Co(I) species.
Reoxidation of Co(I) to Co(II) by Mn(OAc)3.2H2O, which
acts both as the acetoxy source and the terminal oxidant,
then continues the catalytic cycle.
3
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10.1002/adsc.201800398
Advanced Synthesis & Catalysis
Acknowledgements
W.S. and A.M. thank CSIR and A.B. thanks UGC for their
fellowships; I.D. thanks IICB, HCP-0011 and DST-India (CS-
016/2013) for research funds. We thank Mr. Sandip Kundu and
Mr. Santu Paul for recording X-ray and HRMS respectively.
References
[1] a) R. Rais, J. Vꢀvra, T. Tichꢁ, R. P. Dash, A. J.
Gadiano, L. Tenora, L. Monincova, C. Barinka, J. Alt,
S. C. Zimmermann, C. E. Slusher, Y. Wu, K. Wozniak,
P. Majer, T. Tsukamoto, B. S. Slusher, J. Med. Chem.
2017, 60, 7799. b) D. E. Nichols, S. Frescas, Synthesis
1999, 935. c) L. D. Patterson, M. J. Miller, J. Org.
Chem. 2010, 75, 1289. d) E. P. Fuerst, C. J. Arntzen, K.
Pfister, D. Penner, Weed Sci. 1986, 34, 344. e) S. E. O’
Connor, A. Grosset, P. Janiak, Fundam. Clin.
Pharmacol. 1999, 13, 145. f) B. Zhang, R. Guo, Y. Hu,
X. Dong, N. Lin, X. Dai, H. Wu, S. Ma, B. Yang, RSC
Adv. 2017, 7, 31899. g) A. Ortega, J. F. Blount, P. S.
Manchand, J. Chem. Soc., Perkin Trans. 1 1982, 2505.
h) A. Murakami, Y. Kitazono, S. Jiwajinda, K.
Koshimizu, H. Ohigashi, Planta Med. 1998, 64, 319.
Scheme 4. Plausible reaction mechanism
Conclusions
[2] For representative examples and reviews see: a) A. R.
Dick, K. R. Hull, M. S. Sanford, J. Am. Chem. Soc.
2004, 126, 2300. b) L. V. Desai, K. L. Hull, M. S.
Sanford, J. Am. Chem. Soc. 2004, 126, 9542. c) R. Giri,
J. Liang, J.-G. Lei, J.-J. Li, D.-H. Wang, X. Chen, I. C.
Naggar, C. Guo, B. M. Foxman, J.-Q. Yu, Angew.
Chem. Int. Ed. 2005, 44, 7420. d) L. V. Desai, H. A.
Malik, M. S. Sanford, Org. Lett. 2006, 8, 1141. e) G.-
W. Wang, T. T. Yuan, X.-L. Wu, J. Org. Chem. 2008,
73, 4717. f) F. R. Gou, X. C. Wang, P. F. Huo, H. P. Bi,
Z. H. Guan, Y. M. Liang, Org. Lett. 2009, 11, 5726. g)
T. W. Lyons, M. S. Sanford, Chem. Rev. 2010, 110,
1147. h) S. R. Neufeldt, M. S. Sanford, Org. Lett. 2010,
12, 532. i) C. J. Vickers, T.-S. Mei, J.-Q. Yu, Org. Lett.
2010, 12, 2511. j) Z. Ren, F. Mo, G. Dong, J. Am.
Chem. Soc. 2012, 134, 16991. k) M. R. Yadav, R. K.
Rit, A. K. Sahoo, Chem. Eur. J. 2012, 18, 5541. l) R. K.
Rit, M. R. Yadav, A. K. Sahoo, Org. Lett. 2012, 14,
3724. m) L. Y. Chan, X. Meng, S. Kim, J. Org. Chem.
2013, 78, 8826. n) M. Wang, Y. Yang, Z. Fan, Z.
Cheng, W. Zhu, A. Zhang, Chem. Commun. 2015, 51,
3219. o) S. Moghimi, M. Mahdavi, A. Shafiee, A.
Foroumadi, Eur. J. Org. Chem. 2016, 3282. p) K. Chen,
D. Wang, Z.-W. Li, Z. Liu, F. Pan, Y.-F. Zhang, Z.-J.
Shi, Org. Chem. Front. 2017, 4, 2097.
In conclusion, we have demonstrated a cobalt
catalyzed ortho sp2 CH acetoxylation of unactivated
arenes, assisted by the 8-aminoquinoline directing
group. This reaction protocol is attractive due to the
simple reaction conditions, use of inexpensive cobalt
catalyst, and unravelling of a novel acetoxy source in
Mn(OAc)3.2H2O. The methodology is applicable to a
broad range of substrates and tolerates a wide array of
functional groups. Further investigations to expand
the scope of its applications are in progress.
Experimental Section
Representative procedure for Co- catalyzed CH
acetoxylation: In an oven dried 10 mL Schlenk tube, 2-
methyl-N-(quinolin-8-yl)benzamide (1a) (52.5 mg, 0.2
mmol, 1.0 equiv), Co(acac)2 (5.1 mg, 0.02 mmol, 0.1
equiv) and Mn(OAc)3.2H2O (214.5 mg, 0.8 mmol, 4.0
equiv) were taken and the reaction mixture was degassed
and backfilled with nitrogen. Under nitrogen 2.0 mL (0.1
M) of anhydrous DCE was added. Then it was degassed
and backfilled with nitrogen (3 times). The tube was closed
with a teflon-lined cap and kept on stirring in an oil bath.
The bath temperature was slowly increased to 100 °C.
After 24 h, the reaction was stopped and cooled to room
temperature. The reaction mixture was filtered through a
short pad of celite and concentrated under vacuo. The
crude reaction mixture was directly purified by column
chromatography on silica gel using ethyl acetate/petroleum
ether as eluent to obtain 3-methyl-2-(quinolin-8-
ylcarbamoyl)phenyl acetate (2a) (49.7 mg, 78% yield).
[3] a) T. Okada, K. Nobushige, T. Satoh, M. Miura, Org.
Lett. 2016, 18, 1150. b) K. Raghuvanshi, D. Zell, L.
Ackermann, Org. Lett. 2017, 19, 1278.
[4] a) W. Yu, J. Chen, K. Gao, Z. Liu, Y. Zhang, Org. Lett.
2014, 16, 4870. b) Y. Wu, B. Zhou, Org. Lett. 2017, 19,
3532. c) A. Mishra, T. K. Vats, M. P. Nair, A. Das, I.
Deb, J. Org. Chem. 2017, 82, 12406.
Full characterization data and copies of relevant spectra of
all new products are provided in the Supporting
Information.
[5] a) X. Chen, X.-S. Hao, C. E. Goodhue, J.-Q. Yu, J. Am.
Chem. Soc. 2006, 128, 6790. b) Z. Wang, Y. Kuninobu,
M. Kanai, Org. Lett. 2014, 16, 4790. c) X. Wu, Y.
Zhao, H. Ge, Chem. Asian J. 2014, 9, 273. d) F. Wang,
CCDC 1819213 (2a), CCDC 1819214 (2d), and CCDC
1819212 (2z) contain the supplementary crystallographic
data for this paper. These data can be obtained free of
charge from The Cambridge Crystallographic Data Centre
via www.ccdc.cam.ac.uk/data_request/cif.
4
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10.1002/adsc.201800398
Advanced Synthesis & Catalysis
Q. Hu, C. Shu, Z. Lin, D. Min, T. Shi, W. Zhang, Org.
Lett. 2017, 19, 3636.
J.-L. Niu, M.-P. Song, Angew. Chem. Int. Ed. 2016, 55,
13571. g) T. Yamaguchi, Y. Kommagalla, Y. Aihara, N.
Chatani, Chem. Commun. 2016, 52, 10129. h) R.
Manoharan, G. Sivakumar, M. Jeganmohan, Chem.
Commun. 2016, 52, 10533. i) V. G. Landge, S. P.
Midya, J. Rana, D. R. Shinde, E. Balaraman, Org. Lett.
2016, 18, 5252. j) X. Zhu, J.-H. Su, C. Du, Z.-L. Wang,
C.-J. Ren, J.-L. Niu, M.-P. Song, Org. Lett. 2017, 19,
596. k) J. Lan, H. Xie, X. Lu, Y. Deng, H. Jiang, W.
Zeng, Org. Lett. 2017, 19, 4279. l) Q. Li, W. Hu, R. Hu,
H. Lu, G. Li, Org. Lett. 2017, 19, 4676.
[6] For reviews on cobalt catalyzed CH functionalizations
see: a) K. Gao, N. Yoshikai, Acc. Chem. Res. 2014, 47,
1208. b) N. Yoshikai, Bull. Chem. Soc. Jpn. 2014, 87,
843. c) M. Moselage, J. Li, L. Ackermann, ACS Catal.
2016, 6, 498. d) D. Wei, X. Zhu, J.-L. Niu, M.-P. Song,
ChemCatChem. 2016, 8, 1242. e) T. Yoshino, S.
Matsunaga, Adv. Synth. Catal. 2017, 359, 1245. f) S.
Weng, S.-J. Chen, X.-Q. Yu, Chem. Commun. 2017, 53,
3165.
[10] For selected and recent examples of 8-aminoquinoline
directed CH functionalizations see: a) V. G. Zaitsev,
D. Shabashov, O. Daugulis, J. Am. Chem. Soc. 2005,
127, 13154. b) D. Shabashov, O. Daugulis, J. Am.
Chem. Soc. 2010, 132, 3965. c) L. D. Tran, I. Popov, O.
Daugulis, J. Am. Chem. Soc. 2012, 134, 18237. d) J.
Roane, O. Daugulis, Org. Lett. 2013, 15, 5842. e) S.
Asako, L. Ilies, E. Nakamura, J. Am. Chem. Soc. 2013,
135, 17755. f) Y. Aihara, N. Chatani, J. Am. Chem. Soc.
2014, 136, 898.
[7] For selected and recent examples on low valent cobalt
catalyzed CH functionalizations see: a) K. Gao, P.-S.
Lee, T. Fujita, N. Yoshikai, J. Am. Chem. Soc. 2010,
132, 12249. b) K. Gao, N. Yoshikai, Angew. Chem. Int.
Ed. 2011, 50, 6888. c) K. Gao, N. Yoshikai, J. Am.
Chem. Soc. 2011, 133, 400. d) Q. Chen, L. Ilies, E.
Nakamura, J. Am. Chem. Soc. 2011, 133, 428. e) W.
Song, L. Ackermann, Angew. Chem. Int. Ed. 2012, 51,
8251. f) K. Gao, N. Yoshikai, Chem. Commun. 2012,
48, 4305. g) K. Gao, R. Paira, N. Yoshikai, Adv. Synth.
Catal. 2014, 356, 1486. h) M. Moselage, N. Sauermann, [11] a) L.-B. Zhang, X.-Q. Hao, S.-K. Zhang, Z.-J. Liu, X.-
S. C. Richter, L. Ackermann, Angew. Chem. Int. Ed.
2015, 54, 6352. i) W. Xu, N. Yoshikai, Angew. Chem.
Int. Ed. 2016, 55, 12731.
X, Zheng, J.-F, Gong, J.-L. Niu, M.-P. Song, Angew.
Chem. Int. Ed. 2015, 54, 272. b) C. Lin, Z. Chen, Z.
Liu, Y. Zhang, Adv. Synth. Catal. 2018, 360, 519. c) R.
Ueno, S. Natsui, N. Chatani, Org. Lett. 2018, 20, 1062.
During our ongoing work and preparation of
manuscript 11b and 11c were published.
[8] For selected and recent examples on high valent
Cp*Co(III) catalyzed CH functionalizations see: a) T.
Yoshino, H. Ikemoto, S. Matsunaga, M. Kanai, Angew.
Chem. Int. Ed. 2013, 52, 2207. b) T. Yoshino, H.
Ikemoto, S. Matsunaga, M. Kanai, Chem. Eur. J. 2013,
19, 9142. c) D.-G.Yu, T. Gensch, F. de Azambuja, S.
Vásquez-Céspedes, F. Glorius, J. Am. Chem. Soc. 2014,
136, 17722. d) B. Sun, T. Yoshino, H. Ikemoto, S.
Matsunaga, M. Kanai, Adv. Synth. Catal. 2014, 356,
1491. e) J. Li, L. Ackermann, Angew. Chem. Int. Ed.
2015, 54, 3635. f) A. B. Pawar, S. Chang, Org. Lett.
2015, 17, 660. g) M. Sen, B. Emayavaramban, N.
Barsu, J. R. Premkumar, B. Sundaraju, ACS Catal.
2016, 6, 2792. h) T. Gensch, F. J. R. Klauck, F. Glorius,
Angew. Chem. Int. Ed. 2016, 55, 11287. i) M. Yoshida,
K. Kawai, R. Tanaka, T. Yoshino, S. Matsunaga, Chem.
Commun. 2017, 53, 5974. j) M. R. Sk, S. S. Bera, M. S.
Maji, Org. Lett. 2018, 20, 134.
[12] a) A. Mishra, I. Deb, Adv. Synth. Catal. 2016, 358,
2267. b) A. Mishra, T. K. Vats, I. Deb, J. Org. Chem.
2016, 81, 6525. c) A. Mishra, U. Mukherjee, T. K. Vats,
I. Deb, J. Org. Chem. 2018, 83, 3756.
[13] O. Planas, C. J. Whiteoak, V. M. Diaconescu, I.
Gamba, J. M. Luis, T. Parella, A. Company, X. Ribas, J.
Am. Chem. Soc. 2016, 138, 14388.
[9] For selected and recent examples on affordable cobalt
catalyzed CH functionalizations see: a) L. Grigorjeva,
O. Daugulis, Angew. Chem. Int. Ed. 2014, 53, 10209.
b) L. Grigorjeva, O. Daugulis, Org. Lett. 2014, 16,
4684. c) D. Kalsi, B. Sundararaju, Org. Lett. 2015, 17,
6118. d) S. Maity, R. Kancherla, U. Dhawa, E. Hoque,
S. Pimparkar, D. Maiti, ACS Catal. 2016, 6, 5493. e) Q.
Yan, T. Xiao, Z. Liu, Y. Zhang, Adv. Synth. Catal.
2016, 358, 2707. f) C. Du, P.-X. Li, X. Zhu, J.-F. Suo,
5
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10.1002/adsc.201800398
Advanced Synthesis & Catalysis
COMMUNICATION
Cobalt-Catalyzed Directed sp2 CH Acetoxylation
of Arenes Employing Mn(OAc)3.2H2O as Acetoxy
Source
Adv. Synth. Catal. Year, Volume, Page – Page
†
Writhabrata Sarkar, Arup Bhowmik, Aniket
†
Mishra, Tripta Kumari Vats and Indubhusan Deb*
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