Pd(ii)-catalysed o-aroylation of directing arenes using terminal aryl alkenes and alkynes

Article abstract of DOI:10.1039/c4ra11014e

A substrate-directed Pd-catalysed o-aroylation strategy has been demonstrated using new aroyl surrogates viz. terminal aryl alkenes and alkynes in the presence of TBHP. By a subtle change in catalyst from Cu to Pd, a differential selectivity is observed.

Full text of DOI:10.1039/c4ra11014e

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Pd(II)-catalysed o-aroylation of directing arenes
using terminal aryl alkenes and alkynes†
Cite this: RSC Adv., 2014, 4, 54532
*
Nilufa Khatun, Arghya Banerjee, Sourav K. Santra, Ahalya Behera and Bhisma K. Patel
Received 23rd September 2014
Accepted 17th October 2014
DOI: 10.1039/c4ra11014e
www.rsc.org/advances
A substrate-directed Pd-catalysed o-aroylation strategy has been various metal catalysts such as Rh, Ru and even Pd5 as shown in
demonstrated using new aroyl surrogates viz. terminal aryl alkenes and Scheme 1, path-II. Very recently our group have demonstrated a
alkynes in the presence of TBHP. By a subtle change in catalyst from Cu(II)-catalysed o-benzoxylation of 2-phenylpyridine using both
Cu to Pd, a differential selectivity is observed. While terminal aryl terminal aryl alkenes and alkynes as arylcarboxy (ArCOO–)
alkenes/alkynes in the presence of Cu/TBHP are reported to act as o- surrogates as shown in Scheme 1, path-III.6
aryloxy (ArCOO–) sources, the use of Pd/TBHP installs an aroyl
Catalyst-controlled selectivity during directed or non-
(ArCO–) group at the ortho position with respect to the directing directed C–C or C-heteroatom bond formation is not unprece-
arenes.
dented in literature. In one of our recent report during the
synthesis of 2-aminobenzothiazoles from 2-halothioureas, Cu
preferred dehalogenative path while Pd followed C–H activation
path.7 Differential reactivity is also observed during directed o-
functionalisation of 2-phenylpyridine with alkylbenzenes, while
Pd catalyst is reported to give o-aroylated (ArCO–) product,8 Cu
catalyst installs an aryl carboxy (ArCOO–) group at the ortho
site.9 Taking cues from these literature reports on catalyst-
controlled selectivities and from our recent success on transi-
tion metal catalysed ortho C–H functionalisations,6,8 we thought
to implement Pd catalyst during the reaction between 2-phe-
nylbenzothiazole and terminal aryl alkenes. Now the query
arises whether this catalytic condition provides o-vinylation
as reported with catalysts like Ru, Rh and Pd or o-benzoxylation
as has been demonstrated with Cu catalyst or all together
a differential reactivity leading to a new product may be
observed.
Introduction
The development of efficient and new strategies for the
construction of carbon–carbon (C–C) bonds is of immense
interest to synthetic chemists. Formation of complex molecular
architecture starting from simple molecules has been previ-
ously achieved via various classical approaches like nucleo-
philic additions, substitutions, Friedel–Cra type reactions,
pericyclic reactions and even transition metal-catalysed cross-
coupling approaches. Of late extensive investigation on transi-
tion metal-catalysed C–H bond activation strategies have greatly
revolutionalised the C–C bond forming processes. The direct
use of C–H bonds to generate C–C bonds is highly desirable
since it has the potential to streamline synthetic schemes by
shortening the number of synthetic steps and thus maintaining
better atom economy of the processes. In particular, most C–H
bond functionalisations processes rely on two elegant
approaches viz. directing-group assisted C–H functionalisation1
or cross-dehydrogenative coupling (CDC).2
Aryl alkenes are susceptible to undergo Wacker type oxida-
tion to give phenylacetaldehyde3 (Scheme 1, path-I(a)) while
diarylethenes are reported to form 1,2-diketones4 (Scheme 1,
path-I(b)) using Pd and Ru catalysts respectively. In a separate
study, terminal aryl alkenes are reported to introduce a vinyl
moiety at the ortho site of ligand directed substrates using
Department of Chemistry, Indian Institute of Technology Guwahati, 781 039, Assam,
India. E-mail: patel@iitg.ernet.in; Fax: +91-3612690762
† Electronic supplementary information (ESI) available: 1H and 13C NMR spectra.
See DOI: 10.1039/c4ra11014e
Scheme 1 Catalyst-controlled selectivity of alkenes oxidation.
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Table 1 Screening of reaction conditionsa,b
Results and discussion
With the above possibilities in mind, an initial trial reaction was
performed with 2-phenylbenzothiazole (1) (1 equiv.) and styrene
(a) (2.5 equiv.) in the presence of catalyst Pd(OAc)2 (5 mol%) and
ꢀ
TBHP in decane (5–6 M) (2 equiv.) in chlorobenzene at 120 C.
Surprisingly, the reaction gave a o-aroylated product (2-(benzo-
[d]thiazol-2-yl)phenyl)(phenyl)methanone (1a) in a mere yield of
25%. This result is contrary to the previous substrate directed
vinylation using Pd catalyst, of course a different combinations
of oxidants are used.5d Synthesis of aroyl ketones via ligand
directed ortho C–H functionalisation using various aroyl
surrogates are well documented in literature. In recent times, a
number of o-aroylation protocols of directing arenes have been
reported between ortho C–H bonds with various aroyl sources
viz. aldehydes10 (Scheme 2, path-a), benzyl alcohols11 (Scheme 2,
path-b), alkylbenzenes8a,12 (Scheme 2, path-c) diketones13
(Scheme 2, path-d) and carboxylic acids14 (Scheme 2, path-e) for
the synthesis of aryl ketones. Decarboxylative o-aroylation
protocols using a range of directing arenes have also been
reported using a-keto acids as aroyl equivalents as shown in
Scheme 2, path-f.15 Very recently aryl methyl amines16 and
benzyl ethers17 are introduced as new o-aroyl sources during
Pd-catalysed substrate-directed processes as illustrated in
Scheme 2, path-g and path-h. However, the use of terminal aryl
alkenes as aroyl surrogate using Pd-catalyst substrate directed
processes is not reported till date.18
Entry
Catalyst (mol%)
Oxidant (equiv.)
Solvent
Yield (%)
1
2
3
4
5
6
7
8
Pd(OAc)2 (5)
PdCl2 (5)
TBHP (2)
TBHP (2)
TBHP (2)
TBHP (2)
TBHP (2)
TBHP (4)
TBHP (5)
TBHP (5)c
H2O2
TBHP (5)
TBHP (5)
TBHP (5)
TBHP (5)
TBHP (5)
PhCl
PhCl
PhCl
PhCl
PhCl
PhCl
PhCl
PhCl
PhCl
THF
25
17
9
Pd(TFA)2 (5)
PdCl2(PPh3)2 (5)
Pd(OAc)2 (10)
Pd(OAc)2 (10)
Pd(OAc)2 (10)
Pd(OAc)2 (10)
Pd(OAc)2 (10)
Pd(OAc)2 (10)
Pd(OAc)2 (10)
Pd(OAc)2 (10)
Pd(OAc)2 (10)
Pd(OAc)2 (10)
12
42
57
63
29
00
<9
43
27
33
52
9
10
11
12
13
14
Dioxane
DMF
DMSO
DCE
a
Reaction conditions: 2-phenylbenzothiazole (1), (1 equiv., 0.5 mmol),
styrene (a) (2.5 equiv., 1.25 mmol), and TBHP in decane (5–6 M)
b
(5 equiv., 500 mL) in chlorobenzene (1.0 mL), 12 h. Isolated yield.
c
aq. TBHP.
Encouraged by this unprecedented result, a set of reactions
were performed by varying reaction parameters to achieve the
best possible yield of o-aroylated product (1a). Among the
various Pd catalysts screened, Pd(OAc)2 (Table 1, entry 1) was
found to be superior (25%) over other catalysts such as PdCl2
(17%), Pd(TFA)2 (9%), PdCl2(PPh3)2 (12%) as shown in Table 1,
entries 1–4. An increase in the catalyst loading from 5 to 10
mol%, the product yield improved from 25% to 42% (Table 1,
entry 5). Interestingly, when the oxidant quantity (TBHP in
decane) was increased by two fold, the yield improved upto 57%
(Table 1, entry 6). A further improvement in the yield (63%) was
observed when the reaction was performed with 5 equiv. of
oxidant. The use of an excess (beyond 5 equiv.) of TBHP has no
substantial effect on the product yield. The nature of oxidant
and their medium of storage have profound effect on the
product yield. For instance, when an aqueous TBHP was used in
lieu of a decane TBHP the yield dropped to 29% whereas
aqueous H2O2 failed to produce the expected product (Table 1,
entries 8 and 9). The reaction failed to afford any desired
product either in the absence of catalyst or the oxidant. In a
quest to improve the yield further various solvents viz. THF,
DMF, DMSO, 1,4-dioxane and DCE were screened (Table 1,
entries 10–14) but all were found inferior to chlorobenzene. A
decrease in reaction temperature from 120 ꢀC to 100 ꢀC had an
adverse effect on the product yield (53%). Finally, a mixture of
2-phenylbenzothiazole (1) (1 equiv.) and styrene (a) (2.5 equiv.),
Pd(OAc)2 (10 mol%) and TBHP in decane (5 equiv.) in chloro-
ꢀ
benzene at 120 C was chosen as the best optimised reaction
conditions (Table 1, entry 7).
Aer establishing the optimised condition, the present
methodology was then implemented on 2-phenylbenzothiazole
(1) with a variety of terminal alkenes. Terminal aryl alkenes
possessing both electron-donating and electron-withdrawing
substituents coupled efficiently with the directing substrate
(1). Terminal aryl alkenes having weekly activating substituent
p-Me (b) efficiently reacted with (1) giving 61% yield of (1b)
while strongly activating substituent p-OMe (c) provided
lower yield (48%) of the corresponding product (1c) as shown in
Scheme 2 Various approaches to o-aroylation of substrate directed
arenes.
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Table 2. Alkene having weekly electron withdrawing substituent such as p-Me (b), p-OMe (c) and deactivated substituents p-Cl
p-Cl (d) showed smooth conversion with 2-phenylbenzothiazole (d), p-Br (e) and m-NO2 (f) when treated with 2-phenyl pyridine
(1) providing 70% yield of (1d). Further, this selective o-aroyla- (7), all provided modest to good yields of their corresponding o-
tion protocol was extended to substituted 2-phenyl- aroylated products (7b–7f) respectively. Similarly, p-methyl-2-
benzothiazole containing both electron-donating and electron- phenylpyridine (8) also reacted with styrene (a) and
withdrawing substituents. 2-Aryl substituted benzothiazoles substituted styrenes such as p-Cl (d), p-Br (e), m-NO2 (f) and even
with mild activating substituents in 2-phenyl ring such as p-Me 2-napthylstyrene (g) providing their desired o-aroylated prod-
(2) when treated with styrene (a) and p-Cl styrene (d) gave (2a) ucts (8a), (8d), (8e), (8f) and (8g) as shown in Table 3. Use of
and (2d) in 65% and 69% yields respectively. Similarly, p-tBu (3) styrenes (a) and (d) as o-aroyl equivalents have been demon-
efficiently reacted with styrene (a) providing 68% yield of (3a) as strated through successful aroylation of benzoquinoline (9)
shown in Table 2. Styrene containing electro-neutral –H (a), p-Cl giving products (9a) and (9d) respectively as shown in Table 3.
(d) and p-Br (e) when treated with directing substrate (4) pos- This strategy was found to be successful with another directing
sessing a strongly electron-donating substituent p-OMe under arene 2,3-diphenylquinoxaline containing p-Me substituent (10)
the opitimised condition, all provided corresponding o-aroy- at its 2,3-aryl rings providing their desired o-aroylated products
lated products (4a), (4d) and (4e) in good yields (Table 2). (10a) and (10d) respectively when treated with styrene (a) and its
Substrate (5) possessing p-OBu group when treated with styrene p-Cl derivative (d). Interestingly, arenes possessing removable
(a), a good yield (73%) of corresponding product (5a) was directing groups such as 2-aroyloxypyridine (11–12) and aceto-
obtained. Next, 2-phenylbenzothiazole having a weekly deacti- phenone O-methyl oxime (13) were successfully o-aroylated
vating substituent such as p-Cl (6) when treated with styrene (a), under the present optimised conditions. 2-Aroyloxypyridine
a moderate yield (49%) of (6a) was obtained.
containing electron neutral –H (11) and p-OMe (12) substituents
Aer successfully achieving o-aroylation of benzothiazoles
(Table 2) using terminal alkenes as aroyl surrogates the protocol
was then extended to other substrate directed arenes. At rst,
commonly investigated N-directed arene, 2-phenyl pyridine (7)
when reacted with styrene (a) under the identical condition, a
good yield (79%) of (7a) was obtained aer 15 h. As demon-
strated in Table 3, styrenes bearing both activated substituents
Table 3 Scope of directing arenes for o-aroylation with terminal
alkenesa,b
Table 2 Scope of o-aroylation of 2-arylbezthiazoles with terminal
alkenesa,b
a
a
Reaction conditions: 2-arylbenzothiazole (1–6), (0.5 mmol), alkenes
Reaction conditions: directing arenes (7–13), (0.5 mmol), alkenes (a–g)
(a–e) (1.25 mmol), and TBHP in decane (5–6 M) (500 mL) in (1.25 mmol), and TBHP in decane (5–6 M) (500 mL) in chlorobenzene
chlorobenzene (1.0 mL), 120 ꢀC, 5–15 h. b Yields of isolated product.
(1.0 mL), 120 ꢀC, 9–24 h. b Yields of isolated product.
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reacted with styrene derivatives (a), (c) and (d) providing their
Several control reactions were carried out to illustrate a
corresponding o-aroylated products (11a), (12a), (12c–d) plausible mechanistic path for this Pd-catalysed aroylation.
respectively. Similarly, acetophenone O-methyl ketoxime (13) Styrene in the presence of oxidant TBHP may form styrene oxide
when reacted with styrene (1) gave decent yield of the o-aroy- (A) or 1-phenyl-1,2-ethane diol (B) in the medium. To ascertain
lated product (13a).
which one of this (A or B) intermediate is involved, both were
Alkynylation of sp2 and sp3 C–H bonds using terminal reacted separately with 2-phenylpyridine (7) under otherwise
alkynes by metal catalysed cross coupling reactions are well identical conditions. In the former case (Scheme 3, experiment
investigated.19,20 Specially, phenylacetylenes are used as o-alke- I) no desired product was obtained whereas the later (Scheme 3,
nylated partner in the chelation assisted C–H activation proc- experiment II) provided 61% yield of the desired product (7a)
ess.20c Besides terminal alkenes, terminal alkynes are found to suggesting (B) as one of the possible active intermediates in the
be the efficient source of carboxy group under Cu/TBHP reaction. Analysis of the crude reaction mixture between
system.6 So in next approach, we wish to see if phenyl acety- styrene, TBHP and Pd aer one hour divulged the presence of
lene can act as a benzoxy source (PhCOO–) or it will be a source phenylglyoxal (C), benzaldehdye (D) and benzoic acid (E) in the
of aroyl group (PhCO–) similar to styrene as discussed above. medium.
Thus when (1) and phenyl acetylene (a0) were reacted under the
Therefore (C), (D) and (E) are other possible intermediates
identical conditions to that of styrene (a), surprisingly o-aroy- (in addition to (B)) which may lead to o-aroylation of (7), an
lated product (1a) was again obtained but in a poor yield of 25%. observation consistent with our recent result.6,20 To conrm the
Hence, further optimisation reactions were performed to get an other possible active intermediates, 2-phenylpyridine (7) was
improved yield. Even by increasing the catalyst quantity 20 treated separately with (C), (D) and (E) under identical condi-
mol% and TBHP (10 equiv.), the yield did not improve beyond tions. While reaction with (C) (Scheme 3, experiment III) and (D)
32%. Thus high catalytic loading (20 mol%) condition was (Scheme 3, experiment IV) provided product (7a) in 81% and
chosen and applied for all aryl acetylenes towards substrate 87% yields respectively, benzoic acid (E) (Scheme 3, experiment
directed o-aroylation. Subsequently substrate 2-phenyl benzo- V) failed to give any trace of (7a). A possible pathway for the
thiazole (1) when treated with p-Cl phenyl acetylene (d0) under formation of phenylglyoxal (C), benzaldehyde (D), benzoic acid
the modied optimised condition, gave (1d) in 35% yield. Other (E) (except (B)) from styrene has been recently demonstrated by
directed arenes such as 2-phenylpyridine derivatives (7) and (8), us.6,21 To deduce the nature of the reaction a standard reaction
benzoquinoline (9), 2-aroyloxypyridines (11) and (12) when was carried out in the presence of a radical quencher, TEMPO.
treated with various terminal alkynes (a0) and (d0), yielded their Detection of TEMPO-ester (Y) along with substantial drop in
corresponding aroylated products in the range of 21–35% only product yield (9%) of (7a) suggests the radical nature of the
as shown in Table 4. Alkynes provided much lower yields than reaction (Scheme 3, experiment VI). In fact all the active inter-
alkenes because of possible homo-coupling which make the mediates (B), (C) and (D) are capable of generating aroyl radical
aroyl sources unavailable for further o-aroylation reactions.
under the reaction conditions toward o-aroylation.
Based on results obtained from controlled experiments and
recent literature,6,22,23
proposed for this transformation as shown in Scheme 4. In
a plausible mechanism has been
Table 4 Scope of substrate directed arenes for o-aroylation with
terminal alkynesa,b
a
Reaction conditions: directing arenes (1–12), (0.5 mmol), alkynes
(a0–d0) (1.25 mmol), and TBHP in decane (5–6 M) (500 mL) in
chlorobenzene (1.0 mL), 120 ꢀC, 15–28 h. b Yields of isolated product.
Scheme 3 Various control experiments with 2-phenylpyridine (7).
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radical mechanism has been proposed. This strategy have been
implemented to a wide range of ligand directed substrates and
afforded modest to good yields. This strategy showed a good
tolerance of functional groups. Differential selectivities of Cu
and Pd have been demonstrated; while Cu/TBHP combination
installs an o-aryloxy (ArCOO–) the use of Pd/TBHP incorporate
an o-aroyl (ArCO–) group using both alkenes and alkynes.
General procedure for the synthesis of
(2-(benzo[d]thiazol-2-yl)phenyl)
(phenyl)methanone (1a) from
2-phenylbenzo[d]thiazole (1) and
styrene (a)
An oven-dried ask was charged with 2-phenylbenzo[d]thiazole
(1), (0.5 mmol, 0.105 g), styrene (a) (1.25 mmol, 0.13 g), Pd(OAc)2
(10 mol%, 0.011 g), TBHP in decane (5–6 M) (500 mL) in chlo-
robenzene (1 mL). The ask was tted to a condenser and the
resultant reaction mixture was stirred in a preheated oil bath at
120 ꢀC for 12 h. Aer stipulated time, the reaction mixture was
cooled down to room temperature and diluted with ethyl acetate
(1 ꢁ 10 mL). This diluted reaction mixture passed through a
celite bed and subsequently washed with additional (2 ꢁ 10 mL)
ethyl acetate. The combined organic layer then washed with
10% aq. saturated solution of NaHCO3 (2 ꢁ 5 mL) followed by
water (2 ꢁ 5 mL). The organic layer was dried over anhydrous
Na2SO4 and evaporated under reduced pressure. The crude
product was further puried by silica gel column chromatog-
raphy using (hexane/ethylacetate ¼ 19 : 1) as eluent to yield
pure [2-(benzo[d]thiazol-2-yl)phenyl](phenyl)methanone (1a,
0.198 g, 63%) as a gummy material.
Scheme 4 Plausible mechanism for o-aroylation.
path-I, styrene possibly form a four-membered dioxetane
intermediate (B0) by the action of Pd/TBHP. The ring opening of
the intermediate (B0) may give 1-phenyl-1,2-ethanediol (B),
which readily oxidised to give phenylglyoxal (C) under the
oxidative reaction condition. Alternatively, cyclic intermediate
(B0) may undergo oxidation to generate another cyclic interme-
diate (B00) which may also be directly obtained from phenyl-
acetylene (a0) (Scheme 4, path II). Formation of intermediate
(B00) from (B0) has been reported by Jiao et al.24 The ring frag-
mentation of intermediate (B00), may provide phenylglyoxal (C).
Intermediate (C) in presence of TBHP leads to the formation of
benzyldehyde (D) with the extrusion of CO. Further benzalde-
hyde (D) in presence of TBHP leads to the formation of benzoyl
radical (D0). In path-III, cyclopalladation of the directing arene
(7) leads to the formation of Pd–substrate complex (F). In the
next step, the oxidative addition of in situ generated benzoyl
radical (D0) to Pd–substrate complex (F) leads to the formation
of a Pd(IV)22 or a dimeric Pd(III)25 intermediate (G). During the
course of this reaction, the formations of the cationic Pd(IV)
intermediate (G0) has been detected by the ESI/MS analysis of
reaction aliquot (see ESI†). Finally, a reductive elimination of
the Pd from (G) leads to C–C bond formation to afford o-aroy-
lated product (7a) along with the regeneration of the Pd(II)
catalyst for the next cycle.
General procedure for the synthesis of
phenyl(2-(pyridin-2-yl)phenyl)
methanone (7a) from 2-phenylpyridine
(7) and phenylacetylene (a0)
An oven-dried ask was charged with phenyl acetylene (a0),
(0.125 mmol, 0.128 g), 2-phenylpyridine (1), (0.5 mmol, 0.078 g),
Pd(OAc)2 (20 mol%, 0.022 g), TBHP in decane (5–6 M) (1.0 mL)
in chlorobenzene (1 mL). The ask was tted to a condenser
and the resultant reaction mixture was stirred in a preheated oil
bath at 120 ꢀC for 25 h. Aer stipulated time, the reaction
mixture was cooled down to room temperature and diluted with
ethyl acetate (1 ꢁ 10 mL). This diluted reaction mixture passed
through a celite bed and subsequently washed with additional
(2 ꢁ 10 mL) ethyl acetate. The combined organic layer then
washed with 10% aq. saturated solution of NaHCO3 (2 ꢁ 5 mL)
followed by water (2 ꢁ 5 mL). The organic layer was dried over
anhydrous Na2SO4 and evaporated under reduced pressure. The
Conclusions
We have developed a new, efficient Pd-catalysed directing group crude product was further puried by silica gel column chro-
assisted aroylation of arenes using terminal alkenes and matography using (hexane/ethylacetate ¼ 9 : 1) as eluent to
alkynes as the new aroyl surrogate. Based on the detection of yield pure phenyl(2-(pyridin-2-yl)phenyl)methanone (7a, 0.083
reaction intermediates and taking cues from the literature a g, 32%) as brown solid.
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A. Banerjee, S. K. Santra, S. Guin, S. K. Rout and
B. K. Patel, Eur. J. Org. Chem., 2013, 1367; (i) A. Banerjee,
A. Bera, S. K. Santra, S. Guin and B. K. Patel, RSC Adv.,
2014, 4, 8558; (j) S. K. Santra, A. Banerjee and B. K. Patel,
Tetrahedron, 2014, 70, 2422.
Acknowledgements
B. K. P acknowledges the support of this research by the Science
and Engineering Research Board (SERB) (SB/S1/OC-53/2013),
New Delhi, and the Council of Scientic and Industrial
Research (CSIR) (02(0096)/12/EMR-II). N.K., A.B. and S.K.S.
thank CSIR.
11 For selected examples of alcohol as aroyl surrogates, see: (a)
´
F. Xiao, Q. Shuai, F. Zhao, O. Basle, G. Deng and C.-J. Li, Org.
Lett., 2011, 13, 1614; (b) J. Park, A. Kim, S. Sharma, M. Kim,
E. Park, Y. Jeon, Y. Lee, J. H. Kwak, Y. H. Jung and I. S. Kim,
Org. Biomol. Chem., 2013, 11, 2766; (c) M. Kim, S. Sharma,
J. Park, M. Kim, Y. Choi, Y. Jeon, J. H. Kwak and I. S. Kim,
Tetrahedron, 2013, 69, 6552; (d) S. Sharma, M. Kim, J. Park,
M. Kim, J. H. Kwak, Y. H. Jung, J. S. Oh, Y. Lee and
I. S. Kim, Eur. J. Org. Chem., 2013, 6656.
References
1 (a) G. Dyker, Handbook of CꢂH transformations: Application in
Organic Synthesis, Weinheim, 2005; (b) Activation and
Functionalization of CꢂH Bond, ed. K. I. Goldberg and A. S.
Goldman, ACS Symposium Series 885, American Chemical
Society, Washington, DC, 2004; (c) N. Chatani, Directed 12 (a) S. Guin, S. K. Rout, A. Banerjee, S. Nandi and B. K. Patel,
Metallation, Springer, Berlin, Germany, 2008; (d)
O. Daugulis, H. Q. Do and D. Shabashov, Acc. Chem. Res.,
Org. Lett., 2012, 14, 5294; (b) Y. Wu, P. Y. Choy, F. Mao and
F. Y. Kwong, Chem. Commun., 2013, 49, 689.
2009, 42, 1074; (e) D. A. Colby, R. G. Bergman and 13 W. Zhou, H. Li and L. Wang, Org. Lett., 2012, 14, 4594.
J. A. Ellman, Chem. Rev., 2010, 110, 624.
2 (a) C.-J. Li, Acc. Chem. Res., 2009, 42, 335; (b) J. A. Ashenhurst,
14 J. Lu, H. Zhang, X. Chen, H. Liu, Y. Jiang and H. Fu, Adv.
Synth. Catal., 2013, 355, 529.
Chem. Soc. Rev., 2010, 39, 540; (c) C. J. Scheuermann, Chem. – 15 For selected examples of a-keto acid as aroyl surrogate via
Asian J., 2010, 5, 436.
3 P. Teo, K. Z. Wickens, G. Dong and H. R. Grubbs, Org. Lett.,
2012, 14, 3237.
4 S. Chen, Z. Liu, E. Shi, L. Chen, W. Wei, H. Li, Y. Cheng and
X. Wan, Org. Lett., 2011, 13, 2274.
5 (a) V. Ritleng, C. Sirlin and M. Pfeffer, Chem. Rev., 2002, 102,
1731; (b) E. M. Beccalli, G. Broggini, M. Martinelli and
S. Sottocornola, Chem. Rev., 2007, 107, 5318; (c) J. L. Bras
and J. Muzart, Chem. Rev., 2011, 111, 1170; (d) C. S. Yeung
and V. M. Dong, Chem. Rev., 2011, 111, 1215.
6 S. K. Rout, S. Guin, A. Gogoi, G. Majji and B. K. Patel, Org.
Lett., 2014, 16, 1614.
decarboxylation, see: (a) P. Fang, M. Li and H. Ge, J. Am.
Chem. Soc., 2010, 132, 11898; (b) M. Li and H. Ge, Org.
Lett., 2010, 12, 3464; (c) H. Wang, L.-N. Guo and
X.-H. Duan, Org. Lett., 2012, 14, 4358; (d) M. Kim, J. Park,
S. Sharma, A. Kim, E. Park, J. H. Kwak, Y. H. Jung and
I. S. Kim, Chem. Commun., 2013, 49, 925; (e) J. Park,
M. Kim, S. Sharma, E. Park, A. Kim, S. H. Lee, J. H. Kwak,
Y. H. Jung and I. S. Kim, Chem. Commun., 2013, 49, 1654;
(f) S. Sharma, A. Kim, E. Park, J. Park, M. Kim, J. H. Kwak,
S. H. Lee, Y. H. Jung and I. S. Kim, Adv. Synth. Catal., 2013,
355, 667; (g) L. Yu, P. Li and L. Wang, Chem. Commun.,
2013, 49, 2368; (h) H. Li, P. Li, Q. Zhao and L. Wang,
Chem. Commun., 2013, 49, 9170; (i) J. Miao and H. Ge, Org.
Lett., 2013, 15, 2930.
7 S. K. Sahoo, A. Banerjee, S. Chakraborty and B. K. Patel, ACS
Catal., 2012, 2, 544.
8 (a) S. Guin, S. K. Rout, A. Banerjee, S. Nandi and B. K. Patel, 16 Q. Zhang, F. Yang and Y. Wu, Chem. Commun., 2013, 49,
Org. Lett., 2012, 14, 5294; (b) A. Banerjee, A. Bera, S. Guin,
6837.
S. K. Rout and B. K. Patel, Tetrahedron, 2013, 69, 2175; (c) 17 S. Han, S. Sharma, J. Park, M. Kim, Y. Shin, N. K. Mishra,
S. K. Rout, S. Guin, K. K. Ghara, A. Banerjee and
B. K. Patel, Org. Lett., 2012, 14, 3982; (d) S. K. Rout,
J. J. Bae, J. H. Kwak, Y. H. Jung and I. S. Kim, J. Org.
Chem., 2014, 79, 275.
S. Guin, A. Banerjee, N. Khatun, A. Gogoi and B. K. Patel, 18 While this manuscript was under preparation, an analogous
Org. Lett., 2013, 15, 4106; (e) A. Gogoi, S. Guin, S. K. Rout
and B. K. Patel, Org. Lett., 2013, 15, 1802.
9 Y.-J. Bian, C.-B. Xiang, Z.-M. Chen and Z.-Z. Huang, Synlett,
2011, 16, 2407.
method was reported by BhanageA. B. Khemnar and
B. M. Bhanage, et al., using 2-phenylpyridine, terminal
alkenes and TBHP using Pd catalyst, Eur. J. Org. Chem.,
2014, 6746.
10 For selected examples of aldehydes as aroyl surrogates, see: 19 W. Wang, F. Luo, S. Zhang and J. Cheng, J. Org. Chem., 2010,
(a) X. Jia, S. Zhang, W. Wang, F. Luo and J. Cheng, Org. Lett., 75, 2415.
2009, 11, 3120; (b) J. Park, E. Park, A. Kim, Y. Lee, K.-W. Chi, 20 (a) F. Kakiuchi, Y. Yamamoto, N. Chatani and S. Murai,
J. H. Kwak, Y. H. Jung and I. S. Kim, Org. Lett., 2011, 13, 4390;
(c) S. Sharma, E. Park, J. Park and I. S. Kim, Org. Lett., 2012,
14, 906; (d) S. Sharma, J. Park, E. Park, A. Kim, M. Kim,
J. H. Kwak, Y. H. Jung and I. S. Kim, Adv. Synth. Catal.,
2013, 355, 332; (e) C.-W. Chan, Z. Zhou, A. S. C. Chan and
W.-Y. Yu, Org. Lett., 2010, 12, 3926; (f) Y. Yang, B. Zhou
and Y. Li, Adv. Synth. Catal., 2012, 354, 291; (g) S. Sharma,
Chem. Lett., 1995, 681; (b) Y.-G. Lim, K.-H. Lee, B. T. Koo
and J.-B. Kang, Tetrahedron Lett., 2001, 42, 7609; (c)
K. Cheng, B. Yao, J. Zhao and Y. Zhang, Org. Lett., 2008,
10, 5309; (d) B. Zhou, H. Chen and C. Wang, J. Am. Chem.
Soc., 2013, 135, 1264; (e) G. D. Johnson, M. J. Lynam,
S. N. Mistry, M. J. Slattery, J. R. Thatcher and
C. A. Whitwood, J. Am. Chem. Soc., 2013, 135, 2222.
A. Kim, J. Park, M. Kim, J. H. Kwak, Y. H. Jung, J. S. Park 21 G. Majji, S. Guin, S. K. Rout, A. Behera and B. K. Patel, Chem.
and I. S. Kim, Org. Biomol. Chem., 2013, 11, 7869; (h)
Commun., 2014, 50, 12193.
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¨
¨
¨
22 (a) N. R. Deprez and M. S. Sanford, J. Am. Chem. Soc., 2009,
131, 11234; (b) J. M. Racowski, A. R. Dick and
P. J. R. Sjoberg, C. Skold, J. Savmarker, L. R. Odell and
M. Larhed, Chem.–Eur. J., 2013, 19, 13803.
M. S. Sanford, J. Am. Chem. Soc., 2009, 131, 10974; (c) 24 C. Zhang and N. Jiao, J. Am. Chem. Soc., 2010, 132, 28.
C. F. Rosewall, P. A. Sibbald, D. V. Liskin and 25 (a) D. C. Powers, M. A. L. Geibel, J. E. M. N. Klein and
F. E. Michael, J. Am. Chem. Soc., 2009, 131, 9488.
T. Ritter, J. Am. Chem. Soc., 2009, 131, 17050; (b)
D. C. Powers and T. Ritter, Nat. Chem., 2009, 1, 302.
¨
23 (a) J. Lindh, P. J. R. Sjoberg and M. Larhed, Angew. Chem., Int.
Ed., 2010, 49, 7733; (b) J. Rydord, F. Svensson, A. Trejos,
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