An Efficient synthesis of Weinreb amides and ketones via palladium nanoparticles on ZIF-8 catalysed carbonylative coupling

Article abstract of DOI:10.1039/c4ra04614e

Heterogeneously catalysed carbonylative coupling reactions such as aminocarbonylation and Suzuki-carbonylation are reported using Pd nanoparticles supported on ZIF-8 for efficient and environmentally attractive synthesis of Weinreb amides and ketones from aryl bromides or iodides. The catalyst is air stable, offers high activity with very low palladium leaching and is recyclable. The presence of a phosphine ligand was required when aryl bromides were used as substrates, while no ligand was necessary when aryl iodides were used. the Partner Organisations 2014.

Full text of DOI:10.1039/c4ra04614e

RSC Advances
View Article Online
View Journal | View Issue
PAPER
An Efficient synthesis of Weinreb amides and
ketones via palladium nanoparticles on ZIF-8
catalysed carbonylative coupling†
Cite this: RSC Adv., 2014, 4, 30019
*
Tuan Thanh Dang, Anqi Chen and Abdul Majeed Seayad
Heterogeneously catalysed carbonylative coupling reactions such as aminocarbonylation and Suzuki-
carbonylation are reported using Pd nanoparticles supported on ZIF-8 for efficient and environmentally
attractive synthesis of Weinreb amides and ketones from aryl bromides or iodides. The catalyst is air
stable, offers high activity with very low palladium leaching and is recyclable. The presence of a
phosphine ligand was required when aryl bromides were used as substrates, while no ligand was
necessary when aryl iodides were used.
Received 16th May 2014
Accepted 23rd June 2014
DOI: 10.1039/c4ra04614e
www.rsc.org/advances
ligand to afford a variety of Weinreb amides in up to 99% yield
from the corresponding aryl bromides under atmospheric
pressure of carbon monoxide at 80 ꢀC. The same catalyst system
was used by Odell and co-workers8 in the presence of Mo(CO)6
or W(CO)6 as a carbon monoxide source under microwave
irradiation conditions and by Venturello and co-workers9 to
synthesise a,b-unsaturated Weinreb amides from the corre-
Introduction
Carbonylative coupling is an environmentally attractive three-
component methodology to synthesize several value added
carbonyl functionalised compounds such as carboxylic acid/
esters, amides, ketones, etc. from readily available starting
materials.1 Among the amides, an important class is the
Weinreb amides (N-methoxy-N-methyl amides) that are widely
used as acylating agents to afford a variety of value added
carbonyl compounds having applications in the syntheses of
complex natural products, pharmaceuticals and ne chem-
icals.2 In the conventional method, Weinreb amides are
produced by the direct reaction of N,O-dimethylhydroxyamine
hydrochloride (DMHA$HCl) with an acid chloride in the pres-
ence of a base.3 Other acid derivatives such as anhydrides,
lactones, esters and amides could also be used.2,4 Direct reac-
tion of carboxylic acids with DMHA could be a simple alterna-
tive, however this requires various coupling agents to generate
the activated carbonyl component for coupling,5 thus making it
environmentally unattractive. Under this context, the amino-
carbonylation6 strategy in which an activated metal–acyl
complex is catalytically generated in situ for coupling with
DMHA offers an environmentally benign method for Weinreb
amide synthesis. In spite of its advantages only a few reports7–10
are available on this promising reaction, mainly using homo-
geneous palladium catalysts.
´
sponding heterocyclic triates. Recently, Kollar and co-workers
reported Pd(OAc)2 in the presence of PPh3 as an alternative
homogeneous catalyst for aryl and alkeny iodides as substrates,
however at 40–60 bar pressure of carbon monoxide.10 Most of
these homogeneously catalyzed aminocarbonylation reactions
to synthesize Weinreb amides have the obvious disadvantage of
separation of the catalyst from the product and its subsequent
recycle. In addition, small amounts of palladium residues in the
product would be a concern for pharmaceutical applications.
Hence, an efficient heterogeneous catalyst system is required to
make this promising aminocarbonylation strategy as an
industrially viable and sustainable alternative route to Weinreb
amide synthesis. However, to the best of our knowledge, a
promising heterogeneous catalyst system for this purpose is not
reported so far. Recently, we have reported palladium nano-
particles supported on MOF-5 (Metal Organic Framework)11 and
ZIF-8 (Zeolitic Imidazolate Framework)12 as promising hetero-
geneous catalysts for the synthesis of various amides under
aminocarbonylation conditions.13 Herein, we report an easy and
environmentally attractive synthesis of various functionalised
Weinreb amides from the corresponding aryl bromides or
iodides following aminocarbonylation strategy in the presence
of recyclable palladium nanoparticles supported on ZIF-8 (Pd/
ZIF-8) as an efficient catalyst. The efficiency of the catalyst
system was also demonstrated for the synthesis of ketones
using Suzuki-carbonylation strategy.
Buchwald and co-workers7 reported an efficient catalyst
system comprising of Pd(OAc)2 in the presence of Xantphos as a
Institute of Chemical and Engineering Sciences, 8 Biomedical Grove, #07-01 Neuros,
Singapore 138665. E-mail: abdul_seayad@ices.a-star.edu.sg; Fax: +65-6464-2102;
Tel: +65-6799-8527
† Electronic supplementary information (ESI) available: 1H and 13C NMR Spectra
of compounds, HRMS of 2l
10.1039/c4ra04614e
& 2p, recycle and leaching studies. See DOI:
This journal is © The Royal Society of Chemistry 2014
RSC Adv., 2014, 4, 30019–30027 | 30019

View Article Online
RSC Advances
Paper
was used as the substrate at atmospheric pressure of CO and up
to 92% yield was achieved at 1 bar of carbon monoxide and was
increased to quantitative yield upon increasing the pressure to
3 bar.
Results and discussion
An initial investigation showed that synthesis of the Weinreb
amide, N-methoxy-N,4-dimethylbenzamide (2a) could be ach-
ieved in up to 72% yield from p-bromotoluene (1a) as a standard
substrate and DMHA$HCl using 1 wt% Pd/ZIF-8 (ref. 14) as the
catalyst in the presence of dpePhos as a ligand and K2CO3 as a
base at 3 bar of carbon monoxide and 105 ꢀC aer 12 h of
reaction (Table 1, entry 1).
A ligand optimization study (Table 1) showed that, under
these conditions, common ligands such as PPh3, dppf, dppp,
and BINAP provided lower yields (<40%) of the desired product
(entries 2–5), while quantitative yield was achieved when Xant-
phos was used as the ligand. To our delight, near quantitative
yield was also achieved even at 1 bar pressure of carbon
monoxide using Xantphos as the ligand (entry 7). Among the
bases screened, K2CO3 performed the best and Na2CO3 was also
effective with only a slight decrease in the yield (96%). However,
when K3PO4 was used, the yield decreased drastically to 23%.
Soluble organic bases can also be used and up to 68% and 92%
Next, we applied these optimized conditions to explore the
synthesis of various functionalized Weinreb amides from the
corresponding functionalized aryl bromides and iodides.
Initially, relatively inexpensive and readily available aryl
bromides were chosen as substrates in the presence of Xant-
phos ligand at 3 bar pressure of carbon monoxide to ensure
higher conversion when less reactive aryl bromides were also
used (Table 2). Good to excellent isolated yields were obtained
with unsubstituted (1b) and para-substituted (1a, 1c, and 1g–k)
aryl bromides. Sterically demanding o-Me substituted aryl
bromide (1d) gave up to 75% yield of 2d. Mono- and multi-
methoxy substituents at various positions of the aromatic ring
(1e and 1f) were well tolerated and the corresponding Weinreb
amides 2e and 2f were obtained in 94–96% yields.
Presence of other halogen atoms such p-Cl and p-F was also
tolerated and the products 2g and 2h were formed in 95% and
77% yields, respectively. Electron withdrawing NO2 substituent
gave 2i in good yield of 79%, whereas up to 98% yield of 2j was
achieved from p-CN substituted aryl bromide. Unprotected
amino (1k), aldehyde (1l) and keto (1m) groups at para position
were well tolerated and the corresponding Weinreb amides 2k,
2l and 2m were obtained in 68%, 84% and 78%, respectively,
¨
yields were observed in the presence of triethylamine and Hunig
base, respectively. Pd/MOF-5 as a catalyst gave a comparable
yield of 95%, while Pd/MCM-41 gave a lower yield of 75%.
Interestingly, no ligand was necessary when p-iodotoluene (1a0)
Table 1 Optimizations of aminocarbonylation of p-bromotoluene
with N,O-dimethylhydroxyamine hydrochloridea
Table 2 Synthesis of Weinreb amides from aryl bromides using Pd/
ZIF-8 catalyzed aminocarbonylationa
Entry Base
PCO (bar) Ligand
Catalyst
Yieldb (%)
1
2
3
4
5
6
7
8
K2CO3
3
3
3
3
3
3
1
1
1
1
1
1
1
1
3
dpePhos
PPh3
dppf
dppp
BINAP
Xantphos Pd/ZIF-8
Xantphos Pd/ZIF-8
Xantphos Pd/ZIF-8
Xantphos Pd/ZIF-8
Xantphos Pd/ZIF-8
Xantphos Pd/ZIF-8
Xantphos Pd/MOF-5
Pd/ZIF-8
Pd/ZIF-8
Pd/ZIF-8
Pd/ZIF-8
Pd/ZIF-8
72
12
38
14
19
>99
99
96
23
68
92
95
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
Na2CO3
K3PO4
Et3N
(i-Pr)2NEt
K2CO3
K2CO3
K2CO3
K2CO3
9
10
11
12
13
14
15
Xantphos Pd/MCM-41 75
—
—
Pd/ZIF-8
Pd/ZIF-8
92c
>99c
a
a
Conditions: p-bromotoluene (1a, 1 mmol), N,O-dimethylhydroxyamine
Conditions: aryl bromide (1(a–o), 1 mmol), N,O-dimethylhydroxyamine
hydrochloride (DMHA$HCl, 1.5 mmol), 1 wt% Pd/ZIF-8 (24 mg, 0.21 hydrochloride (DMHA$HCl, 1.5 mmol),
1 wt% Pd/ZIF-8 (24 mg,
mol%), ligand (1 mol%), K2CO3 (2.5 equiv.), toluene (2 mL) 105 ꢀC, 12 0.21 mol%), Xantphos (1 mol%), K2CO3 (2.5 equiv.), toluene (2 mL),
b
b
h. Yield was determined by 1H-NMR using mesitylene as an internal CO (3 bar), 105 ꢀC, 12 h. Isolated yields are given. Incomplete
c
standard. p-Iodotoluene (1a0) was used as the substrate.
conversion observed.
30020 | RSC Adv., 2014, 4, 30019–30027
This journal is © The Royal Society of Chemistry 2014

View Article Online
Paper
RSC Advances
demonstrating good functional group compatibility of the
catalyst system. Heteroaromatic Weinreb amides 2n and 2o
were also easily obtained in excellent yields from the corre-
sponding heteroaryl bromides 1n and 1o using the present
catalyst system.
More reactive aryl iodides as the substrate did not require
phosphine ligands under the present aminocarbonylation
conditions and various functionalized Weinreb amides were
obtained in good to excellent yields at 3 bar pressure of carbon
monoxide at 105 ꢀC as shown in Table 3. Similar to the case of
aryl bromides, several functional groups were tolerated
including nitro (2i), hydroxy (2p), and carbonyl (2q) groups.
Interestingly, bromide as a functional group was well toler-
ated under ligand free condition and the para- and meta-bromo-
substituted Weinreb amides 2r and 2s were obtained in up to
88% isolated yields. The bromo-substituted Weinreb amides
can be further functionalized using common protocols to afford
several value added products and intermediates. For instance,
4-bromobenzophenone (3) was prepared in 82% isolated yield
from 4-bromo-N-methoxy-N-methylbenzamide (2r) by reaction
with phenyl magnesium bromide (Scheme 1) and was further
coupled with acetamide using copper catalyst15 affording N-(4-
benzoylphenyl)acetamide (4), an intermediate for the synthesis
of Mebendazole16 (5), which is an anthelmintic drug.
Scheme 1 Synthesis of Mebendazole from 4-bromo-N-methoxy-N-
methylbenzamide.
under the optimized carbonylation condition using 1 wt% Pd/
ZIF-8 as the catalyst in the absence of ligands. As shown in
Table 4, the product ketone (8) was obtained in up to 55% yield,
however, the biaryl 9 was formed as a side product in
substantial amount when inorganic bases were used (entries
1–4, Table 4). To our delight, formation of the 9 by the direct
coupling between aryl iodide and aryl boronic acid was
¨
completely suppressed when organic bases such as Hunig base
Direct synthesis of ketone is possible if DMHA$HCl is
replaced with a suitable coupling partner. Accordingly, Suzuki-
carbonylation17 was examined using iodobenzene (6) and
p-methoxyphenylboronic acid (7) as the standard substrates
and triethylamine were used and the product 8 was obtained in
36% and 42% yields respectively. The yield was further
improved to 85% when 6 bar pressure of carbon monoxide was
used with the reaction time prolonged to 24 h (entry 7, Table 4).
With aryl bromide as a substrate, presence of a phosphine
ligand was found to be necessary for Suzuki-carbonylation
using 1 wt% Pd/ZIF-8 as the catalyst. CataCXium A was found to
be one of the best ligands under the present catalyst system in
the presence of triethylamine as a base. As shown in Scheme 2,
up to 74% yield to the ketone 11 was achieved at 10 bar of
Table 3 Synthesis of Weinreb amides from aryl iodides using Pd/ZIF-8
catalyzed aminocarbonylationa
Table
4 Synthesis of ketone via Suzuki-carbonylation of
iodobenzenea
Yieldb (%)
Entry
Base
PCO (bar)
Time (h)
8
9
1
2
3
4
5
6
7
K2CO3
K3PO4
Na2CO3
NaHCO3
(i-Pr)2NEt
Et3N
3
3
3
3
3
3
6
12
12
12
12
12
12
24
46
55
46
12
36
42
85c
30
22
25
4
N.d.
N.d.
N.d.
Et3N
a
Conditions: aryl iodide (1 mmol), N,O-dimethylhydroxyamine
a
hydrochloride (DMHA$HCl, 1.5 mmol),
1 wt% Pd/ZIF-8 (24 mg,
Conditions: iodobenzene (6, 0.5 mmol), p-methoxyphenylboronic acid
0.21 mol%), Xantphos (1 mol%), K2CO3 (2.5 equiv.), toluene (2 mL),
(7, 1.5 equiv.), 1 wt% Pd/ZIF-8 (24 mg, 0.42 mol%), base (2.5 equiv.),
b
b
CO (3 bar), 105 ꢀC, 12 h. Isolated yields are given. Incomplete
toluene (2 mL) 105 ꢀC.
Yield was determined by GC using
hexadecane as an internal standard. c 78% isolated yield.
conversion observed.
This journal is © The Royal Society of Chemistry 2014
RSC Adv., 2014, 4, 30019–30027 | 30021

View Article Online
RSC Advances
Paper
conditions. This procedure offers a sustainable alterative
synthesis of various functionalized Weinreb amides in high
yields. The potential application of this catalyst system has been
demonstrated for the synthesis of an intermediate towards the
synthesis of anthelmintic drug Mebendazole from the corre-
sponding Weinreb amide. The possibility of direct synthesis of
ketones by Suzuki-carbonylation was also demonstrated. The
catalyst Pd/ZIF-8 could be efficiently recycled and the Pd leach-
ing was found to be less than 3 ppm. Scale up possibility was also
demonstrated in a gram scale achieving a TON of about 1500.
Scheme 2 Suzuki-carbonylation of aryl bromides.
carbon monoxide for 18 h at 100 ꢀC from bromobenzene 1b and
the boronic acid 10.
Experimental section
General information
The 1 wt% Pd/ZIF-8 catalyst was found to be recyclable and
no appreciable change in catalytic performance was observed
aer six cycles for the aminocarbonylation of p-iodotoluene.
Very low palladium leaching (<3 ppm) was observed in each run.
A ltrate test was carried out to investigate the possible
involvement of homogeneously catalysed reaction. No appre-
ciable reaction was observed when the ltrate of an amino-
carbonylation reaction, aer removing the solid catalyst, was
subjected to a second aminocarbonylation reaction by adding
fresh reaction mixture. This observation could possibly indicate
that the catalytic reaction pathway originating from the leached
out palladium leading to a homogeneous pathway may be much
less important compared to a heterogeneous pathway.
When aryl bromides were used as a substrate for both amino-
and Suzuki-carbonylations, presence of a suitable phosphine
ligand was found to be necessary together with 1 wt% Pd/ZIF-8 as
the catalyst. The adsorbed phosphine ligand onto palladium
nanoparticles could alter the electronic properties to facilitate
the activation of less reactive aryl bromides during the initial
oxidative addition step.18 Though presence of phosphine ligands
could potentially enhance leaching of palladium into solution
thereby driving the reaction through homogeneous pathway,
low leaching (<4 ppm)13a and efficient recyclability of the catalyst
observed shows either such homogeneous pathway is negligible
owing to the stability19 of Pd/ZIF-8 catalyst or the efficient re-
adsorption of palladium on to the support (ZIF-8) aer a
potential homogeneous reaction (quasi-heterogeneous catal-
ysis).20 Further mechanistic investigation is necessary to
understand the dynamic nature of Pd nanoparticles21 and the
appropriate share of heterogeneous and homogeneous reaction
pathways in the absence and presence of ligands when Pd/ZIF-8
is used as a catalyst under the present reaction conditions.
The scalabilityof thereaction wasalsoinvestigatedusingboth
p-bromo- and p-iodo-toluene (1a and 1a0) under the optimized
conditions using 5 mmol of substrate using 24 mg of catalyst for
24 h, achieving a TON of about 1500 with about 68–70% yields.
All chemicals and reagents were purchased from Aldrich or Alfa
Aesar and were used without further purication. For chro-
matographic purications, technical-grade solvents were used.
Reactions were checked by thin layer chromatography (TLC)
using Merck Silica Gel 60 F254 plates under UV light. The
chromatographic purication of the products was performed on
silica gel. NMR-spectra were measured in the given solvent at
room temperature on a Bruker Avance 400 (400 MHz, 1H-NMR;
100 MHz, 13C-NMR). Chemical shis d are given in parts per
1
million (ppm) relative to tetramethylsilane (TMS) for H- and
13C-NMR spectra and also calibrated against the solvent
residual peak. Multiplicities are reported as follows: s ¼ singlet,
d ¼ doublet, t ¼ triplet, q ¼ quartet, m ¼ multiplet, br ¼ broad
signal or as a combination of them. Coupling constants (J) are
given in Hertz (Hz).
Preparation of 1 wt% Pd/ZIF-8 catalyst13a
K2PdCl4 (16.32 mg, 0.05 mmol) was dissolved in 30 mL of water
to form an orange solution. 0.5 g of ZIF-8 was added into the
solution, and the mixture was stirred for 30 minutes at room
temperature. Then, 2.0 mL of polyvinyl alcohol (PVA) solution
(1 wt%) was introduced. Aer stirring for 20 minutes, a solution
of hydrazine (1.0 mL, excess) in 30 mL of water was added drop-
wise for 60 min into the reaction mixture under strong stirring.
Colour of the mixture turned to gray immediately upon addi-
tion. Aer stirring for another 60 minutes, the dark solid was
isolated by ltration, washed 2 times with water (10 mL), one
time with methanol followed by dry ether (10 mL) and dried
overnight under vacuum at 100 ꢀC. Pd on support (1.0 wt%) was
obtained as a gray powder, and stored under nitrogen
atmosphere. ICP analysis showed 92–96% palladium incorpo-
ration. BET specic surface area of the catalyst is found to be
1303 m2 gꢁ1. The sharp XRD peaks showed good crystallinity
and were nearly identical to the support itself.14 The Pd nano-
particles having a size distribution of 4–9 nm are well distrib-
uted on the external surface of ZIF-8 and no obvious aggregation
was observed.
Conclusions
General procedure for aminocarbonylation
We have reported an easy synthesis of Weinreb amides using an
efficient and recyclable heterogeneous catalyst from the corre- A 10 mL glass vial containing a magnetic stirrer bar was charged
sponding aryl bromides or iodides with N,O-dimethylhydroxy- with a mixture of 1 wt% Pd/ZIF-8 (24 mg, 0.21 mol% Pd),
amine hydrochloride under relatively mild aminocarbonylation Xantphos (5.8 mg, 1.0 mol%), K2CO3 (345 mg, 2.5 mmol), aryl
30022 | RSC Adv., 2014, 4, 30019–30027
This journal is © The Royal Society of Chemistry 2014

View Article Online
Paper
RSC Advances
N,3,4-Trimethoxy-N-methylbenzamide.23 (2e) The general
procedure was followed by using 4-bromo-1,2-dimethoxy-
benzene (217 mg, 1.0 mmol) and DMHA$HCl (143.4 mg, 1.5
mmol) for 12 h at 105 ꢀC. The product was isolated aer column
chromatography (elution with hexane–ethyl acetate 10 : 1–1 : 1)
bromide (1.0 mmol), DMHA$HCl (1.5 mmol) and 2 mL of
toluene. The vial was placed in a HEL CAT-7 pressure reactor,
which was purged with nitrogen, followed by carbon monoxide
and was lled with the required pressure (1–3 bar) of carbon
monoxide. The reaction was continued with stirring for 12 h at
105 ꢀC, cooled to room temperature and was analyzed by NMR
aer ltering through a short pad of Celite and evaporating the
solvents and volatiles. In most cases the compound was nearly
pure and was further puried by column chromatography using
gradient elution with EtOAc–hexane (10 : 1–1 : 1). No ligand was
added when aryl iodide was used as the substrate instead of aryl
bromide.
N-Methoxy-N,4-dimethylbenzamide.7 (2a) The general
procedure was followed by using p-bromotoluene (171 mg, 1.0
mmol) and DMHA$HCl (143.4 mg, 1.5 mmol) for 12 h at 105 ꢀC.
The product was isolated aer column chromatography (elution
with hexane–ethyl acetate 10 : 1–1 : 1) as a colorless liquid 173.6
mg (0.97 mmol, 97%). 1H NMR (400 MHz, CDCl3): d 2.37 (s, 3H),
3.34 (s, 3H), 3.55 (s, 3H), 7.19 (d, J ¼ 7.6, 3H), 7.58 (d, J ¼ 7.6,
3H); 13C NMR (100 MHz, CDCl3): d 21.5, 34.0, 61.0, 128.4, 128.8,
131.3, 141.0, 170.1. Compound 2a was also obtained by ami-
nocarbonylation of p-iodotoluene (218 mg, 1.0 mmol) and
DMHA$HCl (143.4 mg, 1.5 mmol) for 12 h at 105 ꢀC. The
product was isolated aer column chromatography (elution
with hexane–ethyl acetate 10 : 1–1 : 1) as a colorless liquid 168.2
mg (0.94 mmol, 94%).
1
as a colorless liquid 216.1 mg (0.96 mmol, 96%). H NMR (400
MHz, CDCl3): d 3.29 (s, 3H), 3.51 (s, 3H), 3.84 (s, 3H), 3.85 (s,
2H), 6.81 (d, J ¼ 7.6, 1H), 7.32 (m, 1H), 7.26 (s, 1H); 13C NMR
(100 MHz, CDCl3): d 34.0, 55.9, 56.0, 60.9, 110.2, 112.1, 122.1,
126.1, 148.4, 151.2, 169.3.
N,3,4,5-Tetramethoxy-N-methylbenzamide.23 (2f) The general
procedure was followed by using 5-bromo-1,2,3-trimethoxy-
benzene (247 mg, 1.0 mmol) and DMHA$HCl (143.4 mg, 1.5
mmol) for 12 h at 105 ꢀC. The product was isolated aer column
chromatography (elution with hexane–ethyl acetate 10 : 1–1 : 1)
1
as a colorless solid 242.2 mg (0.95 mmol, 95%). H NMR (400
MHz, CDCl3): d 3.31 (s, 3H), 3.56 (s, 3H), 3.84 (s, 9H), 6.93 (s,
2H); 13C NMR (100 MHz, CDCl3): d 34.0, 56.3, 60.9, 61.2, 106.0,
129.1, 140.2, 152.8, 169.4. Compound 2f was also obtained by
aminocarbonylation using 5-iodo-1,2,3-trimethoxybenzene (294
mg, 1.0 mmol) and DMHA$HCl (143.4 mg, 1.5 mmol) for 12 h at
105 ꢀC. The product was isolated aer column chromatography
(elution with hexane–ethyl acetate 10 : 1–1 : 1) as a white solid
232.1 mg (0.91 mmol, 91%).
4-Chloro-N-methoxy-N-methylbenzamide.7 (2g) The general
procedure was followed by using p-chlorobromobenzene (191.5
mg, ꢀ1.0 mmol) and DMHA$HCl (143.4 mg, 1.5 mmol) for 12 h at
105 C. The product was isolated aer column chromatography
(elutionwithhexane–ethylacetate10 : 1–1 : 1)asacolorlessliquid
187.1 mg (0.94 mmol, 94%). 1H NMR (400 MHz, CDCl3): d 3.24 (s,
3H), 3.43(s, 3H), 7.27 (d, J ¼ 7.6, 3H), 7.56(d, J ¼ 7.6, 3H); 13C NMR
(100 MHz, CDCl3): d 33.3, 60.9, 128.1, 129.7, 132.3, 136.5, 168.4.
4-Fluoro-N-methoxy-N-methylbenzamide.24 (2h) The general
procedure was followed by using p-bromouorobenzene (175
mg, 1.0 mmol) and DMHA$HCl (143.4 mg, 1.5 mmol) for 12 h at
105 ꢀC. The product was isolated aer column chromatography
(elution with hexane–ethyl acetate 10 : 1–1 : 1) as a colorless
liquid 140.9 mg (0.77 mmol, 77%). 1H NMR (400 MHz, CDCl3): d
3.35 (s, 3H), 3.53 (s, 3H), 7.05 (m, 2H), 7.73 (m, 2H); 13C NMR
(100 MHz, CDCl3): d 33.7, 61.1, 115.2 (d, J ¼ 21.8 Hz), 130.1 (d, J
¼ 83.4 Hz), 130.9 (d, J ¼ 8.6 Hz), 164.2 (d, J ¼ 251.1 Hz), 168.8.
N-Methoxy-N-methyl-4-nitrobenzamide.24 (2i) The general
procedure was followed by using 1-bromo-4-nitrobenzene (202
mg, 1.0 mmol) and DMHA$HCl (143.4 mg, 1.5 mmol) for 12 h at
105 ꢀC. The product was isolated aer column chromatography
(elution with hexane–ethyl acetate 10 : 1–1 : 1) as a colorless
liquid 165.9 mg (0.79 mmol, 79%). 1H NMR (400 MHz, CDCl3): d
3.33 (s, 3H), 3.49 (s, 3H), 7.78 (d, J ¼ 7.6, 3H), 8.19 (d, J ¼ 7.6, 3H);
13CNMR(100MHz, CDCl3):d33.1, 61.4, 123.2, 129.2, 140.1, 148.8,
167.7. Compound 2i was also obtained by aminocarbonylation of
1-iodo-4-nitrobenzene(249mg, 1.0mmol)andDMHA$HCl(143.4
mg, 1.5 mmol) for 12 h at 105 ꢀC. The product was isolated aer
column chromatography (elution with hexane–ethyl acetate
10 : 1–1 : 1) as a colorless liquid 201.4 mg (0.96 mmol, 96%).
4-Cyano-N-methoxy-N-methylbenzamide.23 (2j) The general
procedure was followed by using 4-bromobenzonitrile (182 mg,
N-Methoxy-N-methylbenzamide.7 (2b) The general procedure
was followed by using bromobenzene (157 mg, 1.0 mmol) and
DMHA$HCl (143.4 mg, 1.5 mmol) for 12 h at 105 ꢀC. The
product was isolated aer column chromatography (elution
with hexane–ethyl acetate 10 : 1–1 : 1) as a colorless liquid 156.8
mg (0.95 mmol, 95%). 1H NMR (400 MHz, CDCl3): d 3.35 (s, 3H),
3.54 (s, 3H), 7.36–7.46 (m, 3H), 7.65 (m, 2H); 13C NMR (100 MHz,
CDCl3):
d 33.9, 61.1, 128.1, 128.3, 130.7, 134.3, 170.1.
Compound 2b was also obtained by aminocarbonylation of o-
iodotoluene (218 mg, 1.0 mmol) and DMHA$HCl (143.4 mg, 1.5
mmol) for 12 h at 105 ꢀC. The product was isolated aer column
chromatography (elution with hexane–ethyl acetate 10 : 1–1 : 1)
as a yellow oil 141.5 mg (0.79 mmol, 79%).
N,4-Dimethoxy-N-methylbenzamide.22 (2c) The general
procedure was followed by using 1-methoxy-4-bromobenzene
(187 mg, 1.0 mmol) and DMHA$HCl (143.4 mg, 1.5 mmol) for 12
h at 105 ꢀC. The product was isolated aer column chroma-
tography (elution with hexane–ethyl acetate 10 : 1–1 : 1) as a
colorless liquid 183.2 mg (0.94 mmol, 94%). 1H NMR (400 MHz,
CDCl3): d 3.35 (s, 3H), 3.56 (s, 3H), 3.84 (s, 3H), 6.90 (d, J ¼ 7.6,
3H), 7.72 (d, J ¼ 7.6, 3H); 13C NMR (100 MHz, CDCl3) d 34.0,
55.5, 61.0, 113.4, 126.2, 130.7, 161.7, 169.5.
N-Methoxy-N,2-dimethylbenzamide.22 (2d) The general
procedure was followed by using o-bromotoluene (171 mg, 1.0
mmol) and DMHA$HCl (143.4 mg, 1.5 mmol) for 12 h at 105 ꢀC.
The product was isolated aer column chromatography (elution
with hexane–ethyl acetate 10 : 1–1 : 1) as a yellow oil 134.2 mg
1
(0.75 mmol, 75%). H NMR (400 MHz, CDCl3): d 2.26 (s, 3H),
3.21 (s, 3H), 3.44 (s, 3H), 7.11 (m, 2H), 7.20 (m, 2H); 13C NMR
(100 MHz, CDCl3): d 18.9, 32.9, 60.9, 125.3, 126.0, 129.0, 130.0,
134.6, 135.2, 170.8.
This journal is © The Royal Society of Chemistry 2014
RSC Adv., 2014, 4, 30019–30027 | 30023

View Article Online
RSC Advances
Paper
1.0 mmol) and DMHA$HCl (143.4 mg, 1.5 mmol) for 12 h at 105 (elution with hexane–ethyl acetate 10 : 1–1 : 1) as a colorless
ꢀC. The product was isolated aer column chromatography liquid 101.4 mg (0.56 mmol, 56%). 1H NMR (400 MHz, CDCl3): d
(elution with hexane–ethyl acetate 10 : 1–1 : 1) as a colorless 3.35 (s, 3H), 3.55 (s, 3H), 6.82 (d, J ¼ 7.6, 3H), 7.58 (d, J ¼ 7.6,
liquid 186.1 mg (0.98 mmol, 98%). 1H NMR (400 MHz, CDCl3): d 3H), 8.59 (s, br, OH); 13C NMR (100 MHz, CDCl3): d 34.5, 61.1,
3.32 (s, 3H), 3.48 (s, 3H), 7.66 (d, J ¼ 7.6, 3H), 7.73 (d, J ¼ 7.6, 115.3, 124.2, 130.7, 159.7, 170.2.
3H); 13C NMR (100 MHz, CDCl3): d 33.2, 61.3, 114.1, 118.1,
5-Formyl-N,2,3-trimethoxy-N-methylbenzamide (2q). The
128.8, 131.8, 138.3, 167.9.
general procedure was followed by using 3-iodo-4,5-
4-Amino-N-methoxy-N-methylbenzamide.25 (2k) The general dimethoxybenzaldehyde (292 mg, 1.0ꢀmmol) and DMHA$HCl
procedure was followed by using bromotoluene (172 mg, 1.0 (143.4 mg, 1.5 mmol) for 12 h at 105 C. The product was iso-
mmol) and DMHA$HCl (143.4 mg, 1.5 mmol) for 12 h at 105 ꢀC. lated aer column chromatography (elution with hexane–ethyl
The product was isolated aer column chromatography (elution acetate 10 : 1–1 : 1) as a yellow solid 237.8 mg (0.94 mmol, 94%).
with hexane–ethyl acetate 10 : 1–1 : 1) as a colorless liquid 122.3 1H NMR (400 MHz, CDCl3): d 3.31 (s, br, 3H), 3.46 (s, br, 3H),
mg (0.68 mmol, 68%). 1H NMR (400 MHz, CDCl3): d 3.29 (s, 3H), 3.90 (s, 3H), 3.92 (s, 3H), 7.36 (s, 1H), 7.43 (s, 1H), 9.83 (s, 1H);
3.53 (s, 3H), 3.93 (s, 2H, br, NH2), 6.57 (d, J ¼ 7.6, 3H), 7.56 (d, J 13C NMR (100 MHz, CDCl3): d 32.3, 56.1, 61.3, 61.5, 111.4, 123.6,
¼ 7.6, 3H); 13C NMR (100 MHz, CDCl3): d 34.2, 60.7, 113.7, 130.5, 132.2, 151.0, 153.0, 167.8, 190.3. HRMS (ESI TOF): calcd
122.8, 130.6, 149.3, 169.8.
for C12H16NO5 [M + H]+ 254.1023; found: 254.1023.
4-Formyl-N-methoxy-N-methylbenzamide (2l). The general
4-Bromo-N-methoxy-N-methylbenzamide.24 (2r) The general
procedure was followed by using p-bromobenzaldehyde (185 procedure was followed by using 4-bromo-1-iodobenzene (283
mg, 1.0 mmol) and DMHA$HCl (143.4 mg, 1.5 mmol) for 12 h at mg, 1.0 mmol) and DMHA$HCl (143.4 mg, 1.5 mmol) for 12 h at
105 ꢀC. The product was isolated aer column chromatography 105 ꢀC. The product was isolated aer column chromatography
(elution with hexane–ethyl acetate 10 : 1–1 : 1) as a colorless (elution with hexane–ethyl acetate 10 : 1–1 : 1) as a colorless
liquid 162.1 mg (0.84 mmol, 84%). 1H NMR (400 MHz, CDCl3): d liquid 214.7 mg (0.88 mmol, 88%). 1H NMR (400 MHz, CDCl3): d
3.34 (s, 3H), 3.50 (s, 3H), 7.78 (d, J ¼ 7.6, 3H), 7.88 (d, J ¼ 7.6, 3.36 (s, 3H), 3.54 (s, 3H), 7.55 (d, J ¼ 7.6, 3H), 7.58 (d, J ¼ 7.6,
3H), 10.03 (s, 1H); 13C NMR (100 MHz, CDCl3): d 33.4, 61.3, 3H); 13C NMR (100 MHz, CDCl3): d 33.7, 61.3, 125.3, 130.2,
128.7, 129.3, 137.5, 139.8, 168.8, 191.7. HRMS (ESI TOF): calcd 131.4, 133.0, 168.9.
for C10H12NO3 [M + H]+ 194.0812; found: 194.0811.
3-Bromo-N-methoxy-N-methylbenzamide.28 (2s) The general
4-Acetyl-N-methoxy-N-methylbenzamide.8 (2m) The general procedure was followed by using 3-bromo-1-iodobenzene (283
procedure was followed by using 1-(4-bromophenyl)ethan-1-one mg, 1.0 mmol) and DMHA$HCl (143.4 mg, 1.5 mmol) for 12 h at
(199 mg, 1.0 mmol) and DMHA$HCl (143.4 mg, 1.5 mmol) for 12 105 ꢀC. The product was isolated aer column chromatography
h at 105 ꢀC. The product was isolated aer column chroma- (elution with hexane–ethyl acetate 10 : 1–1 : 1) as a colorless
tography (elution with hexane–ethyl acetate 10 : 1–1 : 1) as a liquid 212.3 mg (0.85 mmol, 85%). 1H NMR (400 MHz, CDCl3): d
colorless liquid 161.5 mg (0.78 mmol, 78%). 1H NMR (400 MHz, 3.29 (s, 3H), 3.49 (s, 3H), 7.22 (m, 1H), 7.48–7.62 (m, 2H), 7.7 (s,
CDCl3): d 2.58 (s, 3H), 3.32 (s, 3H), 3.49 (s, 3H), 7.70 (d, J ¼ 7.6, 1H); 13C NMR (100 MHz, CDCl3): d 33.5, 61.1, 121.9, 126.7,
2H), 7.94 (d, J ¼ 7.6, 2H); 13C NMR (100 MHz, CDCl3): d 26.7, 129.6, 131.2, 133.5, 136.0, 168.1.
33.4, 61.2, 127.9, 128.5, 138.3, 138.4, 168.9, 197.4.
4-Bromobenzophenone.29 (3) An ether solution of phenyl-
N-Methoxy-N-methylnicotinamide.8 (2n) The general proce- magnesium bromide (3.0 M, 0.2 mL, 0.6 mmol) was introduced
dure was followed by using 3-bromopyridine (158 mg, 1.0 into a 10 mL of ether solution of 4-bromo-N-methoxy-N-
mmol) and DMHA$HCl (143.4 mg, 1.5 mmol) for 12 h at 105 ꢀC. methylbenzamide (97.6 mg, 0.4 mmol) under stirring at 0 ꢀC
The product was isolated aer column chromatography (elution and the reaction mixture was stirred overnight. The crude
with hexane–ethyl acetate 10 : 1–1 : 1) as a colorless liquid 157.6 mixture was worked up with 20 mL of HCl (2 M) solution and
mg (0.95 mmol, 95%). 1H NMR (400 MHz, CDCl3): d 3.23 (s, 3H), 30 mL EtOAc. The product was isolated aer column chroma-
3.41 (s, 3H), 7.21 (ddd, J ¼ 7.9, 4.9, 0.9 Hz, 1H), 7.88 (dt, J ¼ 7.9, tography (elution with hexane–ethyl acetate 10 : 1–5 : 1) as a
2.0 Hz, 1H), 8.53 (dd, J ¼ 4.9, 1.7 Hz, 1H), 8.80 (dd, J ¼ 2.2, 1.0 white solid 85.6 mg (0.328 mmol, 82%). 1H NMR (400 MHz,
Hz, 1H); 13C NMR (100 MHz, CDCl3): d 33.0, 61.1, 122.8, 129.7, CDCl3): d 7.44–7.55 (m, 2H), 7.56–7.65 (m, 3H), 7.68 (d, J ¼
135.9, 149.1, 151.2, 167.2.
N-Methoxy-N-methylpyrimidine-5-carboxamide.26 (2o) The d 127.6, 128.5, 130.0, 131.6, 131.7, 132.7, 136.5, 137.3, 195.6.
general procedure was followed by using 5-bromopyrimidine
N-(4-Benzoylphenyl)acetamide.18 (4) Dry dioxane (0.8 mL)
8.7 Hz, 2H), 7.74–7.82 (m, 2H); 13C NMR (100 MHz, CDCl3):
(159 mg, 1.0 mmol) and DMHA$HCl (143.4 mg, 1.5 mmol) for 12 was added to a mixture of 78.3 mg (0.3 mol) of 3, acetamide (0.6
h at 105 ꢀC. The product was isolated aer column chroma- mmol), CuI (5.7 mg, 10 mol%), cyclohexane-1,2-diamine (6.8
tography (elution with hexane–ethyl acetate 10 : 1–1 : 1) as a mg, 20 mol%) and K2CO3 (125 mg, 0.9 mmol), in a 5 mL Schlenk
colorless liquid 163.8 mg (0.98 mmol, 98%). 1H NMR (400 MHz, ask. The reaction mixture was degassed using argon for 2 min
CDCl3) d 3.37 (s, 3H), 3.56 (s, 3H), 7.06 (s, 2H), 9.24 (s, 1H); 13
C
and was heated at 120 ꢀC for 24 h under stirring. The crude
NMR (100 MHz, CDCl3): d 33.0, 61.6, 127.9, 156.8, 159.9, 164.9. mixture was worked up with 20 mL of saturated NaCl solution
4-Hydroxy-N-methoxy-N-methylbenzamide.27
(2p) The and 30 mL EtOAc. The product was isolated aer column
general procedure was followed by using p-iodophenol (220 mg, chromatography (elution with hexane–ethyl acetate 10 : 1–2 : 1)
1.0 mmol) and DMHA$HCl (143.4 mg, 1.5 mmol) for 12 h at as a white solid 53.8 mg (0.225 mmol, 75%). 1H NMR (400 MHz,
105 ꢀC. The product was isolated aer column chromatography CDCl3): d 2.19 (s, 3H), 7.40–7.29 (m, 1H), 7.46 (m, 1H), 7.56 (d, J
30024 | RSC Adv., 2014, 4, 30019–30027
This journal is © The Royal Society of Chemistry 2014

View Article Online
Paper
RSC Advances
¼ 8.7 Hz, 1H) 7.70–7.59 (m, 2H), 8.24 (s, br, OH). 13C NMR (100 and NMR for product aer ltering off the catalyst and inor-
MHz, CDCl3): d 23.9, 117.9, 127.4, 129.0, 130.8, 131.4, 132.3, ganic materials. Similarly, the scale up of p-bromotoluene was
137.0, 140.9, 167.6, 194.7.
conducted in the presence of Xantphos ligand.
4-Methoxybenzophenone (8).30 A 10 mL glass vial containing
a magnetic stirrer bar was charged with a mixture of 1 wt% Pd/
ZIF-8 (24 mg, 0.42 mol% Pd), Et3N (303 mg, 3 mmol), iodo-
Acknowledgements
benzene (0.5 mmol) and (4-methoxyphenyl)boronic acid (0.75 This work was funded by “GSK-EDB Singapore Partnership for
mmol) and 2 mL of toluene. The vial was placed in a HEL CAT-7 Green and Sustainable manufacturing” and the Institute of
pressure reactor, which was purged with nitrogen, followed by Chemical and Engineering Sciences (ICES), Agency for Science,
carbon monoxide and was lled with the required pressure of Technology and Research (A*STAR), Singapore.
carbon monoxide. The reaction was continued with stirring for
24 h at 105 ꢀC, cooled to room temperature and was analyzed by
NMR aer ltering through a short pad of Celite and evapo-
Notes and references
rating the solvents and volatiles. The crude product was puried
by column chromatography by gradient elution with EtOAc–
hexane (10 : 1–1 : 1) to provide the ketone (8) as a colorless
1 (a) L. Kollar. Modern Carbonylation Methods, Wiley-VCH,
Weinheim, 2008; (b) S. Sumino, A. Fusano, T. Fukuyama
and I. Ryu, Acc. Chem. Res., 2014, 47, 1563; (c) S. T. Gadge
and B. M. Bhanage, RSC Adv., 2014, 4, 10367; (d) X.-F. Wu,
H. Neumann and M. Beller, Chem. Soc. Rev., 2011, 40,
4986; (e) X. Feng, J. Song, H. Liu, L. Wang, X. Yu and
M. Bao, RSC Adv., 2013, 3, 18985.
1
solid, 83 mg (0.39 mmol, 78%). H NMR (400 MHz, CDCl3) d:
3.88 (s, 3H), 6.95–6.98 (m, 2H), 7.47 (dd, J ¼ 7.5,7.9 Hz, 2H),
7.54–7.59 (m, 1H), 7.75 (dd, J ¼ 1.4, 8.5 Hz, 2H), 7.81–7.85 (m,
2H); 13C NMR (100 MHz, CDCl3) d: 55.6, 113.7, 128.3, 129.8,
130.3, 131.9, 132.7, 138.5, 163.4, 195.6.
2 (a) A. Kamal, N. Shankaraiah, N. Markandaya, L. K. Reddy
and S. Reddy, Tetrahedron Lett., 2008, 49, 1465; (b)
T. Yoshino, F. Ng and S. J. Danishefsky, J. Am. Chem. Soc.,
2006, 128, 14185; (c) L. Z. Dias and M. A. De Sousa,
Tetrahedron Lett., 2003, 44, 562; (d) A. Zamri and
M. A. Abdallah, Tetrahedron, 2000, 56, 249; (e) J. Liu,
N. Ikemoto, D. Petrillo and J. D. Armstrong, Tetrahedron
Lett., 2002, 43, 8223; (f) D. A. Evans, S. W. Kaldor,
T. K. Jones, J. Clardy and T. J. Stout, J. Am. Chem. Soc.,
1990, 112, 7001; (g) B. N. Manjunath, N. P. Sane and
I. S. Aidhen, Eur. J. Org. Chem., 2006, 2851; (h)
J.-M. Nuzillard, A. Boumendjel and G. Massiot, Tetrahedron
Lett., 1989, 30, 3779; (i) C. Beney, A. Boumendjel and
A.-M. Mariotte, Tetrahedron Lett., 1998, 39, 5779; (j)
K. Ando, Synlett, 2001, 1272; (k) S. Fortin, F. Dupont and
P. Deslongchamps, J. Org. Chem., 2002, 67, 5437; (l)
A. Avenoza, C. Cativiela, J. M. Peregrina, D. Sucunza and
M. M. Zurbano, Tetrahedron: Asymmetry, 2001, 12, 1383; (m)
K. E. Rodriques, Tetrahedron Lett., 1991, 32, 1275; (n)
V. Selvamurugan and I. S. Aidhen, Tetrahedron, 2001, 57,
6065; (o) V. Selvamurugan and I. S. Aidhen, Synthesis, 2001,
2239; (p) T. Olpp and R. Bruckner, Angew. Chem., Int. Ed.,
2005, 44, 1553; (q) K. R. Prasad and A. Chandrakumar,
Tetrahedron, 2007, 63, 1798; (r) K. R. Prasad and
P. Anbarasan, Tetrahedron: Asymmetry, 2006, 17, 2465; (s)
K. R. Prasad and P. Anbarasan, J. Org. Chem., 2007, 72,
3155; (t) N. Satyamurthi, J. Singh and I. S. Aidhen,
Synthesis, 2000, 375; (u) B. Sivaraman and I. S. Aidhen,
Synlett, 2007, 959, reviews on Weinreb amides, see: (v)
M. Mentzel and H. M. R. Hoffmann, J. Prakt. Chem., 1997,
339, 517; (w) J. Singh, N. Satyamurthi and I. S. Aidhen, J.
Prakt. Chem., 2000, 342, 340; (x) S. Balasubramaniam and
I. S. Aidhen, Synthesis, 2008, 23, 3707.
(3,4-Methylenedioxyphenyl)phenylmethanone (11).31 The
procedure for the preparation of 8 was followed in a Parr reactor
at 10 bar of CO by using bromobenzene (2b, 157 mg, 1.0 mmol),
3,4-(methylenedioxy)phenylboronic acid (10, 249 mg, 1.5
mmol), Pd/ZIF-8 (24 mg, 1 wt%, 0.21 mol% Pd), Et3N (606 mg, 6
mmol), and CataCXium A (10.8 mg, 2 mol%) in 7 mL dry
toluene for 18 h at 120 ꢀC. Purication by ash chromatography
(PE–Et2O ¼ 10 : 1–1 : 1) gave 167.2 mg (0.74 mmol, 74%) of the
1
ketone 11 as a yellow oil; H NMR (400 MHz, CDCl3): d 6.05 (s,
2H), 6.85 (dq, J ¼ 1.8, 1.1 Hz, 1H), 7.37 (dd, J ¼ 9.1, 1.3 Hz, 2H),
7.46 (ddd, J ¼ 8.1, 6.6, 1.2 Hz, 2H), 7.52–7.60 (m, 1H), 7.68–7.78
(m, 2H); 13C NMR (100 MHz, CDCl3): d 101.9, 107.8, 110.0, 126.9,
128.3, 129.8, 132.1, 138.3, 148.1, 151.6, 195.2.
Recycle experiments
The recycle experiments were conducted using the isolated
catalyst aer the standard aminocarbonylation of p-iodoto-
luene. The catalyst was isolated by centrifugation and decanting
the solution, washed twice with fresh toluene and charged to
the subsequent aminocarbonylation reaction.
Filtration test
Filtrate test32 was conducted by adding fresh reaction mixture
(without the catalyst) to the ltrate of the standard amino-
carbonylation reaction of iodotoluene.
Scale-up synthesis
Scale-up reactions were conducted in a Parr 25 mL Hastelloy-C
high pressure reactor. 5 mmol of p-iodotoluene in 10 mL of
toluene was added to 24 mg of 1 wt% Pd/ZIF-8, 2.5 equiv of
K2CO3, and 7.5 mmol N,O-dimethylhydroxyamine hydrochlo-
ride and charged to the Parr reactor. Aer purging with
nitrogen, 3 bar carbon monoxide was charged and the reaction
3 S. Nahm and S. M. Weinreb, Tetrahedron Lett., 1981, 22,
3815.
4 (a) T. Raghuram, S. Vijayasaradhi, J. Singh and I. Singh,
Synth. Commun., 1999, 29, 3215; (b) F. D'Aniello, A. Mann
ꢀ
was carried out for 24 h at 105 C. The reactor was cooled to
room temperature and the reaction mixture was analyzed by GC
This journal is © The Royal Society of Chemistry 2014
RSC Adv., 2014, 4, 30019–30027 | 30025

View Article Online
RSC Advances
Paper
and M. J. J. Taddei, J. Org. Chem., 1996, 61, 4870; (c) 12 (a) R. Banerjee, A. Phan, B. Wang, C. Knobler, H. Furukawa,
S. Nakamura and M. Shibasaki, Tetrahedron Lett., 1994, 35,
4145; (d) M. Miyashita, Y. Toshimitu, T. Shiratani and
H. Irie, Tetrahedron: Asymmetry, 1993, 4, 1573; (e)
M. Furber, M. E. Cooper and D. K. Donald, Tetrahedron
M. O'Keeffe and O. M. Yaghi, Science, 2008, 319, 939; (b)
^ ´
K. S. Park, Z. Ni, A. P. Cote, J. Y. Choi, R. Huang,
F. J. U. Romo, H. K. Chae, M. O'Keeffe and O. M. Yaghi,
Proc. Natl. Acad. Sci. U. S. A., 2006, 103, 10187.
Lett., 1993, 34, 1351; (f) R. S. Garigipati, D. M. Tschaen and 13 (a) T. T. Dang, Y. Zhu, J. S. Y. Ngiam, S. C. Ghosh, A. Chen
S. M. Weinreb, J. Am. Chem. Soc., 1985, 107, 7790; (g)
Y. Hamada, F. Yokokawa, M. Kabeya, K. Hatano, Y. Kurono
and T. Shiori, Tetrahedron, 1996, 52, 8297; (h)
and A. M. Seayad, ACS Catal., 2013, 3, 1406; (b) T. T. Dang,
Y. Zhu, S. C. Ghosh, A. Chen, C. L. L. Chai and
A. M. Seayad, Chem. Commun., 2012, 48, 1805.
J. A. Marshall, B. M. Seletsky and G. P. Luke, J. Org. Chem., 14 See [ref. 13a] for detailed characterization (SEM, TEM and
1994, 59, 3413; (i) M. Murakami, Y. Hoshino, H. Ito and
Y. Ito, Chem. Lett., 1998, 163.
XRD) of palladium nanoparticles on ZIF-8 (1 wt% Pd/ZIF-8)
catalyst.
5 (a) L. De Luca, G. Giacomelli and M. Taddei, J. Org. Chem., 15 (a) D. S. Surry and S. L. Buchwald, Chem. Sci., 2010, 1, 13; (b)
2001, 66, 2534; (b) C. O. Kangani, D. E. Kelley and
B. W. Day, Tetrahedron Lett., 2006, 47, 6289; (c) T. Niu,
F. Monnier and M. Taillefer, Angew. Chem., Int. Ed., 2009, 48,
6954.
W. Zhang, D. Huang, C. Xu, H. Wang and Y. Hu, Org. Lett., 16 N. R. Ayyangar, R. J. Lahoti and T. Daniel, Org. Prep. Proced.
2009, 11, 4474; (d) I. Maugars, J. Poncet and P. Jouin, Int., 1991, 23, 627.
Tetrahedron, 1990, 46, 2807; (e) M. Falorni, G. Giacomelli 17 (a) M. Cai, G. Ding, W. Hao and J. Peng, Green Chem., 2011,
and A. M. Spanedda, Tetrahedron: Asymmetry, 1998, 9,
3039; (f) J. Einhorn, C. Einhorn and J. L. Luche, Synth.
Commun., 1990, 20, 1105; (g) M. Braun and D. Waldmuller,
Synthesis, 1989, 856; (h) J. C. S. Woo, E. Fenster and
G. R. Dake, J. Org. Chem., 2004, 69, 8984; (i) A. R. Tunoori,
J. M. White and G. I. Georg, Org. Lett., 2000, 2, 4091; (j)
M. P. Sibi, C. C. Stessman, J. A. Schultz, J. W. Christensen,
J. Lu and M. Marvin, Synth. Commun., 1995, 25, 1255.
13, 190; (b) H. Neumann, A. Brennfuehrer and M. Beller,
Chem.–Eur. J., 2008, 14, 3645; (c) T. Hayashi, T. Ishiyama,
H. Kizaki, N. Miyaura, A. Suzuki and A. Suzuki, J. Org.
Chem., 1998, 63, 4726; (d) P. J. Tambade, Y. P. Patil,
A. G. Panda and B. M. Bhanage, Eur. J. Org. Chem., 2009,
3022; (e) J.-J. Brunet and R. Chauvin, Chem. Soc. Rev., 1995,
2, 89; (f) A. Ahlburg, A. T. Lindhardt, R. H. Taaning,
A. E. Modvig and T. Skrydstrup, J. Org. Chem., 2013, 78,
10310; (g) K. M. Bjerglund, T. Skrydstrup and
G. A. Molander, Org. Lett., 2014, 16, 1888; (h) Z. S. Qureshi,
K. M. Deshmukh, P. J. Tambade and B. M. Bhanage,
Synthesis, 2011, 243; (i) D. Mingji, B. Liang, C. Wang,
Z. You, J. Xiang, G. Dong, J. Chen and Z. Yang, Adv. Synth.
Catal., 2004, 346, 1669; (j) E. Maerten, F. Hassouna,
S. Couve-Bonnaire, A. Mortreux, J.-F. Carpentier and
Y. Castanet, Synlett, 2003, 12, 1874; (k) H. Li, M. Yang,
Y. Qi and J. Xue, Eur. J. Org. Chem., 2011, 2662; (l)
M. Khedkar, P. J. Tambade, Z. S. Qureshi and
B. M. Bhanage, Eur. J. Org. Chem., 2010, 6981; (m) A. Petz,
G. Peczely, Z. Pinter and L. Kollar, J. Mol. Catal. A: Chem.,
2006, 255, 97.
6 (a) A. Schoenberg and R. F. Heck, J. Org. Chem., 1974, 39,
¨
3327; (b) A. Brennfuhrer, H. Neumann and M. Beller,
Angew. Chem., Int. Ed., 2009, 48, 4114; (c) R. Grigg and
S. P. Mutton, Tetrahedron, 2010, 66, 5515; (d)
C. F. J. Barnard, Organometallics, 2008, 27, 5402; (e) S. Roy
and G. W. Gribble, Tetrahedron, 2012, 68, 9867; (f)
A. Schoenberg and R. F. Heck, J. Org. Chem., 1974, 39, 3327;
(g) Y. Uozumi, T. Arii and T. Watanabe, J. Org. Chem., 2001,
66, 5272; (h) M. V. Khedkar, T. Sasaki and B. M. Bhanage,
ACS Catal., 2013, 3, 287; (i) S. Ho, G. Bondarenko, D. Rosa,
B. Dragisic and A. Orellana, J. Org. Chem., 2012, 77, 2008; (j)
V. Fuente, C. Godard, C. Claver and S. Castillon, Adv. Synth.
Catal., 2012, 354, 1971; (k) Z. S. Qureshi, S. A. Revankar,
M. V. Khedkar and B. M. Bhanage, Catal. Today, 2012, 198, 18 (a) T. Tagata and M. Nishida, J. Org. Chem., 2003, 68, 9412.
148; (l) F. Tinnis, O. Verho, K. P. Gustafson, C. W. Tai, 19 (a) Z. Guo, C. Xiao, R. V. Maligal-Ganesh, L. Zhou, T. W. Goh,
¨
J. E. Backvall and H. Adolfsson, Chem.–Eur. J., 2014, 20,
X. Li, D. Tesfagaber, A. Thiel and W. Huang, ACS Catal.,
2014, 4, 1340; (b) H.-L. Jiang, B. Liu, T. Akita, M. Haruta,
H. Sakurai and Q. Xu, J. Am. Chem. Soc., 2009, 131, 11302;
(c) H. Furukawa, K. E. Cordova, M. O'Keeffe and
O. M. Yaghi, Science, 2008, 319, 939.
5885; (m) H. Mei, J. Hu, S. Xiao, Y. Lei and G. Li, App.
Catal., A, 2014, 475, 40; (n) R. Skoda-Foldes and L. Kollar,
Curr. Org. Chem., 2002, 6, 1097.
7 (a) J. R. Martinelli, D. M. M. Freckmann and S. L. Buchwald,
Org. Lett., 2006, 21, 4843; (b) J. R. Martinelli, D. A. Watson, 20 (a) D. A. Conlon, B. Pipik, S. Ferdinand, C. R. LeBlond,
D. M. M. Freckmann, T. E. Barder and S. L. Buchwald, J.
Org. Chem., 2008, 73, 7102.
8 A. Wieckowska, R. Fransson, L. R. Odell and M. Larhed, J.
Org. Chem., 2011, 76, 978.
9 A. Deagostino, P. Larini, E. G. Occhiato, L. Pizzuto, C. Prandi
and P. Venturello, J. Org. Chem., 2008, 73, 1941.
J. R. Sowa Jr, B. Izzo, P. Collins, G.-J. Ho, J. M. Williams,
Y.-J. Shi and Y. Sun, Adv. Synth. Catal., 2003, 345, 931; (b)
S. P. Andrews, A. F. Stepan, H. Tanaka, S. V. Ley and
M. D. Smitha, Adv. Synth. Catal., 2005, 347, 647; (c)
J. P. Simeone and J. R. Sowa Jr, Tetrahedron, 2007, 63,
12646; (d) H. Ke, H. Chen and G. Zao, Appl. Organomet.
Chem., 2013, 28, 54; (e) S. Jayasree, A. Seayad and
R. V. Chaudhari, Chem. Commun., 1999, 1067; (f)
Y. Nishina, J. Miyata, R. Kawaib and K. Gotoh, RSC Adv.,
2012, 2, 9380.
´
´
10 A. Takacs, A. Petz and L. Kollar, Tetrahedron, 2010, 66, 4479.
11 (a) J. L. C. Rowsell, E. C. Spenser, J. Eckert, J. A. K. Howard
and O. M. Yaghi, Science, 2005, 309, 1350; (b) D. Bradshaw,
A. Garai and J. Huo, Chem. Soc. Rev., 2012, 41, 2344.
30026 | RSC Adv., 2014, 4, 30019–30027
This journal is © The Royal Society of Chemistry 2014

View Article Online
Paper
RSC Advances
21 (a) A. S. Kashin and V. P. Ananikov, J. Org. Chem., 2013, 78,
11117; (b) A. Balanta, C. Godard and C. Claver, Chem. Soc.
J. P. Sullivan, T. A. Esbenshade, G. B. Fox and
A. A. Hancock, J. Med. Chem., 2005, 48, 38.
Rev., 2011, 40, 4973; (c) V. P. Ananikov and I. P. Beletskaya, 28 C. Marlon, F. Ramin, C. P. Michael, G. A. Gregory,
Organometallics, 2012, 31, 1595.
22 G. I. Georg, A. R. Tunoori and J. M. White, Org. Lett., 2000, 2,
B. L. Youssef, B. A. Lawrence, P. Liping, M. C. Kennan,
S. P. James, E. A. Timothy, F. B. Gerard and H. A. Arthur, J.
Med. Chem., 2005, 48, 38.
4091.
23 B. Etienne, H. Abdallah, P. B. Jean-Francois and A. M. Jean- 29 T. Ishiyama, H. Kizaki, T. Hayashi, A. Suzuki and N. Miyaura,
Daniel, Org. Lett., 2010, 12, 4042. J. Org. Chem., 1998, 63, 4726.
24 C. W. Muir, A. R. Kennedy, J. M. Redmond and 30 M. Cai, J. Peng, L. Zha and G. Zheng, Eur. J. Org. Chem., 2009,
A. J. B. Watson, Org. Biomol. Chem., 2013, 11, 3337. 1585.
25 K. Joong-Gon and J. D. Ok, Bull. Korean Chem. Soc., 2010, 31, 31 (a) A. M. Echavarren and J. K. Stille, J. Am. Chem. Soc., 1988,
171.
110, 1557; (b) H. Xu, K. Ekoue-Kovi and C. Wolf, J. Org.
Chem., 2008, 73, 7638.
32 N. T. S. Phan, M. Van Der Sluys and C. W. Jones, Adv. Synth.
Catal., 2006, 348, 609.
26 C. Brands, G. Dolling and W. Kennedy, Synthesis, 2001, 12,
1784.
27 M. Cowart, R. Faghih, M. P. Curtis, G. A. Gfesser,
Y. L. Bennani, L. A. Black, L. Pan, K. C. Marsh,
This journal is © The Royal Society of Chemistry 2014
RSC Adv., 2014, 4, 30019–30027 | 30027