Pd-catalyzed site selective C-H acetoxylation of aryl/heteroaryl/thiophenyl tethered dihydroquinolinones

Article abstract of DOI:10.1039/c3ra41312h

Described herein is an efficient protocol for the site selective oxidative C-H activation/acetoxylation of a series of 2-aryl/heteroaryl/thiophenyl tethered dihydroquinolinones using palladium acetate as the catalyst and iodobenzene diacetate as an oxidan

Full text of DOI:10.1039/c3ra41312h

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Pd-catalyzed site selective C–H acetoxylation of aryl/
heteroaryl/thiophenyl tethered dihydroquinolinones3
Cite this: RSC Advances, 2013, 3,
10251
Santhosh Reddy Patpi,a Balasubramanian Sridhar,b Prabhakar Rao Tadikamallac
and Srinivas Kantevari*a
Described herein is an efficient protocol for the site selective oxidative C–H activation/acetoxylation of a
series of 2-aryl/heteroaryl/thiophenyl tethered dihydroquinolinones using palladium acetate as the
catalyst and iodobenzene diacetate as an oxidant. All these transformations progressed well at less
sterically encumbered and electronically favourable C–H bonds to give corresponding ortho-acetoxylated
derivatives in good yields. Further, acetoxylation of thiophenyl embedded dihydroquinolinones resulted in
single regioisomers, acetoxylated at the C-2 position on the thiophenyl moiety. However, when the C-2
position on the thiophene unit was blocked, the acetoxy group was exclusively installed at the C-4
position. Further, we noticed that acetoxylation of dihydroquinolin-5(6H)-one-oxime did not alter ligand
preferentiality to give the ortho-acetoxylated product.
Received 19th March 2013,
Accepted 9th April 2013
DOI: 10.1039/c3ra41312h
www.rsc.org/advances
H+ exchange inhibitor (Fig. 1). Therefore induction of
structural and functional diversity on the dihydroquinolinone
Introduction
In recent years, the palladium-mediated oxidative transforma-
tion of inert carbon–hydrogen bonds of arenes into new
functional groups has gained momentum.1 They are more
interesting when applied to regioselective derivatization of
complex molecules of biological importance.2 Reports from
research groups including those of Sanford,1,3 Yu,1g,4
Daugulis5 and others6 use directed group strategies for Pd-
catalyzed C–H oxidative acetoxylation, alkoxylation, arylation,
etc. However, the key challenge still remains in the differ-
entiating magnitude of C–H bonds present in complex organic
molecules to induce selectivity/reactivity during synthetic
transformation(s).7
On the other hand, dihydroquinolinones are an important
class of pharmacophoric substructures,8 which frequently
occur in natural and synthetic drug candidates.9 For instance,
MRZ-8676 (Fig. 1) is a negative allosteric modulator of subtype
5 metabotropic glutamate receptors (mGluR5) with therapeu-
tic potential as an anxiolytic and analgesic drug. Further
variations in the substituents on the quinolinone nucleus vary
their biological preferences as an mGluR1 modulator or Na+/
nucleus is highly desirable for various drug discovery pursuits.
Continuing our work on bioactive dihydroquinolinone deriva-
tives,10 selective acetoxylations of arene C–H bonds in 2-aryl/
heteroaryl/thiophene tethered dihydroquinolin-5(6H)-ones are
desirable for improving their activity profile. To the best of our
knowledge, this is the first report on oxidative aryl C–H
activation/acetoxylation efforts on substrate directed dihydro-
quinolin-5(6H)-ones having multiple reactive aryl C–H bonds.
The results described herein demonstrate that ortho-acetoxyla-
tion of 2-aryl/heteroaryl/thiophenyl units conjugated to dihy-
droquinolin-5(6H)-ones 3a–m, 4a–m and 5a–m typically
proceed regioselectively to give the respective acetoxylated
products 6a–m, 7a–m and 8a–m in good yields via palladium
aCPC Division (Organic Chemistry Division-II), CSIR-Indian Institute of Chemical
Technology, Hyderabad-500 007, India. E-mail: kantevari@yahoo.com;
kantevari@gmail.com; Fax: +91-4027193382; Tel: +914027191438
bCentre for Nuclear Magnetic Resonance, CSIR-Indian Institute of Chemical
Technology, Hyderabad-500 007, India
cLaboratory of X-ray Crystallography, CSIR-Indian Institute of Chemical Technology,
Hyderabad-500 007, India
Electronic supplementary information (ESI) available: Copies of 1H and 13C
3
NMR and HRMS spectra. CCDC reference numbers 902322 (for 6k) and 902323
(for 7e). For ESI and crystallographic data in CIF or other electronic format see
DOI: 10.1039/c3ra41312h
Fig. 1 Examples of bioactive dihydroquinolinone analogues.
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Table 1 Optimization of reaction conditionsa
Entry
Catalyst
Solvent
Time (h)
Yield (%)b
1
2
3
4
5
6
7
8
PdCl2
Benzene
Benzene
Benzene
Benzene
Benzene
Benzene
Benzene
Acetonitrile
Acetonitrile
Dichloroethane
Acetonitrile
Acetonitrile
Acetonitrile
12
12
12
24
6
12
18
6
12
6
6
6
6
32.5
40.0
41.0
36.5
64.0
25.0
28.0
65.0
66.0
Pd(PPh3)4
Pd(PPh3)2Cl2
Pd(OCOCF3)2
Pd(OAc)2
Pd(dba)2
Pd(dppf)2Cl2
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
No catalyst
9
10
11
12
13
60.5
5.0c
Traced
Trace
Scheme 1 Synthesis of dihydro-6H-quinolin-5-ones 3a–m, 4a–m and 5a–m
used in the study. Reaction conditions: (A) DMF–DMA, toluene, reflux, 7 h; (B)
1,3-cyclohexanedione (or) 5,5-dimethyl-1,3-cyclohexanedione (or) 4,4-dimethyl-
1,3-cyclohexanedione, ammonium acetate, CeCl3?7H2O–NaI, i-PrOH, reflux, 4 h.
a
3c (1 mmol), PhI(OAc)2 (1 mmol), catalyst (5 mol%), and acetic
b
anhydride (2 mL) in solvent (4 mL) were heated at 100 uC. The
percent value given refers to the isolated yield of purified materials.
c
d
PhI(OAc)2 (2.5 mmol), product 9 was obtained in 58% yield. In
the absence of oxidant PhI(OAc)2.
acetate catalyzed ligand directed site selective oxidative C–H
activation.
With the optimized reaction conditions in hand, initially,
we explored the scope of the reaction with various para-
substituted aryl embodied dihydroquinolinones 3a–e, 4a–e
and 5a–e. As summarized in Table 2, we were pleased to note
that all the substrates reacted well in the presence of
palladium acetate (5 mol%), PhI(OAc)2 (1.0 equivalent) in
acetic anhydride and acetonitrile to give ortho-acetoxylated
products 6a–e, 7a–e and 8a–e in very good yields (58–73%). All
the acetoxylated products were fully characterized by their
spectral analysis. The structure and regioselectivity of acet-
oxylated product 7e was unambiguously proved with single
crystal X-ray analysis (Fig. 2). It was allso found that a gem-
dimethyl group on dihydroquinolinone nucleus did not
influence the course of the reaction. Further, we observed
that the oxidative C–H acetoxylation of meta-substituted aryl-
dihydroquinolinones 3f–g, 4f–g and 5f–g proceeded with
excellent site selectivity at less sterically encumbered C–H
bonds to give respective acetoxylated derivatives 6f–g, 7f–g and
8f–g. Similar site selectivity at less hindered C–H bonds was
also noted in naphthyl substituted substrates 3h–i, 4h–i and
5h–i, giving excellent yields of respective ortho-acetoxylated
derivatives 6h–i, 7h–i and 8h–i.
Results and discussion
Dihydro-6H-quinolin-5(6H)-ones 3a–m, 4a–m and 5a–m
required for the study were prepared from aryl/heteroaryl/
thiophenyl methyl ketones 1a–m by following the procedures
developed in our laboratory10 (Scheme 1). Intermediate
b-enaminones 2a–m were converted to dihydro-6H-quinolin-
5-ones 3a–m, 4a–m and 5a–m using Bohlmann–Rahtz pyridine
type synthesis.11 All the known and new compounds were fully
characterized by spectral analysis.
Our studies commenced in exploring the acetoxylation of 2-
(4-methoxyphenyl) dihydroquinolin-5(6H)-one (3c) as a repre-
sentative example, in the presence of various general and
commercially available palladium catalysts (Table 1).
Iodobenzene diacetate was chosen as the terminal oxidant
on the basis of its ease of handling, ready availability and
known utility in Pd-catalyzed reactions.12 Upon screening the
various palladium catalysts (Table 1), we found that dihydro-
quinolinone 3c, with a stoichiometric amount of PhI(OAc)2 in
the presence of palladium acetate (5 mol%) and acetic
anhydride in acetonitrile, undergoes oxidative ortho-acetoxyla-
tion efficiently to give 6c in 65% isolated yield. Similar results
were also obtained in benzene and dichloroethane solvents. In
the absence of Pd(OAc)2 or an oxidant the desired C–H
acetoxylation was not observed (entries 12 and 13).
Furthermore, use of 2.5 equivalents of PhI(OAc)2 results in
the formation of diacetoxylated product 9 in 58% yield. (entry
11).
To gain further insight into the substrate scope, we next
examined heteroaryl analogues, 2-benzo[b][1,4]oxazin-3(4H)-
one conjugated dihydroquinolinones 3j, 4j and 5j with two
accessible aryl ortho-C–H bonds. The oxidative acetoxylation
under optimized conditions resulted in site selective acetoxy-
lated products 6j, 7j and 8j in excellent yields. More
importantly, this site selectivity seems to be general in all
the above substrates and ligand directed palladium catalyzed
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Table 2 Site selective acetoxylation of 5-aryl/heteroaryl dihydro-6H-quinolin-5-
ones 3a–j, 4a–j and 5a–ja,b
Table 2 (Continued)
Entry
24
Product
Yield (%)
70
Entry
Product
Yield (%)
25
26
27
7h: R = H
7i: R = OCH3
58
71
74
1
2
3
4
5
6
7
6a: R1 = H, R2 = H
6b: R1 = H, R2 = CH3
6c: R1 = H, R2 = OCH3
6d: R1 = H, R2 = Cl
6e: R1 = H, R2 = Ph
6f: R1 = OCH3, R2 = H
6g: R1 = Cl, R2 = H;
61
62
65
58
68
70
68
8
9
10
11
12
13
14
7a: R1 = H, R2 = H
7b: R1 = H, R2 = CH3
7c: R1 = H, R2 = OCH3
7d: R1 = H, R2 = Cl
7e: R1 = H, R2 = Ph
7f: R1 = OCH3, R2 = H
7g: R1 = Cl, R2 = H;
58
62
73
66
65
69
74
28
29
30
8h: R = H
8i: R = OCH3
58
72
75
a
Reaction conditions: substrate (1 mmol), PhI(OAc)2 (1 mmol),
palladium acetate (5 mol%), acetic anhydride (2 mL) in acetonitrile
(4 mL) were heated for 6 h at 100 uC. The percent value given
refers to the isolated yield of purified material and is an average of
two experiments.
15
16
17
18
19
20
21
8a: R1 = H, R2 = H
8b: R1 = H, R2 = CH3
8c: R1 = H, R2 = OCH3
8d: R1 = H, R2 = Cl
8e: R1 = H, R2 = Ph
8f: R1 = OCH3, R2 = H
8g: R1 = Cl, R2 = H;
58
65
71
70
60
72
66
b
22
23
6h: R = H
6i: R = OCH3
50
66
Fig. 2 ORTEP representation of 7e with thermal displacement ellipsoids drawn
at the 30% probability level.
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Table 3 Site selective acetoxylation of 2-thiophenyl dihydro-6H-quinolin-5-ones
3k–m, 4k–m and 5k–ma,b
Fig. 3 ORTEP representation of 6k with thermal displacement ellipsoids drawn
at the 30% probability level.
Considering the importance of thiophenes as key structural
motifs in bioactive molecules, we next probed the oxidative C–
H acetoxylation of thiophene embedded dihydroquinolinones
3k, 4k and 5k (Table 3). Interestingly, a single regioisomer,
acetoxylated at the C-2 position on the thiophene moiety
resulted, giving 6k, 7k and 8k in moderate yields. The
structure of regioselective isomer 6k was also proved by
NMR and single crystal X-ray studies (Fig. 3).13
Further, to access site selectivity, acetoxylation of substrates
3l–m, 4l–m and 5l–m was examined, in which the C-2
positions on the thiophene moieties were blocked with chloro
and bromo substituents. In all these cases the acetoxy group
was selectively installed at the C-4 position of the thiophene
moiety. These observations suggested that the sulphur atom
coordinates to palladium in example 6k and that the
acetoxylation occurred at the closer C-2 position.14 However,
in the presence of an electron-withdrawing group such as a
halogen, the coordinating ability of the sulphur weakens and
becomes labile. Hence the thiophene flipped over and the C–H
activation occurred at the C-4 position.
Also noted in the examples used for the study, ketone is
ineffective as a directing group because of its poor ligand
properties to form PdII-complexes. Recently Sanford et al.
developed a C–H acetoxylation protocol activating ketone as a
directing group by masking it as an oxime.3i To further our
study 2-(4-methoxyphenyl)dihydroquinolin-5(6H)-one (3c) was
derivatized to its oxime analogue 10 using methoxylamine
hydrogen chloride. Acetoxylation of 10 under our optimized
reaction conditions (Scheme 2) resulted in 11 as the only
product, ortho-acetoxylated on the arene ring proximal to the
pyridine nucleus.
a
Reaction conditions: dihydroquinolinone (1 mmol), PhI(OAc)2 (1
mmol), palladium acetate (5 mol%), and acetic anhydride (2 mL) in
acetonitrile (4 mL) were heated for 6 h at 100 uC. The percent
value given refers to the isolated yield of purified material and is an
average of two experiments.
b
oxidative C–H activation takes place with high sensitivity to the
steric environment around the aryl/heteroaryls coupled to
dihydroquinolinones. Such selectivity towards less steric C–H
bonds is consistent with recent related literature precedent-
s.1a,4a,5a
Further in vitro evaluation of all the new acetoxylated
dihydroquinolinone analogues against mycobacterium tuber-
culosis is in progress and will be reported in due course.
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2-(4-Methoxyphenyl)-7,8-dihydroquinolin-5(6H)-one O-methyl
oxime (10)
A mixture of dihydroquinolin-5(6H)-one 3c (0.5 g, 1.97 mmol),
methoxyl amine?HCl (0.445 g, 5.33 mmol) and sodium acetate
(0.713g, 8.69 mmol) in ethanol : water (1 : 3, 20 mL), was
heated at 70 uC for 2 h. After monitoring by TLC, the reaction
mixture was cooled to room temperature, concentrated under
reduced pressure, extracted with ethyl acetate (3 6 10 mL),
dried over sodium sulphate and evaporated under reduced
pressure to obtain a white solid product (0.51 g) in 92% yield;
Scheme 2 Acetoxylation of O-methyl oxime 10. Reaction conditions: (a) 3c
(1.97 mmol), NH2–OMe?HCl (5.33 mmol), sodium acetate (8.69 mmol), ethanol
(5 mL)–water (15 mL), 70 uC, 2 h, 92%; (b) 10 (1 mmol), PhI(OAc)2 (1 mmol),
palladium acetate (5 mol%), acetic anhydride (2 mL) in acetonitrile (4 mL) were
heated for 6 h at 100 uC, 60%.
1
mp 97–99 uC; H NMR (CDCl3, 300 MHz) d 8.26 (d, J = 8.2 Hz,
1H), 7.98 (d, J = 8.6 Hz, 2H), 7.52 (d, J = 8.2 Hz, 1H), 6.98 (d, J =
8.6 Hz, 2H), 4.00 (s, 3H), 3.86 (s, 3H), 2.99 (t, J = 6.0 Hz, 2H),
2.76 (t, J = 6.4 Hz, 2H), 1.95 (qt, J = 6.0 Hz, 2H); 13C NMR
(CDCl3, 75 MHz) d 160.5, 158.2, 156.6, 153.0, 139.3, 132.3,
128.2, 124.1, 117.7, 114.0, 62.0, 55.2, 32.7, 23.7, 20.8; IR(KBr)
Conclusions
2944, 1602, 1580, 1509, 1424, 1351, 1247, 1180, 1052 cm21
;
MS(ESI) m/z 283 (M + H)+; HRMS(ESI) Calcd for C17H19N2O2 (M
In summary, the results presented here describe the palladium
acetate catalyzed site selective oxidative C–H activation/
acetoxylation of a wide range of aryl/heteroaryl/thiophenyl
embodied dihydroquinolinone substrates 3a–m, 4a–m and 5a–
m. Here dihydroquinolinone was effective as a directing unit
for preferential installation of the acetoxy group at less
sterically encumbered and electronically favourable C–H
bonds. The regioselectivities of all acetoxylated products 6a–
m, 7a–m and 8a–m were assessed by spectral and single crystal
X-ray analysis. In dihydroquinolinone substrates 3k, 4k and
5k, the acetoxy group was exclusively installed at the C-2
position of the thiophene moiety. However, when the C-2
position was blocked in 3l–m, 4l–m and 5l–m, the acetoxy
group was directed to the C-4 position on the thiophene unit.
We further noticed that the site selective installation of the
acetoxy group was not altered even after converting the keto
functionality to an oxime in dihydroquinolin-5(6H)-one. The
broad substrate scope makes the reaction potentially useful for
regioselective acetoxylation of bioactive molecules.
+ H)+: 283.14410, found: 283.14710.
General procedure for acetoxylation of dihydroquinolinones
3a–m, 4a–m, 5a–m and 10
To a mixture of dihydroquinolin-5(6H)-one 3a–m, 4a–m, 5a–m
or 10 (1.0 mmol), iodobenzene diacetate (1.0 mmol) and 5
mol% Pd(OAc)2 in acetonitrile (4 mL), was added Ac2O (2 mL)
and the resulting mixture heated at 100 uC for 6 h under a
nitrogen atmosphere. After monitoring by TLC, the reaction
mixture was cooled to room temperature, concentrated under
reduced pressure and purified by silica gel column chromato-
graphy eluting with hexane : ethyl acetate (8 : 2) to obtain
respective pure acetoxylated products 6a–m, 7a–m, 8a–m and
11.
2-(5-Oxo-5,6,7,8-tetrahydroquinolin-2-yl)phenyl acetate (6a)
Yield: 0.153 g (61%); mp 87–89 uC; 1H NMR (CDCl3, 300 MHz)
d 8.29 (d, J = 8.1 Hz, 1H), 7.74 (dd, J = 1.7 Hz and 7.7 Hz, 1H),
7.53 (d, J = 8.1 Hz, 1H), 7.45 (dt, J = 1.7 Hz and 7.3 Hz, 1H), 7.35
(dt, J = 1.3 Hz and 7.5 Hz, 1H), 7.14 (dd, J = 1.1 Hz and 7.9 Hz,
1H), 3.19 (t, J = 6.2 Hz, 2H), 2.70 (t, J = 6.2 Hz, 2H), 2.25 (qt, J =
6.2 Hz, 2H), 2.19 (s, 3H); 13C NMR (CDCl3, 75 MHz) d 197.7,
169.7, 163.4, 159.2, 148.0, 135.2, 132.8, 132.1, 130.8, 130.4,
126.4, 123.3, 121.9, 38.4, 32.5, 21.7, 20.9; IR(KBr) 2924, 1675,
Experimental section
General procedure for the preparation of
dihydroisoquinolinones (3a–m, 4a–m and 5a–m)
1591, 1580, 1472, 1422, 1350, 1299, 1240, 1191, 760 cm21
;
MS(ESI) m/z 282 (M + H)+; HRMS(ESI) Calcd for C17H16NO3 (M
To a mixture of b-enaminone 2a–m (1.0 mmol), 1,3-cyclohex-
anedione (or) 5,5-dimethyl-1,3-cyclohexanedione (or) 4,4-
dimethyl-1,3-cyclohexanedione (1.2 mmol), and ammonium
acetate (2.0 mmol) in 2-propanol (5 mL) were added
CeCl3?7H2O (0.2 mmol) and NaI (0.2 mmol) and the mixture
refluxed for 4 h (monitored by TLC). The reaction mixture was
cooled to room temperature; the solid precipitate was filtered
and washed with ice cold 2-propanol. The combined solvent
was evaporated, and the crude residue thus obtained was
subjected to column chromatography (silica gel; hexane : ethyl
acetate, 9 : 1) to give dihydroisoquinolinones 3a–m, 4a–m and
5a–m.
+ H)+: 282.11247, found: 282.11273.
5-Methyl-2-(5-oxo-5,6,7,8-tetrahydroquinolin-2-yl)phenyl
acetate (6b)
Yield: 0.154 g (62%); mp 126–128 uC; 1H NMR (CDCl3, 300
MHz) d 8.27 (d, J = 8.3 Hz, 1H), 7.65 (d, J = 7.9 Hz, 1H), 7.51 (d, J
= 8.3 Hz, 1H), 7.15 (d, J = 7.9 Hz, 1H), 6.94 (s, 1H), 3.18 (t, J =
6.0 Hz, 2H), 2.69 (t, J = 6.0 Hz, 2H), 2.43 (s, 3H), 2.23 (qt, J = 6.0
Hz, 2H), 2.19 (s, 3H); 13C NMR (CDCl3, 75 MHz) d 197.4, 169.0,
163.2, 159.1, 147.9, 140.9, 134.9, 130.4, 129.1, 127.0, 126.0,
123.7, 121.5, 38.2, 32.5, 21.6, 20.9, 20.7; IR(KBr) 2924, 1768,
1684, 1582, 1455, 1346, 1200, 768 cm21; MS(ESI) m/z 296 (M +
H)+; HRMS(ESI) Calcd for C18H18NO3 (M + H)+: 296.12812,
found: 296.12882.
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197.6, 163.7, 157.8, 146.6, 143.6, 135.4, 131.9, 130.7, 130.3,
129.2, 127.6, 124.8, 121.9, 38.5, 32.6, 21.8, 20.9; IR(KBr) 2924,
1754, 1681, 1582, 1462, 1289, 1229 cm21; MS(ESI) m/z 316 (M +
H)+; HRMS(ESI) Calcd for C17H15ClNO3 (M + H)+: 316.07350,
found: 316.07477.
5-Methoxy-2-(5-oxo-5,6,7,8-tetrahydroquinolin-2-yl)phenyl
acetate (6c)
Yield: 0.159 g (65%); mp 133–135 uC; 1H NMR (CDCl3, 400
MHz) d 8.21 (d, J = 8.1 Hz, 1H), 7.69 (d, J = 8.5 Hz, 1H), 7.47 (d, J
= 8.1 Hz, 1H), 6.85 (dd, J = 2.3 Hz and 8.5 Hz, 1H), 6.63 (d, J =
2.3 Hz, 1H), 3.83 (s, 3H), 3.13 (t, J = 6.0 Hz, 2H), 2.65 (t, J = 6.0
Hz, 2H), 2.20 (t, J = 6.0 Hz, 2H), 2.19 (s, 3H); 13C NMR (CDCl3,
75 MHz) d 197.6, 168.9, 163.3, 161.3, 159.1, 149.3, 135.0, 131.7,
125.9, 124.6, 121.3, 112.4, 108.9, 55.5, 38.4, 32.6, 21.8, 20.9;
IR(KBr) 2929, 1769, 1678, 1580, 1446, 1212 cm21; MS(ESI) m/z
312 (M + H)+; HRMS(ESI) Calcd for C18H18NO4 (M + H)+:
312.12303, found: 312.12383.
3-(5-Oxo-5,6,7,8-tetrahydroquinolin-2-yl)naphthalen-2-yl
acetate (6h)
Yield: 0.121 g (50%); mp 119–121 uC; 1H NMR (CDCl3, 300
MHz) d 8.36 (d, J = 8.3 Hz, 1H), 8.25 (s, 1H), 7.98–7.89 (m, 1H),
7.88–7.80 (m, 1H), 7.69–7.62 (m, 2H), 7.59–7.47 (m, 2H), 3.24
(t, J = 6.2 Hz, 2H), 2.75 (t, J = 6.2 Hz, 2H), 2.26 (qt, J = 6.2 Hz,
3H), 2.24 (s, 3H); 13C NMR (CDCl3, 75 MHz) d 197.6, 169.3,
163.5, 159.4, 145.6, 135.2, 133.9, 131.4, 131.2, 128.3, 127.8,
127.4, 127.2, 126.4, 126.2, 122.1, 120.7, 38.4, 32.7, 21.8, 20.9;
5-Chloro-2-(5-oxo-5,6,7,8-tetrahydroquinolin-2-yl)phenyl
acetate (6d)
IR(KBr) 2925, 1762, 1682, 1580, 1198, 1153, 1022 cm21
;
Yield: 0.142 g (58%); mp 139–141 uC; 1H NMR (CDCl3, 300
MHz) d 8.32 (d, J = 8.1 Hz, 1H), 7.73 (d, J = 8.4 Hz, 1H), 7.53 (d, J
= 8.1 Hz, 1H), 7.36 (dd, J = 1.8 Hz and 8.4 Hz, 1H), 7.22 (d, J =
1.8 Hz, 1H), 3.19 (t, J = 6.2 Hz, 2H), 2.72 (t, J = 6.2 Hz, 2H), 2.23
(qt, J = 6.2 Hz, 2H), 2.21 (s, 3H); 13C NMR (CDCl3, 75 MHz) d
197.5, 168.6, 163.6, 158.2, 148.5, 135.7, 135.3, 131.8, 130.8,
126.7, 126.6, 123.9, 121.8, 38.5, 32.6, 21.8, 20.9; IR(KBr) 2924,
1773, 1686, 1591, 1384, 1225, 1083 cm21; MS(ESI) m/z 316 (M +
H)+; HRMS(ESI) Calcd for C17H15NO3Cl (M + H)+: 316.07350,
found: 316.07361.
MS(ESI) m/z 332 (M + H)+; HRMS(ESI) Calcd for C21H18NO3
(M + H)+: 332.12812, found: 332.12976.
7-Methoxy-3-(5-oxo-5,6,7,8-tetrahydroquinolin-2-
yl)naphthalen-2-yl acetate (6i)
Yield: 0.157 g (66%); mp 156–158 uC; 1H NMR (CDCl3, 300
MHz) d 8.33 (d, J = 8.1 Hz, 1H), 8.18 (s, 1H), 7.81 (d, J = 8.8 Hz,
1H), 7.63 (d, J = 8.1 Hz, 1H), 7.52 (s, 1H), 7.16 (dd, J = 2.4 Hz
and 8.8 Hz, 1H), 7.10 (d, J = 2.6 Hz, 1H), 3.93 (s, 3H), 3.22 (t, J =
6.0 Hz, 2H), 2.73 (t, J = 6.0 Hz, 2H), 1.33–1.25 (m, 5H); 13C NMR
(CDCl3, 75 MHz) d 197.7, 169.3, 163.4, 159.6, 158.9, 146.3,
135.5, 135.2, 130.9, 129.9, 128.9, 126.9, 126.2, 121.9, 119.6,
119.2, 105.1, 55.2, 38.5, 32.7, 21.8, 21.0; IR(KBr) 2928, 1755,
1681, 1581, 1478, 1391, 1208, 1024 cm21; MS(ESI) m/z 362 (M +
H)+; HRMS(ESI) Calcd for C22H20NO4 (M + H)+: 362.13868,
found: 362.14072.
4-(5-Oxo-5,6,7,8-tetrahydroquinolin-2-yl)biphenyl-3-yl
acetate(6e)
Yield: 0.162 g (68%); mp 140–142 uC; 1H NMR (CDCl3, 300
MHz) d 8.33 (d, J = 8.1 Hz, 1H), 7.86 (d, J = 8.1 Hz, 1H), 7.70–
7.57 (m, 4H), 7.55–7.34 (m, 4H), 3.21 (t, J = 6.2 Hz, 2H), 2.73 (t,
J = 6.2 Hz, 2H), 2.32–2.18 (m, 5H); 13C NMR (CDCl3, 75 MHz) d
197.7, 169.1, 163.5, 159.0, 148.5, 143.7, 139.3, 135.2, 131.3,
130.8, 128.8, 128.0, 127.0, 126.4, 125.0, 121.9, 121.8, 38.5, 32.7,
21.8, 21.0; IR(KBr) 2952, 1764, 1677, 1575, 1367, 1213, 1172
cm21; MS(ESI) m/z 358 (M + H)+; HRMS(ESI) Calcd for
C23H20NO3 (M + H)+: 358.14377, found: 358.14370.
4-Methyl-3-oxo-6-(5-oxo-5,6,7,8-tetrahydroquinolin-2-yl)-3,4-
dihydro-2H-benzo[b][1,4] oxazin-7-yl acetate (6j)
Yield: 0.166 g (70%); mp 169–171 uC; 1H NMR (CDCl3, 500
MHz) d 8.30 (d, J = 8.2 Hz, 1H), 7.54 (d, J = 8.2 Hz, 1H), 7.44 (s,
1H), 6.83 (s, 1H), 4.68 (s, 2H), 3.43 (s, 3H), 3.20 (t, J = 6.3 Hz,
2H), 2.72 (t, J = 6.3 Hz, 2H), 2.24 (qt, J = 6.3 Hz, 2H), 2.20 (s,
3H); 13C NMR (CDCl3, 75 MHz) d 197.6, 169.0, 163.7, 163.7,
158.1, 146.3, 144.1, 135.3, 127.9, 126.6, 126.4, 121.7, 116.6,
112.0, 67.4, 38.5, 32.6, 28.2, 21.8, 20.9; IR(KBr) 2956, 1756,
1678, 1580, 1427, 1376, 1270, 1206, 1166 cm21; MS(ESI) m/z
367 (M + H)+; HRMS(ESI) Calcd for C20H19N2O5 (M + H)+:
367.12885, found: 367.13079.
4-Methoxy-2-(5-oxo-5,6,7,8-tetrahydroquinolin-2-yl)phenyl
acetate (6f)
1
Yield: 0.172 g (70%); mp 86–88 uC; H NMR (CDCl3, 500 MHz)
d 8.30 (d, J = 8.1 Hz, 1H), 7.53 (d, J = 8.1 Hz, 1H), 7.28 (d, J = 3.2
Hz, 1H), 7.08 (d, J = 8.6 Hz, 1H), 6.98 (dd, J = 3.2 Hz and 8.6 Hz,
1H), 3.86 (s, 3H), 3.20 (t, J = 6.4 Hz, 2H), 2.72 (t, J = 6.4 Hz, 2H),
2.23 (qt, J = 6.4 Hz, 2H), 2.17 (s, 3H); 13C NMR (CDCl3, 75 MHz)
d 197.7, 169.6, 163.5, 159.1, 157.4, 141.6, 135.2, 132.9, 126.5,
124.2, 121.9, 116.1, 115.3, 55.6, 38.5, 32.6, 21.8, 20.9; IR(KBr)
2926, 1744, 1679, 1582, 1386, 1300, 1199, 1035 cm21; MS(ESI)
m/z 312 (M + H)+; HRMS(ESI) Calcd for C18H18NO4 (M + H)+:
312.12303, found: 312.12387.
5-(5-Oxo-5,6,7,8-tetrahydroquinolin-2-yl)thiophen-2-yl acetate
(6k)
Yield: 0.120 g (48%); mp 161–163 uC; 1H NMR (CDCl3,300
MHz) d 8.22 (d, J = 8.3 Hz, 1H), 7.53 (d, J = 8.3 Hz, 1H), 7.44 (d, J
= 4.1 Hz, 1H), 6.74 (d, J = 4.1 Hz, 1H), 3.12 (t, J = 6.2 Hz, 2H),
2.68 (t, J = 6.2 Hz, 2H), 2.35 (s, 3H), 2.19 (qt, J = 6.2 Hz, 2H); 13
C
4-Chloro-2-(5-oxo-5,6,7,8-tetrahydroquinolin-2-yl)phenyl
acetate (6g)
NMR (CDCl3, 75 MHz) d 197.3, 166.8, 163.8, 155.4, 155.3,
135.2, 125.9, 123.0, 116.1, 114.4, 38.3, 32.4, 21.6, 20.6; IR(KBr)
2924, 1747, 1679, 1576, 1466, 1352, 1206, 1124 cm21; MS(ESI)
m/z 288 (M + H)+; HRMS(ESI) Calcd for C15H14NO3S (M + H)+:
288.06889, found: 288.06983.
Yield: 0.166 g (68%); mp 173–175 uC; 1H NMR (CDCl3, 300
MHz) d 8.33 (d, J = 8.1 Hz, 1H), 7.78 (d, J = 2.4 Hz, 1H), 7.54 (d, J
= 8.1 Hz, 1H), 7.42 (dd, J = 2.4 Hz and 8.4 Hz, 1H), 7.13 (d, J =
8.4 Hz, 1H), 3.20 (t, J = 6.0 Hz, 2H), 2.73 (t, J = 6.0 Hz, 2H), 2.24
(qt, J = 6.0 Hz, 2H), 2.20 (s, 3H); 13C NMR (CDCl3, 75 MHz) d
10256 | RSC Adv., 2013, 3, 10251–10261
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1677, 1624, 1582, 1302 cm21; MS(ESI) m/z 340 (M + H)+;
HRMS(ESI) Calcd for C20H22NO4 (M + H)+: 340.15433, found:
340.15410.
5-Chloro-2-(5-oxo-5,6,7,8-tetrahydroquinolin-2-yl)thiophen-3-yl
acetate (6l)
Yield: 0.097 g (40%); mp 107–109 uC; 1H NMR (CDCl3, 300
MHz) d 8.25 (d, J = 8.3 Hz, 1H), 7.65 (d, J = 8.3 Hz, 1H), 6.97 (s,
1H), 3.10 (t, J = 6.0 Hz, 2H), 2.68 (t, J = 6.0 Hz, 2H), 2.40 (s, 3H),
2.19 (qt, J = 6.0 Hz, 2H); 13C NMR (CDCl3, 75 MHz) d 197.1,
167.4, 163.6, 153.1, 143.4, 135.7, 133.1, 127.9, 126.1, 123.1,
118.2, 38.4, 32.3, 21.6, 21.0; IR(KBr) 2924, 1762, 1683, 1580,
1459, 1371, 1208 cm21; MS(ESI) m/z 322 (M + H)+; HRMS(ESI)
5-Chloro-2-(7,7-dimethyl-5-oxo-5,6,7,8-tetrahydroquinolin-2-
yl)phenyl acetate (7d)
Yield: 0.158 g (66%); mp 132–134 uC; 1H NMR (CDCl3, 300
MHz) d 8.27 (d, J = 8.1 Hz, 1H), 7.73 (d, J = 8.4 Hz, 1H), 7.51 (d, J
= 8.1 Hz, 1H), 7.34 (dd, J = 2.0 Hz and 8.4 Hz, 1H), 7.19 (d, J =
2.0 Hz, 1H), 3.05 (s, 2H), 2.55 (s, 2H), 2.20 (s, 3H), 1.15 (s, 6H);
13C NMR (CDCl3, 75 MHz) d 197.6, 168.6, 162.1, 158.6, 148.5,
135.8, 135.0, 131.7, 130.7, 126.7, 125.6, 123.9, 121.8, 52.0, 46.5,
32.9, 28.2, 20.9. IR(KBr) 2956, 1779, 1679, 1584, 1381, 1193
cm21; MS(ESI) m/z 344 (M + H)+; HRMS(ESI) Calcd for
Calcd for C15H13ClNO3S (M
322.03048.
+
H)+: 322.02992, found:
5-Bromo-2-(5-oxo-5,6,7,8-tetrahydroquinolin-2-yl)thiophen-3-yl
acetate (6m)
C
19H19Cl NO3 (M + H)+: 344.10480, found: 344.10481.
Yield: 0.090 g (42%); mp 119–121 uC; 1H NMR (CDCl3, 300
MHz) d 8.26 (d, J = 8.3 Hz, 1H), 7.64 (d, J = 8.3 Hz, 1H), 7.10 (s,
1H), 3.10 (t, J = 6.2 Hz, 2H), 2.68 (t, J = 6.2 Hz, 2H), 2.40 (s, 3H),
2.19 (qt, J = 6.2 Hz, 2H); 13C NMR (CDCl3, 75 MHz) d 197.2,
167.5, 163.6, 153.1, 144.1, 135.7, 130.5, 126.5, 126.2, 118.1,
116.1, 38.4, 32.3, 21.7, 21.0; IR(KBr) 2924, 1762, 1680, 1578,
1548, 1454, 1368, 1207 cm21; MS(ESI) m/z 365 (M + H)+;
HRMS(ESI) Calcd for C15H13BrNO3S (M + H)+: 365.97940,
found: 365.98013.
4-(7,7-Dimethyl-5-oxo-5,6,7,8-tetrahydroquinolin-2-yl)biphenyl-
3-yl acetate (7e)
Yield: 0.153 g (65%); mp 127–129 uC; 1H NMR (CDCl3, 300
MHz) d 8.32 (d, J = 8.1 Hz, 1H), 7.85 (d, 8.1 Hz, 1H), 7.68–7.55
(m, 4H), 7.52–7.35 (m, 4H), 3.09 (s, 2H), 2.59 (s, 2H), 2.24 (s,
3H), 1.15 (s, 6H); 13C NMR (CDCl3, 75 MHz) d 197.7, 169.1,
162.0, 159.5, 148.5, 143.7, 139.2, 134.8, 131.2, 130.8, 128.8,
128.0, 127.0, 125.3, 125.0, 122.0, 121.7, 52.0, 46.5, 32.9, 28.2,
21.0; IR(KBr) 2925, 1763, 1680, 1580, 1458, 1373, 1206 cm21
;
2-(7,7-Dimethyl-5-oxo-5,6,7,8-tetrahydroquinolin-2-yl)phenyl
acetate (7a)
MS(ESI) m/z 386 (M + H)+; HRMS(ESI) Calcd for C25H24NO3 (M
+ H)+: 386.17507, found: 386.17749.
Yield: 0.142 g (58%); mp 107–109 uC; 1H NMR (CDCl3, 300
MHz) d 8.30 (d, J = 8.1 Hz, 1H), 7.75 (dd, J = 1.8 Hz and 7.7 Hz,
1H), 7.54 (d, J = 8.1 Hz, 1H), 7.47 (dt, J = 1.8 Hz and 7.7 Hz, 1H),
7.37 (dt, J = 1.3 Hz and 8.8 Hz, 1H), 7.18 (dd, J = 1.1 Hz and 7.9
Hz, 1H), 3.08 (s, 2H), 2.57 (s, 2H), 2.20 (s, 3H), 1.14 (s, 6H); 13C
NMR (CDCl3, 75 MHz) d 197.8, 169.1, 162.0, 159.7, 148.1,
134.8, 132.2, 130.8, 130.4, 126.4, 125.4, 123.4, 121.8, 51.9, 46.5,
32.9, 28.2, 20.9; IR(KBr) 2956, 1766, 1686, 1584, 1305, 1189,
753 cm21; MS(ESI) m/z 310 (M + H)+; HRMS(ESI) Calcd for
C19H20NO3 (M + H)+: 310.14377, found: 310.14449.
2-(7,7-Dimethyl-5-oxo-5,6,7,8-tetrahydroquinolin-2-yl)-4-
methoxyphenyl acetate (7f)
1
Yield: 0.166 g (69%); syrup; H NMR (CDCl3, 300 MHz) d 8.30
(d, J = 8.1 Hz, 1H), 7.53 (d, J = 8.1 Hz, 1H), 7.27 (d, J = 3.0 Hz,
1H), 7.09 (d, J = 8.8 Hz, 1H), 6.99 (dd, J = 3.0 Hz and 8.8 Hz,
1H), 3.08 (s, 2H), 2.58 (s, 2H), 2.18 (s, 3H), 1.14 (s, 6H); 13C
NMR (CDCl3, 75 MHz) d 197.8, 169.5, 162.1, 159.6, 157.5,
141.7, 134.8, 132.9, 125.5, 124.2, 121.8, 116.1, 115.4, 55.7, 52.0,
46.6, 33.0, 28.3, 20.9. IR(KBr) 2957, 1764, 1686, 1582, 1494,
1385, 1303, 1188, 1038 cm21; MS(ESI) m/z 340 (M + H)+;
HRMS(ESI) Calcd for C20H22NO4 (M + H)+: 340.15433, found:
340.15517.
2-(7,7-Dimethyl-5-oxo-5,6,7,8-tetrahydroquinolin-2-yl)-5-
methylphenyl acetate (7b)
Yield: 0.151 g (62%); mp 151–153 uC; 1H NMR (CDCl3, 300
MHz) d 8.24 (d, J = 8.3 Hz, 1H), 7.64 (d, J = 7.7 Hz, 1H), 7.50 (d, J
= 8.3 Hz, 1H), 7.15 (d, J = 7.7 Hz, 1H), 6.94 (s, 1H), 3.05 (s, 2H),
2.53 (s, 2H), 2.43 (s, 3H), 2.19 (s, 3H), 1.15 (s, 6H); 13C NMR
(CDCl3, 75 MHz) d 197.2, 161.8, 159.8, 148.1, 140.9, 134.7,
130.7, 129.4, 127.2, 125.2, 124.0, 121.7, 52.0, 46.7, 33.0, 28.4,
21.8, 21.0; IR(KBr) 2925, 1740, 1684, 1586, 1553, 1453, 1302,
1233 cm21; MS(ESI) m/z 324 (M + H)+; HRMS(ESI) Calcd for
C20H22NO3 (M + H)+: 324.15891, found: 324.15942.
4-Chloro-2-(7,7-dimethyl-5-oxo-5,6,7,8-tetrahydroquinolin-2-
yl)phenyl acetate (7g)
Yield: 0.178 g (74%); mp 136–138 uC; 1H NMR (CDCl3, 500
MHz) d 8.30 (d, J = 8.1 Hz, 1H), 7.78 (d, J = 2.7 Hz, 1H), 7.54 (d, J
= 8.1 Hz, 1H), 7.41 (dd, J = 2.7 Hz and 8.6 Hz, 1H), 7.13 (d, J =
8.6 Hz, 1H), 3.08 (s, 2H), 2.58 (s, 2H), 2.20 (s, 3H), 1.14 (s, 6H);
13C NMR (CDCl3, 75 MHz) d 197.6, 168.8, 162.2, 158.2, 146.6,
134.9, 133.6, 131.8, 130.7, 130.2, 125.8, 124.8, 121.8, 51.9, 46.5,
32.9, 28.2, 20.9; IR(KBr) 2954, 1764, 1685, 1586, 1561, 1489,
1370, 1295, 1231 cm21; MS(ESI) m/z 344 (M + H)+; HRMS(ESI)
Calcd for C19H19ClNO3 (M + H)+: 344.10480, found: 344.10687.
2-(7,7-Dimethyl-5-oxo-5,6,7,8-tetrahydroquinolin-2-yl)-5-
methoxyphenyl acetate (7c)
Yield: 0.176 g (73%); mp 107–109 uC; 1H NMR (CDCl3, 300
MHz) d 8.26 (d, J = 8.1 Hz, 1H), 7.73 (d, J = 8.6 Hz, 1H), 7.51 (d, J
= 8.1 Hz, 1H), 6.92 (dd, J = 2.4 Hz and 8.6 Hz, 1H), 6.71 (d, J =
2.6 Hz, 1H), 3.86 (s, 3H), 3.06 (s, 2H), 2.56 (s, 2H), 2.23 (s, 3H),
1.13 (s, 6H); 13C NMR (CDCl3, 75 MHz) d 197.8, 169.0, 161.9,
161.3, 159.6, 149.3, 134.7, 131.7, 124.9, 124.6, 121.3, 112.4,
108.9, 55.5, 52.0, 46.6, 32.9, 28.2, 21.0; IR(KBr) 2937, 1752,
3-(7,7-Dimethyl-5-oxo-5,6,7,8-tetrahydroquinolin-2-
yl)naphthalen-2-yl acetate (7h)
Yield: 0.138 g (58%); mp 94–96 uC; 1H NMR (CDCl3, 300 MHz)
d 8.34 (d, J = 8.3 Hz, 1H), 8.24 (s, 1H), 7.98–7.90 (m, 1H), 7.89–
7.79 (m, 1H), 7.71–7.62 (m, 2H), 7.61–7.47 (m, 2H), 3.12 (s, 2H),
2.60 (s, 2H), 2.24 (s, 3H), 1.16 (s, 6H); 13C NMR (CDCl3, 75
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MHz) d 197.8, 169.4, 162.0, 160.0, 145.6, 134.9, 133.9, 131.4,
131.1, 128.3, 127.4, 127.2, 126.8, 126.2, 125.4, 122.0, 120.8,
52.0, 46.6, 33.0, 28.2, 21.0; IR(KBr) 2924, 1769, 1678, 1583,
1369, 1187, 1153, 1024 cm21; MS(ESI) m/z 360 (M + H)+;
HRMS(ESI) Calcd for C23H22NO3 (M + H)+: 360.15942, found:
360.16122.
5-Bromo-2-(7,7-dimethyl-5-oxo-5,6,7,8-tetrahydroquinolin-2-
yl)thiophen-3-yl acetate (7m)
Yield: 0.120 g (51%); mp 156–158 uC; 1H NMR (CDCl3, 300
MHz) d 8.24 (d, J = 8.3 Hz, 1H), 7.64 (d, J = 8.3 Hz, 1H), 7.09 (s,
1H), 3.00 (s, 2H), 2.54 (s, 2H), 2.40 (s, 3H), 1.12 (s, 6H); 13C
NMR (CDCl3, 75 MHz) d 197.2, 167.5, 162.3, 153.5, 144.1,
135.2, 130.6, 126.5, 125.2, 118.0, 116.0, 51.9, 46.1, 32.8, 28.2,
3-(7,7-Dimethyl-5-oxo-5,6,7,8-tetrahydroquinolin-2-yl)-7-
methoxynaphthalen-2-yl acetate (7i)
21.0. IR(KBr) 2926, 1774, 1679, 1577, 1549, 1367, 1210 cm21
;
MS(ESI) m/z 394 (M + H)+; HRMS(ESI) Calcd for C17H17BrNO3S
Yield: 0.166 g (71%); mp 139–141 uC; 1H NMR (CDCl3, 500
MHz) d 8.32 (d, J = 8.0 Hz, 1H), 8.17 (s, 1H), 7.81 (d, J = 8.9 Hz,
1H), 7.63 (d, J = 8.0 Hz, 1H), 7.52 (s, 1H), 7.16 (dd, J = 2.3 Hz
and 8.9 Hz, 1H), 7.11 (d, J = 2.3 Hz, 1H), 3.93 (s, 3H), 3.11 (s,
2H), 2.58 (s, 2H), 2.24 (s, 3H), 1.15 (s, 6H); 13C NMR (CDCl3, 75
MHz) d 197.8, 169.4, 162.0, 160.1, 158.9, 146.3, 135.5, 134.8,
130.9, 129.9, 129.0, 126.9, 125.2, 121.8, 119.7, 119.3, 105.1,
55.3, 52.0, 46.6, 33.0, 28.3, 21.1; IR(KBr) 2925, 1769, 1677,
1581, 1476, 1391, 1180, 1141, 1024 cm21; MS(ESI) m/z 390 (M +
H)+; HRMS(ESI) Calcd for C24H24NO4 (M + H)+: 390.16998,
found: 390.17182.
(M + H)+: 394.01070, found: 394.01134.
2-(6,6-Dimethyl-5-oxo-5,6,7,8-tetrahydroquinolin-2-yl)phenyl
acetate (8a)
Yield: 0.142 g (58%); mp 182–184 uC; 1H NMR (CDCl3, 300
MHz) d 8.31 (d, J = 8.3 Hz, 1H), 7.75 (dd, J = 1.7 Hz and 7.5 Hz,
1H), 7.53 (d, J = 8.3 Hz, 1H), 7.45 (dt, J = 1.7 Hz and 7.5 Hz, 1H),
7.35 (dt, J = 1.1 Hz and 7.5 Hz, 1H), 7.14 (dd, J = 0.9 Hz and 7.9
Hz, 1H), 3.19 (t, J = 6.4 Hz, 2H), 2.2 (s, 3H), 2.07 (t, J = 6.4 Hz,
2H), 1.26 (s, 6H); 13C NMR (CDCl3, 75 MHz) d 201.3, 168.5,
162.2, 159.0, 148.3, 136.1, 132.3, 131.0, 130.3, 126.3, 125.2,
123.5, 122.0, 41.4, 35.5, 29.1, 24.3, 21.0; IR(KBr) 2927, 1767,
1683, 1585, 1469, 1383, 1233, 771 cm21; MS(ESI) m/z 310 (M +
H)+; HRMS(ESI) Calcd for C19H20NO3 (M + H)+: 310.14377,
found: 310.14337.
6-(7,7-Dimethyl-5-oxo-5,6,7,8-tetrahydroquinolin-2-yl)-4-
methyl-3-oxo-3,4-dihydro-2H-benzo[b][1,4]oxazin-7-yl acetate
(7j)
Yield: 0.173 g (74%); mp 201–203 uC; 1H NMR (CDCl3, 300
MHz) d 8.29 (d, J = 8.1 Hz, 1H), 7.55 (d, J = 8.1 Hz, 1H), 7.44 (s,
1H), 6.83 (s, 1H), 4.69 (s, 2H), 3.44 (s, 3H), 3.08 (s, 2H), 2.58 (s,
2H), 2.21 (s, 3H), 1.15 (s, 6H); 13C NMR (CDCl3, 75 MHz) d
197.7, 169.0, 163.6, 162.3, 158.5, 146.2, 144.1, 134.8, 127.8,
126.5, 125.4, 121.6, 116.5, 112.0, 67.4, 51.9, 46.4, 32.9, 29.6,
28.2, 20.9; IR(KBr) 2927, 1751, 1683, 1578, 1372, 1206, 1162
cm21; MS(EI) m/z 395 (M + H)+; HRMS (ESI) Calcd for
C22H23N2O5 (M + H)+: 395.16015, found: 395.16195.
2-(6,6-Dimethyl-5-oxo-5,6,7,8-tetrahydroquinolin-2-yl)-5-
methylphenyl acetate (8b)
Yield: 0.158 g (65%); mp 83–85 uC; 1H NMR (CDCl3, 500 MHz)
d 8.27 (d, J = 8.5 Hz, 1H), 7.65 (d, J = 6.1 Hz, 1H), 7.50 (d, J = 8.5
Hz, 1H), 7.14 (d, J = 6.1 Hz, 1H), 6.94 (s, 1H), 3.17 (t, J = 6.1 Hz,
2H), 2.42 (s, 3H), 2.19 (s, 3H), 2.05 (t, J = 6.1 Hz, 2H), 1.25 (s,
6H); 13C NMR (CDCl3, 75 MHz) d 201.4, 168.6, 162.1, 159.0,
148.1, 140.7, 135.9, 130.7, 129.3, 127.1, 124.9, 123.9, 121.7,
41.3, 35.4, 29.0, 24.1, 21.2, 20.9; IR(KBr) 2923, 1768, 1682,
1582, 1384, 1199, 772 cm21; MS(ESI) m/z 324 (M + H)+;
HRMS(ESI) Calcd for C20H22NO3 (M + H)+: 324.15942, found:
324.15933.
5-(7,7-Dimethyl-5-oxo-5,6,7,8-tetrahydroquinolin-2-
yl)thiophen-2-yl acetate (7k)
Yield: 0.112 g (46%); mp 171–173 uC; 1H NMR (CDCl3, 300
MHz) d 8.21 (d, J = 8.3 Hz, 1H), 7.54 (d, J = 8.3 Hz, 1H), 7.44 (d, J
= 4.1 Hz, 1H), 6.74 (d, J = 4.1 Hz, 1H), 3.02 (s, 2H), 2.53 (s, 2H),
2.35 (s, 3H), 1.12 (s, 6H); 13C NMR (CDCl3, 75 MHz) d 197.5,
166.9, 162.6, 156.0, 144.3, 134.9, 125.0, 123.0, 116.2, 114.6,
52.0, 46.3, 32.9, 28.2, 20.7; IR(KBr) 2957, 1759, 1673, 1578,
1468, 1203 cm21; MS(ESI) m/z 316 (M + H)+; HRMS(ESI) Calcd
for C17H18NO3S (M + H)+: 316.10019, found: 316.10116.
2-(6,6-Dimethyl-5-oxo-5,6,7,8-tetrahydroquinolin-2-yl)-5-
methoxyphenyl acetate (8c)
Yield: 0.171 g (71%); mp 161–163 uC; 1H NMR (CDCl3, 300
MHz) d 8.30 (d, J = 8.3 Hz, 1H), 7.74 (d, J = 8.6 Hz, 1H), 7.51 (d, J
= 8.3 Hz, 1H), 6.92 (dd, J = 2.6 Hz and 8.6 Hz, 1H), 6.71 (d, J =
2.4 Hz, 1H), 3.86 (s, 3H), 3.19 (t, J = 6.4 Hz, 2H), 2.23 (s, 3H),
2.05 (t, J = 6.4 Hz, 2H), 1.25 (s, 6H); 13C NMR (CDCl3, 75 MHz) d
202.0, 169.0, 162.1, 161.1, 158.7, 149.1, 136.0, 131.6, 127.9,
124.6, 121.4, 112.2, 108.7, 55.4, 41.2, 35.1, 28.7, 23.9, 20.9;
IR(KBr) 2928, 1767, 1682, 1581, 1455, 1287 cm21; MS(ESI) m/z
340 (M + H)+; HRMS(ESI) Calcd for C20H22NO4 (M + H)+:
340.15433, found: 340.15628.
5-Chloro-2-(7,7-dimethyl-5-oxo-5,6,7,8-tetrahydroquinolin-2-
yl)thiophen-3-yl acetate (7l)
Yield: 0.110 g (46%); mp 159–161 uC; 1H NMR (CDCl3, 300
MHz) d 8.24 (d, J = 8.3 Hz, 1H), 7.66 (d, J = 8.3 Hz, 1H), 6.97 (s,
1H), 3.00 (s, 2H), 2.54 (s, 2H), 2.40 (s, 3H), 1.12 (s, 6H); 13C
NMR (CDCl3, 75 MHz) d 197.3, 167.5, 162.3, 153.5, 143.3,
135.2, 133.1, 125.2, 123.1, 118.1, 51.9, 46.1, 29.6, 28.2, 21.0.
5-Chloro-2-(6,6-dimethyl-5-oxo-5,6,7,8-tetrahydroquinolin-2-
yl)phenyl acetate (8d)
IR(KBr) 2926, 1772, 1675, 1578, 1548, 1457, 1368, 1193 cm21
;
MS(ESI) m/z 350 (M + H)+; HRMS(ESI) Calcd for C17H17ClNO3S
Yield: 0.168 g (70%); mp 144–146 uC; 1H NMR (CDCl3, 300
MHz) d 8.30 (d, J = 8.3 Hz, 1H), 7.74 (d, J = 8.3 Hz, 1H), 7.51 (d, J
= 8.1 Hz, 1H), 7.35 (dd, J = 2.0 Hz and 8.4 Hz, 1H), 7.18 (d, J =
1.8 Hz, 1H), 3.18 (t, J = 6.4 Hz, 2H), 2.21 (s, 3H), 2.06 (t, J = 6.4
Hz, 2H), 1.25 (s, 6H); 13C NMR (CDCl3, 75 MHz) d 202.0, 168.7,
(M + H)+: 350.06122, found: 350.06177.
10258 | RSC Adv., 2013, 3, 10251–10261
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162.4, 157.9, 148.5, 136.2, 135.6, 131.7, 130.8, 126.7, 125.3,
123.8, 121.8, 41.4, 35.1, 28.9, 24.0, 20.9; IR(KBr) 2924, 1684,
1586, 1553, 1384, 1228, 1079 cm21; MS(ESI) m/z 344 (M + H)+;
HRMS(ESI) Calcd for C19H19Cl NO3 (M + H)+: 344.10480,
found: 344.10483.
3-(6,6-Dimethyl-5-oxo-5,6,7,8-tetrahydroquinolin-2-yl)-7-
methoxynaphthalen-2-yl acetate (8i)
Yield: 0.169 g (72%); mp 154–156 uC; 1H NMR (CDCl3, 300
MHz) d 8.35 (d, J = 8.3 Hz, 1H), 8.18 (s, 1H), 7.82 (d, J = 8.8 Hz,
1H), 7.63 (d, J = 8.3 Hz, 1H), 7.52 (s, 1H), 7.16 (dd, J = 2.4 Hz
and 8.8 Hz, 1H), 7.11 (d, J = 2.2 Hz, 1H), 3.93 (s, 3H), 3.24 (t, J =
6.2 Hz, 2H), 2.25 (s, 3H), 2.08 (t, J = 6.2 Hz, 2H), 1.27 (s, 6H);
13C NMR (CDCl3, 75 MHz) d 202.2, 169.4, 162.4, 159.4, 158.9,
146.3, 136.1, 135.5, 131.0, 130.0, 129.0, 127.0, 125.0, 121.9,
119.6, 119.3, 105.1, 55.3, 41.4, 35.3, 29.1, 24.1, 21.1; IR(neat)
2928, 1767, 1679, 1579, 1470, 1383, 1205, 1025 cm21; MS(ESI)
m/z 390 (M + H)+; HRMS(ESI) Calcd for C24H24NO4 (M + H)+:
390.16998, found: 390.17209.
4-(6,6-Dimethyl-5-oxo-5,6,7,8-tetrahydroquinolin-2-yl)biphenyl-
3-yl acetate (8e)
1
Yield: 0.141 g (60%); mp 96–98 uC; H NMR (CDCl3, 300 MHz)
d 8.35 (d, J = 8.1 Hz, 1H), 7.86 (d, J = 8.1 Hz, 1H), 7.67–7.57 (m,
4H), 7.52–7.35 (m, 4H), 3.22 (t, J = 6.6 Hz, 2H), 2.25 (s, 3H), 2.07
(t, J = 6.6 Hz, 2H), 1.27 (s, 6H); 13C NMR (CDCl3, 75 MHz) d
202.1, 169.1, 162.4, 158.8, 148.5, 143.6, 139.3, 136.1, 131.3,
130.9, 128.8, 128.0, 127.0, 125.0, 121.9, 121.8, 41.4, 35.3, 29.0,
24.1, 21.0; IR(KBr) 2924, 1765, 1675, 1574, 1377, 1203 cm21
;
6-(6,6-Dimethyl-5-oxo-5,6,7,8-tetrahydroquinolin-2-yl)-4-
methyl-3-oxo-3,4-dihydro-2H-benzo[b][1,4]oxazin-7-yl acetate
(8j)
MS(ESI) m/z 386 (M + H)+; HRMS(ESI) Calcd for C25H24NO3 (M
+ H)+: 386.17507, found: 386.17755.
Yield: 0.175 g (75%); mp 197–199 uC; 1H NMR (CDCl3, 300
MHz) d 8.33 (d, J = 8.3 Hz, 1H), 7.54 (d, J = 8.3 Hz, 1H), 7.44 (s,
1H), 6.83 (s, 1H), 4.69 (s, 2H), 3.44 (s, 3H), 3.21 (t, J = 6.0 Hz,
2H), 2.22 (s, 3H), 2.07 (t, J = 6.0 Hz, 2H), 1.27 (s, 6H); 13C NMR
(CDCl3, 75 MHz) d 202.0, 169.0, 163.6, 162.6, 157.8, 146.2,
144.1, 136.1, 127.8, 126.6, 125.2, 121.7, 116.5, 112.0, 67.4, 41.4,
35.2, 29.0, 28.2, 24.0, 20.9; IR(KBr) 2926, 1754, 1675, 1576,
1397, 1223, 1170 cm21; MS(ESI) m/z 395 (M + H)+; HRMS(ESI)
Calcd for C22H23N2O5 (M + H)+: 395.16015, found: 395.16113.
2-(6,6-Dimethyl-5-oxo-5,6,7,8-tetrahydroquinolin-2-yl)-4-
methoxyphenyl acetate (8f)
Yield: 0.173 g (72%); mp 180–182 uC; 1H NMR (CDCl3, 500
MHz) d 8.32 (d, J = 8.1 Hz, 1H), 7.53 (d, J = 8.1 Hz, 1H), 7.28 (d, J
= 3.1 Hz, 1H), 7.08 (d, J = 8.8 Hz, 1H), 6.98 (dd, J = 3.1 Hz and
8.8 Hz, 1H), 3.86 (s, 3H), 3.21 (t, J = 6.4 Hz, 2H), 2.18 (s, 3H),
2.06 (t, J = 6.4 Hz, 2H), 1.26 (s, 6H); 13C NMR (CDCl3, 75 MHz) d
202.1, 169.5, 162.4, 158.8, 157.4, 141.6, 136.0, 132.9, 125.2,
124.2, 121.9, 116.0, 115.3, 55.6, 41.4, 35.2, 29.0, 24.0, 20.9;
IR(KBr) 2930, 1763, 1683, 1582, 1455, 1384, 1186, 1037 cm21
;
5-(6,6-Dimethyl-5-oxo-5,6,7,8-tetrahydroquinolin-2-
yl)thiophen-2-yl acetate (8k)
MS(ESI) m/z 340 (M + H)+; HRMS(ESI) Calcd for C20H22NO4 (M
+ H)+: 340.15433, found: 340.15424.
Yield: 0.112 g (46%); mp 163–165 uC; 1H NMR (CDCl3, 300
MHz) d 8.24 (d, J = 8.3 Hz, 1H), 7.53 (d, J = 8.3 Hz, 1H), 7.43 (d, J
= 3.9 Hz, 1H), 6.74 (d, J = 3.9 Hz, 1H), 3.14 (t, J = 6.2 Hz, 2H),
2.35 (s, 3H), 2.02 (t, J = 6.2 Hz, 2H), 1.23 (s, 6H); 13C NMR
(CDCl3, 75 MHz) d 201.8, 166.8, 162.8, 155.3, 155.2, 136.2,
124.7, 122.9, 116.2, 114.5, 41.3, 35.2, 28.8, 24.1, 20.1; IR(KBr)
2938, 1755, 1666, 1579, 1471, 1370, 1348, 1207 cm21; MS(ESI)
m/z 316 (M + H)+; HRMS(ESI) Calcd for C17H18NO3S (M + H)+:
316.10019, found: 316.10110.
4-Chloro-2-(6,6-dimethyl-5-oxo-5,6,7,8-tetrahydroquinolin-2-
yl)phenyl acetate (8g)
1
Yield: 0.158 g (66%); mp 83–85 uC; H NMR (CDCl3, 300 MHz)
d 8.34 (d, J = 8.3 Hz, 1H), 7.78 (d, J = 2.4 Hz, 1H), 7.54 (d, J = 8.3
Hz, 1H), 7.42 (dd, J = 2.4 Hz and 8.4 Hz, 1H), 7.12 (d, J = 8.4 Hz,
1H), 3.21 (t, J = 6.4 Hz, 2H), 2.21 (s, 3H), 2.07 (t, J = 6.4 Hz, 2H),
1.26 (s, 6H); 13C NMR (CDCl3, 75 MHz) d 202.0, 168.9, 162.6,
157.5, 146.6, 136.2, 133.6, 131.8, 130.7, 130.2, 125.5, 124.7,
121.9, 41.4, 35.2, 28.9, 24.0, 20.9; IR(KBr) 2926, 1754, 1678,
1582, 1454, 1382, 1220, 1198, 1102 cm21; MS(ESI) m/z 344 (M +
H)+; HRMS(ESI) Calcd for C19H19ClNO3 (M + H)+: 344.10480,
found: 344.10669.
5-Chloro-2-(6,6-dimethyl-5-oxo-5,6,7,8-tetrahydroquinolin-2-
yl)thiophen-3-yl acetate (8l)
Yield: 0.100 g (42%); mp 140–142 uC; 1H NMR (CDCl3, 300
MHz) d 8.28 (d, J = 8.3 Hz, 1H), 7.64 (d, 8.3 Hz, 1H), 6.96 (s,
1H), 3.12 (t, J = 6.4 Hz, 2H), 2.39 (s, 3H), 2.02 (t, 6.4 Hz, 2H),
1.23 (s, 6H); 13C NMR (CDCl3, 75 MHz) d 201.7, 167.5, 162.5,
152.9, 143.3, 136.6, 133.0, 124.9, 123.1, 118.2, 41.3, 35.1, 28.7,
24.1, 21.0; IR(KBr) 2930, 1776, 1674, 1573, 1458, 1369, 1215,
1059 cm21; MS(ESI) m/z 350 (M + H)+; HRMS(ESI) Calcd for
C17H17ClNO3S (M + H)+: 350.06122, found: 350.06181.
3-(6,6-Dimethyl-5-oxo-5,6,7,8-tetrahydroquinolin-2-
yl)naphthalen-2-yl acetate (8h)
Yield: 0.138 g (58%); mp 100–102 uC; 1H NMR (CDCl3, 300
MHz) d 8.37 (d, J = 8.3 Hz, 1H), 8.25 (s, 1H), 7.99–7.89 (m, 1H),
7.88–7.78 (m, 1H), 7.69–7.61 (m, 2H), 7.60–7.46 (m, 2H), 3.25
(t, J = 6.4 Hz, 2H), 2.25 (s, 3H), 2.09 (t, J = 6.4 Hz, 2H), 1.28 (s,
6H); 13C NMR (CDCl3, 75 MHz) d 202.2, 169.4, 162.4, 159.2,
145.6, 136.1, 133.9, 131.4, 131.2, 128.4, 127.4, 127.2, 126.2,
125.2, 122.1, 120.7, 41.4, 35.3, 29.0, 24.1, 21.0; IR(KBr) 2927,
1754, 1670, 1577, 1369, 1204, 1100 cm21; MS(ESI) m/z 360 (M +
H)+; HRMS(ESI) Calcd for C23H22NO3 (M + H)+: 360.15942,
found: 360.16138.
5-Bromo-2-(6,6-dimethyl-5-oxo-5,6,7,8-tetrahydroquinolin-2-
yl)thiophen-3-yl acetate (8m)
Yield: 0.103 g (44%); mp 127–129 uC; 1H NMR (CDCl3, 300
MHz) d 8.28 (d, J = 8.3 Hz, 1H), 7.64 (d, J = 8.3 Hz, 1H), 7.09 (s,
1H), 3.12 (t, J = 6.4 Hz, 2H), 2.40 (s, 3H), 2.02 (t, J = 6.4 Hz, 2H),
1.23 (s, 6H); 13C NMR (CDCl3, 75 MHz) d 201.7, 167.5, 162.6,
152.9, 144.0, 136.6, 130.6, 126.5, 124.9, 118.1, 115.9, 41.3, 35.1,
28.7, 24.1, 21.0; IR(KBr) 2924, 1775, 1676, 1577, 1454, 1194,
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1054 cm21; MS(ESI) m/z 394 (M + H)+; HRMS(ESI) Calcd for
and F. Glorius, Chem. Soc. Rev., 2011, 40, 4740–4761; (e)
B. Haffemayer, M. Gulias and M. J. Gaunt, Chem. Sci., 2011,
2, 312–315; (f) K. Godula and D. Sames, Science, 2006, 312,
67–72.
C17H17BrNO3S (M + H)+: 394.01070, found: 394.01155.
5-Methoxy-2-(5-oxo-5,6,7,8-tetrahydroquinolin-2-yl)-1,3-
phenylene diacetate (9)
3 Selected examples: (a) S. R. Neufeldt and M. S. Sanford,
Adv. Synth. Catal., 2012, 354, 3517–3522; (b) K.
B. McMurtrey, J. M. Racowski and M. S. Sanford, Org.
Lett., 2012, 14, 4094–4097; (c) D. C. Powers, E. Lee,
A. Ariafard, M. S. Sanford, B. F. Yates, A. J. Canty and
T. Ritter, J. Am. Chem. Soc., 2012, 134, 12002–12009; (d)
A. Kubota, M. H. Emmert and M. S. Sanford, Org. Lett.,
2012, 14, 1760–1763; (e) J. M. Racowski, N. D. Ball and M.
S. Sanford, J. Am. Chem. Soc., 2011, 133, 18022–18025; (f) T.-
H. Park, A. J. Hickman, K. Koh, S. Martin, A. G. Wong-Foy,
M. S. Sanford and A. J. Matzger, J. Am. Chem. Soc., 2011,
133, 20138–20141; (g) M. H. Emmert, A. K. Cook, Y. J. Xie
and M. S. Sanford, Angew. Chem., Int. Ed., 2011, 50,
9409–9412; (h) K. J. Stowers and M. S. Sanford, Org. Lett.,
2009, 11, 4584–4587; (i) L. V. Desai, H. A. Malik and M.
S. Sanford, Org. Lett., 2006, 8, 1141–1144; (j) D. Kalyani, N.
R. Deprez, L. V. Desai and M. S. Sanford, J. Am. Chem. Soc.,
2005, 127, 7330–7331; (k) D. Kalyani and M. S. Sanford, Org.
Lett., 2005, 7, 4149–4152; (l) A. R. Dick, K. L. Hull and M.
S. Sanford, J. Am. Chem. Soc., 2004, 126, 2300–2301.
4 (a) D. Leow, G. Li, T.-S. Mei and J.-Q. Yu, Nature, 2012, 486,
518–522; (b) H. X. Dai, A. F. Stepan, M. S. Plummer, Y.-
H. Zhang and J.-Q. Yu, J. Am. Chem. Soc., 2011, 133,
7222–7228; (c) M. Ye, G.-L. Gao and J.-Q. Yu, J. Am. Chem.
Soc., 2011, 133, 6964–6967.
Yield: 0.169 g (58%); mp 169–171 uC; 1H NMR (CDCl3, 300
MHz) d 8.28 (d, J = 8.1 Hz, 1H), 7.30 (d, J = 8.1 Hz, 1H), 6.67 (s,
2H), 3.83 (s, 3H), 3.16 (t, J = 6.2 Hz, 2H), 2.72 (t, J = 6.4 Hz, 2H),
2.22 (qt, J = 6.2 Hz, 2H), 2.07 (s, 6H); 13C NMR (CDCl3, 75 MHz)
d 197.6, 168.5, 163.1, 160.5, 156.3, 149.6, 134.7, 126.3, 123.7,
119.1, 107.0, 55.7, 38.4, 32.5, 21.8, 20.6; IR(KBr) 2924, 1770,
1683, 1582, 1455, 1328, 1186, 1040 cm21; MS(ESI) m/z 370 (M +
H)+; HRMS(ESI) Calcd for C20H20NO6 (M + H)+: 370.12851,
found: 370.12836.
5-Methoxy-2-(5-(methoxyimino)-5,6,7,8-tetrahydroquinolin-2-
yl)phenyl acetate (11)
Yield: 0.144 g (60%); mp 156–158 uC. 1H NMR (CDCl3, 300
MHz) d 8.26 (d, J = 8.2 Hz, 1H), 7.69 (d, J = 8.6 Hz, 1H), 7.36 (d, J
= 8.2 Hz, 1H), 6.90 (dd, J = 2.2 Hz and 8.6 Hz, 1H), 6.69 (d, J =
2.2 Hz, 1H), 4.00 (s, 3H), 3.84 (s, 3H), 2.97 (t, J = 6.0 Hz, 2H),
2.76 (t, J = 6.4 Hz, 2H), 2.21 (s, 3H), 1.95 (qt, J = 6.4 Hz, 2H); 13
C
NMR (CDCl3, 75 MHz) d 180.0, 177.4, 174.6, 172.1, 168.4,
151.2, 150.8, 144.6, 143.7, 140.4, 131.7, 128.1, 119.9, 81.4, 74.8,
52.0, 42.9, 40.1, 19.2; IR(KBr) 2953, 1767, 1613, 1583, 1507,
1371, 1260, 1200 cm21; MS(ESI) m/z 341 (M + H)+; HRMS(ESI)
Calcd for C19H21N2O4 (M + H)+: 341.14958, found: 341.14959.
5 (a) T. Truong and O. Daugulis, Angew. Chem., Int. Ed., 2012,
51, 11677–1679; (b) L. D. Tran and O. Daugulis, Angew.
Chem., Int. Ed., 2012, 51, 5188–5191; (c) O. Daugulis, Chem.
Heterocycl. Compd., 2012, 26; (d) D. Shabashov and
O. Daugulis, J. Am. Chem. Soc., 2010, 132, 3965–3972; (e)
A. Lazareva and O. Daugulis, Org. Lett., 2006, 8, 5211–5213;
(f) O. Daugulis, V. G. Zaitsev, D. Shabashov, Q.-N. Pham
and A. Lazareva, Synlett, 2006, 3382–3388.
Acknowledgements
The authors are thankful to Dr M. Lakshmikantam, Director,
CSIR-IICT and Dr V. Jayathirtha Rao, Head, CPC Division,
CSIR-IICT, Hyderabad for encouragement, support and finan-
cial assistance from DBT-Biocare, ORIGIN (CSC0108),
DENOVA (CSC0205), TAPSUN (NWP 0054 and NWP 0055),
INTELCOAT and MLP-0002 projects. S.R.P. (SRF) is thankful to
CSIR for a fellowship.
6 Selected examples from other groups: (a) Z. Jiang, L. Zhang,
C. Dong, Z. Cai, W. Tang, H. Li, L. Xu and J. Xiao, Adv.
Synth. Catal., 2012, 354, 3225–3230; (b) A. Petit, J. Flygare,
A. T. Miller, G. Winkel and D. H. Ess, Org. Lett., 2012, 14,
3680–3683; (c) Y. Zhang, Z. Li and Z. Q. Liu, Org. Lett., 2012,
14, 226–229; (d) S. Pankajakshan, Y.-H. Xu, J. K. Cheng, M.
T. Low and T.-P. Loh, Angew. Chem., Int. Ed., 2012, 51,
5701–5705; (e) P. Lennartz, G. Raabe and C. Bolm, Adv.
Synth. Catal., 2012, 354, 3237–3249; (f) B. V. S. Reddy,
G. Narsimhulu, N. Umadevi and J. S. Yadav, Synlett, 2012,
1364–1370; (g) Y. Leng, F. Yang, W. Zhu, Y. Wu and X. Li,
Org. Biomol. Chem., 2011, 9, 5288–5296; (h) G. W. Wang, T.
T. Yuan and X. L. Wu, J. Org. Chem., 2008, 73, 4717–4720; (i)
P. Guo, J. M. Joo, S. Rakshit and D. Sames, J. Am. Chem.
Soc., 2011, 133, 16338–16341; (j) H. S. Lee, S. H. Kim and J.
N. Kim, Bull. Korean Chem. Soc., 2010, 31, 238–241.
7 (a) M. O. Kitching and V. Snieckus, Nature, 2012, 486,
478–479; (b) J. M. Joo, P. Guo and D. Sames, J. Org. Chem.,
2013, 78, 738–743; (c) Y. Chen, F. Wang, A. Jia and X. Li,
Chem. Sci., 2012, 3, 3231–3236; (d) Y. Zhang, Z. Li and Z.-
Q. Liu, Org. Lett., 2012, 14, 226–229; (e) T. W. Lyons, K.
L. Hull and M. S. Sanford, J. Am. Chem. Soc., 2011, 133,
4455–4464; (f) L. V. Desai, K. J. Stowers and M. S. Sanford, J.
Am. Chem. Soc., 2008, 130, 13285–13293.
Notes and references
1 For C–H functionalization reviews, see: (a) S. R. Neufeldt
and M. S. Sanford, Acc. Chem Res., 2012, 45, 936–946; (b) A.
J. Hickman and M. S. Sanford, Nature, 2012, 484, 177–185;
(c) N. Kuhl, M. N. Hopkinson, J. Wencel-Delord and
F. Glorius, Angew. Chem., Int. Ed., 2012, 51, 10236–10254;
(d) K. M. Engle, T. S. Mei, M. Wasa and J. Q. Yu, Acc. Chem.
Res., 2012, 45, 788–802; (e) M. C. White, Synlett, 2012,
2746–2748; (f) T. W. HicLyons and M. S. Sanford, Chem.
Rev., 2010, 110, 1147–1169; (g) X. Chen, K. M. Engle, D.-
H. Wang and J.-Q. Yu, Angew. Chem., Int. Ed., 2009, 48,
5094–5115; (h) D. Kalyani, A. R. Dick, W. Q. Anani and M.
S. Sanford, Tetrahedron, 2006, 62, 11483–11498.
2 Selected examples: (a) D. Y.-K. Chen and S. W. Youn,
Chem.–Eur. J., 2012, 18, 9452–9474; (b) T. S. Mei, L. Kou,
S. Ma, K. M. Engle and J.-Q. Yu, Synthesis, 2012, 778–1791;
(c) M. H. Emmert, A. K. Cook, Y. J. Xie, M. S. Sanford,
L. McMurray, F. O’Hara and M. J. Gaunt, Chem. Soc. Rev.,
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