Synthesis of functionalized 1,2-diphenylacetylene derivatives

Article abstract of DOI:10.1007/s11172-019-2416-4

A series of new functionalized 1,2-diphenylacetylene derivatives, including those containing l-prolinamide substituents at the aromatic nuclei, was synthesized using the Sonogashira coupling at the key step.

Full text of DOI:10.1007/s11172-019-2416-4

Russian Chemical Bulletin, International Edition, Vol. 68, No. 1, pp. 64—67, January, 2019
64
Synthesis of functionalized 1,2-diphenylacetylene derivatives
A. V. Lozanova,a A. V. Stepanov,a K. E. Mel'nik,a,b M. V. Zlokazov,a and V. V. Veselovskya
aN. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences,
47 Leninsky prosp., 119991 Moscow, Russian Federation.
Fax: +7 (499) 135 5328. E-mail: ves@ioc.ac.ru
bHigher Chemical College of the Russian Academy of Sciences,
D. I. Mendeleev Russian University of Chemical Technology,
9 Miusskaya pl., 125047 Moscow, Russian Federation.
Fax: +7 (499) 978 8660
A series of new functionalized 1,2-diphenylacetylene derivatives, including those containing
L-prolinamide substituents at the aromatic nuclei, was synthesized using the Sonogashira
coupling at the key step.
Key words: 1,2-diphenylacetylenes, Sonogashira coupling, proline derivatives.
Derivatives of 1,2-diphenylacetylene attract an attention
as the valuable intermediates in the synthesis of function-
alized indoles1—4 and benzofurans, including those among
natural products.5—8 The application prospect of such com-
pounds has been shown for the obtaining of organic ferro-
magnetic materials9 and electrode components of lithium-ion
batteries.10 Derivatives of 1,2-diphenylacetylene bearing
carboxyl groups at the each of aromatic nuclei have been
utilized as the so-called "dicarboxylate linkers" in Metal-
Organic Frameworks (MOFs) that proved to be efficient
in heterogeneous catalysis11,12 and promising as materials
for hydrogen storage.13 A number of examples of their
application for these purposes is still small and mostly
limited to the usage of frame structures based on their
simplest representative, 1,2-bis(4-carboxyphenyl)acetylene.
Most popular approaches for the production of 1,2-di-
phenylacetylene derivatives are the various embodiments of
halogenoarene alkynylation via the Sonogashira coupling
(e.g., see Ref. 14). In particular, acetylene by itself15—17
or its synthetic equivalent (CaC2/H2O system)18 used in
combination with various aryl iodides as the starting com-
pounds allow one to obtain symmetric 1,2-diarylacetylenes
in good yields via the two successive alkylation processes.
In order to enhance the number of available 1,2-di-
phenylacetylene derivatives that are promising for applica-
tions in the above mentioned areas, the present work re-
ports on the synthesis of series of symmetrically substituted
acetylenes 1—3 bearing methoxycarbonyl and carboxyl
groups in aromatic cycles, including non-racemic chiral
derivatives 3a,b. Asymmetrically substituted diarylacetyl-
enes 4a,b were also obtained.*
1—4: R = Me (a), H (b)
The Sonogashira coupling of methyl 4-iodobenzoate
(5) with acetylene gave symmetric diarylacetylene 1a in
a good yield (Scheme 1). In the case of aryl iodide 6, the
process in wet acetonitrile using calcium carbide as the
in situ source of acetylene was efficient, which provided
new diarylacetylene 2a. Compound 3a has been for the
* Atom numbering on structures 1—4 and 8 corresponds to that
given in the NMR spectra descriptions.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 0064—0067, January, 2019.
1066-5285/19/6801-0064 © 2019 Springer Science+Business Media, Inc.

1,2-Diarylacetylenes
Russ. Chem. Bull., Int. Ed., Vol. 68, No. 1, January, 2019
65
first time obtained (in the yield of 95%) in the similar way
under these reaction conditions taking L-proline-contain-
ing aryl iodide 8. The latter was synthesized via the con-
densation of anthranilic acid derivative 6 with N-Boc-L-
proline 7. The saponification of diesters 1a, 2a, and 3a
resulted in the corresponding dicarboxylic acids 1b, 2b,
and 3b.
parently due to the steric hindrances that can affect the
state of conformational equilibrium of molecules in favor
of two major "rotamers". It should be noted that we have
not found any data on the synthesis of non-racemic 1,2-di-
phenylacetylene derivatives in the literature. The oppor-
tunity of their application, in particular, as the organic
components for the design of new metal-organic frame-
work structures will be the subject of our further researches.
Scheme 1
Experimental
Melting points were measured on a Kofler table. IR spectra
were recorded on a Bruker ALPHA-T instrument. 1H and 13C
NMR spectra of solutions in CDCl3 (unless otherwise noted)
were recorded on Bruker AC-200 and Bruker AM-300 spectro-
meters at 298 K relative to the solvent residual signals (H = 7.27
and C = 77.0 ppm, respectively). High-resolution mass spectra
(HRMS) (ESI) were recorded on a Bruker micrOTOF II spectro-
meter at the capillary potential of 4.5 kV using a direct (syringe)
injection of sample solution in methanol (3 L min–1) in the
positive ions detection mode (mass range of 500—3000 Da), the
main flow of nitrogen was 4 L min–1 (180 C). The optical rota-
tion was measured on a Jasco P-2000 polarimeter. Column
chromatography was performed on a Silica gel 60 (0.04—0.06 mm,
Fluka). The Rf values were measured on Silufol (Chemapol) and
Kieselgel F254 (Fluka) plates possessing a fixed layer. Solvents,
including light petroleum (LP) with b.p. 40—70 C, were purified
and dried according to the standard procedures.22 For ultra-
sonic treatment of the reaction mixtures, a UZV-1/100-TN
(Russia) bath was used.
Commercially available methyl 4-iodobenzoate (5), 5-iodo-
anthranilic acid, N-Boc-L-proline (7), POCl3, Pd(OAc)2, CuI,
Ph3P, CaC2, and pyridine (Acros Organics) were used. Methyl
4-ethynylbenzoate (9)19 and methyl 4-bromo-3-nitrobenzoate
(10)20 were prepared according to the known procedures.
Dimethyl 4,4´-ethyne-1,2-diyldibenzoate (1a). A mixture of
CuI (540 mg, 2.83 mmol), Pd(OAc)2 (37 mg, 0.16 mmol), and
Ph3P (740 mg, 2.82 mmol) in MeCN (30 mL) deaerated by the
ultrasonic treatment (UST) under argon atmosphere was stirred
at 20 C for 20 min. Aryl iodide 5 (1.95 g, 7.44 mmol) and Et3N
(410 mg, 40.42 mmol, 5.6 mL) were then added. The mixture
was stirred under acetylene atmosphere for 5 h, left for 16 h, and
then concentrated in vacuo. The residue was suspended in CHCl3
and filtered through a short layer of SiO2. The filtrate was
evaporated; the residue was purified by chromatography on SiO2
using benzene as the eluent. Diarylacetylene 1a (0.80 g, 73%)
was isolated as light brown crystals, Rf 0.34 (benzene), m.p.
218—221 C. 1H NMR (CDCl3), : 3.94 (s, 6 H, 2 MeCO); 7.61
Reagents and conditions: i. Pd(OAc)2, CuI, Ph3P, Et3N, MeCN,
20 C; ii. 1) NaOH, EtOH, 20 C, 2) conc. HCl; iii. CaC2/H2O,
Pd(OAc)2, CuI, Ph3P, Et3N, MeCN, 20 C; iv. POCl3, pyridine,
–15—5 C; v. 1) aq. NaOH, Me2CO, 20 C, 2) сіtric acid.
Known monoarylacetylene 919 and bromo nitro arene
1020 were taken as the starting compounds for the synthe-
sis of new asymmetric diarylacetylenes 4a,b via the
Sonogogashira coupling (Scheme 2).
The structure of new compounds 2—4 was confirmed
by the dataset of spectral analysis. It is interesting that a
double set of some signals was observed in the NMR
spectra of L-proline-containing diphenylacetylenes 3a,b,
which was similar to that recorded previously21 for their
well-known precursor 8. These spectral features are ap-
Scheme 2
Reagents and conditions: i. Pd(PPh3)2Cl2, CuI, Et3N, THF, 20 C; ii. 1) aq. KOH, THF, 20 C, 2) 1N aq. HCl.

66
Russ. Chem. Bull., Int. Ed., Vol. 68, No. 1, January, 2019
Lozanova et al.
(dd, 4 H, HC(3), HC(3´), HC(5), HC(5´), J = 8.6 Hz, J = 1.9 Hz);
8.05 (dd, 4 H, HC(2), HC(2´), HC(6), HC(6´), J = 8.6 Hz,
J = 1.9 Hz); which is similar to that reported previously.15
4,4´-Ethyne-1,2-diyldibenzoic acid (1b). A mixture of diester
1a (0.91 g, 3.09 mmol) and NaOH (0.72 g, 18 mmol) in EtOH
(30 mL) was refluxed for 6 h, left for 16 h, and then concen-
trated in vacuo. The residue was dissolved in water and acidified
with 10M HCl till pH 1. The precipitated product was filtered off,
washed with water, and dried in vacuo (2 Torr) over P2O5.
Dicarboxylic acid 1b (0.83 g, 97%) was isolated as a brown pow-
der, m.p. >200 C (decomp.) 1H NMR (CDCl3), : 7.70 (br. d,
4 H, HC(3), HC(3´), HC(5), HC(5´), J = 8.0 Hz); 7.99 (br. d,
4 H, HC(2), HC(2´), HC(6), HC(6´), J = 8.0 Hz). 13C NMR
(DMSO-d6), : 91.0 (CC); 126.0 (C(4), C(4´)); 129.6 (2 C(2),
2 C(2´)); 130.9 (2 C(1), 2 C(1´)); 131.7 (2 C(3), 2 C(3´)); 166.6
(2 CO); which is similar to that reported previously.23
HRMS (ESI), found m/z: 297.0866; C16H12N2O4; calculated
297.0870 [M + H]+. IR (KBr), /cm–1: 683, 827, 905, 1169,
1228, 1287, 1326, 1421, 1552, 1625, 1667, 2520—2886, 3384, 3496.
1H NMR (DMSO-d6), : 6.75 (d, 2 H, HC(5), HC(5´), J = 8.6 Hz);
7.24 (dd, 2 H, HC(4), HC(4´), J = 8.6 Hz, J = 1.8 Hz); 7.80 (d,
2 H, HC(2), HC(2´), J = 1.8 Hz). 13C NMR (DMSO-d6), :
87.9 (CC); 109,0 (C(5), C(5´)); 109.9 (C(1), C(1´)); 116.8
(C(3), C(3´)); 134.0 (C(2), C(2´)); 135.9 (C(4), C(4´)); 151.1
(C(6), C(6´)); 169.0 (CO, C´O).
Methyl 2-[(N-tert-butoxycarbonyl-L-prolinoyl)amino]-5-iodo-
benzoate (8). Phosphorus oxychloride (1.47 g, 9.6 mmol, 0.9 mL)
was added dropwise at –10 C to a stirred pyridine (40 mL) solu-
tion of N-Boc-L-proline 7 (1.74 g, 8.08 mmol) and arylamine 6
(2.24 g, 8.08 mmol) under argon atmosphere. The reaction
mixture was stirred for 30 min (–10—5 C), then poured into
water (200 mL) containing ice, and extracted with EtOAc. The
aqueous layer was additionally extracted with EtOAc. The extract
was washed with water, saturated NaHCO3 solution, dried over
Na2SO4, and concentrated in vacuo. The residue was purified by
chromatography on silica gel using CHCl3 as the eluent. The
isolated product with Rf 0.56 (EtOAc/LP, 1 : 2) was crystallized
from petroleum ether to give amide 8 (2.8 g, 74%) as light brown
crystals, m.p. 92—95 C, [α]23 –103.96 (c = 1.0, CHCl3).
1H NMR (CDCl3), : 1.35 and 1.4D9 (both br.s, integral ratio of 5/4,
9 H, Me3C); 1.74—2.42 (m, 4 H, HC(4´), HC(5´)); 3.39—3.80
(m, 2 H, HC(3´)); 3.91 (s, 3 H, MeO); 4.27 and 4.41 (both m,
integral ratio of 5/4, 1 H, HC(1´)); 7.81 (br.d, 1 H, HC(3),
J = 8.2 Hz); 8.34 (br.s, 1 H, HC(4)); 8.57 (br.d, 1 H, HC(6), J =
= 8.2 Hz); 11.43 (m, 1 H, HN) (mixture of rotamers, see Ref. 21).
Dimethyl 3,3´-ethyne-1,2-diylbis[6-(N-tert-butoxycarbonyl-
L-prolinoylamino)benzoate] (3a). A mixture of CuI (114 mg,
0.60 mmol), Pd(OAc)2 (67 mg, 0.30 mmol), and Ph3P (160 mg,
0.61 mmol) in MeCN (50 mL) deaerated under argon atmosphere
was stirred at 20 C for 20 min. Solution of iodoarene 8 (2.8 g,
5.9 mmol) in MeCN (5 mL), Et3N (1.82 g, 18 mmol, 2.5 mL),
H2O (0.22 g, 12.2 mmol), and finely grounded CaC2 (1.15 g,
17.9 mmol) were then added. The mixture was stirred for 5 h and
then concentrated in vacuo (30—40 C, 2 Torr). The residue was
pounded with ButOMe and filtered. The filtrate was evaporated
to dryness in vacuo, and the residue was purified by chromato-
graphy on SiO2 using a LP—EtOAc gradient till 40% of the
latter. Product 3a (2.02 g, 95%) was isolated as light brown crys-
tals, m.p. 126—130 C (ButOMe—LP), [α]23D –152.63 (c = 1.0,
CHCl3). HRMS (ESI), found m/z: 719.3279, 741.3101, 757.2836;
C38H46N4O10; calculated 719.3287 [M + H]+, 741.3106 [M + Na]+,
757.2846 [M + K]+. IR (KBr), /cm–1: 769, 855, 1082, 1159,
1240, 1291, 1379, 1460, 1512, 1580, 1698, 2876, 2958, 2975, 3250.
1H NMR (CDCl3), : 1.21 and 1.35 (both br.s, integral ratio of
3/2, 18 H, 2 Me3C); 1.96 (m, 4 H, HC(9), HC(9´)); 2.23
(m, 4 H, HC(8), HC(8´)); 3.44—3.79 (m, 4 H, HC(10),
HC(10´)); 3.94 (s, 6 H, MeO, Me´O); 4.31 and 4.45 (both m,
integral ratio of 3/2, 2 H, HC(7), HC(7´)); 7.69 (br.d, 2 H,
HC(4), HC(4´), J = 8.5 Hz); 8.23 (br.s, 2 H, HC(2), HC(2´));
8.80 (br.d, 2 H, HC(5), HC(5´), J = 8.5 Hz); 11.57 (m, 2 H, HN,
HN´) (mixture of rotamers).
Methyl 2-amino-5-iodobenzoate (6). Concentrated H2SO4
(3.7 mL) was added dropwise at 20 C under argon atmosphere
to a stirred solution of 5-iodoanthranilic acid (5.0 g, 19 mmol)
in MeOH (20 mL), and the mixture was refluxed for 7 h. The
mixture was then concentrated in vacuo to the volume of 10 mL,
poured into a vigorously stirred saturated solution of NaHCO3
(80 mL), and extracted with EtOAc. The organic layer was washed
with a brine solution, dried over Na2SO4, and concentrated
in vacuo; the residue was purified by chromatography on SiO2
(eluent was benzene). Ester 6 (3.68 g) was isolated as yellow
crystals, m.p. 80—82 C (LP). 1H NMR (CDCl3), : 3.87 (s, 3 H,
MeO); 5.76 (br.s, 2 H, H2N); 6.46 (d, 1 H, HC(3), J = 8.7 Hz);
7.48 (dd, 1 H, HC(4), J = 8.7 Hz, J = 2.2 Hz); 8.14 (d, 1 H,
2 HC(6), J = 2.2 Hz); which is similar to that reported previously.24
Dimethyl 3,3´-ethyne-1,2-diylbis(6-aminobenzoate) (2a).
A mixture of CuI (110 mg, 0.58 mmol), Pd(OAc)2 (60 mg,
0.27 mmol), and Ph3P (130 mg, 0.49 mmol) in MeCN (30 mL)
deaerated (UST) under argon atmosphere was stirred at 20 C
for 20 min. Iodide 5 (1.39 g, 5.0 mmol), Et3N (1.53 g, 15.11 mmol,
2.1 mL), H2O (0.15 g, 8.33 mmol), and finely ground CaC2 (1.0 g,
15.60 mmol) were then added. The reaction mixture was stirred
for 7 h and concentrated in vacuo; the residue was extracted with
hot EtOAc. The extract was filtered and concentrated in vacuo,
the residue was purified by chromatography on SiO2 using gradi-
ent elution of PhH  PhH/EtOAc (4 : 1). Diarylalkyne 2a (0.57 g,
70%) was isolated as yellow crystals, m.p. 245—249 C. HRMS
(ESI), found m/z: 325.1179, 347.0997; C18H16N2O4; calculated
325.1183 [M + H]+, 347.1002 [M + Na]+. IR (KBr), /cm–1
:
788, 834, 985, 1103, 1162, 1235, 1300, 1430, 1506—1663, 1688,
1
2342, 2361, 2838—3033, 3367, 3464. H NMR (DMSO-d6), :
3.82 (s, 6 H, 2 MeO); 6.75 (d, 2 H, HC(5), HC(5´), J = 8.6 Hz);
7.26 (dd, 2 H, HC(4), HC(4´), J = 8.6 Hz, J = 1.9 Hz); 7.83
(d, 2 H, HC(2), HC(2´), J = 1.9 Hz). 13C NMR (DMSO-d6), :
51.3 (Me, Me´); 86.9 (C C); 108,8 (C(5), C(5´)); 109.0 (C(3),
C(3´)); 116.9 (C(1), C(1´)); 133.9 (C(2), C(2´)); 136.0 (C(4),
C(4´)); 150.8 (C(6), C(6´)); 167.1 (CO, C´O).
3,3´-Ethyne-1,2-diyilbis(6-aminobenzoic acid) (2b). Sodium
hydroxide solution (15 mL, 5%) was added to a solution of dies-
ter 2a (0.45 g, 1.39 mmol) in acetone (25 mL) stirred at 20 C
under argon atmosphere. The mixture was stirred at 20 C for
10 h, concentrated in vacuo to the volume of 15 mL, and
acidified with citric acid till pH 4. The formed precipitate was
filtered off, washed with water and then EtOAc, and dried in vacuo
(2 Torr) till the constant weight. Dicarboxylic acid 2b (0.40 g,
97%) was isolated as a yellow powder, m.p. >200 C (decomp.).
3,3´-Ethyne-1,2-diylbis[6-(N-tert-butoxycarbonyl-L-prolino-
ylamino)benzoic acid] (3b). Sodium hydroxide solution (10 mL,
5%) was added to a solution of diester 3a (0.76 g, 1.06 mmol) in
acetone (20 mL) stirred at 20 C under argon atmosphere. The
mixture was stirred at 20 C for 4 h, then acidified with citric acid
till pH ~4, concentrated in vacuo to the volume of 10 mL, and

1,2-Diarylacetylenes
Russ. Chem. Bull., Int. Ed., Vol. 68, No. 1, January, 2019
67
extracted with EtOAc. The extract was washed with water and
then brine, dried over Na2SO4, and concentrated in vacuo.
The residue was purified by chromatography on SiO2 using
a LP ButOMe gradient. Compound 6 (0.9 g, 72%) was iso-
lated as light brown crystals, m.p. (THF—ButOMe) >200 C
This work was financially supported by the Russian
Foundation for Basic (project No. 18-03-00170).
References
(decomp.), [α]23 –153.77 (c = 1.0, MeOH). HRMS (ESI),
D
found m/z: 691.2966, 713.2787, 729.2528; C36H42N4O10; calcu-
lated 691.2974 [M + H]+, 713.2793 [M + Na]+, 729.2533
[M + K]+. IR (KBr), /cm–1: 844, 1089, 1161, 1292, 1397, 1410,
1515, 1581, 1654, 1699, 2886, 2977, 3436. 1H NMR (DMSO-d6),
: 1.29 and 1.43 (both br.s, integral ratio of 2/1, 18 H, 2 Me3C);
1.81—2.39 (m, 8 H, HC(8), HC(8´), HC(9), HC(9´)); 3.51 (m,
4 H, HC(10), HC(10´)); 4.18 (m, 2 H, HC(7), HC(7´)); 7.68
(dd, 2 H, HC(4), HC(4´), J = 8.7 Hz, J = 1.9 Hz); 8.16 (br.d,
2 H, HC(2), HC(2´), J = 1.9 Hz); 8.68 (br.d, 2 H, HC(5), HC(5´),
J = 8.7 Hz); 11.79 and 11.85 (both br.s, integral ratio of 2/1,
2 H, HN, HN´) (mixture of rotamers). 13C NMR (CDCl3/
CD3OD), : 23.9, 24.4 (C(9), C(9´)); 27.0, 28.3 (2 CMe3); 31.6
(C(8), C(8´)); 46.9 (C(10), C(10´)); 62.2, 62.8 (C(7), C(7´));
80.4 (CMe3); 88.4 (C C); 116.0 (C(1), C(1´)); 117,7 (C(3),
C(3´)); 134.9 (C(5), C(5´)); 137.3 (C(2), C(2´), C(4), C(4´));
140.5 (C(6), C(6´)); 154.9 (C(7), C(7´)); 172.3 (CO, C´O).
Methyl 4-(4-methoxycarbonylphenylethynyl)-3-nitrobenzoate
(4a). Complex Pd(PPh3)2Cl2 (44 mg, 0.063 mmol) and salt CuI
(5.7 mg, 0.03 mmol) were added to a stirred solution of methyl
4-ethynylbenzoate 9 (200 mg, 1.25 mmol), bromide 10 (390 mg,
1.5 mmol), and triethylamine (1 mL) in THF (10 mL) under
argon atmosphere. Once the reaction was completed (2 h, TLC
monitoring), the mixture was evaporated in vacuo, and the resi-
due was purified by column chromatography on SiO2. The gradi-
ent elution with benzene—ethyl acetate till 10% of the latter gave
product 4a (250 mg, 59%) as light yellow crystals, m.p. 102 C
(sublimate). HRMS (ESI), found m/z: 340.0823; C18H13NO6;
calculated 340.0816 [M + H]+. IR (KBr), /cm–1: 767, 978, 1016,
1104, 1176, 1232, 1274, 1288, 1353, 1403, 1436, 1535, 1602, 1616,
1720, 2967, 3064, 3422. 1H NMR (CDCl3), : 3.96 (s, 3 H,
CH3—О—C(4´)); 4.01 (s, 3 H, CH3—О—C(1)); 7.68 (d, 2 H,
HC(2´), HC(6´), J = 8.4 Hz); 7.82 (d, 1 H, HC(5), J = 8 Hz);
8.08 (d, 2 H, HC(3´), HC(5´), J = 8.4 Hz); 8.27 (dd, 1 H, HC(6),
J = 8 Hz, J = 1.6 Hz); 8.75 (d, 1 H, HC(2), J = 1.6 Hz). 13C NMR
(CDCl3), : 52.3 (MeO2CC(1)); 52.9 (MeO2CC(4´)); 86.8
(C(1´´)C(2´´)); 99.0 (C(1´´)C(2´´)); 122.1 (C(2)); 125.9
(C(4));126.4 (C(1´)); 129.6 (C(2´), C(6´)); 132.1 (C(3´), C(5´));
133.2 (C(6)); 134.9 (C(5)); 149.5 (C(3)); 164.4 (CO2—C(4´));
166.2 (CO2—C(1)).
4-(4-Carboxyphenylethynyl)-3-nitrobenzoic acid (4b). An
aqueous solution of KOH (25 mL, 0.006%) was added to a solu-
tion of diester 4a (0.2 g, 0.64 mmol) in THF (20 mL). The
mixture was stirred for 4 h and then evaporated to dryness. The
residue was dissolved in water (20 mL), and the resulting solution
was acidified with 1M HCl till pH 2. The formed precipitate was
filtered off and dried in vacuo. Acid 4b (0.12 g, 55%) was isolated
as dark red crystals, m.p. >200 C (decomp.). HRMS (ESI),
found m/z: 334.0318, 350.0058; C16H9NO6; calculated 334.0322
[M + Na]+, 350.0061 [M + K]+. IR (KBr), /cm–1: 758, 770,
858, 917, 1016, 1122, 1242, 1280, 1310, 1342, 1421, 1534, 1558,
1615, 1691, 1616, 2826, 2880, 2990, 3082, 3434. 1H NMR
(CDCl3), : 7.73 (d, 2 H, HC(2´), HC(6´), J = 8.3 Hz); 7.98—8.06
(m, 3 H, HC(5), HC(3´), HC(5´)); 8.08 (d, 2 H, HC(3´),
HC(5´), J = 8.4 Hz); 8.27 (dd, 1 H, HC(6), J = 8.1 Hz,
J = 1.6 Hz); 8.58 (d, 1 H, HC(2), J = 1.6 Hz).
1. L. Ackermann, Org. Lett., 2005, 7, 439.
2. L. T. Kaspar, L. Ackermann, Tetrahedron, 2005, 61, 11311.
3. H. Sakai, K. Tsutsumi, T. Morimoto, K. Kakiuchi, Adv.Synth.
Catal., 2008, 350, 2498.
4. A. Arcadi, S. Cacchi, G. Fabrizi, F. Ghirga, A. Goggiamani,
A. Iazzetti, F. Marinelli, Beilstein J. Org. Chem. 2018, 14, 2411.
5. Z. Novák, G. Timári, A. Kotschy, Tetrahedron, 2003, 59, 7509.
6. H. B. Bang, S. Y. Han, D. H. Choi, D. M. Yang, J. W. Hwang,
H. S. Lee, J.-G. Jun, Synth.Commun., 2009, 39, 506.
7. N. Kaur, Y. Xia, Y. Jin, N. T. Dat, K. Gajulapati, Y. Choi,
Y.-S. Hong, J. J. Lee, K. Lee, Chem. Commun., 2009, 1879.
8. A. Furstner, E. K. Heilmann, P. W. Davies, Angew.Chem.,
Int. Ed., 2007, 46, 4760—4763.
9. M. M. Murray, R. Kaszynski, D. A. Kaisaki, W. Chang, D. A.
Dougherty, J. Am. Chem. Soc., 1994, 116, 8152.
10. W. Walker, S. Grugeon, H. Vezin, S. Laruelle, M. Armand,
F. Wudl, J.-M. Tarascon, J. Mater. Chem., 2011, 21, 1615.
11. G. H. Dang, T. D. Nguyen, D. T. Le, T. Truong, N. T. S.
Phan, ChemPlusChem, 2014, 79, 1129.
12. G. H. Dang, D. T. Le, T. Truong, N. T. S. Phan, J. Mol.
Catal. A: Chemical, 2015, 400, 162.
13. D. J. Tranchemontagne, K. S. Park, H. Furukawa, J. Eckert,
C. B. Knobler, O. M. Yaghi, J. Phys. Chem., C, 2012,
116, 13143.
14. R. Chinchilla, C. Najera, Chem. Soc. Rev., 2011, 40, 5084.
15. A. P. Rudenko, A. V. Vasil´ev, Russ. J. Org. Chem., 1995,
31, 1360.
16. M. Pal, N. G. Kundu, J. Chem. Soc., Perkin Trans. 1,
1996, 449.
17. C.-J. Li, D.-L. Chen, C. W. Costello, Org. Process Res. Dev.,
1997, 1, 325.
18. P. Chuentragool, K. Vongnam, P. Rashatasakhon, M. Suk-
wattanasinitt, S. Wacharasindhu, Tetrahedron, 2011, 67, 8177.
19. A. Smeyanov, A. Schmidt, Synth. Commun., 2013, 43, 2809.
20. P. Larson, T. A. Kucaba, Z. Xiong, M. Olin, T. S. Griffith,
D. M. Ferguson, ACS Med. Chem. Lett., 2017, 8, 1148
(Supporting information).
21. S. S. Kale, A. S. Kotmale, A. K. Dutta, S. Pal, P. R.
Rajamohanan, G. J. Sanjayan, Org. Biomol. Chem., 2012,
10, 8426.
22. A. G. Gordon, R. A. Ford, The Chemist´s Companion.
A Handbook of Practical Data, Techniques, and References,
New York—London—Sydney—Toronto, 1972.
23. A. D. Burrows, L. C. Fisher, D. Hodgson, M. F. Mahon,
N. F. Cessford, T. Düren, C. Richardson, S. P. Rigby,
CrystEngComm, 2012, 14, 188 (Supplementary information).
24. D. Kang, H. Zhang, Z. Zhou, B. Huang, L. Naesens, P. Zhan,
X. Liu, Bioorg. Med. Chem. Lett., 2016, 26, 5182.
Received October 9, 2018;
in revised form November 1, 2018;
accepted November 7, 2018