A simple method for the synthesis of furfuryl ketones and furylacetic acid derivatives

Article abstract of DOI:10.1007/s10593-015-1744-z

A simple preparative method has been developed for the synthesis of aryl(furfuryl) ketones, amides, and furylacetic acid esters, based on radical alkylation of furan derivatives at the α-position with O-ethyl(phenacyl)xanthogenates and phenacyl iodides in the presence of Fenton's reagent (H₂O₂/FeSO₄·7H₂O) in DMSO. The range of applicability and mechanisms for the formation of major and side products have been considered.

Full text of DOI:10.1007/s10593-015-1744-z

DOI 10.1007/s10593-015-1744-z
Chemistry of Heterocyclic Compounds 2015, 51(7), 621–629
Dedicated to the memory of Professor A. V. Butin, friend, colleague, teacher
A simple method for the synthesis of furfuryl ketones
and furylacetic acid derivatives
Petrakis N. Chalikidi1, Tatyana A. Nevolina2, Maxim G. Uchuskin2,
Vladimir T. Abaev1*, Alexander V. Butin2†
1 North-Ossetian State University named after K. L. Khetagurov,
46 Vatutina St., Vladikavkaz 362025, Russia; e-mail: hampazero@mail.ru
2 Perm State National Research University,
15 Bukireva St., Perm 614990, Russia; e-mail: mu@psu.ru
Translated from Khimiya Geterotsiklicheskikh Soedinenii,
2015, 51(7), 621–629
Submitted June 5, 2015
Accepted June 15, 2015
A simple preparative method has been developed for the synthesis of aryl(furfuryl) ketones, amides, and furylacetic acid esters, based on
radical alkylation of furan derivatives at the α-position with О-ethyl(phenacyl)xanthogenates and phenacyl iodides in the presence of
Fenton's reagent (H2O2/FeSO4·7H2O) in DMSO. The range of applicability and mechanisms for the formation of major and side products
have been considered.
Keywords: furans, furylacetamides, furfuryl ketones, esters of furylacetic acids, radical alkylation.
One of the key directions for the development of organic
synthesis in recent years is the emphasis on renewable
resources, especially biomass. The combination of purely
chemical and also economic aspects has allowed to identify
the most promising raw materials of biological origin that
can be used for fine organic synthesis, denoted as
molecular platforms.1a Important examples of such
compounds are furan derivatives, which, on one hand,
undergo reactions typical of aromatic compounds, while on
the other hand can react as synthetic equivalents of alkenes,
1,3-dienes, enol ethers, and 1,4-diketones. Such a unique
reactivity enables the application of furan molecular platforms
for the preparation of practically useful products of furan
series,2 as well as other types of compounds.3 In particular,
furans containing an appropriate functional group may undergo
intramolecular reactions with loss of aromaticity in the furan
ring, producing other heterocycles.4
During our investigation of furan recyclization, we were
interested in their β-carbonyl derivatives, in particular
furfuryl ketones and derivatives of (2-furyl)acetic acids.
The simultaneous presence of a furan ring, carbonyl group,
and easily modified methylene linker in these molecules
creates a significant potential for using such furans as
synthetic building blocks.5
Two major types of methods for the synthesis of (2-furyl)-
acetic acids and furfuryl ketones can be distinguished:
a) reactions leading to the formation of furan ring, contain-
ing the required functional group, and b) functionalization of an
existing furan derivative.6 Thus, synthesis of furylacetic
acids and their derivatives was accomplished by Feist–
Benary condensation of acetonedicarboxylic acid ester with
α-chlorocarbonyl compounds (Route а, Scheme 1)7 and
related transformations.8 Another method for the synthesis
of these compounds is acid-catalyzed interaction of 1,3-di-
carbonyl compounds with 2,5-dimethoxy-2,5-dihydro-
furans9 (Route b, Scheme 1) or its equivalent, 1,2-diacyl-
ethylene.10 Cyclizations of γ-(alkynyl) ketones11 (Route c,
Scheme 1), 2-en-4-yn-1-ols,12 2,4-diene-1,6-diones13 (Route
d, Scheme 1) and related processes are also important.14
Among the methods for functionalization of substituted
furans, we should mention the hydrolysis of (2-furyl)aceto-
nitriles15 (Route e, Scheme 1), oxidation of the respective
alcohols,16 Suzuki reaction,17 and other processes.18
The presence of furfuryl ketone fragment in a range of
natural compounds that are of interest to medicinal
chemistry motivates the development of new methods for
the synthesis of furfuryl ketones and (2-furyl)acetic acids.
The promise of direct functionalization of 2-substituted
furans is based on their ready availability from furfural, a
product of biomass processing (Route f, Scheme 1).1b
† Deceased
0009-3122/15/5107-0621©2015 Springer Science+Business Media New York
621

Chemistry of Heterocyclic Compounds 2015, 51(7), 621–629
Scheme 2
Scheme 1
CO2R3
O
R2
X
OMe
O
R4
O
O
O
O
Cl
CO2R3
OMe
R1
a
b
d
O
f
c
O
R2
R1
H
R1
O
R2
e
O
O
R2
R1
CN
R1
O
O
Retrosynthetic analysis of
of conditions for the model reaction between xanthogenate
2a and 2-methylfuran (4a) (Scheme 3). We found that the
maximum yield of the product was obtained by performing
the reaction for 1 h with 1:8:4 molar ratio of 2a:H2O2:4а.
Using a smaller excess of furan 4а relative to compound 2a
(1:2) resulted in a slightly lower yield of the final
product.25 On the other hand, increasing the excess of
2-methylfuran (4a) to 1:10 and above did not noticeably
increase the yield of 2-(phenacyl)furan 5a. A lower amount
of peroxide was insufficient for complete conversion of
xanthogenate 2а, while increasing the amount of peroxide
led to a decreased yield of product 5a, apparently due to its
oxidation with excess peroxide. Increased reaction time
also resulted in accumulation of products from
decomposition of 2-phenacylfuran 5а. Besides that, we
studied the possibility of alkylating furan 4а with О-tert-
butyl-, О-[2-(methylsulfanyl)ethyl]-, and O-[2-(dimethyl-
amino)ethyl]xanthogenates, but found that the results of the
reaction were not improved by using these relatively
difficult to prepare reagents.
Under the optimized conditions we obtained a series of
2-(phenacyl)furans 5a–h (Table 1). We should note that the
formation of two by-products was always observed. These
by-products were isolated in three cases, characterized by
spectroscopy and elemental analysis, and assigned with the
structure of sulfones 6a,e,g, while 1,4-diaryl 1,4-diketones
7a,e,g were obtained in smaller quantities (5–7%) (Scheme 3).
Nevertheless, good yields of products 5 were obtained
both for 2-alkylfurans 4a,b and furan itself (4d), as well as
for 2-arylfuran 4с. On the other hand, the introduction of
electron-withdrawing substituent at the α-position of furan
ring suppressed the alkylation, as in the case of
(2-furyl)acetic acid and furfuryl ketones
However, the introduction of 2-oxoalkyl group in the furan
ring via Friedel–Crafts reaction is limited to the use of
glyoxylates,19
α-acyl-α-chlorosulfides,20
and
related
compounds, leading to α-substituted products. On the other
hand, oxoalkylation of furan with radicals generated by
oxidation of acetone or malonic ester with Mn(III) acetate
was described in 1981 and gave moderate yields.21 Esters
of 2-(hetaryl)acetic acids, containing electron-withdrawing
substituents at the С-5 atom, were obtained by using ethyl
xanthogenacetate,22 but this procedure is not generally
applicable, for example, it is not suitable for the
modification of 2-alkylfurans.23 The Baciocchi method is
more promising, where furan is alkylated with iodoacetic
acid ester in DMSO at room temperature in the presence of
Fenton's reagent (H2O2/FeSO4·7H2O), giving ethyl ester of
(2-furyl)acetic acid in 65% yield.23,24
Our preliminary results show that using О-ethyl-
(phenacyl)xanthogenates under these conditions for
alkylation of 2-methylfuran allowed to obtain the
corresponding 2-(phenacyl)furans in good yields.25 In the
current work, we present the complete results regarding
radical alkylation of furan derivatives with phenacyl
iodides and xanthogenates, as well as describe for the first
time the preparation of phenyl esters and arylamides of
furylacetic acid under the aforementioned conditions. The
starting О-ethyl(phenacyl)xanthogenates 2 and phenacyl
iodides 3 were obtained from readily available phenacyl
bromides 1 (Scheme 2).
We started the study of furan alkylation by optimization
Scheme 3
R2
R1
R3
H2O2, FeSO47H2O
+
R4
X
O
DMSO, H2O
O
1) 510°C, 30 min; 2) rt, 2 h
2ae X = SC(S)OEt
3ae X = I
4ad
R2
R1
R3
O
R2
R1
R3
R2
R1
R3
O
SO2Me
R2
R1
+
+
O
R4
O
5a h

O
6a,e,g
R3
7a,e,g
622

Chemistry of Heterocyclic Compounds 2015, 51(7), 621–629
Table 1. Structures and yields of phenacylfurans 5a–h, sulfones 6a,e,g, and diketones 7a,e,g
Xanthogenate
or iodide
R1
R2
R3
Furan
R4
2-Phenacylfuran (Yield, %)
Sulfone (Yield, %)
Diketone (Yield, %)
H
H
H
H
H
H
H
H
H
Br
Br
Br
Br
Br
H
H
H
H
H
H
H
H
H
H
H
H
NO2
NO2
Me
Me
t-Bu
4-ClC6H4
H
CO2Et
Me
Me
Me
Me
Me
Me
5a (61)
5a (54)
5b (58)
5c (55)
5d (53)
–
5e (55)
5e (47)
5f (58)
5f (35)
5g (64)
5g (56)
5h (52)
5h (37)
6а (22)
–
–
–
7а (7)
–
–
–
–
–
7е (5)
–
–
–
2a
3a
2a
2a
2a
2a
2b
3b
2c
3c
2d
3d
2e
3e
4a
4a
4b
4c
4d
4е
4a
4a
4a
4a
4a
4a
4a
4a
–
Br
6а (62)
6e (31)
–
–
NO2
NO2
OMe
OMe
OMe
OMe
OMe
OMe
H
–
OMe
OMe
OMe
OMe
6g (25)
7g (5)
–
–
–
–
–
–
Me
Me
Scheme 4
xanthogenate 2а reaction with ester 4e, where the only
product isolated in 62% yield was the sulfone 6a.
Analogous result was obtained for 2-acetylfuran. We
should also note that iodides 3 gave somewhat lower yields
of alkylation products, compared to the respective
xanthogenates.
The proposed reaction mechanism is shown in Scheme 4.
The first stage of this process is the well-known single-
electron reduction of hydrogen peroxide in the presence of
Fe(II) salts with the formation of a hydroxide ion and a
hydroxyl radical. The high reactivity of hydroxyl radical
may be moderated by using DMSO as solvent, increasing
the reaction selectivity. Indeed, the use of other solvents
(DMF, acetonitrile, 1,4-dioxane) gave significantly inferior
results. Thus, the yield of phenacylfuran 5a in DMF was
merely 20%, while in acetonitrile and 1,4-dioxane this
product was formed in trace amounts, detected only
chromatographically. Hydroxyl radical is well known to
react rapidly with DMSO, forming intermediate A,
decomposition of which gives methyl radical В and
methylsulfinic acid 8.26 The interaction of radical B with
xanthogenate 2 is accompanied by the formation of
phenacyl radical C, which reacts with furan 4, giving
compound 5. The formation of sulfone 6 as by-product
apparently can be explained by the interaction of radical C
with methylsulfinic acid 8 that accumulates in the reaction
mixture, leading to intermediate D. Oxidation of the latter
with Fe(III) ions produces the sulfone 6.
We also studied the possibility of using radical
alkylation with xanthogenates in DMSO in the presence of
Fenton's reagent for the synthesis of phenyl esters and
amides of (5-methylfuran-2-yl)acetic acid. The starting
xanthogenates 11a–i were obtained in two stages – by
acylation of amines 9a–g and phenols 9h,i with
chloroacetyl chloride, followed by treatment of the
obtained chlorides 10 with potassium xanthogenate in
acetone. We found that, under analogous conditions to
those used for preparation of phenacylfurans 5,
xanthogenates 11 alkylated 2-methylfuran (4a) in moderate
yields, forming amides 12a–g and phenyl esters 12h,i
(Scheme 5).
Despite moderate yields, the simplicity of this method
for the synthesis of esters and amides of furylacetic acid
and the availability of starting compounds are significant
advantages, compared to the traditional acylation of less
available furylacetic acids.
Thus, we have shown that alkylation of furans in the
presence of Fenton's reagent (H2O2/FeSO4·7H2O) with the
appropriate xanthogenates in DMSO at room temperature
allowed to obtain various 2-oxoalkyl derivatives of furan in
moderate yields. The reaction worked with xanthogenates
of various structures and furans that contained alkyl or
aromatic substituents, as well as unsubstituted furan. In
contrast, furans with electron-withdrawing substituents did
not participate in this reaction. It was shown that the use of
phenacyl xanthogenates resulted in the formation of methyl-
(phenacyl)sulfones and symmetrical 1,4-diaryl 1,4-diketones
as by-products. A mechanism for the formation of both the
major and minor reaction products has been postulated.
Experimental
IR spectra were recorded on FSM-1202 (compounds 2e,
5b–d,g,h, 11c,e,f–i, 12b,c,e–i) and Bruker Alpha FT-IR
spectrometers (compounds 11d, 2d). 1Н and 13С NMR
623

Chemistry of Heterocyclic Compounds 2015, 51(7), 621–629
Scheme 5
spectra were acquired on Bruker DRX-300 (300 and 75 MHz,
respectively), Bruker Avance 600 (600 and 150 MHz,
respectively), and Bruker Avance III HD 400 (400 and 100
MHz respectively) instruments at room temperature in
CDCl3 or DMSO-d6; the residual solvent protons were used
as internal standard (CDCl3: 7.26 ppm for 1H nuclei, 77.16
ppm for 13C nuclei; DMSO-d6: 2.50 ppm for 1H nuclei, 39.52
ppm for 13C nuclei). Mass spectra were recorded on a
Kratos MS-30 mass spectrometer, EI ionization (ionization
voltage 70 eV, ionization chamber temperature 200°C) or a
HEVO TQD ACQUITY UPLC-I chromato-mass
spectrometer with electrospray ionization. Elemental
analysis was performed on a vario MICRO cube CHNS
analyzer. Melting points were determined on a Stuart
SMP30 apparatus. TLC analysis was performed on Sorbfil
plates. Reaction mixtures were purified by using KSK
silica gel.
ppm: 13.9; 43.5; 55.7; 70.7; 114.2 (2C); 129.1; 131.0 (2C);
164.2; 191.0; 213.7.
O-Ethyl S-[2-(3,4-dimethoxyphenyl)-2-oxoethyl] dithio-
carbonate (2d). Yield 84%, white powder, mp 75–77°C
(3:1 petroleum ether–CH2Cl2) (mp 73–74°C (EtOH)27).
1H NMR spectrum (400 MHz, CDCl3), δ, ppm (J, Hz): 1.39
(3H, t, 3J = 7.1, OCH2CH3); 3.93 (3H, s, OCH3); 3.95 (3H,
3
s, OCH3); 4.63 (2H, s, CH2); 4.63 (2H, q, J = 7.1,
3
OCH2CH3); 6.91 (1H, d, J = 8.4, H Ar); 7.54 (1H, d,
3
4
4J = 1.8, H Ar); 7.67 (1H, dd, J = 8.4, J = 1.8, H Ar).
13C NMR spectrum (100 MHz, CDCl3), δ, ppm: 13.9; 43.3;
56.2; 56.3; 70.8; 110.3; 110.7; 123.4; 129.1; 149.4; 154.0;
191.0; 213.7.
O-Ethyl S-[2-(4,5-dimethoxy-2-nitrophenyl)-2-oxoethyl]
dithiocarbonate (2e). Yield 88%, light-yellow powder, mp
117–119°C (3:1 petroleum ether–EtOAc). IR spectrum
(Nujol), ν, cm–1: 1721 (C=O), 1581, 1533, 1335, 1279,
1219, 1177, 1114, 1055, 1005. 1H NMR spectrum (400 MHz,
Phenacyl xanthogenates 2 were obtained according to a
published procedure.27
CDCl3), δ, ppm (J, Hz): 1.38 (3H, t, J = 7.1, OCH2CH3);
3
S-[2-(4-Bromophenyl)-2-oxoethyl] O-ethyl dithiocarbo-
nate (2a). Yield 88%, white powder, mp 84–86°C (3:1
petroleum ether–CH2Cl2) (mp 81–83°C28). 1H NMR
spectrum (400 MHz, CDCl3), δ, ppm (J, Hz): 1.40 (3H, t,
3J = 7.1, OCH2CH3); 4.61 (2H, s, CH2); 4.64 (2H, q,
3.97 (3H, s, OCH3); 3.99 (3H, s, OCH3); 4.43 (2H, s, CH2);
3
4.59 (2H, q, J = 7.1, OCH2CH3); 6.89 (1H, s, H Ar); 7.64
(1H, s, H Ar). 13C NMR spectrum (100 MHz, CDCl3), δ,
ppm: 13.8; 45.7; 56.7; 56.9; 71.2; 106.7; 110.0; 130.9;
138.5; 150.0; 154.2; 196.0; 213.7. Mass spectrum (EI), m/z
(Irel, %): 345 [M]+ (29), 312 (39), 299 (32), 240 (23), 224
(35), 210 (100), 195 (52), 181 (51), 164 (38), 136 (71), 123
(40), 106 (43), 93 (62), 75 (55). Found, %: C 45.18; H 4.42;
N 4.09. C13H15NO6S2. Calculated, %: C 45.21; H 4.38; N 4.06.
Phenacyl iodides 3 were obtained according to a
published procedure.30
3
3J = 7.1, OCH2CH3); 7.65 (2H, AA'BB' system, J = 8.4,
H Ar); 7.88 (2H, AA'BB' system, 3J = 8.4, H Ar). 13C NMR
spectrum (100 MHz, CDCl3), δ, ppm: 13.9; 43.5; 71.0;
129.2; 130.1 (2C); 132.3 (2C); 134.7; 191.6; 213.3.
O-Ethyl S-[2-(4-nitrophenyl)-2-oxoethyl] dithiocarbo-
nate (2b). Yield 87%, white powder, mp 87–89°C (3:1
petroleum ether – CH2Cl2) (mp 88–89°C (petroleum ether–
1-(4-Bromophenyl)-2-iodoethanone (3a). Yield 89%,
colorless needles, mp 94–96°C (3:1 petroleum ether–
1
diethyl ether)29). H NMR spectrum (400 MHz, CDCl3), δ,
ppm (J, Hz): 1.41 (3H, t, 3J = 7.1, OCH2CH3); 4.64 (2H, q,
3J = 7.1, OCH2CH3); 4.66 (2H, s, CH2); 8.18 (2H, AA'BB'
system, 3J = 8.8, H Ar); 8.35 (2H, AA'BB' system, 3J = 8.8,
H Ar). 13C NMR spectrum (100 MHz, CDCl3), δ, ppm:
13.9; 43.6; 71.3; 124.1 (2C); 129.6 (2C); 140.6; 150.8;
191.5; 213.0.
EtOAc) (mp 95–96°C (6:1 hexane–EtOAc)30). H NMR
1
spectrum (400 MHz, CDCl3), δ, ppm (J, Hz): 4.31 (2H, s,
3
CH2); 7.63 (2H, AA'BB' system, J = 8.5, H Ar); 7.85 (2H,
AA'BB' system, 3J = 8.5, H Ar). 13C NMR spectrum (100 MHz,
CDCl3), δ, ppm: 1.0; 129.2; 130.7 (2C); 132.4 (2C); 132.6;
191.9.
O-Ethyl S-[2-(4-methoxyphenyl)-2-oxoethyl] dithiocarbo-
nate (2c). Yield 83%, beige powder, mp 68–69°C (4:1
2-Iodo-1-(4-nitrophenyl)ethanone (3b). Yield 92%,
yellow powder, mp 96–98°C (3:1 petroleum ether–EtOAc)
1
1
petroleum ether–EtOAc) (mp 67°C (hexane–EtOAc)31). H
(mp 93.5–94.5°C32). H NMR spectrum (400 MHz, CDCl3),
NMR spectrum (400 MHz, CDCl3), δ, ppm (J, Hz): 1.40
δ, ppm (J, Hz): 4.39 (2H, s, CH2); 8.14 (2H, AA'BB' system,
3J = 8.7, H Ar); 8.33 (2H, AA'BB' system, 3J = 8.7, H Ar). 13C
NMR spectrum (100 MHz, CDCl3), δ, ppm: 0.8; 124.2 (2C);
130.2 (2C); 138.3; 150.9; 191.3.
(3H, t, 3J = 7.1, OCH2CH3); 3.89 (3H, s, OCH3); 4.62 (2H,
3
s, CH2); 4.65 (2H, q, J = 7.1, OCH2CH3); 6.97 (2H,
3
AA'BB' system, J = 8.8, H Ar); 8.00 (2H, AA'BB' system,
3J = 8.8, H Ar). 13C NMR spectrum (100 MHz, CDCl3), δ,
2-Iodo-1-(4-methoxyphenyl)ethanone (3c). Yield 86%,
624

Chemistry of Heterocyclic Compounds 2015, 51(7), 621–629
pale-yellow powder, mp 59–60°C (4:1 petroleum ether–
13C NMR spectrum (100 MHz, CDCl3), δ, ppm: 29.2 (3C);
32.7; 39.1; 103.1; 108.7; 128.5; 130.4 (2C); 132.0 (2C);
135.3; 145.6; 164.1; 194.4. Mass spectrum (EI), m/z (Irel, %):
322 [M(81Br)]+ (2), 320 [M(81Br)]+ (2), 185 (14), 183 (15), 159
(5), 157 (5), 137 (100), 122 (9), 107 (9), 95 (7), 76 (5). Found, %:
C 59.72; H 5.30. C16H17BrO2. Calculated, %: C 59.83; H 5.33.
1-(4-Bromophenyl)-2-[5-(4-chlorophenyl)furan-2-yl]-
ethanone (5c). Yield 2.06 g (55%), light-beige powder, mp
118–120°C (2:1 petroleum ether–CH2Cl2). IR spectrum
(Nujol), ν, cm–1: 1689 (C=O), 1582, 1221, 1096, 1074, 1016,
960. 1H NMR spectrum (400 MHz, CDCl3), δ, ppm (J, Hz):
1
EtOAc) (mp 58–59°C32). H NMR spectrum (400 MHz,
CDCl3), δ, ppm (J, Hz): 3.88 (3H, s, OCH3); 4.31 (2H, s,
CH2); 6.94 (2H, AA'BB' system, 3J = 8.9, H Ar); 7.97 (2H,
AA'BB' system, 3J = 8.9, H Ar). 13C NMR spectrum (100 MHz,
CDCl3), δ, ppm: 1.8; 55.7; 114.1 (2C); 126.5; 131.5 (2C);
164.1; 191.6.
2-Iodo-1-(3,4-dimethoxyphenyl)ethanone (3d). Yield
88%, pale-yellow powder, mp 66–67°C (3:1 petroleum
ether–EtOAc) (mp 65.2–66.2°C (pentane–acetone)33).
1H NMR spectrum (300 MHz, CDCl3), δ, ppm (J, Hz): 3.93
(3H, s, OCH3); 3.95 (3H, s, OCH3); 4.32 (2H, s, CH2); 6.89
3
4.33 (2H, s, CH2); 6.32 (1H, d, J = 3.3, H Fur); 6.58 (1H,
3
4
3
3
(1H, d, J = 8.4, H Ar); 7.53 (1H, d, J = 2.0, H Ar); 7.61
(1H, dd, 3J = 8.4, 4J = 2.0, H Ar). 13C NMR spectrum (75 MHz,
CDCl3), δ, ppm: 1.4; 56.2; 56.3; 110.2; 111.1; 124.0;
126.7; 149.4; 154.0; 191.8.
d, J = 3.3, H Fur); 7.32 (2H, AA'BB' system, J = 8.6,
H Ar); 7.53 (2H, AA'BB' system, 3J = 8.6, H Ar); 7.63 (2H,
3
AA'BB' system, J = 8.0, H Ar); 7.90 (2H, AA'BB' system,
3J = 8.0, H Ar). 13C NMR spectrum (100 MHz, CDCl3), δ,
ppm: 38.8; 106.7; 110.9; 125.0 (2C); 128.9; 129.0 (2C);
129.3; 130.3 (2C); 132.2 (2C); 133.0; 135.0; 148.0; 152.8;
193.8. Mass spectrum (EI), m/z (Irel, %): 378/377/376/375/374
[M]+ (3/2/10/1/6), 193 (35), 191 (100), 157 (10), 155 (10),
128 (25), 76 (10). Found, %: C 57.61; H 3.27. C18H12BrClO2.
Calculated, %: C 57.55; H 3.22.
2-Iodo-1-(4,5-dimethoxy-2-nitrophenyl)ethanone (3e).
Yield 93%, yellow powder, mp 153–155°C (1:1 petroleum
ether–CH2Cl2) (mp 138–141°C (EtOH) 34). 1H NMR
spectrum (400 MHz, CDCl3), δ, ppm (J, Hz): 4.00 (3H, s,
OCH3); 4.01 (3H, s, OCH3); 4.20 (2H, s, CH2); 6.92 (1H, s,
H Ar); 7.66 (1H, s, H Ar). 13C NMR spectrum (100 MHz,
CDCl3), δ, ppm: 6.9; 56.8; 57.0; 106.9; 112.1; 129.4;
138.3; 150.3; 154.4; 195.3.
1-(4-Bromophenyl)-2-(furan-2-yl)ethanone (5d). Yield
1.40 g (53%), light-yellow powder, mp 97–98°C (9:1
petroleum ether–EtOAc). IR spectrum (Nujol), ν, cm–1:
1698 (C=O), 1586, 1465, 1328, 1071, 993. 1H NMR
spectrum (400 MHz, CDCl3), δ, ppm (J, Hz): 4.27 (2H, s,
CH2); 6.23 (1H, d, 3J = 3.0, H Fur); 6.34 (1H, dd, 3J = 3.0,
Preparation of 2-(phenacyl)furans 5a–h, acetamides
12a–g, and carboxylates 12h,i (General method). A solution
of xanthogenate 2a–e or 11a–i or iodide 3a–e (10 mmol) and
of furan 4a–d (80 mmol of furans 4a,b,12 mmol of furan 4c,
200 mmol of furan 4d) in DMSO (30 ml) was cooled (5–
10°C) and treated with FeSO4·7H2O (1.52 g, 5 mmol). Then
34% aqueous H2O2 (2 ml, 20 mmol) was dropwise added.
After adding H2O2, the reaction mixture was stirred for 30 min
at 5–10°C, then for 2 h at room temperature (control by
TLC). Once the reaction was complete, the mixture was
poured into water (300 ml), extracted with ethyl acetate
(4×50 ml), the combined extracts were washed with
saturated aqueous NaCl solution, dried over anhydrous
Na2SO4, and evaporated to dryness. The residue was
separated by silica gel column chromatography with 4:1
petroleum ether–EtOAc as eluent (9:1 for compounds
5g,h).
4
4J =2.0, H Fur); 7.37 (1H, d, J = 2.0, H Fur); 7.61 (2H,
AA'BB' system, 3J = 8.5, H Ar); 7.87 (2H, AA'BB' system,
3J = 8.5, H Ar). 13C NMR spectrum (100 MHz, CDCl3), δ,
ppm: 38.7; 108.6; 110.9; 128.8; 130.3 (2С); 132.2 (2С);
135.1; 142.4; 148.0; 194.2. Mass spectrum (EI), m/z (Irel, %):
266 [M(81Br)]+ (8), 264 [M(79Br)]+ (8), 185 (98), 183 (100),
157 (34), 155 (35), 104 (15), 76 (40), 53 (30). Found, %:
C 54.41; H 3.37. C12H9BrO2. Calculated, %: C 54.37; H 3.42.
2-(5-Methylfuran-2-yl)-1-(4-nitrophenyl)ethanone (5е).25
Yield 1.35 g (55%), light-beige needles, mp 67–69°C (4:1
petroleum ether–EtOAc) (mp 67–69°C (petroleum ether–
1
EtOAc)25). H NMR spectrum (400 MHz, CDCl3), δ, ppm
(J, Hz): 2.24 (3H, s, CH3); 4.28 (2H, s, CH2); 5.91 (1H, d,
1-(4-Bromophenyl)-2-(5-methylfuran-2-yl)ethanone (5a).25
Yield 1.70 g (61%), light-beige powder, mp 58–59°C (9:1
petroleum ether–EtOAc) (mp 58–59°C (petroleum ether–
3J = 3.0, H Fur); 6.11 (1H, d, J = 3.0, H Fur); 8.15 (2H,
3
3
AA'BB' system, J = 8.5, H Ar); 8.29 (2H, AA'BB' system,
3J = 8.5, H Ar). 13C NMR spectrum (100 MHz, CDCl3), δ,
ppm: 13.6; 39.3; 106.8; 109.7; 124.0 (2C); 129.8 (2C); 140.8;
145.1; 150.5; 152.3; 193.9.
1
EtOAc)25). H NMR spectrum (400 MHz, CDCl3), δ, ppm
(J, Hz): 2.25 (3H, s, CH3); 4.20 (2H, s, CH2); 5.90 (1H, d,
3
3J = 3.0, H Fur); 6.08 (1H, d, J = 3.0, H Fur); 7.60 (2H,
1-(4-Methoxyphenyl)-2-(5-methylfuran-2-yl)ethanone
(5f).25 Yield 1.33 g (58%), light-beige powder, mp 69–70°C
(4:1 petroleum ether–diethyl ether) (mp 69–70°C
(petroleum ether–EtOAc)25). 1H NMR spectrum (400 MHz,
CDCl3), δ, ppm (J, Hz): 2.25 (3H, s, CH3); 3.86 (3H, s,
3
AA'BB' system, J = 8.5, H Ar); 7.86 (2Н, AA'BB' system,
3J = 8.5, H Ar). 13C NMR spectrum (100 MHz, CDCl3), δ,
ppm: 13.6; 38.9; 106.8; 109.3; 128.6; 130.3 (2C); 132.1
(2C); 135.4; 146.1; 152.0; 194.3.
3
1-(4-Bromophenyl)-2-(5-tert-butylfuran-2-yl)ethanone (5b).
Yield 1.86 g (58%), light-beige powder, mp 57–60°C (4:1
petroleum ether–EtOAc). IR spectrum (Nujol), ν, cm–1:
1689 (C=O), 1584, 1334, 1209, 1071, 994. 1H NMR
spectrum (400 MHz, CDCl3), δ, ppm (J, Hz): 1.23 (9H, s,
OCH3); 4.20 (2H, s, CH2); 5.89 (1H, d, J = 3.0, H Fur);
3
6.07 (1H, d, J = 3.0, H Fur); 6.93 (2H, AA'BB' system,
3J = 8.8, H Ar); 7.99 (2H, AA'BB' system, 3J = 8.8, H Ar).
13C NMR spectrum (100 MHz, CDCl3), δ, ppm: 13.7; 38.5;
55.6; 106.6; 108.9; 113.9 (2C); 129.4; 131.1 (2C); 146.8;
151.7; 163.8; 194.1.
3
C(CH3)3); 4.21 (2H, s, CH2); 5.87 (1H, d, J = 3.1, H Fur);
3
6.07 (1H, d, J = 3.1, H Fur); 7.60 (2H, AA'BB' system,
1-(3,4-Dimethoxyphenyl)-2-(5-methylfuran-2-yl)etha-
none (5g). Yield 1.66 g (64%), colorless needles, mp 116–
3J = 8.6, H Ar); 7.87 (2H, AA'BB' system, 3J = 8.6, H Ar).
625

Chemistry of Heterocyclic Compounds 2015, 51(7), 621–629
117°C (4:1 petroleum ether–EtOAc). IR spectrum (KBr),
spectrum (100 MHz, CDCl3), δ, ppm: 33.4; 124.4; 129.6;
ν, cm–1: 1677 (C=O), 1582, 1517, 1417, 1265, 1162, 1019,
795. 1H NMR spectrum (300 MHz, CDCl3), δ, ppm (J, Hz):
2.24 (3H, s, CH3); 3.91 (3H, s, OCH3); 3.93 (3H, s, OCH3);
4.19 (2H, s, CH2); 5.89 (1H, d, 3J = 3.0, H Fur); 6.07 (1H, d,
141.3; 150.9; 197.2.
1-(3,4-Dimethoxyphenyl)-2-(methylsulfonyl)ethanone
(6g). Isolated along with the product 5g. Yield 0.65 g
(25%), white powder, mp 142–143°C (EtOAc). IR
spectrum (KBr), ν, cm–1: 1675 (C=O), 1516, 1303, 1152,
1119, 1020, 976. 1H NMR spectrum (400 MHz, CDCl3), δ,
ppm (J, Hz): 3.11 (3H, s, CH3); 3.91 (3H, s, ОCH3); 3.93
3
3J = 3.0, H Fur); 6.88 (1H, d, J = 8.4, H Ar); 7.56 (1H, d,
3
4
4J = 2.0, H Ar); 7.65 (1H, dd, J = 8.4, J = 2.0, H Ar). 13C
NMR spectrum (75 MHz, CDCl3), δ, ppm: 13.6; 38.4; 56.0;
56.2; 106.6; 108.9; 110.1; 110.8; 123.6; 129.6; 146.8; 149.1;
151.6; 153.5; 194.0. Mass spectrum (EI), m/z (Irel, %): 260
[M]+ (25), 165 (100), 137 (33), 122 (32), 107 (24), 95 (70), 77
(66), 43 (38). Found, %: C 69.13; H 6.29. C15H16O4.
Calculated, %: C 69.22; H 6.20.
3
(3H, s, ОCH3); 4.55 (2H, s, CH2); 6.90 (1H, d, J = 8.5,
H Ar); 7.50 (1H, d, 4J = 2.0, H Ar); 7.60 (1H, dd, 3J = 8.5,
4J = 2.0, H Ar). 13C NMR spectrum (150 MHz, CDCl3), δ,
ppm: 41.7; 56.0; 56.2; 61.1; 110.3; 110.6; 125.0; 128.8; 149.4;
154.8; 187.4. Mass spectrum (EI), m/z (Irel, %): 258 [M]+ (100),
166 (22), 165 (90), 151 (13), 137 (14), 43 (20). Found, %:
C 51.22; H 5.51. C11H14O5S. Calculated, %: C 51.15; H 5.46.
1,4-Bis(3,4-dimethoxyphenyl)butane-1,4-dione (7g).27
Isolated along with the product 5g. Yield 0.18 g (5%), colorless
needles, mp 185–187°C (ethanol) (mp 176–178°C27).
1H NMR spectrum (400 MHz, CDCl3), δ, ppm (J, Hz): 3.41
1-(4,5-Dimethoxy-2-nitrophenyl)-2-(5-methylfuran-2-yl)-
ethanone (5h). Yield 1.59 g (52%), light-yellow needles,
mp 117–118°C (3:1 petroleum ether–CH2Cl2). IR spectrum
(KBr), ν, cm–1: 1706 (C=O), 1578, 1524, 1334, 1287, 1229,
1
1176, 1084, 1024, 950. H NMR spectrum (400 MHz,
CDCl3), δ, ppm (J, Hz): 2.19 (3H, s, CH3); 3.90 (3H, s,
OCH3); 3.96 (3H, s, OCH3); 4.05 (2H, s, CH2); 5.85 (1H, d,
3J = 3.0, H Fur); 6.03 (1H, d, 3J = 3.0, H Fur); 6.59 (1H, s,
H Ar); 7.60 (1H, s, H Ar). 13C NMR spectrum (100 MHz,
CDCl3), δ, ppm: 13.6; 42.7; 56.6; 56.7; 106.7; 106.8;
109.3; 110.0; 132.0; 138.3; 145.6; 149.6; 152.1; 154.0;
198.7. Mass spectrum (EI), m/z (Irel, %): 305 [M]+ (1), 211
(4), 181 (3), 136 (7), 121 (3), 110 (10), 95 (100). Found, %:
C 58.91; H 5.03; N 4.67. C15H15NO6. Calculated, %:
C 59.01; H 4.95; N 4.59.
3
(4H, s, CH2); 3.92 (6H, s, OCH3); 6.89 (2H, d, J = 8.1,
3
H Ar); 7.55 (2H, br. s, H Ar); 6.89 (2H, br. d, J = 8.1,
H Ar). 13C NMR spectrum (100 MHz, CDCl3), δ, ppm: 32.7;
56.4; 56.5; 110.5; 110.6; 123.2; 130.5; 149.4; 153.7; 197.9.
2-Chloroacetamides 10a–i were obtained according to
the described procedure and used in further reactions
without identification.39
Preparation of xanthogenates 11a–i (General method).
A solution of 2-chloroacetamide 10a–i (18 mmol) in
anhydrous acetone (60 ml) was cooled (5–10°C) and
treated by portionwise addition of potassium ethyl
xanthogenate (3.52 g, 22 mmol). The reaction mixture was
stirred for 30 min at room temperature, then refluxed for 3 h.
The solvent was evaporated to dryness at reduced pressure.
The obtained residue in flask was treated with 200 ml of
cold water, the precipitate that formed was filtered off,
washed with water (3×50 ml), and air-dried.
1-(4-Bromophenyl)-2-(methylsulfonyl)ethanone (6a).
Isolated along with the product 5a. Yield 0.61 g (22%),
light-yellow needles, mp 142–144°C (EtOAc) (mp 134–
1
139°C35). H NMR spectrum (400 MHz), δ, ppm (J, Hz):
3.13 (3H, s, CH3); 4.55 (2H, s, CH2); 7.68 (2H, AA'BB'
3
3
system, J = 8.6, H Ar); 7.87 (2H, AA'BB' system, J = 8.6,
H Ar). 13C NMR spectrum (100 MHz), δ, ppm: 42.0; 61.6;
130.6; 130.9 (2C); 132.6 (2C); 134.6; 188.5.
1,4-Bis(4-bromophenyl)butane-1,4-dione (7a). Isolated
along with the product 5a. Yield 0.28 g (7%), light-beige
needles, mp 174–175°C (ethanol) (mp 176–178°C36).
1H NMR spectrum (400 MHz, CDCl3), δ, ppm (J, Hz): 3.40
S-(2-Amino-2-oxoethyl) O-ethyl dithiocarbonate (11a).
Yield 2.51 g (78%), white powder, mp 114–115°C (4:1
petroleum ether–EtOAc) (mp 114–115°C40). 1H NMR
spectrum (400 MHz, CDCl3), δ, ppm (J, Hz): 1.43 (3H, t,
3J = 7.1, OCH2CH3); 3.85 (2H, s, CH2); 4.67 (2H, q,
3J = 7.1, OCH2CH3); 6.05 (1H, br. s, NH); 6.27 (1H, br. s,
NH). 13C NMR spectrum (100 MHz, CDCl3), δ, ppm: 13.8;
38.9; 71.3; 169.8; 213.0.
3
(4H, s, CH2); 7.60 (4H, AA'BB' system, J = 8.3, H Ar);
3
7.87 (4H, AA'BB' system, J = 8.3, H Ar). 13C NMR
spectrum (100 MHz, CDCl3), δ, ppm: 32.9; 128.8; 130.1;
132.4; 135.8; 197.9.
2-(Methylsulfonyl)-1-(4-nitrophenyl)ethanone
(6е).
S-[2-(Benzylamino)-2-oxoethyl)] O-ethyl dithiocarbo-
nate (11b). Yield 3.87 g (80%), white powder, mp 86–88°
Isolated along with the product 5e. Yield 0.75 g (31%), light-
yellow needles, mp 155–157°C (EtOAc) (mp 148.9–149.4°C
(hexane–CH2Cl2)37). 1H NMR spectrum (600 MHz,
CDCl3), δ, ppm (J, Hz): 3.16 (3H, s, CH3), 4.65 (2H, s,
CH2); 8.19 (2H, AA'BB' system, 3J = 8.8, H Ar); 8.37 (2H,
AA'BB' system, 3J = 8.8, H Ar). 13C NMR spectrum (150 MHz,
CDCl3), δ, ppm: 41.9; 61.9; 124.3 (2С); 130.6 (2С); 140.0;
151.2; 188.2.
1
C (4:1 petroleum ether–EtOAc) (mp 94–95°C41). H NMR
spectrum (400 MHz, CDCl3), δ, ppm (J, Hz): 1.42 (3H, t,
3J = 7.1, OCH2CH3); 3.92 (2H, s, СH2); 4.48 (2H, d, 3J = 5.8,
3
CH2NH); 4.66 (2H, q, J = 7.1, OCH2CH3); 6.66 (1H, br. s,
NH); 7.28–7.37 (5H, m, H Ar). 13C NMR spectrum (100 MHz,
CDCl3), δ, ppm: 13.8; 39.3; 44.0; 71.3; 127.7; 127.8 (2C);
128.8 (2C); 137.9; 167.0; 213.1.
1,4-Bis(4-nitrophenyl)butane-1,4-dione (7е). Isolated
along with the product 5e. Yield 0.16 g (5%), yellow needles,
mp 178–180°C (ethanol) (mp 195–196°C (CHCl3)38).
1H NMR spectrum (400 MHz, CDCl3), δ, ppm (J, Hz): 3.51
O-Ethyl S-{2-[(4-fluorophenyl)amino]-2-oxoethyl} di-
thiocarbonate (11c). Yield 4.37 g (89%), light-beige
needles, mp 108–109°C (4:1 petroleum ether–EtOAc). IR
spectrum (KBr), ν, cm–1: 3306 (N–H), 1667 (C=O), 1549,
3
1
(4H, s, CH2); 8.17 (4H, AA'BB' system, J = 7.3, H Ar);
1362, 1229, 1113, 1047. H NMR spectrum (400 MHz,
3
3
8.33 (4H, AA'BB' system, J = 8.3, H Ar). 13C NMR
CDCl3), δ, ppm (J, Hz): 1.43 (3H, t, J = 7.1, OCH2CH3);
626

Chemistry of Heterocyclic Compounds 2015, 51(7), 621–629
3.99 (2H, s, CH2); 4.68 (2H, q, 3J = 7.1, OCH2CH3); 6.97–7.03
(C=O), 1562, 1535, 1407, 1295, 1241, 1204, 1179, 1114,
(2H, m, H Ar); 7.42–7.47 (2H, m, H Ar); 8.28 (1H, br. s,
1050. 1H NMR spectrum (400 MHz, CDCl3), δ, ppm (J, Hz):
NH). 13C NMR spectrum (100 MHz, CDCl3), δ, ppm
1.29 (3H, t, J = 7.5, CH2CH3); 1.37 (3H, t, J = 7.1,
3
3
2
3
(J, Hz): 13.9; 40.0; 71.7; 115.8 (2C, d, JCF = 22.5); 122.1
OCH2CH3); 1.42 (3H, t, J = 7.1, OCH2CH3); 2.74 (2H, q,
3
4
(2С, d, JCF = 7.9); 133.5 (1С, d, JCF = 2.8); 159.7 (1С, d,
1JCF = 244.2); 165.6; 213.9. Mass spectrum (EI), m/z (Irel, %):
273 [M]+ (48), 184 (19), 163 (98), 150 (18), 135 (21), 124
(27), 111 (100), 95 (27), 82 (16), 47 (43), 43 (35). Found, %:
C 48.27; H 4.39; N 5.16. C11H12FNO2S2. Calculated, %:
C 48.33; H 4.42; N 5.12.
3J = 7.5, CH2CH3); 4.07 (2H, s, CH2); 4.34 (2H, q, 3J = 7.1,
3
OCH2CH3); 4.69 (2H, q, J = 7.1, OCH2CH3); 6.88 (1H, s,
H Th); 11.41 (1H, br. s, NH). 13C NMR spectrum (100 MHz,
CDCl3), δ, ppm: 13.8; 14.5; 15.7; 23.0; 39.4; 60.8; 71.2;
113.4; 119.5; 137.7; 146.1; 164.3; 165.3; 211.8. Mass
spectrum (ESI), m/z (Irel, %): 384 [M+Na]+ (99), 163 (100).
Found, %: C 46.64; H 5.19; N 3.86. C14H19NO4S3.
Calculated, %: C 46.51; H 5.30; N 3.87.
O-Ethyl S-{2-[(4-nitrophenyl)amino]-2-oxoethyl} dithio-
carbonate (11d). Yield 4.75 g (88%), light-beige needles,
mp 108–109°C (4:1 petroleum ether–EtOAc). IR spectrum
(ATR), ν, cm–1: 3360 (NH), 1680 (C=O), 1552, 1493, 1333,
1252, 1114, 1051, 851. 1H NMR spectrum (300 MHz,
(4-Methoxyphenyl) 2-[(ethoxycarbothioyl)sulfanyl]acetate
(11h). Yield 4.53 g (88%), light-yellow oil. IR spectrum
(Nujol), ν, cm–1: 1762 (C=O), 1596, 1504, 1235, 1192,
1109, 1051, 938. 1H NMR spectrum (400 MHz, CDCl3), δ,
ppm (J, Hz): 1.44 (3H, t, 3J = 7.1, OCH2CH3); 3.79 (3H, s,
OCH3); 4.12 (2H, s, CH2); 4.68 (2H, q, 3J = 7.1,
3
CDCl3), δ, ppm (J, Hz): 1.45 (3H, t, J = 7.1, OCH2CH3);
3
4.05 (2H, s, CH2); 4.70 (2H, q, J = 7.1, OCH2CH3); 7.69
3
(2H, AA'BB' system, J = 9.1, H Ar); 8.20 (2H, AA'BB'
3
3
system, J = 9.1, H Ar); 8.69 (1H, br. s, NH). 13C NMR
OCH2CH3); 6.88 (2H, AA'BB' system, J = 9.1, H Ar);
3
spectrum (75 MHz, CDCl3), δ, ppm: 13.9; 40.3; 72.1; 119.5
(2C); 125.2 (2C); 143.4; 143.9; 166.3; 214.3. Mass
spectrum (EI), m/z (Irel, %): 300 [M]+ (100), 277 (13), 240
(54), 211 (52), 180 (31), 163 (84), 147 (23), 138 (56), 122
(23), 108 (27), 95 (21), 75 (26), 43 (42). Found, %: C 44.07;
H 4.11; N 9.38. C11H12N2O4S2. Calculated, %: C 43.99;
H 4.03; N 9.33.
7.03 (2H, AA'BB' system, J = 9.1, H Ar). 13C NMR
spectrum (100 MHz, CDCl3), δ, ppm: 13.9; 38.0; 55.7;
71.0; 114.6 (2C); 122.2 (2C); 144.3; 157.6; 167.0; 212.6.
Mass spectrum (EI), m/z (Irel, %): 286 [M]+ (1), 163 (100),
135 (84), 124 (68), 109 (60), 95 (19), 81 (15), 65 (10).
Found, %: C 50.28; H 4.99. C12H14O4S2. Calculated, %:
C 50.33; H 4.93.
O-Ethyl S-{2-[(2-nitrophenyl)amino]-2-oxoethyl} dithio-
carbonate (11e). Yield 4.43 g (82%), light-yellow needles,
mp 89–91°C (4:1 petroleum ether–EtOAc). IR spectrum
(Nujol), ν, cm–1: 3306 (NH), 1664 (C=O), 1552, 1511, 1230,
(4-Fluorophenyl) 2-[(ethoxycarbothioyl)sulfanyl]ace-
tate (11i). Yield 4.39 g (89%), colorless needles, mp
43–45°C (3:1 petroleum ether–CH2Cl2). IR spectrum
(Nujol), ν, cm–1: 1760 (C=O), 1502, 1308, 1229, 1192,
1
1
1114, 1050. H NMR spectrum (400 MHz, CDCl3), δ, ppm
1150, 1110, 1046, 946. H NMR spectrum (400 MHz,
(J, Hz): 1.44 (3H, t, 3J = 7.1, OCH2CH3); 4.10 (2H, s, CH2);
4.71 (2H, q, 3J = 7.1, OCH2CH3); 7.17–7.23 (1H, m, H Ar);
7.63–7.67 (1H, m, H Ar); 8.19–8.21 (1H, m, H Ar); 8.72–8.74
(1H, m, H Ar); 10.90 (1H, br. s, NH). 13C NMR spectrum
(100 MHz, CDCl3), δ, ppm: 13.9; 40.9; 71.5; 122.6; 123.9;
125.9; 134.3; 135.9; 137.1; 166.4; 212.1. Mass spectrum (ESI),
m/z (Irel, %): 323 [M+Na]+ (100). Found, %: C 44.04; H 4.09;
N 9.36. C11H12N2O4S2. Calculated, %: C 43.99; H 4.03;
N 9.33.
CDCl3), δ, ppm (J, Hz): 1.44 (3H, t, J = 7.1, OCH2CH3);
3
3
4.13 (2H, s, CH2); 4.68 (2H, q, J = 7.1, OCH2CH3); 7.04–
7.11 (4H, m, H Ar). 13C NMR spectrum (100 MHz, CDCl3),
δ, ppm (J, Hz): 13.2; 37.3; 70.4; 115.6 (2С, d, 2JCF = 23.5);
122.2 (2С, d, 3JCF = 8.7); 145.9 (1С, d, 4JCF = 2.9); 159.8 (1С,
1
d, JCF = 245.0); 166.1; 211.9. Mass spectrum (EI), m/z (Irel,
%): 163 [M–4-FC6H4O]+ (100), 135 (93), 112 (78), 107 (43),
93 (11), 83 (37), 75 (11), 57 (16). Found, %: C 48.21;
H 4.00. C11H11FO3S2. Calculated, %: C 48.16; H 4.04.
2-(5-Methylfuran-2-yl)acetamide (12a). Yield 0.86 g
(62%), beige powder, mp 124–126°C (4:1 petroleum ether–
EtOAc) (mp 112–114°C (petroleum ether)42). 1H NMR
spectrum (400 MHz, CDCl3), δ, ppm (J, Hz): 2.25 (3H, s,
CH3); 3.53 (2H, s, CH2); 5.79 (1H, br. s, NH); 5.90 (1H, d,
O-Ethyl S-[2-oxo-2-(pyridin-2-ylamino)ethyl] dithio-
carbonate (11f). Yield 3.59 g (78%), white powder, mp
98–100°C (4:1 petroleum ether–EtOAc). IR spectrum
(Nujol), ν, cm–1: 1667 (C=O), 1577, 1551, 1433, 1328,
1
1287, 1229, 1205, 1177, 1117, 1054. H NMR spectrum
3
3
(400 MHz, CDCl3), δ, ppm (J, Hz): 1.44 (3H, t, J = 7.1,
3J = 2.8, H Fur); 6.08 (1H, d, J = 2.8, H Fur); 6.16 (1H,
3
OCH2CH3); 4.04 (2H, s, CH2); 4.70 (2H, q, J = 7.1,
br. s, NH). 13C NMR spectrum (100 MHz, CDCl3), δ, ppm:
OCH2CH3); 7.03–7.06 (1H, m, H Py); 7.68–7.73 (1H, m,
H Py); 8.17–8.19 (1H, m, H Py); 8.26–8.28 (1H, m, H Py);
8.71 (1H, br. s, NH). 13C NMR spectrum (100 MHz,
CDCl3), δ, ppm: 13.9; 40.5; 71.5; 114.3; 120.3; 138.6;
147.9; 151.2; 165.8; 212.9. Mass spectrum (EI), m/z (Irel, %):
256 [M]+ (3), 210 (25), 168 (30), 137 (28), 78 (100), 59
(16). Found, %: C 46.94; H 4.69; N 10.86. C10H12N2O2S2.
Calculated, %: C 46.85; H 4.72; N 10.93.
13.6; 36.1; 106.7; 109.4; 146.9; 152.3; 172.0.
N-Benzyl-2-(5-methylfuran-2-yl)acetamide
(12b).
Yield 1.44 g (63%), white powder, mp 65–67°C (4:1
petroleum ether–EtOAc). IR spectrum (Nujol), ν, cm–1:
3286 (NH), 1644 (C=O), 1545, 1262, 1160, 1080, 1016. 1H
NMR spectrum (400 MHz, CDCl3), δ, ppm (J, Hz): 2.25
3
(3H, s, CH3); 3.60 (2H, s, CH2); 4.45 (2H, d, J = 5.8,
3
CH2NH); 5.90 (1H, d, J = 2.8, H Fur); 6.03 (1H, br. s,
3
O-Ethyl S-(2-{[5-ethyl-3-(ethoxycarbonyl)thiophen-
2-yl]amino}-2-oxoethyl) dithiocarbonate (11g). Yield 5.46 g
(84%), white powder, mp 48–50°C (9:1 petroleum ether–
EtOAc). IR spectrum (Nujol), ν, cm–1: 3285 (N–H), 1677
NH); 6.10 (1H, d, J = 2.8, H Fur); 7.22–7.34 (5H, m,
H Ar). 13C NMR spectrum (100 MHz, CDCl3), δ, ppm: 13.6;
36.6; 43.7; 106.8; 109.6; 127.5; 127.6 (2C); 128.8 (2C); 138.3;
146.9; 152.4; 169.0. Mass spectrum (EI), m/z (Irel, %): 229 [M]+
627

Chemistry of Heterocyclic Compounds 2015, 51(7), 621–629
(12), 147 (5), 96 (68), 95 (100), 91 (40), 65 (11). Found, %:
147.1; 151.1; 152.8; 167.8. Mass spectrum (EI), m/z (Irel, %):
216 [M]+ (90), 122 (42), 96 (20), 95 (100), 79 (21), 78 (74), 67
(22), 51 (24), 43 (32). Found, %: C 66.71; H 5.63; N 12.99.
C12H12N2O2. Calculated, %: C 66.65; H 5.59; N 12.96.
C 73.42; H 6.58; N 6.14. C14H15NO2. Calculated, %: C 73.34;
H 6.59; N 6.11.
N-(4-Fluorophenyl)-2-(5-methylfuran-2-yl)acetamide
(12c). Yield 1.56 g (67%), colorless needles, mp 116–117°C
(4:1 petroleum ether–EtOAc). IR spectrum (Nujol), ν, cm–1:
3276 (N–H), 1658 (C=O), 1533, 1507, 1218, 1032, 833.
1H NMR spectrum (400 MHz, CDCl3), δ, ppm (J, Hz): 2.29
Ethyl 5-ethyl-2-[2-(5-methylfuran-2-yl)acetamido]-
thiophene-3-carboxylate (12g). Yield 1.73 g (54%), light-
yellow prisms, mp 77–78°C (9:1 petroleum ether–EtOAc).
IR spectrum (Nujol), ν, cm–1: 3253 (N–H), 1661 (C=O),
3
1
(3H, s, CH3); 3.69 (2H, s, CH2); 5.96 (1H, d, J = 3.0,
1530, 1401, 1226, 1037, 782. H NMR spectrum (300 MHz,
3
3
H Fur); 6.17 (1H, d, J = 3.0, H Fur); 6.95–7.00 (2H, m,
CDCl3), δ, ppm (J, Hz): 1.27 (3H, t, J = 7.5, CH2CH3);
3
H Ar); 7.40–7.44 (2H, m, H Ar); 7.66 (1H, br. s, NH).
13C NMR spectrum (100 MHz, CDCl32), δ, ppm (J, Hz):
13.7; 37.3; 106.9; 110.0; 115.7 (2C, d, JCF = 22.5); 122.0
1.33 (3H, t, J = 7.1, OCH2CH3); 2.33 (3H, s, CH3); 2.71
3
(2H, q, J = 7.5, CH2CH3); 3.80 (2H, s, CH2); 4.27 (2H, q,
3J = 7.1, OCH2CH3); 5.97 (1H, d, 3J = 3.0, H Fur); 6.20 (1H, d,
3J = 3.0, H Fur); 6.83 (1H, s, H Th); 11.11 (1H, br. s, NH). 13C
NMR spectrum (75 MHz, CDCl3), δ, ppm: 13.6; 14.5; 15.7;
22.9; 36.5; 60.5; 106.7; 110.0; 112.8; 119.2; 137.1; 145.2;
146.4; 153.0; 165.2; 166.1. Mass spectrum (EI), m/z (Irel, %):
321 [M]+ (61), 226 (22), 216 (18), 199 (100), 184 (40), 180
(38), 153 (46), 138 (31), 122 (39), 96 (42), 95 (45), 58 (37), 44
(52), 42 (41). Found, %: C 59.68; H 6.01; N 4.33. C16H19NO4S.
Calculated, %: C 59.79; H 5.96; N 4.36.
3
4
(2С, d, J = 7.9); 133.7 (1С, d, JCF = 2.9); 146.4; 152.7;
1
159.6 (1С, d, JCF = 243.7); 167.3. Mass spectrum (EI), m/z
(Irel, %): 233 [M]+ (94), 150 (10), 138 (25), 122 (38), 111 (45),
96 (66), 95 (100), 81 (36), 67 (22), 43 (32). Found, %: C 66.92;
H 5.23; N 5.96. C13H12FNO2. Calculated, %: C 66.94; H 5.19;
N 6.01.
2-(5-Methylfuran-2-yl)-N-(4-nitrophenyl)acetamide
(12d). Yield 1.96 g (65%), light-beige powder, mp 138–
139°C (4:1 petroleum ether–EtOAc). IR spectrum (ATR),
ν, cm–1: 3266 (N–H), 1665 (C=O), 1552, 1512, 1342, 1256,
854. 1H NMR spectrum (300 MHz, CDCl3), δ, ppm (J, Hz):
(4-Methoxyphenyl) 2-(5-methylfuran-2-yl)acetate
(12h). Yield 1.33 g (54%), light-yellow oil. IR spectrum
(Nujol), ν, cm–1: 1762 (C=O), 1597, 1571, 1506, 1341,
3
1
2.30 (3H, s, CH3); 3.76 (2H, s, CH2); 5.98 (1H, d, J = 3.0,
1298, 1249, 1192, 1124, 1022, 971. H NMR spectrum
3
H Fur); 6.21 (1H, d, J = 3.0, H Fur); 7.67 (2H, AA'BB'
(400 MHz, CDCl3), δ, ppm (J, Hz): 2.29 (3H, s, CH3); 3.79
3
3
system, J = 9.1, H Ar); 7.93 (1H, br. s, NH); 8.18 (2H,
(3H, s, OCH3); 3.85 (2H, s, CH2); 5.94 (1H, d, J = 3.0,
AA'BB' system, 3J = 9.1, H Ar). 13C NMR spectrum (75 MHz,
CDCl3), δ, ppm: 13.7; 37.7; 107.1; 110.4; 119.3 (2C);
125.1 (2C); 143.5; 143.7; 145.6; 153.1; 167.6. Mass
spectrum (EI), m/z (Irel, %): 260 [M]+ (54), 165 (11), 150
(26), 122 (15), 104 (12), 96 (100), 95 (98), 81 (24), 76 (16),
59 (20), 53 (30), 44 (54). Found, %: C 59.94; H 4.61;
N 10.82. C13H12N2O4. Calculated, %: C 60.00; H 4.65;
N 10.76.
H Fur); 6.18 (1H, d, J = 3.0, H Fur); 6.88 (2H, AA'BB'
3
system, 3J = 9.0, H Ar); 7.02 (2H, AA'BB' system, 3J = 9.0,
H Ar). 13C NMR spectrum (100 MHz, CDCl3), δ, ppm:
13.7; 34.4; 55.7; 106.6; 109.2; 114.6 (2C); 122.3 (2C);
144.4; 145.3; 152.0; 157.5; 168.6. Mass spectrum (EI), m/z
(Irel, %): 246 [M]+ (6), 122 (69), 109 (8), 95 (100), 79 (5).
Found, %: C 68.23; H 6.01. C14H14O4. Calculated, %:
C 68.28; H 5.73.
2-(5-Methylfuran-2-yl)-N-(2-nitrophenyl)acetamide
(12e). Yield 1.61 g (62%), light-yellow powder, mp 65–67°C
(4:1 petroleum ether–EtOAc). IR spectrum (Nujol), ν, cm–1:
3263 (N–H), 1675 (C=O), 1592, 1574, 1532, 1521, 1365,
(4-Fluorophenyl) 2-(5-methylfuran-2-yl)acetate (12i).
Yield 1.31 g (56%), light-yellow oil. IR spectrum (Nujol),
ν, cm–1: 1764 (C=O), 1569, 1503, 1341, 1186, 1124, 1022,
971. 1H NMR spectrum (400 MHz, CDCl3), δ, ppm (J, Hz):
2.29 (3H, s, CH3); 3.86 (2H, s, CH2); 5.94 (1H, d, 3J = 2.9,
1
1314, 1215, 1196, 1023. H NMR spectrum (400 MHz,
3
DMSO-d6), δ, ppm (J, Hz): 2.24 (3H, s, CH3); 3.60 (2H, s,
H Fur); 6.18 (1H, d, J = 2.9, H Fur); 7.02–7.26 (4H, m,
3
3
CH2); 6.02 (1H, d, J = 3.0, H Fur); 6.20 (1H, d, J = 3.0,
H Fur); 7.32–7.36 (1H, m, H Ar); 7.68–7.72 (1H, m, H Ar);
7.90–7.92 (1H, m, H Ar); 7.98–8.00 (1H, m, H Ar); 10.34
(1H, br. s, NH). 13C NMR spectrum (100 MHz, DMSO-d6),
δ, ppm: 13.2; 36.0; 106.6; 109.0; 124.5; 124.9; 125.0;
131.6; 134.3; 141.2; 146.5; 151.0; 167.3. Mass spectrum
(EI), m/z (Irel, %): 260 [M]+ (14), 122 (15), 95 (100), 79 (5), 65
(6), 55 (5).
H Ar). 13C NMR spectrum (100 MHz, CDCl3), δ, ppm
(J, Hz): 13.6; 34.3; 106.6; 109.3; 116.2 (2С, d, 2JCF = 23.6);
3
4
123.0 (2С, d, JCF = 8.6); 145.0; 146.7 (1С, d, JCF = 3.0);
1
152.2; 160.4 (1С, d, JCF = 244.3); 168.3. Mass spectrum
(EI), m/z (Irel, %): 234 [M]+ (7), 122 (20), 112 (3), 95 (100),
83 (6). Found, %: C 66.79; H 4.81. C13H11FO3. Calculated, %:
C 66.66; H 4.73.
2-(5-Methylfuran-2-yl)-N-(pyridin-2-yl)acetamide (12f).
Yield 1.34 g (62%). Light-beige powder, mp 94–95°C (4:1
petroleum ether–EtOAc). IR spectrum (Nujol), ν, cm–1:
3239 (N–H), 1666 (C=O), 1578, 1537, 1434, 1300, 1221,
775. 1H NMR spectrum (300 MHz, CDCl3), δ, ppm (J, Hz):
1
The Supplementary file to this article containing H and
13C NMR spectra of the synthesized compounds is
available for authorized users.
3
2.28 (3H, s, CH3); 3.75 (2H, s, CH2); 5.94 (1H, d, J = 3.0,
The results of this work were obtained with financial
support from the Grants Council of the President of the
Russian Federation (grant MK-1476.2014.3) and the
Ministry of Education and Science of the Russian
Federation (State Orders No. 2754 and No. 4.246.2014/K).
3
H Fur); 6.19 (1H, d, J = 3.0, H Fur); 7.02–7.07 (1H, m,
H Py); 7.69–7.75 (1H, m, H Py); 8.23–8.26 (2H, m, H Py);
8.63 (1H, br. s, NH). 13C NMR spectrum (75 MHz, CDCl3), δ,
ppm: 13.7; 37.7; 106.9; 110.2; 114.4; 120.0; 139.1; 145.7;
628

Chemistry of Heterocyclic Compounds 2015, 51(7), 621–629
Rae, I. D.; Redwood, A. M. Aust. J. Chem. 1973, 26, 2221.
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