Iron-Catalyzed Synthesis of 2-Aminofurans from 2-Haloketones and Tertiary Amines or Enamines

Article abstract of DOI:10.1002/ejoc.202000293

The selective synthesis of heterocycles from readily available substrates and catalyzed by an abundant and environmental benign catalyst continues to be an attractive topic. In this communication, we report an interesting protocol for the synthesis of 2-aminofurans. Starting from 2-haloketones and tertiary amines, with abundant iron salt as the catalyst, various 2-aminofurans were produced in good yields. Control experiments were performed to understand the reaction pathway. Based on the identified reaction pathway, the substrates for this transformation can be extended from tertiary amines to enamines and even with better final yields. Finally, a formal three-component reaction can also be realized by forming the enamines in-situ from aldehydes and amines.

Full text of DOI:10.1002/ejoc.202000293

A Journal of
Accepted Article
Title: Iron-Catalyzed Synthesis of 2-Aminofurans from 2-Haloketones
and Tertiary Amines or Enamines
Authors: Xiao-Feng Wu, Le-Cheng Wang, Hui-Qing Geng, and Jin-Bao
Peng
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To be cited as: Eur. J. Org. Chem. 10.1002/ejoc.202000293
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10.1002/ejoc.202000293
European Journal of Organic Chemistry
FULL PAPER
Iron-Catalyzed Synthesis of 2-Aminofurans from 2-Haloketones
and Tertiary Amines or Enamines
Le-Cheng Wang,[a] Hui-Qing Geng,[a] Jin-Bao Peng,[a] and Xiao-Feng Wu*[a,b]
[a]
L. C. Wang, H. G. Geng, Dr. J. B. Peng, Prof. Dr. X. F. Wu, Department Department of Chemistry, Zhejiang Sci-Tech University, Xiasha Campus,
Hangzhou 310018, People’s Republicof China
https://www.catalysis.de/mitarbeiter/wu-xiao-feng/
E-mail: xiao-feng.wu@catalysis.de
[b]
Leibniz-Institutfür Katalyse e. V. an der UniversitätRostock, Albert-Einstein-Straβe 29a, 18059Rostock, Germany
Supporting information for this articleis given via a link at theend of the document.
Abstract: The selective synthesis of heterocycles from readily
available substrates and catalyzed by an abundant and
environmental benign catalyst continues to be an attractive topic.
In this communication, we report an interesting protocol for the
synthesis of 2-aminofurans. Starting from 2-haloketones and
tertiary amines, with abundant iron salt as the catalyst, various 2-
aminofurans were produced in good yields. Control experiments
were performed to understand the reaction pathway. Based on the
identified reaction pathway, the substrates for this transformation
can be extended from tertiary amines to enamines and even with
better final yields. Finally, a formal three-component reaction can
also be realized by forming the enamines in-situ from aldehydes
and amines.
and meaningful.7 Regarding the applicable catalysts, iron salt
is non-expensive, abundant and environmental benign. Under
all these backgrounds, herein, we wish to report a new
synthetic procedure for the synthesis of 2-aminofurans.
Starting from 2-haloketones and tertiary amines or enamines,
with abundant iron salt as the catalyst, various desired 2-
aminofurans were produced in good yields. Control
experiments were performed to get insight into the reaction
pathway.
Results and Discussion
Initially, 2-bromoacetophenone and tripropylamine were
chosen as the model substrates to establish the catalytic
system. By using 2,2’-bipyridyl as the ligand and DTBP as the
Introduction
o
oxidant in toluene at 150 C, various non-expensive catalyst
As requested by sustainable development and green chemistry,
the efficiency on new chemical bond formation in organic
synthesis is becoming more and more important.1 Among the
various possibilities, domino reaction offers an ideal option.2
From readily available and abundant substrates, high value
chemicalscan be produced in an easy manner.
salts were tested (Table 1, entries 1-10). To our delight, the
desired 3-methyl-5-phenyl-N,N-dipropylfuran-2-amine can be
detected in all the tested reactions. The best results were
obtained when FeCl3 was used as the catalyst (Table 1, entry
3). Different ligands were tested subsequently; however, no
better results could be obtained (Table 1, entries 11-16).
Solvents (DMSO; DMF, DCE, THF, Xylene) and oxidants
(TBHP, IBX, etc.) were varied as well, but all lead to decreased
reaction efficiency and selectivity. The loading of amine and
reaction temperature were also varied, the best yield of the
target product can be achieved by performing the reaction at
On the other hand, heterocyclic compounds are holding
crucial applications in many areas. Among them, furans are
attractive due to their known biological activities and frequently
present in pharmaceuticals and natural products.3 In the known
furan derivatives, 2-aminofurans have been explored as a
class of important starting materials or intermediates in organic
syntheses.4 Many novel organic transformations can only be
achieved when starting from 2-aminofuran substrates. Due to
the recognized importance of 2-aminofurans, many synthetic
procedures have been developed as expected.5 Traditionally,
2-aminofurans were prepared by a base-promoted reaction of
α-hydroxyketones or 2-haloketones with malononitrile.5
Recently, catalyzed procedures have been developed as well.6
Starting from acylidenemalononitriles and aryl aldehydes,
carbenoids and enamines, ynamides, allenyl amides, 1-
cyanocyclopropane 1-esters, or homoallenyl amides, with the
presence of the proper catalyst, the desired 2-aminofurans can
be obtained effectively. However, besides the accepted
importance of the developed procedures, challenges such as
noble metal catalysts usage and/or limited availability of the
applied substratesstill need to be overcome.
o
135 C (Table 1, entry 18). Prolong the reaction time led to
decreased yield due to product decomposition. In the absence
of catalyst or lower catalyst loading, no or low yield of the
desired 2-aminofuran was obtained (Table 1, entry19).
Table 1. Optimization of the reaction parameters.[a]
Entry Catalyst
Ligand
Yield (%)
1
2
3
FeCl3·6H2O 2,2’-Bipyridyl
51
37
69
Fe(OTf)3
FeCl3
2,2’-Bipyridyl
2,2’-Bipyridyl
Furthermore, tertiary amines are frequently present in
natural products and advanced materials. The further
activation and functionalization of tertiary amines is attractive
1
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10.1002/ejoc.202000293
European Journal of Organic Chemistry
FULL PAPER
4
Fe(OAc)2
Cu(OAc)2
Cu(OTf)2
CuI
2,2’-Bipyridyl
2,2’-Bipyridyl
2,2’-Bipyridyl
2,2’-Bipyridyl
2,2’-Bipyridyl
2,2’-Bipyridyl
2,2’-Bipyridyl
1,10-Phen
46
33
31
26
37
8
[a] Reaction condition: Under air, 1a (0.5 mmol), 2a (1.5
mmol), catalyst (10 mol %), ligand (15 mol %), DTBP (2
equiv), toluene (2 mL), 150 °C, 14 h, yields were
determined by GC using dodecane as the internal
standard. [b] 2a (1.25 mmol). [c] 2a (1.25 mmol), 135 C.
[d] Isolated yield. [e] FeCl3 (0 mol%), 2,2’-Bipyridyl (0
mol%). [f] FeCl3 (5 mol%), 2,2’-Bipyridyl (7.5 mol%).
5
6
o
7
8
CuCl
With the optimal reaction conditions in hand, the substrates
scope of this transformation was carried out subsequently.
Numbers of 2-bromoacetophenones were tested with
tripropylamine at the first stage (Table 2). It is important to
mention that 2-iodoacetophenone and 2-chloroacetophenone
were proper substrates for this transformation as well.
Substitutions at different positions with various properties can
be well tolerated and provided the corresponding 2-
aminofurans in moderate to good yields. Besides heterocyclic
substrates (3ra), 1-bromopropan-2-one is also a suitable
starting material here and produced the desired 3,5-dimethyl-
N,N-dipropylfuran-2-amine 3qa in 79% isolated yield. However,
the reaction failed when 2-bromopropiophenone was tested,
onlytrace amountof the desired product could be detected.
Afterwards, numbers of tertiary amines were tested as well
(Table 3). Symmetric alkyl substituted amines can gave the
corresponding products in moderate yields (Table 3, 3ab-3ae).
As examples of non-symmetric substituted amines, N-alkyl-N-
arylanilines, were prepared and tested under our standard
conditions. To our delight, the desired N,N-diarylfuran-2-amine
products were isolated in 55-61%yields(Table 3, 3af-3aj).
9
CoBr
10
11
12
13
14
15
Co(acac)3
FeCl3
5
53
53
13
56
FeCl3
TMEDA
FeCl3
α,α‘,α‘‘-Tripyridyl
2,2′-Bi(γ-picoline)
FeCl3
FeCl3
6,6′-Dimethyl-2,2′-dipyridyl 46
4,4′-Di-tert-butyl-2,2′-
dipyridyl
16
FeCl3
20
17
18
19
FeCl3
FeCl3
FeCl3
2,2’-Bipyridyl
2,2’-Bipyridyl
2,2’-Bipyridyl
73b
75c(72)d
0e, 56f
Table 2. Synthesis of 2-aminofurans from 2-haloketones.[a]
[a] Under air, 1 (0.5 mmol), 2a (1.25 mmol), FeCl3 (10 mol % ), bipyridine (15 mol %), DTBP (2 equiv), toluene (2 mL), 135 oC,
14 h, isolated yield. [b] 2-iodo-1-phenylethan-1-one was used. [c] 2-chloro-1-phenylethan-1-one was used. [d] 2-chloro-1-(4-
fluorophenyl)ethan-1-one was used.
2
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10.1002/ejoc.202000293
European Journal of Organic Chemistry
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Table 3. Synthesis of 2-aminofurans from amines.[a]
[a] Under air, 1a (0.5 mmol), 2 (1.25 mmol), FeCl3 (10 mol % ), bipyridine (15 mol %), DTBP (2 equiv), toluene (2 mL), 135 oC,
14 h, isolated yield.
In order to get some insight to the reaction pathway, control
experiments were designed and performed (Scheme 1). As we
could detect enamine and related by-products during the
optimization process, enamine is assumed to be the
intermediate. Hence, (E)-N,N-dimethyl-2-phenylethen-1-amine
was prepared and tested with 2-bromoacetophenone (Scheme
1, eq a). To our delight, the desired N,N-dimethyl-3,5-
diphenylfuran-2-amine was formed in 88% yield with only 1
equivalent of DTBP added. In the absence of DTBP under air
atmosphere, the yield of furan 4a decreased to 27% and N,N-
dimethyl-3,5-diphenyl-2,3-dihydrofuran-2-amine
can
be
detected meanwhile (Scheme 1, eq b). By performing the
reaction under nitrogen atmosphere without DTBP, 10% of
dihydrofuran can be produced (Scheme 1, eq c). These results
suggested that Fe(III) may acts as an oxidant to transform
dihydrofuran into furan and also oxidize amine to enamine. The
Fe(III) can be regenerated in the presence of air and/or DTBP.
In
the
case
of
using
N,4-dimethyl-N-
(phenylethynyl)benzenesulfonamide as the starting material,
no reaction occurred besides the debromination of 2-
bromoacetophenone (Scheme 1, eq d). Significant amount of
acetophenone can be obtained. Those experiments imply that
enamine which produced from amine dehydrogenation and
dihydrofuran are the key intermediates of this transformation.
In order to understand the transformation of dihydrofuran to
furan, we chosen 2,3-dihydrobenzofuran as the model
substrate for further studies. The desired benzofuran can be
obtained in the presence of DTBP with or without iron catalyst
(Scheme 1, eq e and f).
Scheme 1. Control experiments.
However, the yield of benzofuran was better when the
presence of iron catalyst (Scheme 1, eq e). These results imply
that 1) oxidant itself is enough for transforming dihydrofuran
into furan, 2) the presence of iron catalyst can improve the
3
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10.1002/ejoc.202000293
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reaction efficiency. The results from the reactions of 2-amino-
2,3-dihydrobenzofuran are agreed with our deduction (Scheme
1, eq g). Finally, the oxidation of N,N-dimethyl-2-phenylethan-
1-amine was carried out in the absence of 2-
bromoacetophenone under our standard conditions (Scheme 1,
eq h). After 14 hours, the desired enamine could be detected in
Table 4. Synthesis of 2-aminofurans from enamines.[a]
GC-MS but not isolatable which may due to its low stability.
Instead, 75% yield of N1,N2-dimethyl-N1,N2-diphenethylethane-
1,2-diamine was isolated which produced by DTBP-promoted
dimerization of the tertiaryamine.8
o
[a] 1a (0.5 mmol), 5 (1.25 mmol), FeCl3 (10 mol % ), bipyridine (15 mol %), DTBP (1 equiv), toluene (2 mL), 135 C, 14 h,
isolated yield.
Table 5. Synthesis of 2-aminofurans from enamines without DTBP.[a]
4
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[a] 1 (0.5 mmol), 5 (1 mmol), FeCl3 (10 mol % ), L (15 mol %), CH3COONa (2 equiv), CH3COOAg (2 equiv), 4 Å MS (200 mg),
toluene (2 mL), 135 oC, 14 h, isolated yield. [b] 2-chloro-1-phenylethan-1-one was used. [c] 2-chloro-1-(4-fluorophenyl)ethan-1-one
was used.
were transformed into the corresponding 2-aminofurans in
With the aim to further support our proposed reaction
pathway and also to broaden the substrates tolerance,
enamines were prepared and applied in this transformation as
well (Table 4). In these cases, the loading of oxidant can be
decreased to 1 equivalent. As we shown, the yields of the
terminal products are generally improved. Many enamines
good to excellent yields (Table 4, 4a-4j). The results on
variation of 2-bromoacetophenones were promising as well,
good to excellent yields were achieved in general (Table 4, 4k-
4s).
Scheme 2. Three-component synthesis of 2-aminofuran.
can be produced in moderate to excellent yields in general
Moreover, although the loading of organic peroxide can be (Table 5).
decreased to 1 equivalent, its volatile property motivated us to
In order to further proven the usefulness of this procedure, a
find an alternative solution for this transformation.9 Hence we three-component reaction was performed as well (Scheme 2, eq
carried out studies to find a new catalytic system. We found that
a and b). By simply combining 2-bromoacetophenone, N-
silver salt can act as the oxidant for this transformation as well. methylaniline and 2-phenylacetaldehyde in one pot under our
As AcOAg is a one electron oxidant, hence two equivalents of it
are needed. The addition of molecular sieve is to prevent the
hydrolysis of enamines. The using of AcONa is to neutralize the
standard reaction conditions, the desired N-methyl-N,3,5-
triphenylfuran-2-amine can be obtained in 58% yield. Aliphatic
amine can be applied as well, and 51% yield of the
produced HBr and also prevent the decomposition of enamine. corresponding 2-aminofuran can be produced without any
Under our new reaction conditions, the desired 2-aminofurans
further optimization (Scheme 2, eq b). Then alkyl substituted
5
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10.1002/ejoc.202000293
European Journal of Organic Chemistry
FULL PAPER
enamines were prepared and tested, moderate to good yields of
the target products can be produced (Scheme 2, eq c; 6a-6f).
The enamines can be prepared in situ as well, albeit the yields
of the final products were lower (Scheme 2, eq d). This result
shows the practicality of this procedure for 2-aminofurans
preparation.
according to general procedure. The crude residue was purified by flash
chromatography (Petroleum ether/ethyl acetate = 200:1, Rf = 0.30) to
give the product as a brownish yellow oily liquid (79.6 mg, 68%).
1H NMR (400 MHz, CDCl3) δ 7.57 (d, J = 7.4 Hz, 2H), 7.33 (t, J = 7.8 Hz,
2H), 7.17 (t, J = 7.4 Hz, 1H), 6.43 (s, 1H), 3.02 (t, J = 7.4 Hz, 4H), 1.96 (s,
3H), 1.51 (h,
J
=
7.4 Hz, 4H), 0.90 (t,
J = 7.5 Hz, 6H).
13C NMR (101 MHz, CDCl3) δ 153.1, 147.0, 131.6, 128.5, 126.2, 122.8,
109.9, 108.3, 55.9, 21.4, 11.6, 9.9.
HRMS (ESI): [M+H]+ calcd. for C17H24NO 258.1852, found 258.1858.
3-Methyl-N,N-dipropyl-5-(p-tolyl)furan-2-amine
(3ba).
The
title
Conclusion
compound was prepared from 2-bromo-1-(p-tolyl)ethan-1-one (106 mg,
0.5 mmol) and tripropylamine (245 uL, 1.25 mmol), according to general
procedure. The crude residue was purified by flash chromatography
(Petroleum ether/ethyl acetate = 200:1, Rf = 0.30) to give the product as
a brownish yellow oily liquid (89.4 mg, 66%).
In summary, we have developed an interesting protocol for the
synthesis of 2-aminofurans from tertiary amines and 2-
haloketones. With abundant and environmental benign iron salt
as the catalyst, various desired 2-aminofurans were produced in
good yields. Control experiments were performed to understand
the reaction pathway and a reasonable reaction mechanism is
been proposed as well. Based on the reaction pathway, the
substrates for this transformation can be extended from tertiary
amines to enamines and even with better final yields. Finally, a
formal three-component reaction can also be realized by forming
the enamines in-situ from aldehydes and amines.
1H NMR (400 MHz, CDCl3) δ 7.46 (d, J = 8.1 Hz, 2H), 7.14 (d, J = 8.1 Hz,
2H), 6.36 (s, 1H), 3.01 (t, J = 7.4 Hz, 4H), 2.34 (s, 3H), 1.95 (s, 3H), 1.50
(h,
J
=
7.4 Hz,
4H),
0.90 (t,
J
=
7.4 Hz,
6H).
13C NMR (101 MHz, CDCl3) δ 152.7, 147.3, 135.9, 129.2, 128.9, 122.9,
110.1, 107.5, 56.03, 21.4, 21.2, 11.6, 9.9.
HRMS (ESI): [M+H]+ calcd. for C18H26NO 272.2009, found 272.2017.
3-Methyl-N,N-dipropyl-5-(o-tolyl)furan-2-amine
(3ca).
The
title
compound was prepared from 2-bromo-1-(o-tolyl)ethan-1-one (106 mg,
0.5 mmol) and tripropylamine (245 uL, 1.25 mmol), according to general
procedure. The crude residue was purified by flash chromatography
(Petroleum ether/ethyl acetate = 200:1, Rf = 0.30) to give the product as
a brownish yellow oily liquid (93.5 mg, 69%)
1H NMR (400 MHz, CDCl3) δ 7.68 (d, J = 7.5 Hz, 1H), 7.22-7.32 (m, 1H),
7.28 (t, J = 7.3 Hz, 1H), 7.20 (t, J = 7.1 Hz, 1H), 6.39 (s, 1H), 3.05 (t, J =
7.2 Hz, 4H), 2.55 (s, 3H), 2.06 (s, 3H), 1.52 (h, J = 7.4 Hz, 4H), 0.98 (t, J
Experimental Section
General procedure with amine: FeCl3 (8.1 mg, 10 mol %), bpy (11.5 mg,
15 mol %), 2-bromo-1-phenylethan-1-one (100 mg, 0.5 mmol) were
transferred into a 15 mL tube. DTBP (183 uL, 2 equiv), amine (2.5 equiv)
and toluene (2 mL) were added to the reaction tube. Then the vial was
sealed with a screw-top septum cap quickly and placed in a heating block
that was preheated to 135 °C. After a time period of 14 h, the reaction
vial was allowed cooled to room temperature. The reaction mixture was
filtered and washed with EtOAc and then concentrated in vacuum. The
crude product was purified by column chromatography on silica gel to
afford the corresponding product.
=
7.4
Hz,
6H).
13C NMR (101 MHz, CDCl3) δ 152.8, 146.9, 133.8, 131.1, 130.8, 126.4,
126.1, 125.8, 112.0, 109.3, 55.9, 22.0, 21.4, 11.6, 9.9.
HRMS (ESI): [M+H]+ calcd. for C18H26NO 272.2009, found 272.2013.
5-(3-Fluorophenyl)-3-methyl-N,N-dipropylfuran-2-amine (3da). The
title compound was prepared from 2-bromo-1-(3-fluorophenyl)ethan-1-
one (108 mg, 0.5 mmol) and tripropylamine (245 uL, 1.25 mmol),
according to general procedure. The crude residue was purified by flash
chromatography (Petroleum ether/ethyl acetate = 200:1, Rf = 0.30) to
give the product as a brownish yellow oily liquid (110 mg, 80%).
1H NMR (400 MHz, CDCl3) δ 7.30 (dd, J = 7.7, 1.3 Hz, 1H), 7.26 (dd, J =
7.8, 2.0 Hz, 1H), 7.24 – 7.20 (m, 1H), 6.89 – 6.79 (m, 1H), 6.44 (s, 1H),
3.00 – 2.94 (m, 4H), 1.95 (s, 3H), 1.46 (dt, J = 14.7, 5.6 Hz, 4H), 0.89 (t,
General procedure with enamine: FeCl3 (8.1 mg, 10 mol %), ligand (15
mol %), 2-bromo-1-phenylethan-1-one (100 mg, 0.5 mmol) were
transferred into a 15 mL tube. DTBP (92 uL, 1 equiv) or [4 Å MS (200
mg), CH3COONa (2 equiv, 83 mg), and CH3COOAg (2 equiv, 167 mg)],
enamine (2.5 equiv) and toluene (2 mL) were added to the reaction tube.
Then the vial was sealed with a screw-top septum cap quickly and placed
in a heating block that was preheated to 135 °C. After a time period of 14
h, the reaction vial was allowed cooled to room temperature. The
reaction mixture was filtered and washed with EtOAc and then
concentrated in vacuum. The crude product was purified by column
chromatography on silica gel to afford the corresponding product.
J
=
7.4
Hz,
6H).
13C NMR (101 MHz, CDCl3) δ163.2 (d, J = 244.2 Hz), 153.7, 145.6,
133.6 (d, J = 8.5 Hz), 130.0 (d, J = 8.6 Hz), 128.8, 128.0, 118.3, 112.7 (d,
J = 21.6 Hz), 109.5 (d, J = 26.7 Hz), 55.6, 21.4, 11.6, 9.9.
19F NMR (376 MHz, CDCl3): –113.40.
Spectroscopic Data of Products
HRMS (ESI): [M+H]+ calcd. for C17H23FNO 276.1758, found 276.1768.
5-(4-Fluorophenyl)-3-methyl-N,N-dipropylfuran-2-amine (3ea). The
title compound was prepared from 2-bromo-1-(4-fluorophenyl)ethan-1-
one (108 mg, 0.5 mmol) and tripropylamine (245 uL, 1.25 mmol),
according to general procedure. The crude residue was purified by flash
chromatography (Petroleum ether/ethyl acetate = 200:1, Rf = 0.30) to
give the product as a brownish yellow oily liquid (94.9 mg, 69%).
The title compound was prepared from 2-chloro-1-(4-fluorophenyl)ethan-
1-one (86 mg, 0.5 mmol) and 3-(dipropylamino)propan-1-ylium (245 uL,
1.25 mmol), according to general procedure. The crude residue was
purified by flash chromatography (Petroleum ether/ethyl acetate = 200:1,
Rf = 0.30) to give the product as a brownish yellow oily liquid (89.4 mg,
65%).
3-Methyl-5-phenyl-N,N-dipropylfuran-2-amine
(3aa).
The
title
compound was prepared from 2-bromo-1-phenylethan-1-one (100 mg,
0.5 mmol) and tripropylamine (245 uL, 1.25 mmol), according to general
procedure. The crude residue was purified by flash chromatography
(Petroleum ether/ethyl acetate = 200:1, Rf = 0.30) to give the product as
a brownish yellow oily liquid (84.2 mg, 72%).
The title compound was prepared from 2-chloro-1-phenylethan-1-one (77
mg, 0.5 mmol) and 3-(dipropylamino)propan-1-ylium (245 uL, 1.25 mmol),
according to general procedure. The crude residue was purified by flash
chromatography (Petroleum ether/ethyl acetate = 200:1, Rf = 0.30) to
give the product as a brownish yellow oily liquid (70 mg, 60%).
The title compound was prepared from 2-iodo-1-phenylethan-1-one (123
mg, 0.5 mmol) and 3-(dipropylamino)propan-1-ylium (245 uL, 1.25 mmol),
6
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10.1002/ejoc.202000293
European Journal of Organic Chemistry
FULL PAPER
1H NMR (400 MHz, CDCl3) δ 7.56 – 7.48 (m, 2H), 7.02 (t, J = 8.8 Hz, 2H),
6.35 (s, 1H), 2.99 – 2.93 (m, 4H), 1.95 (s, 3H), 1.44 (dt, J = 14.7, 7.4 Hz,
according to general procedure. The crude residue was purified by flash
chromatography (Petroleum ether/ethyl acetate = 200:1, Rf = 0.30) to
give the product as a brownish yellow oily liquid (103.3 mg, 72%).
4H),
0.90
(t,
J
=
7.4
Hz,
6H).
13C NMR (101 MHz, CDCl3) δ161.5 (d, J = 245.4 Hz), 153.1, 146.3,
127.9, 124.5 (d, J = 7.8 Hz), 115.4 (d, J = 21.8 Hz), 110.1, 107.9, 55.9,
21.4, 11.6, 9.8.
1H NMR (400 MHz, CDCl3) δ 7.24 (d, J = 8.0 Hz, 1H), 7.16 (d, J = 7.8 Hz,
1H), 7.12 – 7.10 (m, 1H), 6.76 – 6.70 (m, 1H), 6.42 (s, 1H), 3.84 (s, 3H),
2.98 (t, J = 7.1 Hz, 4H), 1.95 (s, 3H), 1.45 (h, J = 7.4 Hz, 4H), 0.89 (t, J =
19F NMR (376 MHz, CDCl3): –115.96.
7.4
Hz,
6H).
HRMS (ESI): [M+H]+ calcd. for C17H23FNO 276.1758, found 276.1769.
5-(3-Chlorophenyl)-3-methyl-N,N-dipropylfuran-2-amine (3fa). The
title compound was prepared from 2-bromo-1-(3-chlorophenyl)ethan-1-
one (116 mg, 0.5 mmol) and tripropylamine (245 uL, 1.25 mmol),
according to general procedure. The crude residue was purified by flash
chromatography (Petroleum ether/ethyl acetate = 200:1, Rf = 0.30) to
give the product as a brownish yellow oily liquid (104.8 mg, 72%).
1H NMR (400 MHz, CDCl3) δ 7.56 (t, J = 1.5 Hz, 1H), 7.45 (d, J = 7.8 Hz,
1H), 7.29 (d, J = 8.0 Hz, 1H), 7.19 – 7.13 (m, 1H), 6.49 (s, 1H), 3.05 –
3.00 (m, 4H), 1.99 (s, 3H), 1.55 – 1.44 (m, 4H), 0.94 (t, J = 7.4 Hz, 6H).
13C NMR (101 MHz, CDCl3) δ 153.8, 145.3, 134.5, 133.2, 129.7, 125.9,
122.7, 120.8, 109.7, 109.4, 55.6, 21.4, 11.6, 9.9.
13C NMR (101 MHz, CDCl3) δ 159.8, 153.2, 146.7, 132.9, 129.5, 115.6,
111.7, 109.7, 108.8, 108.5, 55.8, 55.2, 21.4, 11.6, 9.9.
HRMS (ESI): [M+H]+ calcd. for C18H26NO2 288.1958, found 288.1966.
5-(4-Methoxyphenyl)-3-methyl-N,N-dipropylfuran-2-amine (3ka). The
title compound was prepared from 2-bromo-1-(4-methoxyphenyl)ethan-1-
one (114 mg, 0.5 mmol) and tripropylamine (245 uL, 1.25 mmol),
according to general procedure. The crude residue was purified by flash
chromatography (Petroleum ether/ethyl acetate = 200:1, Rf = 0.30) to
give the product as a brownish yellow oily liquid (101.9 mg, 71%).
1H NMR (400 MHz, CDCl3) δ 7.50 (d, J = 8.9 Hz, 2H), 6.88 (d, J = 8.9 Hz,
2H), 6.28 (s, 1H), 3.82 (s, 3H), 2.96 (m, J = 7.3 Hz, 4H), 1.94 (s, 3H),
1.45 (h,
J
=
7.3 Hz, 4H), 0.89 (t,
J
=
7.4 Hz, 6H).
HRMS (ESI): [M+H]+ calcd. for C17H23ClNO 292.1463, found 276.1467.
5-(4-Chlorophenyl)-3-methyl-N,N-dipropylfuran-2-amine (3ga). The
title compound was prepared from 2-bromo-1-(4-chlorophenyl)ethan-1-
one (116 mg, 0.5 mmol) and tripropylamine (245 uL, 1.25 mmol),
according to general procedure. The crude residue was purified by flash
chromatography (Petroleum ether/ethyl acetate = 200:1, Rf = 0.30) to
give the product as a brownish yellow oily liquid (100.4 mg, 69%).
1H NMR (400 MHz, CDCl3) δ 7.46 (d, J = 8.4 Hz, 2H), 7.28 (d, J = 8.5 Hz,
2H), 6.40 (s, 1H), 2.96 (t, J = 7.3 Hz, 4H), 1.94 (s, 3H), 1.49 (h, J = 7.4
13C NMR (101 MHz, CDCl3) δ 158.3, 152.5, 147.3, 124.8, 124.4, 114.0,
110.4, 106.6, 56.2, 55.3, 21.4, 11.7, 9.9.
HRMS (ESI): [M+H]+ calcd. for C18H26NO2 288.1958, found 288.1962.
5-(3,4-Dimethoxyphenyl)-3-methyl-N,N-dipropylfuran-2-amine (3la).
The
title
compound
was
prepared
from
2-bromo-1-(3,4-
dimethoxyphenyl)ethan-1-one (129 mg, 0.5 mmol) and tripropylamine
(245 uL, 1.25 mmol), according to general procedure. The crude residue
was purified by flash chromatography (Petroleum ether/ethyl acetate =
50:1, Rf = 0.30) to give the product as a brownish yellow oily liquid (106.2
mg, 67%).
Hz,
4H),
0.89
(t,
J
=
7.4
Hz,
6H).
13C NMR (101 MHz, CDCl3) δ 153.5, 145.8, 131.6, 130.0, 128.6, 124.0,
1H NMR (400 MHz, CDCl3) δ 7.14 (dd, J = 8.3, 1.6 Hz, 1H), 7.08 (d, J =
1.5 Hz, 1H), 6.85 (d, J = 8.4 Hz, 1H), 6.31 (s, 1H), 3.93 (s, 3H), 3.88 (s,
3H), 2.953 (t, J = 7.4 Hz, 4H), 1.94 (s, 3H), 1.45 (h, J = 7.2 Hz, 4H), 0.89
109.6, 108.9, 55.7, 21.4, 11.6, 9.9.
HRMS (ESI): [M+H]+ calcd. for C17H23ClNO 292.1463, found 276.1476.
5-(3-Bromophenyl)-3-methyl-N,N-dipropylfuran-2-amine (3ha). The
title compound was prepared from 2-bromo-1-(3-bromophenyl)ethan-1-
one (138 mg, 0.5 mmol) and tripropylamine (245 uL, 1.25 mmol),
according to general procedure. The crude residue was purified by flash
chromatography (Petroleum ether/ethyl acetate = 200:1, Rf = 0.30) to
give the product as a brownish yellow oily liquid (105.5 mg, 63%).
1H NMR (400 MHz, CDCl3) δ 7.69 (t, J = 1.6 Hz, 1H), 7.45 (d, J = 7.8 Hz,
1H), 7.26 (d, J = 1.8 Hz, 1H), 7.18 (t, J = 7.9 Hz, 1H), 6.45 (s, 1H), 3.03 –
2.96 (m, 4H), 1.96 (s, 3H), 1.47 (dt, J = 14.7, 7.4 Hz, 4H), 0.90 (t, J = 7.4
(t,
J
=
7.4
Hz,
6H).
13C NMR (101 MHz, CDCl3) δ 152.6, 149.1, 147.9, 147.1, 125.1, 115.6,
111.5, 110.4, 106.9, 106.7, 56.1, 55.98, 55.89, 21.4, 11.6, 9.9.
HRMS (ESI): [M+H]+ calcd. for C19H28NO3 318.2064, found 318.2065.
5-(2,5-Dimethoxyphenyl)-3-methyl-N,N-dipropylfuran-2-amine (3ma).
The
title
compound
was
prepared
from
2-bromo-1-(2,5-
dimethoxyphenyl)ethan-1-one (129 mg, 0.5 mmol) and tripropylamine
(245 uL, 1.25 mmol), according to general procedure. The crude residue
was purified by flash chromatography (Petroleum ether/ethyl acetate =
50:1, Rf = 0.30) to give the product as a brownish yellow oily liquid (91.3
mg, 55%).
Hz,
6H).
13C NMR (101 MHz, CDCl3) δ 153.8, 145.2, 133.5, 130.0, 128.8, 125.6,
122.8, 121.2, 109.8, 109.4, 55.6, 21.4, 11.6, 9.9.
1H NMR (400 MHz, CDCl3) δ 7.30 (d, J = 2.3 Hz, 1H), 6.84 (d, J = 8.9 Hz,
1H), 6.75 (s, 1H), 6.69 (d, J = 6.3 Hz, 1H), 3.88 (s, 3H), 3.82 (s, 3H), 2.98
(t, J = 7.2 Hz, 4H), 1.96 (s, 3H), 1.46 (h, J = 7.2 Hz, 4H), 0.89 (t, J = 7.3
HRMS (ESI): [M+H]+ calcd. for C17H23BrNO 336.0958, found 336.0965.
5-(2-Methoxyphenyl)-3-methyl-N,N-dipropylfuran-2-amine (3ia). The
title compound was prepared from 2-bromo-1-(2-methoxyphenyl)ethan-1-
one (114 mg, 0.5 mmol) and tripropylamine (245 uL, 1.25 mmol),
according to general procedure. The crude residue was purified by flash
chromatography (Petroleum ether/ethyl acetate = 200:1, Rf = 0.30) to
give the product as a brownish yellow oily liquid (80.4 mg, 56%).
Hz,
6H).
13C NMR (101 MHz, CDCl3) δ 153.7, 152.5, 149.6, 143.0, 121.3, 114.2,
112.0, 111.15, 111.07, 109.2, 55.8, 55.8, 55.7, 21.4, 11.6, 9.9.
HRMS (ESI): [M+H]+ calcd. for C19H28NO3 318.2064, found 318.2088.
5-(3,4-Dihydro-2H-benzo[b][1,4]dioxepin-7-yl)-3-methyl-N,N-
1H NMR (400 MHz, CDCl3) δ 7.73 (d, J = 7.7 Hz, 1H), 7.16 (t, J = 7.8 Hz,
1H), 6.98 (t, J = 7.5 Hz, 1H), 6.92 (d, J = 8.2 Hz, 1H), 6.72 (s, 1H), 3.93
(s, 3H), 2.97 (t, J = 7.3 Hz, 4H), 1.96 (s, 3H), 1.46 (h, J = 6.9 Hz, 4H),
dipropylfuran-2-amine (3na). The title compound was prepared from 2-
bromo-1-(3,4-dihydro-2H-benzo[b][1,4]dioxepin -7-yl)ethan-1-one (135
mg, 0.5 mmol) and tripropylamine (245 uL, 1.25 mmol), according to
general procedure. The crude residue was purified by flash
chromatography (Petroleum ether/ethyl acetate = 50:1, Rf = 0.30) to give
the product as a brownish yellow oily liquid (98.7 mg, 60%).
0.89
(t,
J
=
7.3
Hz,
6H).
13C NMR (101 MHz, CDCl3) δ 155.1, 152.3, 143.4, 126.7, 125.2, 120.6,
120.5, 113.8, 110.8, 109.4, 55.9, 55.3, 21.4, 11.6, 9.9.
HRMS (ESI): [M+H]+ calcd. for C18H26NO2 288.1958, found 288.1964.
5-(3-Methoxyphenyl)-3-methyl-N,N-dipropylfuran-2-amine (3ja). The
title compound was prepared from 2-bromo-1-(3-methoxyphenyl)ethan-1-
one (114 mg, 0.5 mmol) and tripropylamine (245 uL, 1.25 mmol),
1H NMR (400 MHz, CDCl3) δ 7.19 (d, J = 2.1 Hz, 1H), 7.12 (dd, J = 8.3,
2.1 Hz, 1H), 6.94 (d, J = 8.3 Hz, 1H), 6.29 (s, 1H), 4.21 (dt, J = 9.7, 5.6
Hz, 4H), 2.96 – 2.90 (m, 4H), 2.21 – 2.16 (m, 2H), 1.93 (s, 3H), 1.47 –
1.39
(m,
4H),
0.88
(t,
J
=
7.4
Hz,
6H).
7
This article is protected by copyright. All rights reserved.

10.1002/ejoc.202000293
European Journal of Organic Chemistry
FULL PAPER
13C NMR (101 MHz, CDCl3) δ 152.7, 151.2, 149.7, 146.5, 127.4, 121.7,
118.1, 116.1, 110.1, 107.6, 70.5, 70.5, 55.9, 31.8, 21.3, 11.5, 9.8.
HRMS (ESI): [M+H]+ calcd. for C20H28NO3 330.2064, found 330.2059.
4-(5-(Dipropylamino)-4-methylfuran-2-yl)benzonitrile (3oa). The title
compound was prepared from 4-(2-bromoacetyl)benzonitrile (112 mg, 0.5
mmol) and tripropylamine (245 uL, 1.25 mmol), according to general
procedure. The crude residue was purified by flash chromatography
(Petroleum ether/ethyl acetate = 100:1, Rf = 0.30) to give the product as
a brownish yellow oily liquid (87.4 mg, 65%).
1H NMR (400 MHz, CDCl3) δ 7.55-7.65 (m, 4H), 6.59 (s, 1H), 3.07 – 3.01
(m, 4H), 1.97 (s, 3H), 1.48 (h, J = 7.4 Hz, 4H), 0.90 (t, J = 7.4 Hz, 6H).
13C NMR (101 MHz, CDCl3) δ 155.1, 143.9, 135.1, 132.4, 122.4, 119.5,
113.0, 108.1, 107.2, 54.8, 21.5, 11.5, 10.1.
HRMS (ESI): [M+H]+ calcd. for C23H28NO 334.2165, found 334.2171.
3-Methyl-5-(naphthalen-2-yl)-N,N-dipropylfuran-2-amine (3ta). The
title compound was prepared from 2-bromo-1-(naphthalen-2-yl)ethan-1-
one (124 mg, 0.5 mmol) and tripropylamine (245 uL, 1.25 mmol),
according to general procedure. The crude residue was purified by flash
chromatography (Petroleum ether/ethyl acetate = 200:1, Rf = 0.30) to
give the product as a brownish yellow oily liquid (104.4 mg, 68%).
1H NMR (400 MHz, CDCl3) δ 8.01 (s, 1H), 7.84 (d, J = 8.0 Hz, 1H), 7.81
– 7.77 (m, 2H), 7.69 (dd, J = 8.6, 1.6 Hz, 1H), 7.48 – 7.39 (m, 2H), 6.57
(s, 1H), 3.05 (t, J = 7.2 Hz, 4H), 2.01 (s, 3H), 1.52 (h, J = 7.3 Hz, 4H),
0.94
(t,
J
=
7.4
Hz,
6H).
13C NMR (101 MHz, CDCl3) δ 153.5, 147.0, 133.7, 132.2, 128.9, 128.1,
127.9, 127.7, 126.3, 125.3, 121.9, 120.6, 109.8, 109.3, 55.8, 21.5, 11.7,
9.9.
HRMS (ESI): [M+H]+ calcd. for C18H23N2O 283.1805, found 283.1811.
3-Methyl-5-(3-nitrophenyl)-N,N-dipropylfuran-2-amine (3pa). The title
compound was prepared from 2-bromo-1-(3-nitrophenyl)ethan-1-one
(121.5 mg, 0.5 mmol) and tripropylamine (245 uL, 1.25 mmol), according
to general procedure. The crude residue was purified by flash
chromatography (Petroleum ether/ethyl acetate = 100:1, Rf = 0.30) to
give the product as a brownish yellow oily liquid (111.7 mg, 74%).
1H NMR (400 MHz, CDCl3) δ 8.33 (s, 1H), 7.96 (dd, J = 8.2, 1.4 Hz, 1H),
7.80 (d, J = 7.9 Hz, 1H), 7.46 (t, J = 8.0 Hz, 1H), 6.59 (s, 1H), 3.03 (t, J =
7.3 Hz, 4H), 1.97 (s, 3H), 1.48 (h, J = 7.3 Hz, 4H), 0.91 (t, J = 7.4 Hz, 6H).
13C NMR (101 MHz, CDCl3) δ 154.6, 148.8, 144.0, 133.0, 129.4, 128.0,
120.2, 117.2, 111.3, 108.7, 55.3, 21.5, 11.5, 9.9.
HRMS (ESI): [M+H]+ calcd. for C21H26NO 308.2009, found 308.2006.
5-(Benzofuran-2-yl)-3-methyl-N,N-dipropylfuran-2-amine (3ua). The
title compound was prepared from 1-(benzofuran-2-yl)-2-bromoethan-1-
one (119 mg, 0.5 mmol) and tripropylamine (245 uL, 1.25 mmol),
according to general procedure. The crude residue was purified by flash
chromatography (Petroleum ether/ethyl acetate = 200:1, Rf = 0.30) to
give the product as a brownish yellow oily liquid (105.4 mg, 71%).
1H NMR (400 MHz, CDCl3) δ 7.57 – 7.54 (m, 1H), 7.49 (d, J = 7.6 Hz,
1H), 7.28 – 7.21 (m, 2H), 6.77 (s, 1H), 6.62 (s, 1H), 3.07 – 3.03 (m, 4H),
2.02 (s, 3H), 1.55
– 1.49 (m, 4H), 0.94 (d, J = 7.4 Hz, 6H).
13C NMR (101 MHz, CDCl3) δ 154.3, 148.9, 139.2, 129.2, 123.6, 122.9,
HRMS (ESI): [M+H]+ calcd. for C17H23N2O3 303.1703, found 303.1709.
3,5-Dimethyl-N,N-dipropylfuran-2-amine (3qa). The title compound
was prepared from 1-bromopropan-2-one (68 mg, 0.5 mmol) and
tripropylamine (245 uL, 1.25 mmol), according to general procedure. The
crude residue was purified by flash chromatography (Petroleum
ether/ethyl acetate = 200:1, Rf = 0.30) to give the product as a brownish
yellow oily liquid (77 mg, 79%).
1H NMR (400 MHz, CDCl3) δ 5.69 (s, 1H), 2.85 (t, J = 7.3 Hz, 4H), 2.17
(s, 3H), 1.85 (s, 3H), 1.38 – 1.34 (h, J = 7.3 Hz, 4H), 0.87 (t, J = 7.4 Hz,
6H).
120.4, 111.6, 110.8, 108.7, 99.0, 55.4, 21.4, 11.5, 9.9.
HRMS (ESI): [M+H]+ calcd. for C19H24NO2 298,1802, found 298,1813.
N,N-Dipentyl-5-phenyl-3-propylfuran-2-amine
(3ab).
The
title
compound was prepared from 2-bromo-1-phenylethan-1-one (100 mg,
0.5 mmol) and tripentylamine (302.5 mg, 1.25 mmol), according to
general procedure. The crude residue was purified by flash
chromatography (Petroleum ether/ethyl acetate = 200:1, Rf = 0.30) to
give the product as a brownish yellow oily liquid (71.6 mg, 42%).
1H NMR (400 MHz, CDCl3) δ 7.57 (d, J = 7.9 Hz, 2H), 7.33 (t, J = 7.7 Hz,
2H), 7.17 (t, J = 7.4 Hz, 1H), 6.46 (s, 1H), 2.97 (t, J = 7.3 Hz, 4H), 2.32 (t,
J = 7.7 Hz, 2H), 1.28-1.57 (m, 14H), 0.96 (t, J = 7.3 Hz, 3H), 0.87 (t, J =
13C NMR (101 MHz, CDCl3) δ 146.0, 129.0, 128.2, 108.0, 56.4, 21.4,
13.8, 11.6, 9.6.
6.3
Hz,
6H).
HRMS (ESI): [M+H]+ calcd. for C12H22NO 196.1696, found 196.1705.
3-Methyl-N,N-dipropyl-5-(thiophen-2-yl)furan-2-amine (3ra)
The title compound was prepared from 2-bromo-1-(thiophen-2-yl)ethan-
1-one (102 mg, 0.5 mmol) and tripropylamine (245 uL, 1.25 mmol),
according to general procedure. The crude residue was purified by flash
chromatography (Petroleum ether/ethyl acetate = 200:1, Rf = 0.30) to
give the product as a brownish yellow oily liquid (69.7 mg, 52%)
1H NMR (400 MHz, CDCl3) δ 7.11 (d, J = 4.0 Hz, 2H), 6.98 (t, J = 4.2 Hz,
1H), 6.27 (s, 1H), 2.94 (t, J = 7.2 Hz, 4H), 1.93 (s, 3H), 1.44 (h, J = 7.3
13C NMR (101 MHz, CDCl3) δ 152.9, 147.3, 131.6, 128.5, 126.2, 122.9,
115.6, 106.9, 54.3, 29.7, 29.4, 27.9, 26.6, 23.3, 22.5, 14.0.
HRMS (ESI): [M+H]+ calcd. for C23H36NO 342.2797, found 342.2804.
3-Butyl-N,N-dihexyl-5-phenylfuran-2-amine (3ac). The title compound
was prepared from 2-bromo-1-phenylethan-1-one (100 mg, 0.5 mmol)
and trihexylamine (355 mg, 1.25 mmol), according to general procedure.
The crude residue was purified by flash chromatography (Petroleum
ether/ethyl acetate = 200:1, Rf = 0.30) to give the product as a brownish
yellow oily liquid (70.9 mg, 37%).
Hz,
4H),
0.89
(t,
J
=
7.4
Hz,
6H).
1H NMR (400 MHz, CDCl3) δ 7.57 (d, J = 8.0 Hz, 2H), 7.33 (t, J = 7.5 Hz,
2H), 7.17 (t, J = 7.0 Hz, 1H), 6.46 (s, 1H), 2.97 (t, J = 7.2 Hz, 4H), 2.34 (t,
J = 7.6 Hz, 2H), 1.46 – 1.24 (m, 20H), 0.94 (t, J = 7.2 Hz, 3H), 0.87 (t, J =
13C NMR (101 MHz, CDCl3) δ 152.7, 142.9, 134.9, 127.4, 122.6, 120.9,
109.9, 108.4, 55.9, 21.4, 11.6, 9.8.
HRMS (ESI): [M+H]+ calcd. for C12H22NOS 264.1417, found 264.1417.
6.5
Hz,
6H).
5-([1,1'-Biphenyl]-4-yl)-3-methyl-N,N-dipropylfuran-2-amine
(3sa).
13C NMR (101 MHz, CDCl3) δ 152.8, 147.3, 131.6, 128.5, 126.2, 122.9,
The title compound was prepared from 1-([1,1'-biphenyl]-4-yl)-2-
bromoethan-1-one (137 mg, 0.5 mmol) and tripropylamine (245 uL, 1.25
mmol), according to general procedure. The crude residue was purified
by flash chromatography (Petroleum ether/ethyl acetate = 200:1, Rf =
0.30) to give the product as a brownish yellow oily liquid (100 mg, 60%).
1H NMR (400 MHz, CDCl3) δ 7.64 (t, J = 8.6 Hz, 4H), 7.59 (d, J = 8.5 Hz,
2H), 7.45 (t, J = 7.6 Hz, 2H), 7.34 (t, J = 7.4 Hz, 1H), 6.48 (s, 1H), 3.03 –
2.98 (m, 4H), 1.99 (s, 3H), 1.49 (m, 4H), 0.92 (t, J = 7.4 Hz, 6H).
13C NMR (101 MHz, CDCl3) δ 153.4, 146.7, 140.9, 138.8, 130.6, 128.8,
127.2, 127.1, 126.8, 123.2, 109.8, 108.7, 55.9, 21.5, 11.6, 9.9.
115.8, 106.9, 54.3, 32.4, 31.7, 28.2, 26.9, 24.2, 22.6, 14.0.
HRMS (ESI): [M+H]+ calcd. for C26H42NO 384.3266, found 384.3262.
3-Hexyl-N,N-dioctyl-5-phenylfuran-2-amine (3ad). The title compound
was prepared from 2-bromo-1-phenylethan-1-one (100 mg, 0.5 mmol)
and trioctylamine (441 mg, 1.25 mmol), according to general procedure.
The crude residue was purified by flash chromatography (Petroleum
ether/ethyl acetate = 200:1, Rf = 0.30) to give the product as a brownish
yellow oily liquid (107.4 mg, 46%).
1H NMR (400 MHz, CDCl3) δ 7.57 (d, J = 8.0 Hz, 2H), 7.33 (t, J = 7.6 Hz,
2H), 7.17 (t, J = 7.3 Hz, 1H), 6.46 (s, 1H), 2.96 (t, J = 6.8 Hz, 4H), 2.33 (t,
8
This article is protected by copyright. All rights reserved.

10.1002/ejoc.202000293
European Journal of Organic Chemistry
FULL PAPER
J
=
7.0 Hz, 2H), 1.55
–
1.18 (m, 32H), 0.90
–
0.86 (m, 9H).
chromatography (Petroleum ether/ethyl acetate = 200:1, Rf = 0.30) to
give the product as a brownish yellow oily liquid (93.2 mg, 55%).
1H NMR (400 MHz, CDCl3) δ 7.70 – 7.61 (m, 2H), 7.39 (t, J = 7.7 Hz, 2H),
7.33 (d, J = 7.7 Hz, 2H), 7.26 (t, J = 7.4 Hz, 1H), 7.21 (t, J = 7.6 Hz, 1H),
7.12 (d, J = 7.7 Hz, 2H), 7.06 (t, J = 7.3 Hz, 1H), 6.95 (d, J = 8.1 Hz, 2H),
6.90 (d, J = 7.4 Hz, 1H), 6.63 (s, 1H), 2.34 (s, 3H), 1.90 (s, 3H).
13C NMR (101 MHz, CDCl3) δ 149.2, 147.2, 145.8, 145.5, 139.0, 130.9,
129.1, 128.9, 128.6, 127.0, 123.5, 123.4, 122.3, 121.8, 120.9, 118.3,
114.3, 108.8, 21.5, 9.5.
13C NMR (101 MHz, CDCl3) δ 152.8, 147.3, 131.6, 128.5, 126.2, 122.9,
115.8, 106.9, 54.3, 31.8, 30.2, 29.7, 29.5, 29.3, 29.1, 28.2, 27.2, 24.5,
22.6, 14.1.
HRMS (ESI): [M+H]+ calcd. for C32H54NO 468.4200, found 428.4190.
3-Decyl-N,N-didodecyl-5-phenylfuran-2-amine
(3ae).
The
title
compound was prepared from 2-bromo-1-phenylethan-1-one (100 mg,
0.5 mmol) and tridodecylamine (670.8 mg, 1.25 mmol), according to
general procedure. The crude residue was purified by flash
chromatography (Petroleum ether/ethyl acetate = 200:1, Rf = 0.30) to
give the product as a brownish yellow oily liquid (124.5 mg, 40%).
HRMS (ESI): [M+H]+ calcd. for C24H22NO 340.1701, found 340.1685.
3-Methyl-N,5-diphenyl-N-(p-tolyl)furan-2-amine
(3aj).
The
title
1H NMR (400 MHz, CDCl3) δ 7.57 (d, J = 7.9 Hz, 2H), 7.33 (t, J = 7.6 Hz,
compound was prepared from 2-bromo-1-phenylethan-1-one (100 mg,
0.5 mmol) and 4-methyl-N-phenyl-N-propylaniline (281.3 mg, 1.25 mmol),
according to general procedure. The crude residue was purified by flash
chromatography (Petroleum ether/ethyl acetate = 200:1, Rf = 0.30) to
give the product as a brownish yellow oily liquid (98.3 mg, 58%)
1H NMR (400 MHz, CDCl3) δ 7.59 (d, J = 7.9 Hz, 2H), 7.33 (t, J = 7.7 Hz,
2H), 7.23 (d, J = 7.4 Hz, 2H), 7.20 (d, J = 7.3 Hz, 1H), 7.10 (d, J = 8.3 Hz,
2H), 7.04 (d, J = 8.4 Hz, 2H), 7.00 (d, J = 8.5 Hz, 2H), 6.96 (t, J = 7.4 Hz,
2H), 7.17 (t, J = 7.3 Hz, 1H), 6.51 (bs, 1H), 2.97 (dd, J = 9.5, 4.7 Hz, 4H),
2.33 (t,
J = 7.6 Hz, 2H), 1.18-1.60 (m, 56H), 0.87 (bs, 9H).
13C NMR (101 MHz, CDCl3) δ 152.8, 147.3, 131.6, 128.5, 126.1, 122.9,
115.8, 106.9, 54.3, 31.9, 30.2, 29.7, 29.6, 29.5, 29.3, 28.3, 27.2, 24.5,
22.7, 14.1.
HRMS (ESI): [M+H]+ calcd. for C44H78NO 636.6083, found 636.6087.
N,N,5-Triphenylfuran-2-amine (3af). The title compound was prepared
from 2-bromo-1-phenylethan-1-one (100 mg, 0.5 mmol) and N-ethyl-N-
phenylaniline (246 mg, 1.25 mmol), according to general procedure. The
crude residue was purified by flash chromatography (Petroleum
ether/ethyl acetate = 200:1, Rf = 0.30) to give the product as a brownish
yellow oily liquid (88.6 mg, 57%).
1H NMR (400 MHz, CDCl3) δ 7.58 (d, J = 7.4 Hz, 2H), 7.34 (d, J = 7.5 Hz,
2H), 7.31 (d, J = 2.0 Hz, 1H), 7.27 (d, J = 7.4 Hz, 4H), 7.13 (d, J = 7.6 Hz,
4H), 7.06 (t, J = 7.3 Hz, 2H), 6.66 (d, J = 3.3 Hz, 1H), 5.96 (d, J = 3.3 Hz,
1H).
1H),
6.57
(s,
1H),
2.33
(s,
3H),
1.85
(s,
3H).
13C NMR (101 MHz, CDCl3) δ 149.1, 147.2, 146.2, 142.8, 132.7, 130.9,
129.8, 129.0, 128.5, 126.9, 123.4, 122.2, 121.7, 119.7, 114.1, 108.7,
20.8, 9.5.
HRMS (ESI): [M+H]+ calcd. for C24H22NO 340.1701, found 340.1690.
N,N-Dimethyl-3,5-diphenylfuran-2-amine (4a). The title compound was
prepared from 2-bromo-1-phenylethan-1-one (100 mg, 0.5 mmol) and
N,N-dimethyl-2-phenylethen-1-amine (184 mg, 1.25 mmol), according to
general procedure. The crude residue was purified by flash
chromatography (Petroleum ether/ethyl acetate = 200:1, Rf = 0.30) to
give the product as a brownish yellow oily liquid (115.7 mg, 88%).
1H NMR (400 MHz, CDCl3) δ 7.67 (d, J = 7.7 Hz, 4H), 7.43 (td, J = 7.7,
13C NMR (101 MHz, CDCl3) δ 152.3, 148.9, 145.9, 130.8, 129.2, 128.6,
126.9, 123.2, 123.1, 122.1, 106.5, 102.4.
HRMS (ESI): [M+H]+ calcd. for C22H18NO 312.1388, found 312.1378.
3-Methyl-N,N,5-triphenylfuran-2-amine (3ag). The title compound was
prepared from 2-bromo-1-phenylethan-1-one (100 mg, 0.5 mmol) and N-
phenyl-N-propylaniline (263.8 mg, 1.25 mmol), according to general
procedure. The crude residue was purified by flash chromatography
(Petroleum ether/ethyl acetate = 200:1, Rf = 0.30) to give the product as
a brownish yellow oily liquid (99 mg, 61%).
5.0 Hz, 4H), 7.31
– 7.24 (m, 2H), 6.89 (s, 1H), 2.93 (s, 6H).
13C NMR (101 MHz, CDCl3) δ 154.7, 146.0, 133.8, 131.1, 128.6, 128.3,
127.0, 126.3, 125.7, 122.72, 107.7, 107.0, 41.8.
HRMS (ESI): [M+H]+ calcd. for C18H18NO 264.1383, found 264.1390.
N,N-Diethyl-3,5-diphenylfuran-2-amine (4b). The title compound was
prepared from 2-bromo-1-phenylethan-1-one (100 mg, 0.5 mmol) and
N,N-diethyl-2-phenylethen-1-amine (218.8 mg, 1.25 mmol), according to
general procedure. The crude residue was purified by flash
chromatography (Petroleum ether/ethyl acetate = 200:1, Rf = 0.30) to
give the product as a brownish yellow oily liquid (113.5 mg, 78%).
1H NMR (400 MHz, CDCl3) δ 7.77 (d, J = 7.9 Hz, 2H), 7.64 (d, J = 7.9 Hz,
2H), 7.37 (t, J = 7.6 Hz, 4H), 7.22 (t, J = 7.3 Hz, 2H), 6.87 (s, 1H), 3.18 (q,
1H NMR (400 MHz, CDCl3) δ 7.62 – 7.58 (m, 2H), 7.34 (t, J = 7.7 Hz, 2H),
7.29 (d, J = 7.5 Hz, 4H), 7.23 (d, J = 7.4 Hz, 1H), 7.09 (d, J = 7.8 Hz, 4H),
7.02 (t,
J
=
7.3 Hz, 2H), 6.58 (s, 1H), 1.85 (s, 3H).
13C NMR (101 MHz, CDCl3) δ 149.3, 147.1, 145.6, 130.8, 129.2, 128.6,
127.0, 123.4, 122.5, 121.0, 114.3, 108.7, 9.5.
HRMS (ESI): [M+H]+ calcd. for C23H20NO 326.1545, found 326.1531.
N,N,5-Triphenyl-3-propylfuran-2-amine (3ah). The title compound was
prepared from 2-bromo-1-phenylethan-1-one (100 mg, 0.5 mmol) and N-
pentyl-N-phenylaniline (298.8 mg, 1.25 mmol), according to general
procedure. The crude residue was purified by flash chromatography
(Petroleum ether/ethyl acetate = 200:1, Rf = 0.30) to give the product as
a brownish yellow oily liquid (102.4 mg, 58%).
1H NMR (400 MHz, CDCl3) δ 7.58 (d, J = 7.7 Hz, 2H), 7.31 (t, J = 7.7 Hz,
2H), 7.25 – 7.22 (m, 4H), 7.18 (d, J = 7.4 Hz, 1H), 7.06 (d, J = 8.1 Hz,
4H), 6.99 (t, J = 7.3 Hz, 2H), 6.59 (s, 1H), 2.17 (t, J = 7.5 Hz, 2H), 1.44
J
=
7.1
Hz,
4H),
1.10
(t,
J
=
7.1
Hz,
6H).
13C NMR (101 MHz, CDCl3) δ 152.7, 147.5, 133.7, 131.2, 128.6, 128.2,
126.6, 126.6, 125.9, 123.0, 113.3, 105.7, 46.8, 13.1.
HRMS (ESI): [M+H]+ calcd. for C20H22NO 292.1696, found 292.1699.
N-Ethyl-3,5-diphenyl-N-propylfuran-2-amine (4c). The title compound
was prepared from 2-bromo-1-phenylethan-1-one (100 mg, 0.5 mmol)
and N-ethyl-N-styrylpropan-1-amine (236.3 mg, 1.25 mmol), according to
general procedure. The crude residue was purified by flash
chromatography (Petroleum ether/ethyl acetate = 200:1, Rf = 0.30) to
give the product as a brownish yellow oily liquid (114.4 mg, 75%).
1H NMR (400 MHz, CDCl3) δ 7.75 (d, J = 7.8 Hz, 2H), 7.64 (d, J = 7.8 Hz,
2H), 7.37 (t, J = 6.6 Hz, 4H), 7.22 (t, J = 7.2 Hz, 2H), 6.87 (s, 1H), 3.18 (q,
J = 7.1 Hz, 2H), 3.13 – 3.06 (m, 2H), 1.56 (t, J = 7.3 Hz, 2H), 1.11 (t, J =
(dd,
J
=
14.9, 7.4 Hz, 2H), 0.79 (t,
J
=
7.3 Hz, 3H).
13C NMR (101 MHz, CDCl3) δ 149.4, 146.7, 145.8, 130.9, 129.1, 128.6,
127.0, 123.4, 122.5, 121.0, 119.4, 107.5, 26.2, 22.4, 13.9.
HRMS (ESI): [M+Na]+ calcd. for C25H24NO 354,1852, found 354,1860.
3-Methyl-N,5-diphenyl-N-(m-tolyl)furan-2-amine
(3ai).
The
title
7.1
Hz,
3H),
0.87
(t,
J
=
7.4
Hz,
3H).
compound was prepared from 2-bromo-1-phenylethan-1-one (100 mg,
0.5 mmol) and 3-methyl-N-phenyl-N-propylaniline (281 mg, 1.25 mmol),
according to general procedure. The crude residue was purified by flash
13C NMR (101 MHz, CDCl3) δ 153.0, 147.3, 133.8, 131.2, 128.6, 128.2,
126.7, 126.5, 125.8, 123.0, 112.7, 105.9, 54.1, 47.4, 21.3, 13.1, 11.7.
HRMS (ESI): [M+H]+ calcd. for C21H24NO 306.1852, found 306.1858.
9
This article is protected by copyright. All rights reserved.

10.1002/ejoc.202000293
European Journal of Organic Chemistry
FULL PAPER
N-Butyl-N-methyl-3,5-diphenylfuran-2-amine (4d). The title compound
was prepared from 2-bromo-1-phenylethan-1-one (100 mg, 0.5 mmol)
and N-methyl-N-styrylbutan-1-amine (236.3 mg, 1.25 mmol), according to
general procedure. The crude residue was purified by flash
chromatography (Petroleum ether/ethyl acetate = 200:1, Rf = 0.30) to
give the product as a brownish yellow oily liquid (117.4 mg, 77%).
1H NMR (400 MHz, CDCl3) δ 7.66 – 7.60 (m, 4H), 7.37 (t, J = 7.5 Hz, 4H),
7.20 (t, J = 7.2 Hz, 2H), 6.83 (s, 1H), 3.12 (t, J = 7.4 Hz, 2H), 2.85 (s, 3H),
1.57 – 1.51 (m, 2H), 1.32 (d, J = 6.4 Hz, 2H), 0.88 (d, J = 7.4 Hz, 3H).
13C NMR (101 MHz, CDCl3) δ 154.2, 146.4, 133.9, 131.2, 128.6, 128.2,
126.9, 126.3, 125.7, 122.8, 109.4, 106.6, 53.9, 39.8, 29.8, 20.2, 13.9.
HRMS (ESI): [M+H]+ calcd. for C21H24NO 306.1852, found 306.1858.
3,5-Diphenyl-N,N-dipropylfuran-2-amine (4e). The title compound was
prepared from 2-bromo-1-phenylethan-1-one (100 mg, 0.5 mmol) and N-
propyl-N-styrylpropan-1-amine (253.8 mg, 1.25 mmol), according to
general procedure. The crude residue was purified by flash
chromatography (Petroleum ether/ethyl acetate = 200:1, Rf = 0.30) to
give the product as a brownish yellow oily liquid (114.8 mg, 72%).
13C NMR (101 MHz, CDCl3) δ 149.7, 148.0, 147.3, 132.0, 130.5, 129.2,
128.7, 127.5, 126.9, 126.3, 123.6, 119.2, 118.1, 113.8, 105.4, 38.1.
HRMS (ESI): [M+H]+ calcd. for C23H20NO 326.1539, found 326.1543.
N-Ethyl-N,3,5-triphenylfuran-2-amine (4i). The title compound was
prepared from 2-bromo-1-phenylethan-1-one (100 mg, 0.5 mmol) and N-
ethyl-N-styrylaniline (278.8 mg, 1.25 mmol), according to general
procedure. The crude residue was purified by flash chromatography
(Petroleum ether/ethyl acetate = 200:1, Rf = 0.30) to give the product as
a brownish yellow oily liquid (110.2 mg, 65%).
1H NMR (400 MHz, CDCl3) δ 7.76 (d, J = 7.5 Hz, 2H), 7.61 (d, J = 7.5 Hz,
2H), 7.45 (t, J = 7.7 Hz, 2H), 7.39 – 7.35 (m, 2H), 7.33 (d, J = 5.1 Hz, 1H),
7.30 (s, 2H), 7.27 (d, J = 8.1 Hz, 1H), 7.09 (s, 1H), 6.91 (d, J = 7.7 Hz,
1H), 6.88 (d, J = 8.3 Hz, 2H), 3.76 (q, J = 7.1 Hz, 2H), 1.33 (d, J = 7.1 Hz,
3H).
13C NMR (101 MHz, CDCl3) δ 150.0, 146.9, 132.1, 130.6, 129.3, 128.7,
128.6, 127.5, 127.4, 126.8, 126.3, 123.7, 119.3, 119.0, 114.2, 105.3,
45.1, 13.1.
HRMS (ESI): [M+H]+ calcd. for C24H22NO 340.1696, found 340.1699.
1H NMR (400 MHz, CDCl3) δ 7.80 – 7.75 (m, 2H), 7.70 – 7.65 (m, 2H),
N-Benzyl-N-methyl-3,5-diphenylfuran-2-amine
(4j).
The
title
7.42 (td, J = 7.8, 2.1 Hz, 4H), 7.28 – 7.24 (m, 2H), 6.90 (s, 1H), 3.15 –
compound was prepared from 2-bromo-1-phenylethan-1-one (100 mg,
0.5 mmol) and N-benzyl-N-methyl-2-phenylethen-1-amine (278.8 mg,
1.25 mmol), according to general procedure. The crude residue was
purified by flash chromatography (Petroleum ether/ethyl acetate = 200:1,
Rf = 0.30) to give the product as a brownish yellow oily liquid (120.3 mg,
71%).
3.11 (m, 4H), 1.63
– 1.57 (m, 4H), 0.90 (t, J = 7.4 Hz, 6H).
13C NMR (101 MHz, CDCl3) δ 153.3, 147.0, 133.8, 131.2, 128.6, 128.2,
126.7, 126.5, 125.8, 122.91, 112.0, 106.0, 54.7, 21.2, 11.6.
HRMS (ESI): [M+H]+ calcd. for C22H26NO 320.2009, found 320.2019.
N,N-Diisopropyl-3,5-diphenylfuran-2-amine (4f). The title compound
was prepared from 2-bromo-1-phenylethan-1-one (100 mg, 0.5 mmol)
and N-isopropyl-N-styrylpropan-2-amine (253.8 mg, 1.25 mmol),
according to general procedure. The crude residue was purified by flash
chromatography (Petroleum ether/ethyl acetate = 200:1, Rf = 0.30) to
give the product as a brownish yellow oily liquid (110 mg, 69%).
1H NMR (400 MHz, CDCl3) δ 7.93 (d, J = 7.3 Hz, 2H), 7.68 (d, J = 7.3 Hz,
2H), 7.41 (d, J = 7.6 Hz, 2H), 7.35 (d, J = 7.8 Hz, 2H), 7.24 (d, J = 5.0 Hz,
1H), 7.21 (d, J = 7.3 Hz, 1H), 6.92 (s, 1H), 3.56 (hpt, J = 6.4 Hz, 2H),
1H NMR (400 MHz, CDCl3) δ 7.67 (t, J = 8.2 Hz, 4H), 7.42 (t, J = 7.7 Hz,
4H), 7.39 – 7.34 (m, 4H), 7.31 – 7.24 (m, 3H), 6.88 (d, J = 1.9 Hz, 1H),
4.34
(s,
2H),
2.83
(s,
3H).
13C NMR (101 MHz, CDCl3) δ 154.0, 146.5, 137.9, 133.7, 131.1, 128.6,
128.5, 128.3, 128.3, 127.2, 127.1, 126.4, 125.9, 122.9, 109.5, 106.8,
58.5, 39.0.
HRMS (ESI): [M+H]+ calcd. for C24H22NO 340.1696, found 340.1699.
N,N-Dimethyl-3-phenyl-5-(p-tolyl)furan-2-amine
(4k).
The
title
1.13
(d,
J
=
6.5
Hz,
12H).
compound was prepared from 2-bromo-1-(p-tolyl)ethan-1-one (106 mg,
0.5 mmol) and N,N-dimethyl-2-phenylethen-1-amine (278.8 mg, 1.25
mmol), according to general procedure. The crude residue was purified
by flash chromatography (Petroleum ether/ethyl acetate = 200:1, Rf =
0.30) to give the product as a brownish yellow oily liquid (106.6 mg, 77%).
1H NMR (400 MHz, CDCl3) δ 7.63 (d, J = 7.5 Hz, 2H), 7.52 (d, J = 8.0 Hz,
2H), 7.38 (t, J = 7.7 Hz, 3H), 7.18 (d, J = 7.9 Hz, 2H), 6.77 (s, 1H), 2.87
13C NMR (101 MHz, CDCl3) δ 150.4, 148.7, 133.9, 131.2, 128.6, 128.1,
126.9, 126.7, 126.1, 123.3, 119.6, 104.5, 50.3, 21.5.
HRMS (ESI): [M+H]+ calcd. for C22H26NO 320.2009, found 320.2018.
N,N-Dicyclohexyl-3,5-diphenylfuran-2-amine (4g). The title compound
was prepared from 2-bromo-1-phenylethan-1-one (100 mg, 0.5 mmol)
and N-cyclohexyl-N-styrylcyclohexanamine (353.8 mg, 1.25 mmol),
according to general procedure. The crude residue was purified by flash
chromatography (Petroleum ether/ethyl acetate = 200:1, Rf = 0.30) to
give the product as a brownish yellow oily liquid (131.7 mg, 66%).
1H NMR (400 MHz, CDCl3) δ 7.97 (d, J = 7.7 Hz, 2H), 7.69 (d, J = 7.7 Hz,
2H), 7.43 – 7.35 (m, 4H), 7.28 (t, 1H), 7.25 – 7.21 (t, 1H), 6.93 (s, 1H),
3.17 (t, J = 10.3 Hz, 2H), 1.98 (d, J = 7.7 Hz, 4H), 1.72 (d, J = 7.3 Hz, 4H),
(s,
6H),
2.37
(s,
3H).
13C NMR (101 MHz, CDCl3) δ 154.4, 146.4, 136.1, 133.9, 129.3, 128.6,
128.3, 126.9, 125.6, 122.8, 108.0, 106.1, 41.9, 21.2.
HRMS (ESI): [M+H]+ calcd. for C19H20NO 278.1539, found 278.1543.
5-(4-Fluorophenyl)-N,N-dimethyl-3-phenylfuran-2-amine (4l). The title
compound was prepared from 2-bromo-1-(3-chlorophenyl)ethan-1-one
(108 mg, 0.5 mmol) and N,N-dimethyl-2-phenylethen-1-amine (278.8 mg,
1.25 mmol), according to general procedure. The crude residue was
purified by flash chromatography (Petroleum ether/ethyl acetate = 200:1,
Rf = 0.30) to give the product as a brownish yellow oily liquid (99.8 mg,
71%)
1.58
(d,
J
=
12.6
Hz,
2H),
1.01-1.39
(m,
10H).
13C NMR (101 MHz, CDCl3) δ 150.7, 148.5, 133.9, 131.3, 128.6, 128.1,
126.9, 126.6, 126.1, 123.4, 119.5, 104.4, 58.8, 32.0, 26.0.
HRMS (ESI): [M+H]+ calcd. for C28H34NO 400.2635, found 400.2638.
N-Methyl-N,3,5-triphenylfuran-2-amine (4h). The title compound was
prepared from 2-bromo-1-phenylethan-1-one (100 mg, 0.5 mmol) and N-
methyl-N-styrylaniline (261.3 mg, 1.25 mmol), according to general
procedure. The crude residue was purified by flash chromatography
(Petroleum ether/ethyl acetate = 200:1, Rf = 0.30) to give the product as
a brownish yellow oily liquid (102.4 mg, 63%).
1H NMR (400 MHz, CDCl3) δ 7.74 (d, J = 7.4 Hz, 2H), 7.58 (d, J = 7.4 Hz,
2H), 7.44 (t, J = 7.7 Hz, 2H), 7.38 (t, J = 7.6 Hz, 2H), 7.31 (d, J = 7.5 Hz,
4H), 7.06 (s, 1H), 6.92 (d, J = 7.3 Hz, 1H), 6.87 (d, J = 8.1 Hz, 2H), 3.35
1H NMR (400 MHz, CDCl3) δ 7.61 (d, J = 7.9 Hz, 2H), 7.57 (dd, J = 8.3,
5.8 Hz, 2H), 7.39 (d, J = 7.6 Hz, 2H), 7.22 (t, J = 7.2 Hz, 1H), 7.07 (t, J =
8.6
Hz,
2H),
6.75
(s,
1H),
2.87
(s,
6H).
13C NMR (101 MHz, CDCl3) δ161.6 (d, J = 245.7 Hz), 154.7, 145.2,
133.7, 128.3, 126.9, 125.7, 124.4, 124.3, 122.7, 115.6 (d, J = 21.9 Hz),
106.6, 41.8.
19F NMR (376 MHz, CDCl3): –115.65.
HRMS (ESI): [M+H]+ calcd. for C18H17FNO 282.1289, found 282.1293.
5-(3-Fluorophenyl)-N,N-dimethyl-3-phenylfuran-2-amine (4m). The
title compound was prepared from 2-bromo-1-(3-fluorophenyl)ethan-1-
(s,
3H).
10
This article is protected by copyright. All rights reserved.

10.1002/ejoc.202000293
European Journal of Organic Chemistry
FULL PAPER
one (108 mg, 0.5 mmol) and N,N-dimethyl-2-phenylethen-1-amine (278.8
mg, 1.25 mmol), according to general procedure. The crude residue was
purified by flash chromatography (Petroleum ether/ethyl acetate = 200:1,
Rf = 0.30) to give the product as a brownish yellow oily liquid (106.5 mg,
75%)
13C NMR (101 MHz, CDCl3) δ 155.1, 144.2, 134.6, 133.6, 132.7, 129.9,
128.3, 127.1, 125.9, 125.8, 122.5, 120.6, 108.6, 107.3, 41.5.
HRMS (ESI): [M+H]+ calcd. for C18H17ClNO 298.0993, found 298.0998.
5-(2,5-Dimethoxyphenyl)-N,N-dimethyl-3-phenylfuran-2-amine
(4r).
The title compound was prepared from 2-bromo-1-(2,5-
1H NMR (400 MHz, CDCl3) δ 7.64 (d, J = 7.4 Hz, 2H), 7.44 (t, J = 7.9 Hz,
3H), 7.38 – 7.32 (m, 2H), 7.28 (t, J = 7.1 Hz, 1H), 6.90 (s, 1H), 2.93 (s,
6H).
13C NMR (101 MHz, CDCl3) δ163.3 (d, J = 244.4 Hz), 155.0, 144.5,
133.7, 133.2 (d, J = 8.7 Hz), 130.1 (d, J = 8.6 Hz), 128.3, 127.1, 125.8,
118.2, 112.8 (d, J = 21.5 Hz), 109.4 (d, J = 23.5 Hz), 108.5, 107.3, 41.5.
19F NMR (376 MHz, CDCl3): –113.17.
dimethoxyphenyl)ethan-1-one (130 mg, 0.5 mmol) and N,N-dimethyl-2-
phenylethen-1-amine (278.8 mg, 1.25 mmol), according to general
procedure. The crude residue was purified by flash chromatography
(Petroleum ether/ethyl acetate = 50:1, Rf = 0.30) to give the product as a
brownish yellow oily liquid (108.2 mg, 67%)
1H NMR (400 MHz, CDCl3) δ 7.61 (d, J = 7.7 Hz, 2H), 7.36 (t, J = 7.5 Hz,
2H), 7.32 (s, 1H), 7.19 (t, J = 7.3 Hz, 1H), 7.13 (s, 1H), 6.87 (d, J = 8.8
Hz, 1H), 6.71 (d, J = 7.5 Hz, 1H), 3.90 (s, 3H), 3.84 (s, 3H), 2.86 (s, 6H).
13C NMR (101 MHz, CDCl3) δ 154.0, 153.7, 149.6, 142.0, 134.2, 129.0,
128.2, 127.1, 125.5, 113.0, 112.0, 111.1, 110.8, 107.2, 55.9, 55.8, 41.6.
HRMS (ESI): [M+H]+ calcd. for C20H22NO3 324.1594, found 324.1596.
5-(3,4-Dihydro-2H-benzo[b][1,4]dioxepin-7-yl)-N,N-dimethyl-3-
phenylfuran-2-amine (4s). The title compound was prepared from 2-
bromo-1-(3,4-dihydro-2H-benzo[b] [1,4]dioxepin-7-yl)ethan-1-one (135
mg, 0.5 mmol) and N,N-dimethyl-2-phenylethen-1- amine (278.8 mg,
1.25 mmol), according to general procedure. The crude residue was
purified by flash chromatography (Petroleum ether/ethyl acetate = 50:1,
Rf = 0.30) to give the product as a brownish yellow oily liquid (105.5 mg,
63%)
1H NMR (400 MHz, CDCl3) δ 7.66 (d, J = 7.6 Hz, 2H), 7.42 (t, J = 7.6 Hz,
2H), 7.30 (s, 1H), 7.23 (d, J = 10.4 Hz, 2H), 7.03 (d, J = 8.3 Hz, 1H), 6.76
(s, 1H), 4.29 (dd, J = 9.6, 4.8 Hz, 4H), 2.90 (s, 6H), 2.28 – 2.23 (m, 2H).
13C NMR (101 MHz, CDCl3) δ 154.5, 151.3, 149.9, 145.6, 133.8, 128.3,
126.9, 125.6, 121.9, 118.0, 116.0, 108.0, 106.2, 70.6, 41.8, 31.9.
HRMS (ESI): [M+H]+ calcd. for C21H22NO3 336.1594, found 336.1598.
5-(4-Chlorophenyl)-N,N-dimethyl-3-phenylfuran-2-amine (4t). The title
compound was prepared from 2-bromo-1-(4-chlorophenyl)ethan-1-one
(116 mg, 0.5 mmol) and N,N-dimethyl-2-phenylethen-1-amine (147 mg, 1
mmol), according to general procedure. The crude residue was purified
by flash chromatography (Petroleum ether/ethyl acetate = 200:1, Rf =
0.30) to give the product as a brownish yellow oily liquid (124.7 mg, 84%).
1H NMR (400 MHz, CDCl3) δ 7.58 (d, J = 7.3 Hz, 2H), 7.52 (d, J = 8.5 Hz,
2H), 7.38 (t, J = 7.6 Hz, 2H), 7.32 (d, J = 8.6 Hz, 2H), 7.22 (t, J = 7.3 Hz,
HRMS (ESI): [M+H]+ calcd. for C18H17FNO 282.1289, found 282.1295.
N,N-Dimethyl-5-(3-nitrophenyl)-3-phenylfuran-2-amine (4n). The title
compound was prepared from 2-bromo-1-(3-nitrophenyl)ethan-1-one
(121.5 mg, 0.5 mmol) and N,N-dimethyl-2-phenylethen-1-amine (278.8
mg, 1.25 mmol), according to general procedure. The crude residue was
purified by flash chromatography (Petroleum ether/ethyl acetate = 20:1,
Rf = 0.30) to give the product as a brownish yellow oily liquid (109.3 mg,
71%)
1H NMR (400 MHz, CDCl3) δ 8.41 (s, 1H), 8.03 (d, J = 8.1 Hz, 1H), 7.88
(d, J = 7.8 Hz, 1H), 7.60 (d, J = 7.5 Hz, 2H), 7.55 (d, J = 8.0 Hz, 1H), 7.44
(d, J = 7.6 Hz, 2H), 7.29 (d, J = 10.2 Hz, 1H), 7.00 (s, 1H), 2.95 (s, 6H).
13C NMR (101 MHz, CDCl3) δ 155.5, 148.9, 142.9, 133.4, 132.6, 129.5,
128.4, 127.7, 127.2, 126.0, 120.2, 117.0, 110.3, 106.9, 41.3.
HRMS (ESI): [M+H]+ calcd. for C18H17N2O3 309.1234, found 309.1238.
N,N-Dimethyl-5-(4-nitrophenyl)-3-phenylfuran-2-amine (4o). The title
compound was prepared from 2-bromo-1-(4-nitrophenyl)ethan-1-one
(121.5 mg, 0.5 mmol) and N,N-dimethyl-2-phenylethen-1-amine (278.8
mg, 1.25 mmol), according to general procedure. The crude residue was
purified by flash chromatography (Petroleum ether/ethyl acetate = 20:1,
Rf = 0.30) to give the product as a brownish yellow oily liquid (170.1 mg,
91%)
1H NMR (400 MHz, CDCl3) δ 8.23 (d, J = 9.0 Hz, 2H), 7.63 (d, J = 8.9 Hz,
2H), 7.53 (d, J = 7.7 Hz, 2H), 7.43 (t, J = 7.7 Hz, 2H), 7.29 (d, J = 6.3 Hz,
1H),
7.06
(s,
1H),
2.96
(s,
6H).
13C NMR (101 MHz, CDCl3) δ 156.3, 144.8, 142.5, 136.5, 133.5, 128.3,
127.6, 126.2, 124.5, 121.7, 113.7, 106.3, 40.8.
HRMS (ESI): [M+H]+ calcd. for C18H17N2O3 309.1234, found 309.1236.
5-([1,1'-Biphenyl]-4-yl)-N,N-dimethyl-3-phenylfuran-2-amine (4p). The
title compound was prepared from 1-([1,1'-biphenyl]-4-yl)-2-bromoethan-
1-one (137 mg, 0.5 mmol) and N,N-dimethyl-2-phenylethen-1-amine
(278.8 mg, 1.25 mmol), according to general procedure. The crude
residue was purified by flash chromatography (Petroleum ether/ethyl
acetate = 200:1, Rf = 0.30) to give the product as a white solid (128.8 mg,
76%)
1H NMR (400 MHz, CDCl3) δ 7.66 (m, 8H), 7.48 (d, J = 6.6 Hz, 2H), 7.46
– 7.40 (m, 3H), 7.27 (d, J = 6.9 Hz, 1H), 6.91 (s, 1H), 2.93 (s, 6H).
13C NMR (101 MHz, CDCl3) δ 154.8, 145.6, 140.8, 138.8, 133.8, 130.1,
128.8, 128.3, 127.3, 127.15, 127.0, 126.8, 125.7, 123.1, 107.7, 107.4,
41.7.
1H),
6.81
(s,
1H),
2.87
(s,
6H).
13C NMR (101 MHz, CDCl3) δ 154.9, 144.8, 133.7, 131.7, 128.8, 128.6,
128.3, 127.0, 125.8, 123.8, 122.7, 107.8, 41.6.
HRMS (ESI): [M+H]+ calcd. for C18H17ClNO 298.0993, found 298.0999.
5-(3-Bromophenyl)-N,N-dimethyl-3-phenylfuran-2-amine (4u). The
title compound was prepared from 2-bromo-1-(3-bromophenyl)ethan-1-
one (139 mg, 0.5 mmol) and N,N-dimethyl-2-phenylethen-1-amine (147
mg, 1 mmol), according to general procedure. The crude residue was
purified by flash chromatography (Petroleum ether/ethyl acetate = 200:1,
Rf = 0.30) to give the product as a brownish yellow oily liquid (121 mg,
71%)
1H NMR (400 MHz, CDCl3) δ 7.74 (s, 1H), 7.58 (d, J = 7.7 Hz, 2H), 7.51
(d, J = 7.5 Hz, 1H), 7.39 (t, J = 7.6 Hz, 2H), 7.31 (d, J = 7.9 Hz, 1H), 7.25
HRMS (ESI): [M+H]+ calcd. for C24H22NO 340.1696, found 340.1699.
5-(3-Chlorophenyl)-N,N-dimethyl-3-phenylfuran-2-amine (4q). The
title compound was prepared from 2-bromo-1-(3-chlorophenyl)ethan-1-
one (116 mg, 0.5 mmol) and N,N-dimethyl-2-phenylethen-1-amine (278.8
mg, 1.25 mmol), according to general procedure. The crude residue was
purified by flash chromatography (Petroleum ether/ethyl acetate = 200:1,
Rf = 0.30) to give the product as a brownish yellow oily liquid (147.3 mg,
79%)
–
7.18
(m,
2H),
6.84
(s,
1H),
2.88
(s,
6H).
13C NMR (101 MHz, CDCl3) δ 155.1, 144.04, 133.7, 133.0, 130.1, 128.9,
128.3, 127.1, 125.8, 125.4, 122.9, 121.0, 108.7, 107.3, 41.5.
HRMS (ESI): [M+H]+ calcd. for C18H17BrNO 342.0488, found 342.0492.
N,N-Dimethyl-5-(2-nitrophenyl)-3-phenylfuran-2-amine (4v). The title
compound was prepared from 2-bromo-1-(2-nitrophenyl)ethan-1-one
(121.5 mg, 0.5 mmol) and N,N-dimethyl-2-phenylethen-1-amine (147 mg,
1 mmol), according to general procedure. The crude residue was purified
by flash chromatography (Petroleum ether/ethyl acetate = 20:1, Rf =
0.30) to give the product as a brownish yellow oily liquid (123 mg, 80%)
1H NMR (400 MHz, CDCl3) δ 7.61 (bs, 3H), 7.51-7.15 (m, 6H), 6.88 (s,
1H),
2.91
(s,
6H).
11
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10.1002/ejoc.202000293
European Journal of Organic Chemistry
FULL PAPER
1H NMR (400 MHz, CDCl3) δ 7.64 – 7.57 (m, 2H), 7.49 (d, J = 7.8 Hz,
3H), 7.34 (s, 2H), 7.24 (s, 1H), 7.20 (d, J = 7.4 Hz, 1H), 6.87 (s, 1H), 2.80
acetate = 100:1, Rf = 0.30) to give the product as a brownish yellow oily
liquid (109 mg, 69%).
1H NMR (400 MHz, CDCl3) δ 8.18 (d, J = 8.9 Hz, 2H), 7.62 (d, J = 8.9 Hz,
2H), 6.77 (s, 1H), 3.11 (q, J = 7.1 Hz, 2H), 3.03 (t, J = 7.4 Hz, 2H), 2.92 –
2.82 (m, 1H), 1.53 – 1.44 (m, 2H), 1.18 (d, J = 6.9 Hz, 6H), 1.07 (t, J =
7.1 Hz, 3H), 0.90 (t, J = 7.4 Hz, 3H).
(s,
6H).
13C NMR (101 MHz, CDCl3) δ 156.0, 146.3, 139.5, 133.5, 131.5, 128.3,
127.4, 126.9, 126.3, 125.9, 124.1, 123.9, 113.3, 106.1, 41.0.
HRMS (ESI): [M+H]+ calcd. for C18H17N2O3 309.1234, found 309.1238.
4-(5-(Dimethylamino)-4-phenylfuran-2-yl)benzonitrile (4w). The title
compound was prepared from 4-(2-bromoacetyl)benzonitrile (111.5 mg,
0.5 mmol) and N,N-dimethyl-2-phenylethen-1-amine (147 mg, 1 mmol),
according to general procedure. The crude residue was purified by flash
chromatography (Petroleum ether/ethyl acetate = 100:1, Rf = 0.30) to
give the product as a brownish yellow oily liquid (95 mg, 66%)
1H NMR (400 MHz, CDCl3) δ 7.59 (s, 4H), 7.51 (d, J = 7.8 Hz, 2H), 7.38
(t, J = 7.7 Hz, 2H), 7.23 (t, J = 7.4 Hz, 1H), 6.95 (s, 1H), 2.89 (s, 6H).
13C NMR (101 MHz, CDCl3) δ 155.9, 143.0, 134.8, 133.5, 132.5, 128.3,
127.4, 126.0, 122.2, 119.4, 112.0, 108.2, 106.5, 41.0.
13C NMR (101 MHz, CDCl3) δ 153.9, 144.9, 137.0, 128.0, 124.4, 122.4,
122.1, 109.9, 55.0, 47.9, 24.1, 23.6, 21.5, 13.4, 11.6.
HRMS (ESI): [M+H]+ calcd. for C18H25N2O3 317.1860, found 317.1866.
N-Butyl-3-isopropyl-N-methyl-5-(4-nitrophenyl)furan-2-amine
(6d).
The title compound was prepared from 2-bromo-1-(4-nitrophenyl)ethan-
1-one (121 mg, 0.5 mmol) and N-butyl-N,3-dimethylbut-1-en-1-amine
(194 mg, 1.25 mmol), according to general procedure. The crude residue
was purified by flash chromatography (Petroleum ether/ethyl acetate =
100:1, Rf = 0.30) to give the product as a brownish yellow oily liquid (128
mg, 81%).
HRMS (ESI): [M+H]+ calcd. for C19H17N2O 289.1335, found 289.1339.
5-(Benzofuran-2-yl)-N,N-dimethyl-3-phenylfuran-2-amine (4x). The
title compound was prepared from 1-(benzofuran-2-yl)-2-bromoethan-1-
one (119 mg, 0.5 mmol) and N,N-dimethyl-2-phenylethen-1-amine,
according to general procedure. The crude residue was purified by flash
chromatography (Petroleum ether/ethyl acetate = 200:1, Rf = 0.30) to
give the product as a brownish yellow oily liquid (87.9 mg, 58%)
1H NMR (400 MHz, CDCl3) δ 8.17 (d, J = 9.0 Hz, 2H), 7.59 (d, J = 9.0 Hz,
2H), 6.78 (s, 1H), 3.10 (t, J = 7.4 Hz, 2H), 2.91 – 2.83 (m, 1H), 2.88 (s,
3H), 1.47 – 1.55 (m, 2H), 1.40 – 1.31 (m, 2H), 1.19 (d, J = 6.9 Hz, 6H),
0.92 (t, J = 7.3 Hz, 3H).
13C NMR (101 MHz, CDCl3) δ 155.4, 143.7, 136.9, 128.0, 124.4, 122.0,
121.1, 110.8, 54.6, 40.2, 29.9, 24.1, 23.6, 20.2, 14.0.
HRMS (ESI): [M+H]+ calcd. for C18H25N2O3 317.1860, found 317.1866.
1-(3-Isopropyl-5-(4-nitrophenyl)furan-2-yl)piperidine (6e). The title
compound was prepared from 2-bromo-1-(4-nitrophenyl)ethan-1-one
(121 mg, 0.5 mmol) and 1-(3-methylbut-1-en-1-yl)piperidine (191 mg,
1.25 mmol), according to general procedure. The crude residue was
purified by flash chromatography (Petroleum ether/ethyl acetate = 100:1,
Rf = 0.30) to give the product as a brownish yellow oily liquid (97 mg,
62%).
1H NMR (400 MHz, CDCl3) δ 7.63 (d, J = 7.8 Hz, 2H), 7.59 (d, J = 6.6 Hz,
1H), 7.52 (d, J = 6.9 Hz, 2H), 7.43 (s, 2H), 7.28 (d, J = 6.8 Hz, 2H), 7.02
(s,
1H),
6.82
(s,
1H),
2.93
(s,
6H).
13C NMR (101 MHz, CDCl3) δ 155.4, 154.4, 148.5, 138.2, 133.5, 129.2,
128.3, 127.2, 125.9, 123.7, 123.0, 120.5, 110.9, 110.4, 106.8, 99.0, 41.4.
HRMS (ESI): [M+H]+ calcd. for C20H18BrNO2 304.1332, found 304.1335.
N,N-Diethyl-3-isopropyl-5-(4-nitrophenyl)furan-2-amine (6a). The title
compound was prepared from 2-bromo-1-(4-nitrophenyl)ethan-1-one
(121 mg, 0.5 mmol) and N,N-diethyl-3-methylbut-1-en-1-amine (176 mg,
1.25 mmol), according to general procedure. The crude residue was
purified by flash chromatography (Petroleum ether/ethyl acetate = 100:1,
Rf = 0.30) to give the product as a brownish yellow oily liquid (109 mg,
72%).
1H NMR (400 MHz, CDCl3) δ 8.17 (d, J = 9.0 Hz, 2H), 7.60 (d, J = 8.9 Hz,
2H), 6.77 (s, 1H), 3.13 (t, J = 5.3 Hz, 4H), 2.95 – 2.76 (m, 1H), 1.77 –
1.64 (m, 4H), 1.62-1.59 (m, 2H), 1.19 (d, J = 6.9 Hz, 6H).
13C NMR (101 MHz, CDCl3) δ 156.1, 145.0, 143.8, 137.0, 124.4, 122.2,
117.8, 110.7, 51.6, 26.0, 24.2, 24.1, 23.5.
HRMS (ESI): [M+H]+ calcd. for C18H23N2O3 315.1703, found 315.1708.
1H NMR (400 MHz, CDCl3) δ 8.18 (d, J = 9.0 Hz, 2H), 7.63 (d, J = 9.0 Hz,
2H), 6.77 (s, 1H), 3.11 (q, J = 7.2 Hz, 4H), 2.95-2.80 (m, 1H), 1.18 (d, J =
6.9 Hz, 6H), 1.07 (t, J = 7.2 Hz, 6H).
1- (5-(4-Nitrophenyl)-3-propylfuran-2-yl)piperidine
(6f).
The
title
compound was prepared from 2-bromo-1-(4-nitrophenyl)ethan-1-one
(121 mg, 0.5 mmol) and 1-(pent-1-en-1-yl)piperidine (191 mg, 1.25
mmol), according to general procedure. The crude residue was purified
by flash chromatography (Petroleum ether/ethyl acetate = 100:1, Rf =
0.30) to give the product as a brownish yellow oily liquid (104 mg, 66%).
1H NMR (400 MHz, CDCl3) δ 8.16 (d, J = 9.0 Hz, 2H), 7.57 (d, J = 9.0 Hz,
2H), 6.72 (s, 1H), 3.17 (t, J = 5.4 Hz, 4H), 2.35 (t, J = 7.6 Hz, 2H), 1.75 –
1.64 (m, 6H), 1.64 – 1.58 (m, 2H), 0.97 (t, J = 7.3 Hz, 3H).
13C NMR (101 MHz, CDCl3) δ 153.5, 145.2, 137.0, 128.0, 124.3, 122.4,
120.3, 109.7, 47.6, 24.1, 23.5, 13.4.
HRMS (ESI): [M+H]+ calcd. for C17H23N2O3 303.1703, found 303.1711.
3-Isopropyl-5-(4-nitrophenyl)-N,N-dipropylfuran-2-amine (6b). The
title compound was prepared from 2-bromo-1-(4-nitrophenyl)ethan-1-one
(121 mg, 0.5 mmol) and 3-methyl-N,N-dipropylbut-1-en-1-amine (211 mg,
1.25 mmol), according to general procedure. The crude residue was
purified by flash chromatography (Petroleum ether/ethyl acetate = 100:1,
Rf = 0.30) to give the product as a brownish yellow oily liquid (129 mg,
78%).
13C NMR (101 MHz, CDCl3) δ 157.1, 144.8, 143.2, 136.9, 124.4, 121.9,
113.6, 109.8, 51.1, 26.8, 25.9, 24.1, 23.3, 14.0.
HRMS (ESI): [M+H]+ calcd. for C18H23N2O3 315.1703, found 315.1708.
2-(Diethylamino)-3-isopropylbenzofuran-5-ol
1H NMR (400 MHz, CDCl3) δ 8.18 (d, J = 8.9 Hz, 2H), 7.61 (d, J = 8.8 Hz,
2H), 6.77 (s, 1H), 3.03 (t, J = 7.4 Hz, 4H), 2.92 – 2.82 (m, 1H), 1.54 –
1.44 (m, 4H), 1.17 (d, J = 6.9 Hz, 6H), 0.90 (t, J = 7.4 Hz, 6H).
13C NMR (101 MHz, CDCl3) δ 154.3, 144.7, 137.0, 128.0, 124.3, 122.3,
121.4, 110.0, 55.4, 24.1, 23.6, 21.5, 11.5.
1H NMR (400 MHz, CDCl3) δ 7.17 (d, J = 8.7 Hz, 1H), 7.04 (d, J = 2.5 Hz,
1H), 6.71 (dd, J = 8.7, 2.6 Hz, 1H), 5.21 (s, 1H), 3.16 - 3.05 (m, 1H), 3.08
(q, J = 7.2 Hz, 4H ), 1.31 (d, J = 7.1 Hz, 6H), 1.03 (t, J = 7.2 Hz, 6H).
13C NMR (101 MHz, CDCl3) δ 154.4, 150.3, 146.7, 129.1, 115.3, 111.0,
110.8, 105.9, 48.1, 24.8, 21.9, 13.4
HRMS (ESI): [M+H]+ calcd. for C19H27N2O3 331.2016, found 331.2021.
N-Ethyl-3-isopropyl-5-(4-nitrophenyl)-N-propylfuran-2-amine (6c)
The title compound was prepared from 2-bromo-1-(4-nitrophenyl)ethan-
1-one (121 mg, 0.5 mmol) and N-ethyl-3-methyl-N-propylbut-1-en-1-
amine (194 mg, 1.25 mmol), according to general procedure. The crude
residue was purified by flash chromatography (Petroleum ether/ethyl
Keywords: 2-Aminofurans; Domino Reaction; Iron catalyst;
Oxidation; Cyclization
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10.1002/ejoc.202000293
European Journal of Organic Chemistry
FULL PAPER
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13
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European Journal of Organic Chemistry
FULL PAPER
Key Topic: Iron catalyst
An interesting iron-catalyzed protocol forthe synthesisof 2-aminofurans hasbeen developed. Starting from 2-haloketonesand
tertiary amines orenamines, various2-aminofuranswere produced in good yields.
14
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