Water-solvent method for the synthesis of N-substituted and N-,4-disubstituted 1,8-naphthalimides under microwave irradiation

Article abstract of DOI:10.1080/00397911.2011.575520

A preparation of a series of N-and N-,4-substituted 1,8-naphthalimides using water as solvent under microwave irradiation, which proceeded via efficient and green reaction of 1,8-naphthalic anhydride derivatives with different amines, is described.

Full text of DOI:10.1080/00397911.2011.575520

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Water-Solvent Method for the Synthesis
of N-Substituted and N-,4-Disubstituted
1,8-Naphthalimides under Microwave
Irradiation
Ye Zhang a b , Shao-Bo Feng a , Kai Wang b , Xiang-Hui Yi b , Heng-
Shan Wang a & Ying-Ming Pan a
a School of Chemistry and Chemical Engineering, Guangxi Normal
University , Guangxi , China
b Department of Chemistry and Engineering Technology , Guilin
Normal College , Guangxi , China
Accepted author version posted online: 10 Jan 2012.Published
online: 21 Jun 2012.
To cite this article: Ye Zhang , Shao-Bo Feng , Kai Wang , Xiang-Hui Yi , Heng-Shan Wang & Ying-
Ming Pan (2012) Water-Solvent Method for the Synthesis of N-Substituted and N-,4-Disubstituted
1,8-Naphthalimides under Microwave Irradiation, Synthetic Communications: An International
Journal for Rapid Communication of Synthetic Organic Chemistry, 42:20, 3042-3052, DOI:
10.1080/00397911.2011.575520
To link to this article: http://dx.doi.org/10.1080/00397911.2011.575520
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Synthetic Communications1, 42: 3042–3052, 2012
Copyright # Taylor & Francis Group, LLC
ISSN: 0039-7911 print=1532-2432 online
DOI: 10.1080/00397911.2011.575520
WATER-SOLVENT METHOD FOR THE SYNTHESIS OF
N-SUBSTITUTED AND N-,4-DISUBSTITUTED
1,8-NAPHTHALIMIDES UNDER MICROWAVE
IRRADIATION
Ye Zhang,1,2 Shao-Bo Feng,1 Kai Wang,2 Xiang-Hui Yi,2
Heng-Shan Wang,1 and Ying-Ming Pan1
1School of Chemistry and Chemical Engineering, Guangxi Normal
University, Guangxi, China
2Department of Chemistry and Engineering Technology,
Guilin Normal College, Guangxi, China
GRAPHICAL ABSTRACT
Abstract A preparation of a series of N- and N-,4-substituted 1,8-naphthalimides using
water as solvent under microwave irradiation, which proceeded via efficient and green reac-
tion of 1,8-naphthalic anhydride derivatives with different amines, is described.
Keywords Green chemistry; microwave; naphthalimides; water-solvent
INTRODUCTION
One of the main aims of green chemistry is the reduction of the use of organic
solvents because of the economical and environmental concerns associated with
them, and therefore the development of water-solvent synthetic methods is of the
utmost importance.[1,2] Water is known to be one of the best green solvents, and it
is cheap, readily available, nontoxic, and apyrous. Compared with many other
solvents, water not only provides a medium for solution chemistry but also often
takes part in elementary chemical events on a molecular scale, and it also offers prac-
tical advantages over organic solvents,[2] for example, its hydrogen bonding effects
and polarity effects.[2] Thus, a considerable interest has been devoted to the reactions
using water as solvent. In addition, microwave irradiation[3] has been considered a
Received February 17, 2010.
Address correspondence to Heng-Shan Wang, School of Chemistry and Chemical Engineering,
Guangxi Normal University, Guangxi, China. E-mail: wang_hengshan@yahoo.com.cn
3042

GREEN SOLVENT METHOD FOR THE SYNTHESIS OF 1,8-NAPHTHALIMIDES 3043
Scheme 1. Synthetic route of naphthalimides 1 and 2.
green technology, and its level of energy consumption is low compared with most
traditional methods. As well as being energy efficient, microwave heating can also
enhance the rate of reactions and even in many cases improve product yields. It is
well known that water is a good microwave-absorbing solvent (with a spot of electric
loss and a very high dielectric constant).[3] Therefore it is very attractive to combine a
water-solvent system with microwave irradiation.[3a,3d,3e]
In recent years, 1,8-naphthalimide derivatives have been the subjects of numer-
ous synthetic efforts, because they have applications in dyeing synthetic polymers
and textile materials,[4] in solar energy collectors[5], as fluorescent tags for use in
molecular biology,[6] for potential photosensitizing biological activity,[7] and in
liquid-crystalline displays.[8] Available methods for naphthalimides are listed in the
literature.[9] Dehydrative condensation of 1,8-naphathalic anhydride with amines
at high temperatures[9a] and the cyclization of N-substituted amic acid in the
presence of acidic reagents[9d] are well-known methods. Direct N-alkylation under
Mitsunobu conditions is another method for the synthesis of naphathlimide deriva-
tives.[9a] The condensation of iminophosphoranes with phthaloyl dichloride followed
by alkaline hydrolysis also affords naphthalimides.[9e] However, most of these routes
are environmentally harmful or require long reaction times.[9] Therefore, preparation
of functionalized 1,8-naphtalimide derivatives is still a major challenge in organic
synthesis. In view of the important application of 1,8-naphthalimide derivatives
and our general interest in green chemistry processes, we explore herein a new,
efficient, mild, and water-solvent method for the synthesis of 1,8-naphthalimide deri-
vatives under microwave irradiation (Schemes 1 and 2). It is important to point out
that the reaction in this method not only includes the formation of imides from
Scheme 2. Synthetic route of naphthalimides 3 and 4.

3044
Y. ZHANG ET AL.
anhydrides but also the Ullmann arylation reaction on naphthalene moiety. To our
knowledge, this method has not been described previously in literature and it is very
simple but useful compared with previously reported methods.
RESULTS AND DISCUSSION
In a sealed and pressurized tube, we carried out the transformation of
N-substituted naphthalimides 1a–1i and 2a–2f in a reaction of 1,8-naphtalic anhy-
dride or 4-bromo-1,8-naphtalic anhydride with different amines in an aqueous
mixture at 80 ꢀC and 450 W under microwave irradiation (Scheme 1). The transform-
ation was complete within 5–8 min, and the N-substituted products of 1 and 2 were
obtained in good yields (51–96%) (Table 1) by filtering off the solution after the reac-
tion system cooled to the room temperature.
It is important to note that in the synthesis of 2a–2f there was another new pro-
duct (it shows as green light in thin-layer chromatography [TLC] under the ultra-
violet [UV] instrument at 365 nm) when the irradiation time in the reaction of
4-bromo-1,8-naphthalic anhydride with amines is prolonged. The new product was
1
confirmed to be N,4-disubstituted naphthalimides 3 by H NMR after separation,
demonstrating that this reaction simultaneously included the formation of imides
and the Ullmann arylation on naphthalene moiety. To the best of our knowledge,
this reaction has not been reported previously under this condition and it aroused
our interest for further progress. Additionally, this class of naphthalimides 3 exhibit
excellent photochemical properties, good light stability, and good spectral proper-
ties, and they have become increasingly popular in a number of areas including laser
active media,[10] potential photosensitive biological units,[7] analgesics in medicine,[11]
ion probes,[12] and so forth. More effort has been invested in search for the best syn-
thetic conditions. Through an optimized experiment, the optimized parameters of
the reaction are summarized in Table 1. Heightening the reaction temperature to
100 ꢀC and the microwave power to 850 W resulted in the formation of 4-alkyl-
amino-naphthalimides 3 in 66–82% yields within 8–10 min.
To enlarge the scope of this method, 3-nitro-4-bromo-1,8-naphthalic anhydride
was used to replace 4-bromo-1,8-naphthalic anhydride. In an aqueous mixture, the
condensation of 3-nitro-4-bromo-1,8-naphthalic anhydride and different primary
amines at 100 ꢀC and 850 W under microwave irradiation afforded 3-nitro-4-alkyl-
amino-naphthalimides 4 in good yield (82–92%). Because of the presence of an
electron-withdrawing nitro group, the elimination of the bromogroup in the
naphthalene moiety was more efficient and easy. It did not yield any N-substituted
naphthalimides as that of 1 or 2 in the course of the transformation of 4, even though
microwave power and the temperature were reduced and reaction time was pro-
longed. It showed high selectivity in this reaction.
In 1H NMR spectra for compounds 1–3, the peaks of the nucleus in
naphthalimides moiety ranged from 7.50 to 8.80 ppm. The peaks of N-H of compound
3 were in the range of 5.24–5.61 ppm. For compounds 4, as a result of the presence of
electron-withdrawing nitro group, the peaks of naphthalimide moiety beside the
nitro group shifted to 8.70–9.40 ppm, and the peaks of N-H shifted to the range of
9.91–10.74 ppm.

GREEN SOLVENT METHOD FOR THE SYNTHESIS OF 1,8-NAPHTHALIMIDES 3045
Table 1. Synthesis of 1,8-naphthalimides 1–4
Amines
(eq.a)
Power
(W)
Temperature
(ꢀC)
Time
(min)
Yield
(%)
Product
Structure
1a
1.2
1.2
450
450
80
80
8
5
51
96
1b
1c
1d
1e
1.2
1.2
1.2
450
450
450
80
80
80
8
8
5
78
65
92
1f
1.2
1.2
450
450
80
80
8
8
68
81
1g
1h
1.2
450
80
8
83
1i
1.2
450
80
8
85
(Continued )

3046
Y. ZHANG ET AL.
Table 1. Continued
Amines
(eq.a)
Power
(W)
Temperature
(ꢀC)
Time
(min)
Yield
(%)
Product
Structure
2a
1.2
1.2
450
450
80
80
5
6
56
95
2b
2c
2d
1.2
1.2
450
450
80
80
8
8
61
80
2e
1.2
450
80
8
81
2f
1.2
2.1
450
850
80
8
83
73
3a
100
10
3b
2.1
850
100
10
66
(Continued )

GREEN SOLVENT METHOD FOR THE SYNTHESIS OF 1,8-NAPHTHALIMIDES 3047
Table 1. Continued
Amines
(eq.a)
Power
(W)
Temperature
(ꢀC)
Time
(min)
Yield
(%)
Product
Structure
3c
2.1
2.1
850
850
100
100
10
80
82
3d
4a
8
2.1
2.1
2.1
850
850
850
100
100
100
10
10
10
84
90
82
4b
4c
4d
4e
2.1
2.1
850
850
100
100
8
8
92
88
aThe dosages of 1,8-naphthalic anhydride, 4-bromo-1,8-naphthalic anhydride, and 3-nitro-4-bromo-
1,8-naphthalic anhydride were 1 mmol.
Upon recrystallization, the single crystal of the representative compounds 1b,
2e, 3b, 4b, and 4d (Fig. 1) were obtained and their structures were determined and
confirmed by x-ray method. That provides good proof of the confirmation of their

3048
Y. ZHANG ET AL.
Figure 1. Single-crystal structures of the representative compounds 1b, 2e, 3b, 4b, and 4d. bCompounds 3b
and 4d are cited here for comparison. (Figure is provided in color online.)
structures. It is well known that naphthalimides have been used as electro-optically
sensitive materials,[4a] anion chemosensors,[13] and human medicines,[14] and so the
single crystals of 3b, 4b, and 4d are expected to be very useful in the design of
new kinds of naphthalimide analogs with novel functions and properties.
In conclusion, we have demonstrated a rapid, green, and efficient water-solvent
method for the synthesis of N- and N-,4-substituted 1,8-naphthalimides under
microwave irradiation. The procedure has the advantages of good yields, short reac-
tion times, environmental friendliness, and easy workup.
EXPERIMENTAL
All reagents were of analytical grade and were dried and purified if necessary.
Microwave irradiation was performed on a WF-4000 M microwave oven. Melting
points were determined on a WRS-IA apparatus without correction. Infrared (IR)
spectra were recorded on a PE Spectrum One Fourier transform (FT)–IR spec-
trometer as KBr pellets. 1H NMR and 13C NMR spectra were recorded on a Bruker
Avance 500 spectrometer in CDCl3 or dimethylsulfoxide (DMSO). Mass spectra
were recorded on Bruker Esquire HCT or VG ZAB-HS spectrometers. All elemental
analyses were performed on a PE 2400II analyzer. The data of single crystals were
collected in a Rigaku Mercury CCD Area Detector.
Compounds 1 and 2
The mixture of primary amine (1.2 mmol), water (10 mL), and 1,8-naphthalic
anhydride (or 4-bromo-1,8-naphthalic anhydride) (1 mmol) was blended together
in a sealed and pressurized tube and reacted at 450 W and 80 ꢀC under microwave
irradiation for a few minutes. After reaction, it was filtered to afford 8-naphthali-
mides 1 and 2. Upon recrystallization from ethanol, the crystals of 1 (white crystals)
and 2 (pale yellow crystals) were obtained.
Compound 1i. Mp: 98–100 ꢀC (from ethanol). IR (KBr, cmꢁ1): 3066, 2957,
1
2927, 2866, 1704, 1663, 1628, 1589, 1512, 1496, 1435, 1416 1379, 1335; H NMR

GREEN SOLVENT METHOD FOR THE SYNTHESIS OF 1,8-NAPHTHALIMIDES 3049
(500 MHz, CDCl3) d 8.59 (d, J ¼ 7.3 Hz, 2H), 8.23 (d, J ¼ 8.0 Hz, 2H), 7.77 (t,
J ¼ 7.7 Hz, 2H), 7.15 (s, 1H), 6.95 (d, J ¼ 8.0 Hz, 2H), 4.24–4.35 (dd, J ¼ 13.3 and
13.4 Hz, 2H, CH2), 3.02–3.04 (m, 2H, CH2), 2.83–2.84 [m, 1H, CH(CH3)2],
2.24–2.26 (m, 2H, CH2), 1.61–1.91 (m, 6H, CH2), 1.27–1.29 (m, 3H), 1.26 [s, 6H,
(CH3)2], 1.11 (s, 3H, CH3), 1.01–1.03 (m, 1H); 13C NMR (125 MHz): 18.1, 18.5,
19.2, 19.7, 20.0, 24.0, 26.1, 30.5, 32.6, 33.4, 34.4, 37.5, 37.8, 37.9, 38.1, 46.4, 49.8,
50.4, 122.4, 123.3, 123.8, 127.0, 128.1, 128.9, 130.1, 131.1, 132.2, 133.3, 135.2,
145.5, 147.4, 164.8. Anal. calcd. for C32H35NO2: C, 82.54; H, 7.58; N, 3.01. Found:
C, 82.71; H, 7.45; N, 3.14.
Compound 2e. Mp 152–154 ꢀC (from ethanol). IR (KBr, cmꢁ1): 3469, 3055,
1
2938, 2876, 1705, 1663, 1617, 1586, 1571; H NMR (500 MHz, CDCl3) d 8.65 (d,
J ¼ 7.2 Hz, 1H), 8.59 (d, J ¼ 8.5 Hz, 1H), 8.40 (d, J ¼ 7.8 Hz, 1H), 8.05 (d, J ¼ 7.8 Hz,
Hz, 1H), 7.86 (t, J ¼ 8.1 Hz, 1H), 7.14 (s, 1H), 6.95 (d, J ¼ 8.1 Hz, 2H), 4.22–4.32 (dd,
J ¼ 13.3 and 13.3 Hz, 2H, CH2), 3.03–3.05 (m, 2H, CH2), 2.85–2.87 [m, 1H,
CH(CH3)2], 2.24–2.26 (m, 2H, CH2), 1.58–1.90 (m, 6H, CH2), 1.28–1.31 (m, 3H),
1.26 [s, 6H, (CH3)2], 1.12 (s, 3H, CH3), 1.02–1.04 (m, 1H); 13C NMR (125 MHz):
18.2, 18.6, 19.2, 19.8, 20.0, 24.0, 26.0, 30.5, 32.6, 33.4, 34.4, 37.5, 37.8, 37.9, 38.1,
46.4, 49.8, 50.4, 122.4, 123.3, 123.8, 127.0, 128.1, 128.9, 130.0, 131.2, 132.2, 133.1,
135.2, 145.4, 147.5, 164.7. Anal. calcd. for C32H34BrNO2: C, 70.58; H, 6.29; N,
2.57. Found: C, 70.41; H, 6.13; N, 2.72.
Compounds 3
The mixture of amines (2.1 mmol), water (10 mL), and 4-bromo-1,8-naphthalic
anhydride (1.0 mmol) was blended together in a sealed and pressurized tube and
reacted at 850 W and 100 ꢀC under microwave irradiation for a few minutes. After
reaction, the gum obtained was purified by silica column chromatography with pet-
roleum ether–ethyl acetate (5:1) as the eluent. Upon recrystallization from ethanol,
yellow crystals of 3 were obtained.
Compound 3a. Mp 229.9–231.6 ꢀC (from ethanol). IR (KBr, cmꢁ1): 3496,
1
3371, 2959, 2930, 2870, 1683, 1636, 1618, 1573, 1549; H NMR (500 MHz, CDCl3)
d 8.58 (d, J ¼ 7.2 Hz, 1H), 8.46 (d, J ¼ 8.4 Hz, 1H), 8.09 (d, J ¼ 8.4 Hz, 1H), 7.59 (t,
J ¼ 7.8 Hz, 1H), 6.72 (d, J ¼ 8.4 Hz, 1H), 5.31 (s, 1H, NH), 4.13 (t, J ¼ 7.68 Hz, 2H),
3.38–3.42 (m, 2H), 1.81–1.90 (m, 2H), 1.74–1.78 (m, 2H), 1.14 (t, J ¼ 7.4 Hz, 3H),
1.01 (t, J ¼ 7.4 Hz, 3H); 13C NMR (125 MHz): 11.8, 12.0, 21.4, 21.6, 41.3, 45.2,
104.2, 107.9, 120.6, 122.3, 124.7, 129.0, 129.9, 131.1, 134.7, 151.2, 163.4, 164.2;
MS (ESI) m=z: 295 (Mþ–1). Anal. calcd. for C18H20N2O2: C, 72.95; H, 6.80; N,
9.45. Found: C, 72.81; H, 6.98; N, 9.62.
Compound 3b. Mp 158.2–159.6 ꢀC (from ethanol). IR (KBr, cmꢁ1): 3443,
2949, 2871, 1694, 1657, 1625, 1591; 1H NMR (500 MHz, CDCl3) d 8.61 (d,
J ¼ 7.3 Hz, 1H), 8.48 (d, J ¼ 8.5 Hz, 1H), 7.64 (d, J ¼ 7.8 Hz, 1H), 7.44 (t, J ¼ 7.8 Hz,
Hz, 1H), 7.32–7.37 (m, 5H), 7.30–7.36 (m, 5H), 6.78 (d, J ¼ 7.4 Hz, 1H), 5.58 (s,
NH), 5.54 (s, 2H), 4.63 (d, J ¼ 5.1 Hz, 2H); 13C NMR (125 MHz): 48.4, 52.3,
110.3, 122.8, 123.8, 126.9, 127.6, 128.0, 128.2, 128.4, 128.8, 129.3, 129.7, 130.6,

3050
Y. ZHANG ET AL.
131.5, 133.1, 133.7, 137.8, 149.0, 162.6, 163.7; MS (ESI) m=z: 392 (Mþ). Anal. calcd.
for C26H20N2O2: C, 79.57; H, 5.14; N, 7.14. Found: C, 79.44; H, 5.26; N, 7.28.
Compound 3c. Mp 231.4–232.8 ꢀC (from ethanol). IR (KBr, cmꢁ1): 3382,
1
2956, 2931, 2865, 1685, 1635, 1571, 1544; H NMR (500 MHz, CDCl3) d 8.60 (d,
J ¼ 8.5 Hz, 1H), 8.49 (d, J ¼ 7.5 Hz, 1H), 8.09 (d, J ¼ 8.6 Hz, 1H), 7.65 (d, J ¼ 7.5 Hz,
Hz, 2H), 6.74 (d, J ¼ 7.4 Hz, 1H), 5.24 (s, 1H, NH), 4.17 (t, J ¼ 7.6 Hz, 2H), 3.44 (t,
J ¼ 7.5 Hz, 2H), 1.84–1.87 (m, 2H), 1.59–1.61 (m, 2H), 1.45–1.48 (m, 4H), 1.01–1.06
(m, 6H, CH3); 13C NMR (125 MHz): 14.1, 14.2, 20.3, 29.5, 30.3, 30.4, 43.0, 104.2,
108.0, 120.6, 122.3, 124.7, 129.1, 129.9, 131.1, 134.7, 151.2, 163.4, 164.2; MS (ESI)
m=z: 323 (Mþ–1). Anal. calcd. for C20H24N2O2: C, 74.01; H, 7.46; N, 8.64. Found:
C, 74.15; H, 7.62; N, 8.46.
Compound 3d. Mp 165.4–167.1 ꢀC (from ethanol). IR (KBr, cmꢁ1): 3420,
3045, 2918, 2832, 2796, 2775, 2752, 2730, 1675, 1631, 1600, 1560; 1H NMR
(500 MHz, CDCl3) d 8.67 (d, J ¼ 7.9 Hz, 1H), 8.41 (d, J ¼ 7.3 Hz, 1H), 8.24 (d,
J ¼ 8.5 Hz, 1H), 7.66 (t, J ¼ 8 Hz, 2H), 7.37 (d, J ¼ 7.9 Hz, 1H), 7.22 (d, J ¼ 8.8 Hz,
1H), 6.80 (d, J ¼ 8.5 Hz, 1H), 4.90 (t, J ¼ 5.15 Hz, 1H), 4.78 (t, J ¼ 5.6 Hz, 1H),
4.09 (t, J ¼ 6.8 Hz, 2H), 3.69 (s, 2H, OH), 3.66–3.69 (dd, J ¼ 4.9 and 5.1 Hz, 2H);
13C NMR (125 MHz): 44.8, 50.0, 58.4, 59.3, 108.1, 120.5, 122.3, 124.6, 128.9,
129.8, 131.0, 134.5, 151.2, 164.3; MS (ESI) m=z: 300 (Mþ). Anal. calcd. for
C16H16N2O4: C, 63.99; H, 5.37; N, 9.33. Found: C, 63.84; H, 5.14; N, 9.65.
Compounds 4
The mixture of amines (2.1 mmol), water (10 mL), and 3-nitro-4-bromo-
1,8-naphthalic anhydride (1 mmol) was blended together in a sealed and pressurized
tube and reacted at 850 W and 100 ꢀC under microwave irradiation for a few min-
utes. After reaction, it was filtered and recrystallized in hot N,N-dimethyl-
formamide–water solution (VDMF:Vwater ¼ 4:1) to afford red-brown crystals of 4.
Compound 4a. Mp 224.3–225.9 ꢀC (from DMF-H2O). IR (KBr, cmꢁ1): 3453,
2965, 2933, 2856, 2812, 1694, 1652, 1602, 1581, 1536; 1H NMR (500 MHz, CDCl3) d
9.91 (s, 1H, NH), 9.25 (s, 1H), 8.65 (t, J ¼ 7.1 Hz, 2H), 7.71 (t, J ¼ 7.8 Hz, 1H), 4.18
(t, J ¼ 7.5 Hz, 2H), 3.96 (t, J ¼ 5.4 Hz, 2H), 1.73–1.91 (m, 4H), 1.03 (s, 6H, CH3); 13
C
NMR (125 MHz): 16.4, 17.2, 27.1, 35.6, 41.3, 45.2, 109.2, 122.7, 123.6, 126.5, 129.4,
129.6, 130.7, 132.1, 133.0, 149.5, 162.7, 163.8; MS (ESI) m=z: 340 (Mþ–1). Anal.
calcd. for C18H19N3O4: C, 66.33; H, 5.61; N, 12.31. Found: C, 66.19; H, 5.73; N,
12.42.
Compound 4b. Mp 233.5–234.7 ꢀC (from DMF-H2O). IR (KBr, cmꢁ1): 3441,
1
3060, 2923, 2851, 1699, 1655, 1601, 1537; H NMR (500 MHz, CDCl3) d 10.02 (s,
1H, NH), 9.36 (s, 1H), 8.70 (d, J ¼ 7.4 Hz, 1H), 8.63 (d, J ¼ 8.5 Hz, 1H), 7.67 (d,
J ¼ 8.3 Hz, 1H), 7.26–7.65 (m, 10H), 5.38 (s, 2H), 5.10 (s, 2H); 13C NMR
(125 MHz): 43.3, 52.3, 110.2, 122.8, 124.0, 126.9, 127.6, 128.0, 128.2, 128.4, 129.1,
129.4, 129.7, 130.6, 131.4, 133.1, 133.7, 137.8, 149.0, 153.1, 162.6, 163.7; MS (ESI)
m=z: 436 (Mþ–1). Anal. calcd. for C26H19N3O4: C, 71.39; H, 4.38; N, 9.61. Found:
C, 71.25; H, 4.51; N, 9.72.

GREEN SOLVENT METHOD FOR THE SYNTHESIS OF 1,8-NAPHTHALIMIDES 3051
Compound 4c. Mp 236.5–236.7 ꢀC (from DMF-H2O). IR (KBr, cmꢁ1): 3462,
3060, 2958, 2929, 2873, 1698, 1649, 1606, 1577, 1538; 1H NMR (500 MHz, CDCl3) d
9.92 (s, 1H, NH), 9.32 (s, 1H), 8.68 (dd, J ¼ 7.4 and 8.5 Hz, 2H), 7.71 (t, J ¼ 7.8 Hz,
1H), 4.18 (t, J ¼ 7.5 Hz, 2H), 3.99 (t, J ¼ 5.5 Hz, 2H), 1.45–1.88 (m, 8H), 1.00 (s, 6H,
CH3); 13C NMR (125 MHz): 14.0, 14.2, 19.9, 20.2, 30.1, 32.1, 49.2, 110.0, 122.8,
123.8, 126.7, 129.5, 129.8, 131.4, 133.1, 133.5, 149.4, 162.5, 163.5; MS (ESI) m=z:
368 (Mþ–1). Anal. calcd. for C20H19N3O4: C, 65.03; H, 6.28; N, 11.37. Found: C,
65.16; H, 6.47; N, 11.24.
Compound 4d. Mp 241.4–243 ꢀC (from DMF-H2O). IR (KBr, cmꢁ1): 3444,
3060, 2943, 2856, 2812, 2787, 2762, 2730, 1697, 1653, 1625, 1590; 1H NMR
(500 MHz, DMSO) d 9.84 (s, 1H, NH), 8.78 (d, J ¼ 8.5 Hz, 1H), 8.70 (s, 1H), 8.43
(d, J ¼ 7.4 Hz, 1H), 7.72 (t, J ¼ 7.9 Hz, 1H), 5.24 (t, J ¼ 4.8 Hz, 1H), 4.78 (t,
J ¼ 6.0 Hz, 1H), 4.02 (t, J ¼ 6.7 Hz, 2H), 3.86 (s, 2H, OH), 3.70–3.73 (dd, J ¼ 4.9
and 4.9 Hz, 2H), 3.55–3.57 (m, 2H); 13C NMR (125 MHz): 40.5, 52.2, 58.2, 60.1,
110.1, 122.8, 123.5, 126.4, 129.1, 129.3, 131.8, 133.6, 134.0, 150.5, 162.5, 163.6;
MS (ESI) m=z: 344 (Mþ–1). Anal. calcd. for C16H15N3O6: C, 55.65; H, 4.38; N,
12.17. Found: C, 55.51; H, 4.51; N, 12.35.
Compound 4e. Mp 245–247 ꢀC (from DMF-H2O). IR (KBr, cmꢁ1): 3447,
1
3226, 3060, 2919, 2851, 1705, 1663, 1599, 1575, 1543, 1511; H NMR (500 MHz,
CDCl3) d 10.74 (s, 1H, NH), 9.37 (s, 1H), 8.63 (d, J ¼ 7.4 Hz, 1H), 8.24 (d,
J ¼ 8.6 Hz, 1H), 7.45 (t, J ¼ 8.3 Hz, 1H), 7.37 (d, J ¼ 8.1 Hz, 2H), 7.20 (d, J ¼ 8.1 Hz,
Hz, 4H), 7.06 (d, J ¼ 8.2 Hz, 2H), 2.47 (s, 3H, CH3), 2.41 (s, 3H, CH3); 13C NMR
(125 MHz): 17.5, 18.5, 108.2, 112.9, 120.0, 122.9, 123.5, 125.0, 126.7, 127.5, 129.0,
129.1, 129.5, 130.9, 131.8, 132.7, 133.7, 135.0, 135.4, 136.1, 140.6, 144.9, 161.1,
162.4, 163.4; MS (ESI) m=z: 436 (Mþ–1). Anal. calcd. for C26H19N3O4: C, 71.39;
H, 4.38; N, 9.61. Found: C, 71.51; H, 4.20; N, 9.48.
ACKNOWLEDGMENTS
The authors thank the National Natural Science Foundation of China (No.
20362002), the 100 Young and Middle-Aged Disciplinary Leaders in Guangxi
Higher Education Institutions, and the Natural Science Foundation of Guangxi
Province (No. 0575046), as well as the Teaching and Research Award Program
for Outstanding Young Teachers in Higher Education Institutions of Chinese
Ministry of Education.
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