Synthesis of β-acylamino furans from glucosamine

Article abstract of DOI:10.1080/07328303.2021.1895195

A facile method for the synthesis of a series of novel β-acylamino furans stating from renewable monosaccharide was achieved. Glucosamine hydrochloride was selectively N-acylated with acyl chlorides in methanol/triethylamine to yield N-acyl-d-glucosamines, which were subsequently converted into β-acylamino furans through dehydration and cyclization under microwave irradiation.

Full text of DOI:10.1080/07328303.2021.1895195

Journal of Carbohydrate Chemistry
ISSN: (Print) (Online) Journal homepage: https://www.tandfonline.com/loi/lcar20
Synthesis of β-acylamino furans from glucosamine
Zhi-ling Cao, Cong Zhu, Wen-ying Wu, Dan-dan Zhu, Dong Qian, Jian Zhu,
Tian-ge Chang, Mei Sheng, Xiu-li Yang & Wei-wei Liu
To cite this article: Zhi-ling Cao, Cong Zhu, Wen-ying Wu, Dan-dan Zhu, Dong Qian,
Jian Zhu, Tian-ge Chang, Mei Sheng, Xiu-li Yang & Wei-wei Liu (2020) Synthesis of β-
acylamino furans from glucosamine, Journal of Carbohydrate Chemistry, 39:9, 472-484, DOI:
10.1080/07328303.2021.1895195
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JOURNAL OF CARBOHYDRATE CHEMISTRY
2020, VOL. 39, NO. 9, 472–484
https://doi.org/10.1080/07328303.2021.1895195
Synthesis of b-acylamino furans from glucosamine
Zhi-ling Cao, Cong Zhu, Wen-ying Wu, Dan-dan Zhu, Dong Qian, Jian Zhu,
Tian-ge Chang, Mei Sheng, Xiu-li Yang, and Wei-wei Liu
Jiangsu Key Laboratory of Marine Pharmaceutical Compound Screening, Jiangsu Institute of
Marine Resources, Co-Innovation Center of Jiangsu Marine Bio-Industry Technology, Jiangsu
Ocean University, Lianyungang, China
ABSTRACT
ARTICLE HISTORY
Received 18 November 2020
Accepted 21 February 2021
A facile method for the synthesis of a series of novel b-acyla-
mino furans stating from renewable monosaccharide was
achieved. Glucosamine hydrochloride was selectively N-acy-
lated with acyl chlorides in methanol/triethylamine to yield N-
acyl-D-glucosamines, which were subsequently converted into
b-acylamino furans through dehydration and cyclization under
microwave irradiation.
KEYWORDS
Glucosamine; amino furan;
synthesis; acylation;
dehydration
GRAPHICAL ABSTRACT
Introduction
The utilization of renewable resources as raw materials to synthesize
organic compounds has increased over the past few decades. For example,
carbohydrates can be converted into various compounds, such as levulinic
acid, 5-hydroxymethylfurfural, and lactic acid, by acid and/or base cataly-
sis.[1–4] Glucosamine is a natural amino sugar widely found in animals and
microorganisms. As a renewable monosaccharide containing an amino
group, glucosamine has been converted into a-amino acids and other het-
erocyclic chemicals including furan derivatives, pyrazine, and substituted
pyrroles compounds.[5–8]
Amino-substituted furans are important structural units in many natural
and pharmaceutical products.[9–12] Amino-substituted furans also represent
CONTACT Zhi-ling Cao
zhilingcao2013@163.com
Jiangsu Key Laboratory of Marine Pharmaceutical
Compound Screening, Jiangsu Institute of Marine Resources, Co-Innovation Center of Jiangsu Marine Bio-Industry
Technology, Jiangsu Ocean University, Lianyungang, China.
ß 2021 Taylor & Francis Group, LLC

JOURNAL OF CARBOHYDRATE CHEMISTRY
473
Scheme 1. Route for the synthesis of b-acylamino furans.
valuable building blocks for organic synthesis.[13] Literature searches
revealed numerous syntheses of b-amino-substituted furans from acyclic
precursors.[14–17] Several groups have reported the preparation of b-amino-
furan derivatives by methods, e.g. reduction of 3-nitrofurans 3-furoyl azide
to the amines, curtius rearrangement of furoyl azides, and copper-catalysed
amidation of 3-bromofuran using CuI and different amides.[18] Another
interesting and green approach for the preparation of 3-acetamido furan
was based on renewable natural amino sugar. Kerton et al. previously
developed an efficient process for converting N-acetyl-D-glucosamine into
3-acetamido-5-acetylfuran (3A5AF) in medium yield.[5] Chen et al.
described the direct conversion of chitin into a 3A5AF for the first
time.[19–21] 3A5AF is an exciting platform and other green methods for its
synthesis are also developed.[22] However, this single product cannot meet
the need of structural and functional diversity.
In order to develop more amino furan derivatives using ammonia sugar,
we investigated the selective N-acylation of glucosamine (1) to prepare a
series of N-acyl-D-glucosamine derivatives (2). They were then used for the
facile synthesis of b-acylamino furans (3) employing boric acid as the dehy-
dration catalyst (Scheme 1).
Results and discussion
First, we investigated the selective N-acylation of 2-amino group in D-glu-
cosamine 1 to afford N-acyl-D-glucosamine compounds (2) as shown in
Scheme 1. In literature,[23,24] glucosamine hydrochloride was usually N-ace-
tylated with acetic anhydride in 10% methanol or pyridine. However, these
methods sometimes give low yields and involve expensive reagents or tedi-
ous work-up procedures.
Glucosamine salts are soluble in water but difficult to dissolve in ordin-
ary organic solvents. When water was used as a solvent, the N-acylated
product was difficult to be isolated because N-acyl-D-glucosamine can

474
Z.-L. CAO ET AL.
dissolve in both water and common organic solvents. We found that triethyl-
amine could both promote the solubility of glucosamine in methanol and act
as an acid-scavenging reagent, and we decide to use a mixture of methanol
and triethylamine for this reaction. After optimization, the synthesis of vari-
ous N-acyl-D-glucosamine compounds 2a–2h was carried out in methanol
containing 3.0 equivalents of triethylamine in good (49–70%) overall isolated
yields using various acyl chlorides as acylation reagent (Table 1).
Table 1. Synthesis of N-acyl-D-glucosamines 2
.
Entry
1
Acylation reagent
Product
Yield (%)
71
2
3
73
60
4
5
6
7
54
49
58
69
(continued)

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475
Table 1. Continued.
Entry
Acylation reagent
Product
Yield (%)
8
CH3COCl
63
Scheme 2. Possible mechanism involved in the dehydration of glucosamine for the formation
of b-acylamino furans.
Boric acid was an efficient catalyst for the dehydration of pyranose
to furan compounds.[25] Compared to glucose, the dehydration of
N-acyl-D-glucosamine and furan ring formation is different.[26] The pro-
posed reaction pathway for the formation of furan derivatives 3 is shown
in Scheme 2. The borate formation of the C-5 OH group with boric acid
prevented the conversion of the open chain tautomer 4 into a six-mem-
bered ring form, thus facilitating the formation of a furan ring intermediate
5. Due to the conjugation effect with the C-2 N-acetyl group, the first
dehydration proceeds between H-2-H and C-3-OH in 5 to give 6.
Subsequent dehydration involving the C-1-OH group leads to 3-acylamino-
5-(10,20-dihydroxyethyl) furan 8.[6] Finally, higher temperature (220 ꢀC)
induced the elimination of water from C-6-OH and C-5-H to form an enol
intermediate 9, which undergoes tautomerization to give ketones 3. In our

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Z.-L. CAO ET AL.
Table 2. Effect of salts on the yield of 3aa
.
Entry
Catalyst/Salt
Yield/%
1
2
3
4
5
6
7
8
9
B(OH)3/VB1
B2O3/VB1
50
42
37
22
30
34
15
55
51
B(OH)3/KH2PO4
B(OH)3/H3PO4
B(OH)3/Na2SO4
B(OH)3/CaSO4
B(OH)3
B(OH)3/NaCl
B2O3/NaCl
aConditions: 2a (0.57 g) in DMA (10 mL); 2a:B(OH)3 or B2O3:salt ¼ 1:1.5:2; MW 220 ꢀC for 15 min.
study, microwave (MW) heating in dimethylacetamide (DMA) was found
to obviously promote dehydration and shorten the reaction time.
However, when only boric acid was used as the catalyst, the yield of the acy-
lamino furans was relatively low (＜15%). We found that the addition of a salt
with B(OH)3 could significantly increase the yield of target compounds, sug-
gesting that the inorganic salts stabilized one or more of the charged intermedi-
ates or the final product.[25,27] This may also be due to the salting effect, which
results in increased solvent polarity and decreased degradation of furan prod-
uct. The experimental results of the influence of different salts on the reaction
yields are presented in Table 2. Clearly, sodium chloride gave the highest yield
(Table 2, entry 8). In comparison with most inorganic salts, experiments with
thiamin hydrochloride (VB1) also resulted in higher yields, indicating that the
chloride anion might have an influence on the catalytic performance.
Furthermore, boric anhydride (B2O3) appeared to be slightly less effective to
promote the formation of 3a as compared to boric acid (entries 2 and 9).
Eventually, the synthesis of b-acylamino furans was performed with
B(OH)3-NaCl using DMA as solvent and MW at 220 ꢀC for 15 min, and
the results are listed in Table 3. b-Acylamino furan derivatives 3a–3h were
prepared in yield around 27–62%. Further studies are necessary to evaluate
the biological activity of these compounds and their chemical applications.
Experimental section
General procedures
All reagents were provided by the J&K Scientific Co. unless otherwise
specified. All MW reactions were carried out with a Discover SP (CEM)

JOURNAL OF CARBOHYDRATE CHEMISTRY
477
Table 3. Reactions to convert N-acetyl-D-glucosamines 2a–h into 3a–h.
Entry
1
Compound 2
R ¼ Ph
Product
Yield/%
55
3a
3b
2
R ¼ 2-naphthyl
62
3
4
5
6
7
R ¼ 2-chlorophenyl
R ¼ 3-nitrophenyl
R ¼ furan-2-yl
3c
3d
3e
3f
51
43
27
45
49
R ¼ thiophen-2-yl
R ¼ t-butyl
3g
8
R ¼ methyl
3h
53

478
Z.-L. CAO ET AL.
MW reactor. NMR data were obtained using a Bruker Avance 500 MHz
nuclear magnetic resonance instrument with internal TMS as standard.
Infrared (IR) data were measured using a NICOLET IS5 Fourier transform
infrared spectrometer. Mass spectra were performed with an Agilent MSD
SL Trap mass spectrometer with an ESI source. Elemental analysis was per-
formed with the Perkin-Elmer 24 elemental analyzer. Flash chromatography
(FC) was carried out with silica gel (200 ꢁ 400 mesh) as the station-
ary phase.
Synthesis of N-acyl-D-glucosamines (2)
Glucosamine hydrochloride (11.6 mmol) was suspended in methanol
(30 mL) containing triethylamine (34.8 mmol). The mixture was vigorously
stirred at room temperature for 0.5 h, and then cooled to 5 ꢀC before the
precipitates of triethylamine hydrochloride were filtered off. Acyl chloride
(15.0 mmol) was slowly added dropwise into the filtrate over 0.5 h, and
diethyl ether (50 mL) was then added. The mixture was vigorously stirred
in an ice bath to rapidly precipitate. After chilling for 2 h, the solid material
was filtered, washed with ether and dichloromethane, and dried to give
products 2a–2h.
Synthesis of b-acylamino furans (3)
N-Acyl-D-glucosamines (2) (2.0 mmol) and boric acid (3.0 mmol) were dis-
solved in DMA (10 mL), and then sodium chloride (4.0 mmol) was added.
The mixture was heated at 220 ꢀC by MW irradiation at 100 W for 15 min.
The reaction mixture was cooled to room temperature, quenched with a
saturated Na2CO3 solution, and extracted with ethyl acetate. The combined
organic phase was washed with water, brine, and dried over anhydrous
Na2SO4. The solvent was removed under reduced pressure, and the result-
ing solid was purified by column chromatography to afford prod-
ucts 3a–3h.
N-Benzoyl-D-glucosamine (2a)
1
White solid; 71% yield; m.p. 197 ꢁ 200 ꢀC (lit.[28] 198 ꢂ 200 ꢀC); H NMR
(500 MHz, D2O) d 7.71 (d, J ¼ 7.6 Hz, 2H), 7.54 (t, J ¼ 7.4 Hz, 1H), 7.45 (t,
J ¼ 6.8 Hz, 2H), 5.26 (d, J ¼ 3.5 Hz, 0.5 H, H-1 of a anomer), 4.79 (d,
J ¼ 8.5 Hz, 0.5 H, H-1 of b anomer), 4.07 ꢁ 3.41 (m, 6H); 13C NMR
(126 MHz, D2O) d 171.7, 171.4, 133.6, 133.4, 132.3, 132.2, 128.8, 128.7,
127.3, 127.1, 94.9, 90.9, 76.0, 73.9, 71.6, 70.6, 70.2, 70.0, 60.8, 60.6, 57.2,
54.7; IR m: 3424, 3424, 1603, 1467, 1072 cmꢁ1.

JOURNAL OF CARBOHYDRATE CHEMISTRY
479
N-(2-Naphthylacetyl)-D-glucosamine (2b)
1
White solid; 73% yield; m.p. 187 ꢁ 188 ꢀC; H NMR (500 MHz, D2O) d
8.43 (d, J ¼ 7.1 Hz, 1H), 7.98 ꢁ 7.90 (m, 4H), 7.57 (td, J ¼ 12.9, 6.8 Hz, 2H),
5.30 (d, J ¼ 3.5 Hz, 0.7 H, H-1 of a anomer), 4.81 (d, J ¼ 8.4 Hz, 0.3 H, H-1
of b anomer), 4.19 ꢁ 3.36 (m, 6H); IR m: 3334, 3334, 2928, 1636, 1503,
1432, 1081(C ꢁ O) cmꢁ1. ESI-MS m/z: 356 [M þ Na]þ; Anal. calcd. for
C17H19NO6: C, 61.25; H, 5.75; N, 4.20. Found: C, 60.86; H, 5.96; N, 4.33.
N-(2-Chlorine-benzoyl)-D-glucosamine (2c)
1
White solid, 60% yield; m.p. 204 ꢁ 205 ꢀC; H NMR (500 MHz, D2O) d
7.49 ꢁ 7.32 (m, 4H), 5.30 (d, J ¼ 3.5 Hz, 0.6 H, H-1 of a anomer), 4.74 (d,
J ¼ 8.5 Hz, 0.4 H, H-1 of b anomer), 4.06 ꢁ 3.37 (m, 6H); IR m: 3373, 3373,
1644, 1594, 1433, 1080 cmꢁ1. ESI-MS m/z: 340 [M þ Na]þ; Anal. calcd. for
C13H16ClNO6: C, 49.14; H, 5.08; N, 4.41. Found: C, 50.17; H, 5.18; N, 4.30.
N-(3-Nitro-benzoyl)-D-glucosamine (2d)
1
White solid, 54% yield; m.p. 171 ꢁ 173 ꢀC; H NMR (500 MHz, D2O) d
8.57 (dd, J ¼ 4.0, 2.2 Hz, 1H), 8.39 ꢁ 8.34 (m, 1H), 8.10 (d, J ¼ 7.8 Hz, 1H),
7.68 (td, J ¼ 8.0, 3.5 Hz, 1H), 5.28 (d, J ¼ 3.5 Hz, 0.7 H, H-1 of a anomer),
4.81 (d, J ¼ 8.5 Hz, 0.3 H, H-1 of b anomer), 4.11 ꢁ 3.43 (m, 6H); IR m:
3374, 3374, 2926, 1634, 1532, 1080 cmꢁ1; ESI-MS m/z: 329 [M þ H]þ; Anal.
calcd. for C13H16N2O8: C, 47.56; H, 4.91; N, 8.53. Found: C, 47.98; H, 5.00;
N, 8.63.
N-Furoyl-D-glucosamine (2e)
1
White solid, 49% yield; m.p. 94 ꢁ 96 ꢀC; H NMR (500 MHz, D2O) d
7.59 ꢁ 7.56 (m, 1H), 7.08 (t, J ¼ 3.1 Hz, 1H), 6.52 (dt, J ¼ 3.7, 2.0 Hz, 1H),
5.22 (d, J ¼ 3.5 Hz, 0.6 H, H-1 of a anomer), 4.78 (d, J ¼ 8.4 Hz, 0.4 H, H-1
of b anomer), 4.04 ꢁ 3.39 (m, 6H); IR m: 3413, 3413, 1631, 1596,
1075 cmꢁ1. ESI-MS m/z: 296 [M þ Na]þ; Anal. calcd. for C11H15NO7: C,
48.35; H, 5.53; N, 5.13. Found: C, 48.70; H, 5.66; N, 5.10.
N-(2-Thienylcarbonyl)-D-glucosamine (2f)
1
White solid, 58% yield; m.p. 139 ꢁ 141 ꢀC; H NMR (500 MHz, D2O) d
7.70 ꢁ 7.60 (m, 2H), 7.09 (dd, J ¼ 6.0, 2.8 Hz, 1H), 5.21 (d, J ¼ 3.4 Hz,
0.3 H, H-1 of a anomer), 4.76 (d, J ¼ 8.4 Hz, 0.7 H, H-1 of b anomer),
4.02 ꢁ 3.37 (m, 6H); IR m: 3425, 3425, 1609, 1469, 1072 cmꢁ1. ESI-MS m/z:

480
Z.-L. CAO ET AL.
312 [M þ Na]þ; Anal. calcd. for C11H15NO6S: C, 45.67; H, 5.23; N, 4.84.
Found: C, 45.34; H, 5.35; N, 4.95.
N-Trimethylacetyl-D-glucosamine (2 g)
1
White solid, 69% yield; m.p. 177 ꢁ 178 ꢀC; H NMR (400 MHz, D2O) d
5.08 (d, J ¼ 3.5 Hz, 0.5 H, H-1 of a anomer), 4.66 (d, J ¼ 8.5 Hz, 0.5 H, H-1
of b anomer), 3.84 ꢁ 3.33 (m, 6H), 1.09 ꢁ 1.10 (m, 9H); 13C NMR
(126 MHz, D2O) d 183.2, 182.9, 94.9, 90.8, 75.9, 73.6 71.5, 70.4, 70.0, 70.0,
60.7, 60.5, 56.7, 54.1, 38.63, 38.5, 26.5, 26.4; IR m: 3376, 3376, 29þ64, 2914,
1646, 1086 cmꢁ1; ESI-MS: m/z [M þ H]þ Calcd for C11H22N2O6 264.14,
Found 264.21. ESI-MS m/z: 264 [M þ H]þ; Anal. calcd. for C11H21NO6: C,
50.18; H, 8.04; N, 5.32. Found: C, 49.93; H, 8.20; N, 5.41.
N-Acetyl-D-glucosamine (2 h)
White solid; 63% yield; m.p. 202 ꢁ 204 ꢀC (lit.[25] 206 ꢀC); 1H NMR
(500 MHz, D2O) d 5.15 (d, J ¼ 3.5 Hz, 0.5 H, H-1 of a anomer), 4.66 (d,
J ¼ 8.5 Hz, 0.5 H, H-1 of b anomer), 3.9 ꢁ 3.4 (m, 6H), 2.00 (s, 3H) .
3-Benzamido-5-acetylfuran (3a)
1
Yellow solid, 55% yield; m.p.140 ꢁ 141 ꢀC; H NMR (500 MHz, DMSO) d
10.70 (s, 1H), 8.40 (s, 1H), 7.98 (d, J ¼ 7.2 Hz, 2H), 7.59 (dt, J ¼ 29.7,
7.2 Hz, 3H), 7.42 (s, 1H), 2.44 (s, 3H); 13C NMR (126 MHz, DMSO) d
186.5, 165.0, 150.3, 136.4, 133.8, 132.4, 129.0, 128.0, 127.7, 112.1, 26.3; IR
ꢀ: 3430, 1607, 1383, 1073 cmꢁ1. ESI-MS m/z: 252 [M þ Na]þ; Anal. calcd.
for C13H11NO3: C, 68.11; H, 4.84; N, 6.11. Found: C, 68.68; H, 4.99;
N, 6.00.
3-(Naphthalene-2-carboxamido)-5-acetylfuran (3 b)
1
Yellow solid, 62% yield; m.p.142 ꢁ 144 ꢀC; H NMR (500 MHz, DMSO-d6)
d 10.89 (s, 1H), 8.59 (s, 1H), 8.45 (s, 1H), 8.13 ꢁ 8.07 (m, 2H), 8.06 ꢁ 8.01
(m, 2H), 7.70 ꢁ 7.63 (m, 2H), 7.46 (s, 1H), 2.46 (s, 3H); 13C NMR
(126 MHz, DMSO-d6) d 186.6, 165.0, 150.3, 136.5, 134.9, 132.6, 131.2,
129.4, 128.8, 128.5, 128.4, 128.2, 127.8, 127.5, 124.6, 112.1, 26.4; IR ꢀ: 3426,
1606, 1467, 1385, 1071 cmꢁ1. ESI-MS m/z: 302 [M þ Na]þ; Anal. calcd. for
C17H13NO3: C, 73.11; H, 4.69; N, 5.02. Found: C, 73.19; H, 4.85; N, 4.90.

JOURNAL OF CARBOHYDRATE CHEMISTRY
481
3-(2-Chlorobenzamido)-5-acetylfuran (3c)
1
Yellow solid, 51% yield; m.p.115 ꢁ 117 ꢀC; H NMR (500 MHz, DMSO-d6)
d 10.87 (s, 1H), 8.36 (d, J ¼ 0.6 Hz, 1H), 7.63 ꢁ 7.58 (m, 2H), 7.54 (d,
J ¼ 1.7 Hz, 1H), 7.49 (dd, J ¼ 7.4, 1.3 Hz, 1H), 7.29 (d, J ¼ 0.6 Hz, 1H), 2.44
(s, 3H); 13C NMR (126 MHz, DMSO-d6) d 186.5, 164.6, 150.4, 136.3, 136.1,
132.0, 130.5, 130.3, 129.5, 127.8, 127.2, 111.7, 26.4; IR ꢀ: 3426, 1647, 1500,
1373, 1073 cmꢁ1. ESI-MS m/z: 286 [M þ Na]þ; Anal. calcd. for
C13H10ClNO3: C, 59.22; H, 3.82; N, 5.31. Found: C, 59.48; H, 3.70; N, 5.22.
3-(3-Nitrobenzamido)-5-acetylfuran (3d)
1
Yellow solid, 43% yield; m.p.214 ꢁ 215 ꢀC; H NMR (500 MHz, DMSO-d6)
d 11.06 (s, 1H), 8.82 (t, J ¼ 1.8 Hz, 1H), 8.47 (dd, J ¼ 8.1, 1.7 Hz, 1H), 8.42
(d, J ¼ 8.8 Hz, 2H), 7.88 (t, J ¼ 8.0 Hz, 1H), 7.43 (s, 1H), 2.46 (s, 3H); 13C
NMR (126 MHz, DMSO-d6) d 186.5, 162.8, 150.4, 148.3, 136.7, 135.1,
134.5, 130.9, 127.3, 127.0, 122.6, 112.0, 26.4 IR ꢀ: 3425, 1655, 1603, 1375,
1073 cmꢁ1. ESI-MS m/z: 297 [M þ Na]þ; Anal. calcd. for C13H10N2O5: C,
56.94; H, 3.68; N, 10.22. Found: C, 56.58; H, 3.75; N, 10.41.
3-(2-Furoylamido)-5-acetylfuran (3e)
1
Yellow solid, 27% yield; m.p.153 ꢁ 154 ꢀC; H NMR (500 MHz, CDCl3) d
8.30 (s, 1H), 8.14 (s, 1H), 7.56 ꢁ 7.51 (m, 1H), 7.27 (d, J ¼ 3.5 Hz, 1H), 7.22
(s, 1H), 6.59 (dd, J ¼ 3.5, 1.7 Hz, 1H), 2.52 (s, 3H); 13C NMR (126 MHz,
DMSO) d 187.2, 155.6, 150.9, 148.9, 144.6, 136.1, 125.8, 115.8, 112.8, 109.8,
25.9; IR ꢀ: 3425, 1655, 1502, 1368, 1071 cmꢁ1. ESI-MS m/z: 242
[M þ Na]þ; Anal. calcd. for C11H9NO4: C, 60.28; H, 4.14; N, 6.39. Found:
C, 60.32; H, 4.22; N, 6.25.
3-(Thiophene-2-carboxamido)-5-acetylfuran (3f)
1
Yellow solid, 45% yield; m.p.159 ꢂ 160 ꢀC; H NMR (500 MHz, DMSO-d6)
d 10.71 (s, 1H), 8.31 (s, 1H), 7.93 (dd, J ¼ 3.7, 0.9 Hz, 1H), 7.89 (dd,
J ¼ 5.0, 0.9 Hz, 1H), 7.39 (s, 1H), 7.26 (s, 1H), 2.44 (s, 3H); 13C NMR
(126 MHz, DMSO-d6) d 186.5, 159.7, 150.3, 138.9, 136.3, 132.7, 129.7,
128.7, 127.30, 111.9, 26.3; IR ꢀ: 3426, 1648, 1499, 1371, 1069 cmꢁ1. ESI-MS
m/z: 258 [M þ Na]þ; Anal. calcd. for C11H9NO3S: C, 56.16; H, 3.86; N,
5.95. Found: C, 56.42; H, 4.01; N, 5.80.

482
Z.-L. CAO ET AL.
3-Trimethylacetamido-5-acetylfuran (3g)
1
Yellow solid, 49% yield; m.p.126 ꢁ 127 ꢀC; H NMR (500 MHz, DMSO-d6)
d 9.68 (s, 1H), 8.23 (d, J ¼ 0.7 Hz, 1H), 7.33 (d, J ¼ 0.7 Hz, 1H), 2.40 (s,
3H), 1.21 (s, 9H); 13C NMR (126 MHz, DMSO-d6) d 186.4, 176.4, 149.9,
135.9, 127.8, 112.1, 39.0, 27.6, 26.3; IR ꢀ: 3390, 1657, 1503, 1369,
1076 cmꢁ1. ESI-MS m/z: 232 [M þ Na]þ; Anal. calcd. for C11H15NO3: C,
63.14; H, 7.23; N, 6.69. Found: C, 63.22; H, 7.45; N, 6.85.
[29,30]
3-Acetamido-5-acetylfuran (3 h)
1
Yellow solid, 53% yield; m.p.120 ꢁ 122 ꢀC; H NMR (500 MHz, DMSO-d6)
d 10.23 (s, 1H), 8.18 (s, 1H), 7.19 (s, 1H), 2.41 (s, 3H), 2.03 (s, 3H); 13C
NMR (126 MHz, DMSO-d6) d 186.5, 168.1, 150.2, 135.71, 127.5, 111.4,
26.3, 23.3; IR ꢀ: 3440(NH), 1631(C ¼ O), 1488(C ¼ C), 1045 (C ꢁ O) cmꢁ1.
Conclusion
Glucosamine hydrochloride was selectively N-acylated to yield N-acyl-D-glu-
cosamines, which were transformed into a series of novel b-acylamino fur-
ans by cyclization and dehydration under MW irradiation. Glucosamine
hydrochloride is industrially produced by the hydrolysis of chitin. Thus,
synthesis of b-acylamino furans from glucosamine hydrochloride is prefer-
able and convenient. This method will also help in the development of util-
ization of marine amino sugar for the synthesis of value-added products.
Funding
The work described in this article was supported by the Natural Science Foundation of
Jiangsu Province [BK20141246], the PAPD Program (A Project Funded by the Priority
Academic Program Development of Jiangsu Higher Education Institutions), the
Postgraduate Research and Practice Innovation Program of Jiangsu Province [SJCX20-1220,
SJCX20-1225, SJCX20-1232] and the Open-end Funds of Jiangsu Institute of Marine
Resources [JSIMR201513].
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