JOURNAL OF CHEMICAL RESEARCH 2018 249
1
3
substrate 2-iodopyridine, which afforded a yield of 87% of
-azidopyridine after 4.5 h.
2H), 7.07–7.03 (m, 1H), 2.22 (s, 3H); C NMR (100 MHz, CDCl ): δ
3
2
138.4, 131.2, 129.6, 127.1, 124.6, 117.9, 17.3.
,4,6-Trimethylphenyl azide (Table 3, entry 9): Light yellow liquid;
yield 78%; H NMR (400 MHz, CDCl ): δ 6.86 (s, 2H), 2.35 (s, 6H),
2
6
2
1
Conclusions
3
13
2
.28 (s, 3H); C NMR (100 MHz, CDCl ): δ 135.3, 134.4, 131.9, 129.5,
In summary, aryl azides were efficiently synthesised in moderate
to excellent yields in short times by the coupling reaction of aryl
iodides with sodium azide using a Cu(OAc) ·H O (10 mol%)/
3
2
0.7, 18.1.
2
4
6
-Chlorophenyl azide (Table 3, entry 10): Colourless oil; yield 75%;
H NMR (400 MHz, CDCl ): δ 7.37 (d, J = 8.0 Hz, 1H), 7.31–7.27 (m,
H), 7.17 (d, J = 8.1 Hz, 1H), 7.08 (t, J = 8.0 Hz, 1H); C NMR (100
MHz, CDCl ): δ 137.2, 130.8, 127.9, 125.6, 125.0, 119.7.
-Hydroxyphenyl azide (Table 3, entry 11): Brown liquid; yield
2
2
1
3
DBU (15 mol%) catalytic system. The established method was
suitable for both electron-rich and electron-deficient aryl iodides.
13
1
3
4
7
2
Experimental
1
7
1%; H NMR (400 MHz, CDCl ): δ 7.08–7.03 (m, 2H), 6.95–6.91 (m,
3
13
All reagents were purchased from commercial sources and used
without further treatment, unless otherwise indicated. The products
2
H); C NMR (100 MHz, CDCl ): δ 147.4, 126.0, 126.0, 121.2, 118.4,
3
1
16.0.
2
1
13
were characterised using H NMR and C NMR (Bruker Avance
00 MHz and Bruker Avance III HD 600 MHz) which used CDCl3
2
8
-Fluorophenyl azide (Table 3, entry 12): Brown liquid; yield 71%;
H NMR (400 MHz, CDCl ): δ 7.14–7.05 (m, 4H); C NMR (100 MHz,
CDCl ): δ 154.9 (d, J = 165 Hz, 1C), 128.0 (d, J = 8 Hz, 1C), 125.8 (d,
J = 5 Hz, 1C), 124.9 (d, J = 3 Hz, 1C), 121.1, 116.7 (d, J = 6 Hz, 1C).
-Nitro-4-methylphenyl azide (Table 3, entry 13): Light yellow
solid; m.p. 70–71 ºC (lit. 67–68 ºC); yield 60%; H NMR (400 MHz,
CDCl ): δ 7.63 (s, 1H), 7.33 (d, J = 8.2 Hz, 1H), 7.16 (d, J = 8.4 Hz, 1H),
2.57 (s, 3H); C NMR (100 MHz, CDCl ): δ 149.7, 139.3, 134.1, 130.0,
4
1
13
3
as the solvent. Data are represented as follows: chemical shift,
integration, multiplicity (s = singlet, d = doublet, dd = double of
doublets, t = triplet, q = quartet, m = multiplet) and coupling constants
3
4
8
3
1
13
(
J) in Hertz (Hz). H NMR and C NMR spectra of the products are
4
8
1
given in the Electronic Supplementary Information.
3
13
Synthesis of aryl azides; general procedure
3
1
23.4, 115.2, 20.0.
CAUTION: Azides are potentially explosive and so appropriate
precautions against blast must be taken when preparing, handling
and heating them. Reactions must be carried out on a small scale.
25
4
-Nitrophenyl azide (Table 3, entry 14): Yellow solid; m.p.
9–70 ºC (lit. 63–66 ºC); yield 90%; H NMR (600 MHz, CDCl ): δ
.25 (d, J = 9.0 Hz, 2H), 7.14 (d, J = 9.0 Hz, 2H); C NMR (151 MHz,
25
1
6
3
13
8
A mixture of the aryl iodide (1.0 mmol), sodium azide (1.2 mmol),
DBU (0.15 mmol) and Cu(OAc) ·H O (0.1 mmol) in DMSO (3.0 mL)
CDCl ): δ 146.9, 144.6, 125.6, 119.4.
3
4
9
3-Nitrophenyl azide (Table 3, entry 15): Yellow solid; m.p.
2
2
49
1
in a 10 mL flask was heated to 95 ºC (the temperature in the reaction
flask was monitored) for 1.5–5.0 h. After the reaction was completed as
judged by TLC, the cooled mixture was poured into water (30 mL)
containing several drops of ammonia. The resulting aqueous phase was
extracted with ethyl acetate (3 × 30 mL). The combined organic phases
were washed with brine (50 mL), dried over anhydrous Na SO and
56–57 ºC (lit. 53.1–54.5 ºC); yield 85%; H NMR (600 MHz, CDCl ):
3
δ 8.01–8.00 (m, 1H), 7.89 (t, J = 2.2 Hz, 1H), 7.54 (t, J = 8.1 Hz, 1H),
13
7.36–7.34 (m, 1H); C NMR (151 MHz, CDCl ): δ 149.2, 142.0, 130.6,
3
124.9, 119.7, 114.1.
2-Azidopyridine: Yellow liquid; yield 87%; H NMR (600 MHz,
5
0
1
CDCl ): δ 8.40 (dd, J = 4.8, 1.7 Hz, 1H), 7.65 (td, J = 7.7, 2.0 Hz, 1H),
2
4
3
1
3
concentrated under reduced pressure. The residue was loaded on a
silica gel column and eluted with petroleum ether (boiling range
7.33 (d, J = 8.0 Hz, 1H), 7.23–7.21 (m, 1H); C NMR (151 MHz,
CDCl ): δ 151.6, 149.8, 138.7, 124.5, 122.2.
3
6
0–90 °C)/ethyl acetate to afford the product.
Phenyl azide (Table 3, entry 1): Light yellow liquid; yield 92%;
2
8
Acknowledgements
1
H NMR (400 MHz, CDCl ): δ 7.38–7.34 (m, 2H), 7.14 (t, J = 7.4 Hz,
H), 7.03 (d, J = 7.6 Hz, 2H); C NMR (100 MHz, CDCl ): δ 140.0,
29.8, 124.9, 119.0.
This work was supported financially by the Innovative Talents
Programme of Henan Province (Nos 164100510015 and
174100510025), the Foundation of Henan Educational Committee
3
13
1
1
3
2
8
4
-Methylphenyl azide (Table 3, entry 2): Light yellow liquid; yield
(
Nos 18A150030, 15A150054 and 16A350015), the Scientific Research
1
8
7%; H NMR (400 MHz, CDCl ): δ 7.16 (d, J = 8.2 Hz, 2H), 6.93 (d,
3
13
Foundation for Doctors (No. qd16106) and the Youth Foundation (No.
2016QK09) of Henan Normal University.
J = 8.4 Hz, 2H), 2.34 (s, 3H); C NMR (100 MHz, CDCl ): δ 137.1,
3
134.6, 130.4, 118.9, 20.9.
2
8
4
-Methoxyphenyl azide (Table 3, entry 3): Yellow liquid; yield
Electronic Supplementary Information
1
8
2
5%; H NMR (400 MHz, CDCl ): δ 6.97–6.95 (m, 2H), 6.90–6.88 (m,
1
13
3
13
H), 3.80 (s, 3H); C NMR (100 MHz, CDCl ): δ 157.0, 132.3, 120.0,
3
115.1, 55.6.
2
8
4
-Bromophenyl azide (Table 3, entry 4): White solid; m.p. 24–25 ºC
4
4
1
(
2
1
lit. 20 ºC); yield 88%; H NMR (400 MHz, CDCl ): δ 7.46–7.44 (m,
3
13
Received 13 January 2018; accepted 16 April 2018
Paper 1805192
Published online: 30 May 2018
H), 6.91–6.89 (m, 2H); C NMR (100 MHz, CDCl ): δ 139.2, 132.8,
3
20.7, 117.8.
4
5
4
-Ethoxyphenyl azide (Table 3, entry 5): Light yellow liquid; yield
1
8
0%; H NMR (400 MHz, CDCl ): δ 6.96–6.94 (m, 2H), 6.89–6.87
3
13
(m, 2H), 4.01 (q, J = 7.0 Hz, 2H), 1.42 (t, J = 7.0 Hz, 3H); C NMR (100
References
MHz, CDCl ): δ 156.3, 132.1, 119.9, 115.7, 63.8, 14.8.
3
4
5
1
2
3
4
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3
,4-Dimethylphenyl azide (Table 3, entry 6): Greenish yellow
liquid; yield 90%; H NMR (400 MHz, CDCl ): δ 7.10 (d, J = 8.0 Hz,
H), 6.81 (s, 1H), 6.77 (d, J = 8.0 Hz, 1H), 2.25 (s, 3H), 2.24 (s, 3H);
1
3
1
1
3
C NMR (100 MHz, CDCl ): δ 138.3, 137.3, 133.4, 130.8, 120.0, 116.3,
3
1
9.9, 19.2.
3
5
6
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2
4
-Chlorophenyl azide (Table 3, entry 7): Light yellow liquid;
yield 85%; H NMR (400 MHz, CDCl ): δ 7.30–7.26 (m, 1H), 7.12 (d,
J = 8.0 Hz, 1H), 7.03 (t, J = 2.0 Hz, 1H), 6.93 (dd, J = 8.1, 2.1 Hz, 1H);
C NMR (100 MHz, CDCl ): δ 141.5, 135.4, 130.7, 125.1, 119.3, 117.2.
-Methylphenyl azide (Table 3, entry 8): Light yellow liquid; yield
5%; H NMR (400 MHz, CDCl ): δ 7.26–7.22 (m, 1H), 7.18–7.11 (m,
1
3
7
2
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13
3
8
9
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2
8
2
1
7
3