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Synlett 2009(19): 3163-3166  
DOI: 10.1055/s-0029-1218346
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

The Use of Calcium Carbide in the Synthesis of 1-Monosubstituted Aryl 1,2,3-Triazole via Click Chemistry

Yubo Jianga, Chunxiang Kuang*a, Qing Yangb
a Department of Chemistry, Tongji University, Siping Road 1239, Shanghai 200092, P. R. of China
Fax: +86(21)65983191; e-Mail: kuangcx@tongji.edu.cn;
b Department of Biochemistry, School of Life Sciences, Fudan University, Handan Road 220, Shanghai 200433, P. R. of China
Further Information

Publication History

Received 28 August 2009
Publication Date:
03 November 2009 (online)

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Abstract

The synthesis of 1-monosubstituted aryl 1,2,3-triazoles was achieved using calcium carbide as a source of acetylene. The copper-catalyzed 1,3-dipolar cycloaddition reactions were carried out without nitrogen protection and in a MeCN-H2O mixture. The yields ranged from moderate to excellent. The reaction conditions were found to be successful for aryl azide reactants, including analogues with various functionalities.

Key words

calcium carbide - 1-monosubstitued 1,2,3-triazole - copper-catalyzed - click chemistry

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General Procedure for the Synthesis of 2 (Conditions A)
To a flask were added MeCN-H2O mixture (12 mL
v/v = 2:1), azide (0.5 mmol), CuI (19 mg, 0.1 mmol), Na ascorbate (20 mg, 0.1 mmol), CaC2 (42 mg, 0.65 mmol). The mixture was stirred at r.t., and the reaction was monitored by TLC. After reaction completed, the system was neutralized to pH = 5 with aq HCl (6%), and the mixture was then extracted with EtOAc (3 × 30 mL). The organic layer was separated, washed with H2O and sat. brine, and dried over anhyd NaSO4. Evaporation of the solvent gave the crude product, which was subjected to column chromatography (silica gel, EtOAc-PE) to afford 1-substitued 1,2,3-triazoles 2.

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General Procedure for the Synthesis of 2 (Conditions B)
To a sealed tube were added MeCN-H2O mixture (12 mL
v/v = 2:1), azide (0.5 mmol), CuI (19 mg, 0.1 mmol), Na ascorbate (20 mg, 0.1 mmol), CaC2 (42 mg, 0.65 mmol). The mixture was stirred at 90 ˚C, and the reaction was monitored by TLC. After reaction completed, the system was neutralized to pH = 5 with aq HCl (6%), and the mixture was then extracted with EtOAc (3 × 30 mL). The organic layer was separated, washed with H2O and sat. brine, and dried over anhyd NaSO4. Evaporation of the solvent gave the crude product, which was subjected to column chromatography (silica gel, EtOAc-PE) to afford
1-substitued 1,2,3-triazoles 2.

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All compounds gave satisfactory analytical and spectral data.
Selected Data
(E)-1-[4-(2-Bromovinyl)phenyl]-1H-1,2,3-triazole (2j): yellow solid, mp 147.8-148.1 ˚C. IR (KBr): 1599, 1511, 1435, 977, 783 cm-¹. ¹H NMR (500 MHz, CDCl3): δ = 8.00 (1 H, s), 7.85 (1 H, s), 7.73 (2 H, d, J = 9.0 Hz), 7.46 (2 H, d, J = 9.0 Hz), 7.16 (1 H, d, J = 13.8 Hz), 6.88 (1 H, d, J = 13.8 Hz). ¹³C NMR (125 MHz, CDCl3): δ = 136.5, 136.4, 135.7, 134.5, 127.3, 121.5, 120.8, 108.3. ESI-MS: m/z (%) = 251(99) [M + 2]+, 249(100) [M+]. HRMS: m/z calcd for C10H8 79BrN3: 248.9902; found: 248.9906
(E)-1-[2-(2-Bromovinyl)phenyl]-1H-1,2,3-triazole (2k): yellow solid, mp 100.9-101.5 ˚C. IR (KBr): 1609, 1496, 1507, 1447, 1193, 983, 783 cm-¹. ¹H NMR (500 MHz, CDCl3): δ = 7.89 (1 H, s), 7.80 (1 H, s), 7.59-7.57 (1 H, m), 7.52-7.46 (2H, m), 7.42 (1 H, d, J = 8.0 Hz), 6.84 (1 H, d, J = 14.0 Hz), 6.78 (1 H, d, J = 14.0 Hz). ¹³C NMR (125 MHz, CDCl3): δ = 134.3, 134.0, 131.7, 131.6, 130.1, 129.1, 127.1, 126.5, 125.7, 110.6. ESI-MS: m/z (%) = 251(99)
[M + 2]+, 249(100) [M+]. HRMS: m/z calcd for C10H8 79BrN3: 248.9902; found: 248.9908.