Synlett 2020; 31(06): 605-609
DOI: 10.1055/s-0039-1690736
cluster
© Georg Thieme Verlag Stuttgart · New York

Metal-Free 1,2,3-Triazole Synthesis in Deep Eutectic Solvents

Filip Sebest
,
Samuel Haselgrove
,
Andrew J. P. White
,
Imperial College London, Department of Chemistry, MSRH, 80 Wood Lane, White City, London, W12 0BZ, UK
› Author Affiliations
This research was financially supported by Imperial College London and by the Engineering and Physical Sciences Research Council (EPSRC) (DTP studentship to F.S. and EP/K030760).
Further Information

Publication History

Received: 08 September 2019

Accepted after revision: 14 October 2019

Publication Date:
05 November 2019 (online)


Published as part of the ISySyCat2019 Special Issue

Abstract

The metal-free regioselective preparation of 1,5- and 1,4-disubstituted triazoles is reported through a cycloaddition–elimination sequence. Reactions were carried out in environmentally friendly deep eutectic solvent (DES) and pure products were isolated without the need for chromatographic techniques.

Supporting Information

 
  • References and Notes

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  • 18 See the Supporting Information for further details.
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  • 21 CCDC 1949637 contains the supplementary crystallographic data for this paper. The data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/getstructures.
  • 22 Procedure for the Preparation of 5-methyl-1-[4-(trifluoromethyl)phenyl]-1H-1,2,3-triazole (2a): 1,1,3,3-Tetramethylguanidine (0.25 mL, 2 mmol) was added into a solution of 1-azido-4-trifluoromethylbenzene (0.37 g, 2 mmol) and 2-methoxypropene (0.77 mL, 8 mmol) in DES (4 mL) in a vial that was fitted with a screw cap. The mixture was stirred vigorously at 90 °C for 24 h before being allowed to cool to room temperature and diluted with water (8 mL). The aqueous layer was extracted with EtOAc (3 × 6 mL) and the combined organic layers were washed with water and brine, dried over MgSO4, filtered and concentrated under reduced pressure to give crude product that was washed with ice-cold pentane to yield the title compound (0.35 g, 77%) as a pale-brown solid; mp 104.6–107.1 °C. IR: 3091, 3004, 2984, 1615 (m), 1525, 1443, 1421 (m), 1413 (m), 1323 (m), 1267 (m), 1233, 1209, 1180, 1156 (m), 1114 (s), 1087 (m), 1067 (s), 1043 (m), 1035 (m), 1009 (m), 972 (m), 862, 847 (s), 825 (s), 781, 707, 698, 657 (m) cm–1. 1H NMR (CDCl3, 400 MHz): δ = 7.84 (d, J = 8.5 Hz, 2 H), 7.66 (d, J = 8.5 Hz, 2 H), 7.62 (s, 1 H), 2.42 (s, 3 H). 13C NMR (CDCl3, 100 MHz): δ = 139.2, 133.9, 133.3, 131.4 (q, J = 33 Hz), 126.8 (q, J = 3 Hz), 125.0, 123.5 (q, J = 273 Hz), 9.5. 19F NMR (CDCl3, 377 MHz): δ = –62.8 (s). HRMS (ESI): m/z [M + H]+ calcd for C10H9N3F3: 228.0749; found: 228.0753.
  • 23 Sebest F, Haselgrove S, White AJ. P, Díez-González S. Imperial College Research Services Data Repository; UK: 2019. DOI: 10.14469/hpc/6043 and sub-collections therein