LETTER
Fluorination using Hydrous Nickel Difluoride
2415
(5) Fang, R. H.; Zhou, Y. G.; Zhang, W. X.; Hou, X. L.; Dai,
L. X. J. Org. Chem. 2004, 69, 335.
(6) (a) Lee, S. J.; Oh, S. J.; Chi, D. Y.; Lee, B. S.; Ryu, J. S.;
Moon, D. H. J. Label Compd. Radiopharm. 2008, 51, 80.
(b) Kim, D. W.; Ahn, D. S.; Oh, Y. H.; Lee, S.; Kil, H. S.
J. Am. Chem. Soc. 2006, 128, 16394.
(7) Fang, R. H.; Hou, X. L. Org. Biomol. Chem. 2003, 1, 1565.
(8) Complete dehydration of NiF24H2O needs vigorous
condition: heating it to 500 °C under an atmosphere of HF.
(9) Typical Procedure for the Ring Opening of Aziridine
with Partially Hydrated Nickel Difluoride: To a stirred
solution of aziridine 1a (0.5 mmol) and partially hydrated
nickel difluoride (NiF2nH2O, n <4, 1.68 g, approx. 1 mmol)
in i-PrOH (3.0 mL) was added Bu4NF (0.1 mmol), and
the mixture was stirred at 90 °C until 1a was consumed
(monitored by TLC). The mixture was filtered by short silica
gel column and washed with CH2Cl2, then the solvent was
removed in vacuum and the residue was purified by flash
column chromatography on silica gel to yield 2a as a white
amorphous solid.
amide under nearly neutral condition using safe and easy-
to-handle fluorine source was developed.
Acknowledgment
This research was financially supported by the National Natural
Science Foundation of China (No. 20872031).
References
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N-(2-Fluorocyclohexyl)-4-methylbenzenesulfonamide
(2a): 82% yield; mp 95–96 °C (lit.5 95–97 °C). 1H NMR
(600 MHz, CDCl3, 25 °C, TMS): δ = 1.22–1.26 (m, 4 H),
1.57–1.70 (m, 2 H), 2.01–2.13 (m, 2 H), 2.43 (s, 3 H), 3.17
(m, 1 H), 4.15, 4.25 (double multiplet, 2JHF = 50.1 Hz, 1 H),
4.81 (d, J = 5.4 Hz, 1 H), 7.30 (d, J = 7.8 Hz, 2 H), 7.76 (d,
J = 8.4 Hz, 2 H). 19F NMR (600 MHz, CDCl3, 25 °C,
CF3COOH): δ = –179.3. IR (KBr): 3302, 2951, 1598, 1327,
1163, 1091, 1045, 893, 816, 667, 572, 551 cm–1.
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Dai, L.-X.; Hou, X.-L. Synlett 2004, 2218.
© Georg Thieme Verlag Stuttgart · New York
Synlett 2012, 23, 2413–2415