C. Urban, F. Cadoret, J.-C. Blazejewski, E. Magnier
FULL PAPER
ter stirring for 13 h, MeOH was removed under reduced pressure,
and the residue was dissolved in water (50 mL). The aqueous layer
was extracted with CH2Cl2 (3ϫ50 mL), and the combined organic
layers were dried with MgSO4 and concentrated under reduced
pressure to furnish an oil which was washed with a pentane/Et2O
solution (85:15, 3ϫ30 mL). Compound 9a was obtained as a white
solid (30 mg, 3%). 19F NMR (188 MHz, CDCl3): δ = –154.3 (s, 4
F), –49.7 and –46.4 (AB system, JAB = 149 Hz, 2 F) ppm. 1H NMR
(200 MHz, CDCl3): δ = 3.42 (s, 6 H), 8.05 (t, J = 8.5 Hz, 2 H),
8.27 (t, J = 7.1 Hz, 1 H), 8.40 (d, J = 8.3 Hz, 2 H) ppm. 13C NMR
(75 MHz, CDCl3): δ = 35.4, 41.4 (d, J = 1.6 Hz), 126.4 (dd, J =
367, 340 Hz, CF2), 126.9, 129.3, 130.4, 132.7, 133.3, 141.7 ppm.
MS (ESI+, for 79Br): m/z = 298 [M]+. HRMS: calcd. for
C9H1179BrF2NOS [M]+ 297.9713; found 297.9729 (Δ = 5.4 ppm).
2-(Chloroethynyl)-6-methoxynaphthalene (11b): MS (ESI+, for
35Cl): m/z = 216 [M]+. HRMS: calcd. for C13H9O35Cl [M]+
216.0342; found 216.0343 (Δ = 0.5 ppm).
Supporting Information (see footnote on the first page of this arti-
cle): Copies of the NMR spectra of all the compounds.
Acknowledgments
C. U. thanks the French Ministry of Research for a Ph.D. grant.
François Metz (Rhodia Company) is gratefully acknowledged for
the gift of fluorinated reagents.
N,N-(Dimethylamino)-S-phenyl-S-dichlorofluoromethyloxosulfon-
ium Tetrafluoroborate (9b): 19F NMR (188 MHz, CDCl3): δ =
–154.4 (s, 4 F), –52.2 (s, 1 F) ppm. H NMR (200 MHz, CDCl3):
δ = 3.46 (s, 6 H), 8.04 (t, J = 7.9 Hz, 2 H), 8.25 (t, J = 7.5 Hz, 1
H), 8.45 (d, J = 8.1 Hz, 2 H) ppm. 13C NMR (75 MHz, CDCl3): δ
= 35.4, 41.7 (d, J = 1.6 Hz), 128.4 (d, J = 298 Hz, CF), 132.6 (d,
J = 2.2 Hz), 133.1, 133.7, 141.5 ppm. MS (ESI+, for 35Cl): m/z =
270 [M + H]+. HRMS: calcd. for C9H1135Cl2FNOS [M + H]+
269.9922; found 269.9908, (Δ = –5.2 ppm).
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1
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General Procedure for the Electrophilic Fluoromethylation as Exem-
plified by the Preparation of 2-(3-Bromo-3,3-difluoropropynyl)-6-
methoxynaphthalene (13): Under an argon atmosphere, butyllith-
ium (1.6 m solution, 0.15 mL, 1.0 equiv.) was added to a solution
of phenylacetylene (44 mg, 0.24 mmol, 1.0 equiv.) in THF (1 mL)
at 0 °C. After 15 min, the mixture was cooled to –78 °C, and 7a
(50 mg, 0.12 mmol, 0.50 equiv.) in THF (1 mL) was added. After
1 h, the mixture was gradually warmed to room over 1 h. Water
was then added, and the product extracted with Et2O (3ϫ10 mL)
and washed with a brine solution. The combined organic phases
were dried with MgSO4, and the solvents were evaporated under
vacuum. Purification by PTLC (preparative TLC, pentane/CH2Cl2,
80:20) afforded 13 (16 mg, 43%) and 14 (8 mg, 23%).
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2-(3-Bromo-3,3-difluoropropynyl)-6-methoxynaphthalene (13a): Yel-
low powder; m.p. 58–60 °C. 19F NMR (188 MHz, CDCl3): δ =
–31.1 (s, 2 F) ppm. 1H NMR (200 MHz, CDCl3): δ = 3.95 (s, 3 H),
7.14 (d, J = 2.5 Hz, 1 H), 7.22 (dd, J = 9.0, 2.6 Hz, 1 H), 7.51 (dd,
J = 8.5, 1.4 Hz, 1 H), 7.74 (d, J = 9.2 Hz, 2 H), 8.04 (s, 1 H) ppm.
13C NMR (75 MHz, CDCl3): δ = 55.4, 80.6 (t, J = 38 Hz), 90.0 (t,
J = 6 Hz), 102.1 (t, J = 287 Hz), 105.8, 113.3, 120.1, 127.2, 128.0,
128.1 (t, J = 1.9 Hz), 129.7, 133.1 (t, J = 2.5 Hz), 135.4, 159.3 ppm.
MS (ESI+, for 79Br): m/z = 311 [M + H]+. HRMS: calcd. for
C14H10O79BrF2 [M + H]+ 310.9883; found 310.9893 (Δ = 3.2 ppm).
[12] Y. Macé, C. Urban, C. Pradet, J. Marrot, J.-C. Blazejewski, E.
Magnier, Eur. J. Org. Chem. 2009, 3150–3153; for other ap-
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[14] The structure of these unfluorinated byproducts retaining an
aromatic skeleton is under study.
[15] As already noted by Hu and co-workers, a stoichiometric or
an excess amount of the electrophilic reagent was detrimental
to the yield.
[16] Sulfoximine 7c was entirely recovered at the end of the process.
[17] The use of sulfoximine 1 was not considered because of its very
poor solubility under the reaction conditions.
2-(Bromoethynyl)-6-methoxynaphthalene (11a): Yellow powder;
m.p. 94–96 °C. 1H NMR (200 MHz, CDCl3): δ = 3.93 (s, 3 H), 7.14
(m, 2 H), 7.45 (dd, J = 8.6, 1.6 Hz, 1 H), 7.66 (m, 2 H), 7.91 (s, 1
H) ppm. 13C NMR (75 MHz, CDCl3): δ = 49.1, 55.4, 80.6, 105.8,
117.5, 119.5, 126.9, 128.3, 129.0, 129.3, 132.0, 134.3, 158.5 ppm.
MS (ESI+, for 79Br): m/z = 260 [M]+, 261 [M + H]+. HRMS: calcd.
for C13H10O79Br [M + H]+ 260.9915; found 260.9930 (Δ =
5.7 ppm).
2-(3,3-Chloro-3-fluoropropynyl)-6-methoxynaphthalene (13b): 19F
NMR (188 MHz, CDCl3): δ = –33.9 (s, 1 F) ppm. 1H NMR
(200 MHz, CDCl3): δ = 3.93 (s, 3 H), 7.13 (m, 2 H), 7.44 (dd, J =
8.6, 1.5 Hz, 1 H), 7.68 (m, 2 H), 7.9 (s, 1 H) ppm. MS (ESI+, for
35Cl): m/z = 282 [M]+, 283 [M + H]+. HRMS: calcd. for
C14H10O35Cl2F [M + H]+ 283.0093; found 283.0095 (Δ = 0.7 ppm).
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Eur. J. Org. Chem. 2011, 4862–4867