J. Leroy et al. / Journal of Fluorine Chemistry 125 (2004) 1379–1382
1381
4. Experimental
was extracted with chloroform (3 Â 10 mL) and the organic
phase washed with water (10 mL) then brine (10 mL) and
dried over MgSO4. Evaporation of the solvent furnished
aldehyde 1 as an off-white powder (0.62 g, 2.04 mmol,
89%). Sublimation of the product at 70–80 8C under
1 mmHg gave slightly more pure compound 1 (0.56 g):
m.p. 130.5–131.5 8C; 1H NMR (250 MHz, CDCl3): d
10.28 (s); 19F NMR (235 MHz, CDCl3): d ꢁ117.8 (m,
2F), ꢁ143.2 (m, 2F); 13C NMR (63 MHz, CDCl3): d 80.7
(t, J ¼ 27:7 Hz, C-4), 115.3 (t, J ¼ 10 Hz, C-1), 145.5 (dm,
J ¼ 266 Hz, C-2), 147.2 (dm, J ¼ 248 Hz, C-3), 181.9
(quint, J ¼ 3 Hz, CHO); IR (neat): n 1693(s), 1655(m),
1630(w), 1472(s), 1440(m), 1415(m), 1284(w), 1266(m),
1032(m), 962(m), 768(w) cmꢁ1; MS (EI) m/z (rel. int.): 304
[M]þ (100), 303 [M–H]þ (48), 275 [M–H–CO]þ (5), 148
[M–H–CO–I]þ (9). Anal. calcd. for C7HIF4O: C, 27.7; H,
0.3; F, 25.0; I, 41.7. Found: C, 27.8; H, 0.4; F, 24.95; I, 41.7.
NMR spectra were recorded on a Bruker AC 250 spectro-
meter. 1H NMR chemical shifts are reported using the
residual protiochloroform as reference (7.24 ppm). 19F
NMR chemical shifts are given relative to internal CFCl3
as reference. 13C NMR chemical shifts are reported using
13CDCl3 as reference (77.0 ppm). Mass spectra were
recorded on a Jeol JMS-700 spectrometer. IR spectra were
recorded on a Tensor 27 (Miracle Ge) spectrometer and the
UV-Vis spectra on a Beckmann DU 7400 spectrophot-
ometer. Elemental analyses were conducted by the Service
de Microanalyse, CNRS (Gif-sur-Yvette and Lyon).
4.1. 2-(2,3,5,6-Tetrafluoro-4-iodo-phenyl)-[1,3]dioxolane
(5)
A dry 100 mL four-necked flask under argon, equipped
with a magnetic stir bar and a dropping funnel, was charged
with dry THF (22 mL) and acetal 4 [5] (1.50 g, 6.75 mmol).
The solution was cooled to ca. ꢁ72 8C and n-BuLi
(4.25 mL, 1.75 M, 7.44 mmol) was added via syringe in
ca. 10 min (temperature was kept below ꢁ60 8C) giving a
yellow gold solution. After 1 h at ꢁ72 8C, a solution of
iodine (1.88 g, 7.41 mmol) in dry THF (6 mL) was added
dropwise via the funnel. Concomitant rapid fading of the
brown solution occurred while keeping the temperature
below ca. ꢁ65 8C. At the end of the addition the light
yellow solution was allowed to reach rt then washed with
saturated aqueous NaHCO3 (5 mL). After separation, THF
(10–20 mL) was added to the organic phase which was
washed with 0.5 M aqueous Na2S2O3 (5 mL). Brine
(10 mL) was added to the mixture making decantation
easier. After drying over MgSO4, evaporation of the solvent
afforded an off white solid (2.21 g) which was recrystallized
at ꢁ20 8C from boiling n-pentane (40 mL) to yield 5 as
colourless small plates (1.54 g, 4.42 mmol, 66%),
m.p. 106.5–107 8C. A second crop was obtained from the
4.3. 5,10,15,20-Tetrakis(2,3,5,6-tetrafluoro-4-iodo-
phenyl)porphyrin (6)
The aldehyde 1 (0.354 g, 1.16 mmol), pyrrole (0.081 mL,
1.16 mmol) and dichloromethane (125 mL) were placed
under argon in a 250 mL round-bottom flask equipped
with a magnetic stirring bar. The mixture was stirred while
BF3 etherate (0.5 mL, 3.95 mmol) was added at once via a
syringe. After 1 h, 2,3-dichloro-5,6-dicyano-1,4-benzoqui-
none (0.55 g) then pyridine (1.6 mL) were added. The reac-
tion mixture was stirred overnight (12–15 h) then filtered
through a short silica gel column using dichloromethane as
eluent. After evaporation of the solvent, the resulting brown
solid was purified by flash column chromatography (50 mm Â
200 mm column, Merck 9385 silica gel, 40–63 mm) with
chloroform as eluent. The head fraction (Rf ꢂ 0:90 by
TLC) was collected and evaporated affording porphyrin 6
as a dark-brown solid (0.070 g, 0.050 mmol, 17%): 1H NMR
(250 MHz, CDCl3): d ꢁ2.92 (s, 2H, NH), 8.91 (s, 8H, b-H);
19F NMR (235 MHz, CDCl3): d ꢁ120.3 (ꢂq, 2F, J ¼ 12 Hz),
ꢁ135.6 (ꢂq, 2F, J ¼ 12 Hz); UV-Vis (CH2Cl2): lmax (nm)
415, 508, 584. HRMS (CI þ NH3) calcd. for C44H11F16I4N4
(M þ H) 1406.6900. Found 1406.6896.
1
mother liquor (0.2 g, total isolated yield 74%): H NMR
(250 MHz, CDCl3): d (ppm) 3.97–4.09 (m, 2H, CH2), 4.13–
4.25 (m, 2H, CH2), 6.21 (s, 1H, CH); 19F NMR (235 MHz,
CDCl3): d ꢁ120.9 (m, 2F), ꢁ142.9 (m, 2F); 13C NMR
(63 MHz, CDCl3): d 66.1 (s, CH2), 73.7 (t, J ¼ 28 Hz, C-
3), 96.8 (m, CH), 117.9 (t, J ¼ 13 Hz, C-6), 144.6 (dm,
J ¼ 256 Hz, C-2), 147.2 (dm, J ¼ 245 Hz, C-3); MS
(CI þ NH3): m/z 348 [M]þ. Anal. calcd. for C9H5IF4O2:
C, 31.1; H, 1.45; F, 21.9; I, 36.5. Found: C, 31.1; H, 1.45; F,
21.8; I, 36.0.
4.4. Crystal data for compound 1
On cooling at ꢁ20 8C, a chloroform solution of aldehyde
1 afforded tabular single crystals. Crystal data were col-
lected on an Enraf Nonius Kappa CCD diffractometer at
293 K using graphite monochromated Mo Ka radiation
˚
(l ¼ 0:71073 A, and o scans). The structure was solved
4.2. 2,3,5,6-Tetrafluoro-4-iodo-benzaldehyde (1)
by direct methods and refined by full-matrix least-squares
refinement on F2 using the program SHELX-97 [15]. Non-
hydrogen atoms were refined anisotropically. The hydrogen
atom, observed via the difference Fourier map, was placed in
geometrically calculated positions and included in the final
refinement using the ‘‘riding’’ model with isotropic tem-
perature factors fixed at 1.2-times that of the parent atom.
The acetal 5 (0.80 g, 2.3 mmol) was dissolved under
stirring in trifluoroacetic acid (2.5 mL). To the solution,
water (7 mL) was added, followed by hydrochloric acid
(1.5 mL, 37%), giving a white precipitate. The mixture was
heated at 65–70 8C for 90 min. After cooling, the suspension