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S. Buscemi et al. / Journal of Fluorine Chemistry 127 (2006) 1601–1605
5.3. Synthesis of 3-pentadecafluoroheptyl-5-
pentafluorophenyl-1,2,4-oxadiazole (2f)
5.4.2. Reaction of 3-phenyl-5-pentafluorophenyl-1,2,4-
oxadiazole 2b with triethanolamine
O,O0,O00-Tris[2,3,5,6-tetrafluoro-4-(3-phenyl-1,2,4-oxadia-
zol-5-yl)-phenyl]-triethanolamine 4b had mp 150–3 8C (crystal,
fromTHF).FT-IR(nujol)n:1653 cmꢀ1.1HNMR(CDCl3)d:3.26
(s broad, 6H), 4.55 (s broad, 6H), 7.45–7.54 (m, 9H), 8.14–8.16
(m, 6H). 19F NMR (THF-d8) d: ꢀ140.86 (bd, 6F, J = 12.7 Hz),
ꢀ160.01 (bd, 6F, J = 13.25 Hz). ESI–MS (positive mode) m/z:
1026.9(M + 1,100%).Anal.CalcdforC48H27F12N7O6:C,56.20;
H, 2.65; N, 9.56; found C, 56.10; H, 2.70; N, 9.60.
A mixture of pentadecafluoroheptylamidoxime (4.28 g,
10 mmol), pyridine (0.88 g, 11 mmol) and pentafluorobenzoyl
chloride (2.54 g, 11 mmol) was stirred in benzene (100 mL) at
0 8C for 10 h. After evaporation of the solvent the residue was
treated with water and filtered. The obtained O-pentafluor-
obenzoyl-pentadecafluoroheptylamidoxime 3 [6.15 g, 98%,
mp 155–6 8C (crystal, from benzene). FT-IR (nujol) n: 3512,
3358, 1749 and 1652 cmꢀ1. 1H NMR (DMSO-d6) d: 7.99 (2H,
exchangeable with D2O)] was put into a Pyrex sealed tube and
heated at 160 8C for 2 h. Chromatography of the residue gave
3-pentadecafluoroheptyl-5-pentafluorophenyl-1,2,4-oxadia-
zole 2f (4.53 g, 75%): mp, 37–8 8C (crystal, from petroleum
O,O0-Di[2,3,5,6-tetrafluoro-4-(3-phenyl-1,2,4-oxadiazol-5-
yl)-phenyl]-triethanolamine 5b had mp 148–149 8C (crystal,
from ethyl acetate). FT-IR (nujol) n: 3504 and 1655 cmꢀ1. H
1
NMR (CDCl3) d: 2.92 (s broad, 2H), 3.18 (s broad, 4H), 3.68 (s
broad, 2H), 4.54 (s broad, 4H), 7.48–7.55 (m, 6H), 8.14–8.16
(m, 4H). 19F NMR (THF-d8) d: ꢀ139.24 (bd, 4F, J = 13.0 Hz),
ꢀ158.09 (bd, 4F, J = 12.7 Hz). ESI–MS (positive mode) m/z:
734.7 (M + 1, 100%). Anal. Calcd for C34H23F8N5O5: C, 55.67;
H, 3.16; N, 9.55; found C, 55.70; H, 3.10; N, 9.60.
ether). FT-IR (nujol) n: 1660, 1581, 1203 cmꢀ1 19F NMR
.
(CDCl3) d: ꢀ79.68 (t, 3F, J = 13.0 Hz), ꢀ113.54 (t, 2F,
J = 12.7 Hz), ꢀ121.63 (s, 2F), ꢀ122.29 (s, 4F), ꢀ122.97 to
ꢀ123.0 (m, 2F), ꢀ126.37 to ꢀ126.42 (m, 2F), ꢀ133.28 to
ꢀ133.45 (m, 2F), ꢀ142.97 (tt, 1F, J = 6.5 and 21.1 Hz),
ꢀ158.32 to ꢀ158.54 (m, 2F). GC–MS m/z: 604 (M+, 100%).
Anal. Calcd. for C15F20N2O: C, 29.82; N, 4.64; found C, 29.70;
N, 4.50.
5.4.3. Reaction of 3-(4-methoxyphenyl)-5-
pentafluorophenyl-1,2,4-oxadiazole 1c with triethanolamine
O,O0,O00-Tris{2,3,5,6-tetrafluoro-4-[3-(4-methoxyphenyl)-
1,2,4-oxadiazol-5-yl]-phenyl}-triethanolamine 4c had mp 171–
6 8C (crystal, from THF). FT-IR (nujol) n: 1653 cmꢀ1. 1H NMR
(THF-d8) d: 3.23 (t, 6H, J = 5 Hz), 3.82 (s, 9H), 4.57 (t, 6H,
5.4. General procedure for the reaction of 5-
pentafluorophenyl-1,2,4-oxadiazoles 2a–f with
triethanolamine (TEA)
J = 5 Hz), 7.01 (d, 6H, J = 7.5 Hz), 8.01 (d, 6H, J = 7.5 Hz). 19
F
NMR (THF-d8) d: ꢀ139.10 (bd, 6F, J = 13.3 Hz), ꢀ158.19 (bd,
6F, J = 13.5 Hz). ESI–MS (positive mode) m/z: 1116.9 (M + 1,
100%). Anal. Calcd for C51H33F12N7O9: C, 54.90; H, 2.98; N,
8.79; found C, 54.80; H, 3.00; N, 8.70.
To a mixture of TEA (0.075 g, 0.5 mmol) in dry
acetonitrile (10 ml) and anidrous K2CO3 (0.621 g, 4.5 mmol),
oxadiazole 2 (1.5 or 1 mmol, see Table 1) was added and
taken under good stirring. The mixture was then evaporated,
treated with water and extracted with EtOAc. The organic
layer was dried over Na2SO4, evaporated and the residue
chromatographed giving compounds 4, 5 and recovered 2 (see
Table 1).
O,O0-Di{2,3,5,6-tetrafluoro-4-[3-(4-methoxyphenyl)-1,2,4-
oxadiazol-5-yl]-phenyl}-triethanolamine 5c had mp 151–4 8C
1
(crystal, from ethyl acetate). FT-IR (nujol) n: 1655 cmꢀ1. H
NMR (THF-d8) d: 2.80 (t, 2H, J = 5 Hz), 3.12 (t, 4H, J = 5 Hz),
3.56 (t, 2H, J = 5 Hz), 3.83 (s, 6H), 4.53 (t, 4H, J = 5 Hz), 7.02 (d,
4H, J = 5 Hz), 8.04 (d, 4H, J = 5 Hz). 19F NMR (THF-d8) d:
ꢀ139.31 (bd, 4F, J = 12.7 Hz), ꢀ158.12 (bd, 4F, J = 12.7 Hz).
ESI-MS (positive mode) m/z: 794.6 (M + 1, 100%). Anal. Calcd
for C36H27F8N5O7 C, 54.48; H, 3.43; N, 8.82; found C, 54.40; H,
3.40; N, 8.70.
5.4.1. Reaction of 3-methyl-5-pentafluorophenyl-1,2,4-
oxadiazole 2a with triethanolamine
O,O0,O00-Tris[2,3,5,6-tetrafluoro-4-(3-methyl-1,2,4-oxa-
diazol-5-yl)-phenyl]-triethanolamine 4a had mp 97–9 8C
1
(crystal, from THF). FT-IR (nujol) n: 1649 cmꢀ1. H NMR
(THF-d8) d: 2.43 (s, 9H), 3.21 (t, 6H, J = 5 Hz), 4.54 (t, 6H,
J = 5 Hz). 19F NMR (THF-d8) d: ꢀ139.47 to ꢀ139.60 (m,
6F), ꢀ158.22 (bd, 6F, J = 13.0 Hz). ESI–MS (positive mode)
m/z: 840.8 (M + 1, 100%). Anal. Calcd for C33H21F12N7O6:
C, 47.21; H, 2.52; N, 11.68. Found: C, 47.30; H, 2.50; N,
11.60.
5.4.4. Reaction of 3-(4-nitrophenyl)-5-pentafluorophenyl-
1,2,4-oxadiazole 1d with triethanolamine
O,O0,O00-Tris{2,3,5,6-tetrafluoro-4-[3-(4-nitrophenyl)-1,2,4-
oxadiazol-5-yl]-phenyl}-triethanolamine 4d had mp 180 8C
(dec.) (crystal, from THF). FT-IR (nujol) n: 1654 cmꢀ1. 1H NMR
(THF-d8) d: 3.22 (t, 6H, J = 5Hz), 4.57 (t, 6H, J = 5Hz), 8.31–
8.35 (m, 12H). 19F NMR (THF-d8) d: ꢀ138.68 to ꢀ180.97 (m,
6F), ꢀ157.85 to ꢀ158.13 (m, 6F). ESI–MS (positive mode) m/z:
1161.7 (M + 1, 100%). Anal. Calcd. for C48H24F12N10O12: C,
49.67; H, 2.08; N, 12.07. Found: C, 49.70; H, 2.10; N, 12.00.
O,O0-Di[2,3,5,6-tetrafluoro-4-(3-methyl-1,2,4-oxadiazol-5-
yl)-phenyl]-triethanolamine 5a had mp 192–5 8C (crystal, from
1
THF). FT-IR (nujol) n: 3474 and 1651 cmꢀ1. H NMR (THF-
d8) d: 2.42 (s, 6H), 2.79 (t, 2H, J = 5 Hz), 3.11 (t, 4H, J = 5 Hz),
3.56 (t, 2H, J = 5 Hz), 4.51 (t, 4H, J = 5 Hz). 19F NMR (THF-
d8) d: ꢀ139.82 (bd, 4F, J = 13.0 Hz), ꢀ158.41 to ꢀ158.65 (m,
4F). ESI–MS (positive mode) m/z: 610.6 (M + 1, 100%). Anal.
Calcd for C24H19F8N5O5: C, 47.30; H, 3.14; N, 11.49. Found:
C, 47.20; H, 3.10; N, 11.50.
5.4.5. Reaction of 3-(4-pyridyl)-5-pentafluorophenyl-1,2,4-
oxadiazole 1e with triethanolamine
O,O0,O00-Tris{2,3,5,6-tetrafluoro-4-[3-(4-pyridyl)-1,2,4-oxa-
diazol-5-yl]-phenyl}-triethanolamine 4e had mp 166–172 8C