Fluoroalkylation of aromatics: An intramolecular radical cyclization of 4-chloro-1,1,2,2,3,3,4,4-octafluorobutylbenzenes

Article abstract of DOI:10.1016/j.jfluchem.2006.05.013

In the presence of sodium dithionite and DMSO, the intramolecular radical cyclization of 4-chloro-1,1,2,2,3,3,4,4-octafluorobutylbenzenes is achieved to give the corresponding cyclic compounds in moderate to good yields.

Full text of DOI:10.1016/j.jfluchem.2006.05.013

Journal of Fluorine Chemistry 127 (2006) 1079–1086
www.elsevier.com/locate/fluor
Fluoroalkylation of aromatics: An intramolecular radical cyclization
of 4-chloro-1,1,2,2,3,3,4,4-octafluorobutylbenzenes
*
Hai-Ping Cao, Ji-Chang Xiao, Qing-Yun Chen
Key Laboratory of Organofluorine Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences,
354 Fenglin Lu, Shanghai 200032, China
Received 12 April 2006; received in revised form 11 May 2006; accepted 15 May 2006
Available online 22 May 2006
Abstract
In the presence of sodium dithionite and DMSO, the intramolecular radical cyclization of 4-chloro-1,1,2,2,3,3,4,4-octafluorobutylbenzenes is
achieved to give the corresponding cyclic compounds in moderate to good yields.
# 2006 Elsevier B.V. All rights reserved.
Keywords: Intramolecular cyclization; Fluoroalkylation; Sulfinatodehalogenation; Free radicals
1. Introduction
of I(CF2)nX (n = 2–5; X = Cl, I) with tetraarylporphyrins (TAP)
under sulfinatodehalogenation conditions, underwent an unex-
pected intramolecular cyclization at the ortho position of a
neighboring phenyl ring as well as an adjacent pyrrolic unit
(Scheme 1) [5]. Five-, six- or seven-membered fused porphyrins
could be also formed, depending on the chain length of the
fluoroalkyl group. These results prompted us to examine the
intramolecular cyclization of ordinary perfluoroalkylbenzenes.
Radical cyclization has become a powerful method for the
construction of five- or six-membered rings via C–C bond
forming process and it actually serves as one of the most
reliable tools in organic synthesis during the past 40 years [1]. A
systematic study of the cyclization of fluoroalkyl radicals by
Dolbier and co-workers demonstrates that per- or partially
fluorinated radicals are much more reactive than their
hydrocarbon counterparts, which is largely attributed to the
high electrophilicity of the fluorinated radicals [2]. Most of
these studies focus on the intramolecular fluoroalkyl radical
additions to double bonds. Nevertheless, intramolecular
fluoroalkyl radical substitution on the aromatic ring has
received limited attention.
2. Results and discussion
1-Chloro-4-iodo-octafluorobutane 2 was chosen as the
fluoroalkylation reagent in the hope of forming a fused six-
membered ring. Because C–Cl bond and C–I bond in 2 could be
both activated using sulfinatodehalogenation system at differ-
ent temperature [5a], we attempted to perform the fluoroalk-
ylation of aromatics and subsequent intramolecular radical
cyclization in one pot. A mixture of 1,4-diaminobenzene 1a and
1-chloro-4-iodo-octafluorobutane 2 was stirred in DMSO at
room temperature in the presence of Na2S2O4 till the complete
conversion of 1a (monitored by TLC) (Scheme 2). Then,
heating the reaction mixture at 100 8C did give the cyclization
product 4a. Unfortunately, the yield was not satisfactory, only
20%. Therefore, we separated the fluoroalkylated benzene
intermediate 3a first, which then underwent six-membered ring
cyclization in the presence of Na2S2O4, leading indeed to the
formation of 4a in 85% yield. Owing to the lower yield of the
On the other hand, sulfinatodehalogenation method discov-
ered by Huang et al. [3] and modified by us [4] has become a
convenient, widely used radical initiation system for perfluor-
oalkyl halides. For instance, initiated by sodium dithionite in
DMSO, per- orpolyfluoroalkylhalides(RFX, X = Cl, Br, I)could
be used as fluoroalkylation agents not only for the addition
reaction to alkenes and alkynes, but also for substitutions on
aromatic compounds [3]. Recently, we found that b-(perfluor-
oalkyl)tetraarylporphyrin radicals, generated from the reaction
* Corresponding author. Fax: +86 21 64166128.
E-mail address: chenqy@mail.sioc.ac.cn (Q.-Y. Chen).
0022-1139/$ – see front matter # 2006 Elsevier B.V. All rights reserved.
doi:10.1016/j.jfluchem.2006.05.013

1080
H.-P. Cao et al. / Journal of Fluorine Chemistry 127 (2006) 1079–1086
Scheme 1. Cyclization of porphyrin.
one pot procedure, we carried the reactions in two steps. Firstly,
we synthesized 3.
pot procedure led to rather low yield of 4c (Table 3, entry 3),
which might be the result of the lability of 3c [6]. In the case of
3d–e, the cyclized products were formed. To our surprise, only
hydrogenated product 4d and defluorinated 4e and 4f were
obtained (Table 3, entries 4–6). The intramolecular cyclization
of 3g–l proceeded smoothly under sulfinatodehalogenation
conditions. The cyclic products 4g–l were obtained in high
yields as sole products with complete conversion of 3g–l. In the
case of compound 3l (Table 3, entry 12), only hydrogenated
product 4l was formed.
Fluoroalkylation of 1-methyl-indole 1b gave a mixture of 2-
and 3-fluoroalkylated product (Table 1, entry 2), which could
not be completely separated by normal column chromato-
graphy because of their very similar polarities. As for the
fluoroalkylation of pyrrole, 2-fluoroalkylated pyrrole 3c was
not isolated either. Because 3c easily hydrolyzes and readily
polymerizes under the reaction condition (Table 1, entry 3) [6].
When 1d–f were used as substrates, the fluoroalkylation
proceeded smoothly and 3d–f were obtained in good yields
(Table 1, entries 4–6).
The structure of the products 4a–l were all confirmed by 1H
and 19F NMR, IR, MS and elemental analyses.
In the case of biphenyl, its direct fluoroalkylation using
sulfinatodehalogenation method might give various isomers. To
avoid complications, we synthesized 3g–l from the copper-
catalyzed cross-coupling reactions of these p-iodo-biphenyl
1g–l and 1-chloro-4-iodo-octafluorobutane 2 (Table 2) [7].
With the fluoroalkylated aromatics 3 in hand, we then
studied their intramolecular radical cyclizations. The results are
shown in Table 3. In the case of 3b, a mixture of 2- and 3-
fluoroalkylated indole, the cyclization formed a sole product 4b
(Table 3, entry 2). As for 2-fluoroalkylated pyrrole 3c, the one
Based on the previous reports [5], it is reasonable to suggest
that this cyclization reaction may be also involved in a single
electron-transfer mechanism in both steps. The aryl tetra-
fluorobutyl radical generated from 3 underwent an intramo-
lecular attack at the ortho position of the fluoroalkyl group to
afford the cyclic product 4, as is usual for free radical aromatic
substitution [8]. However, hydrogenation and defluorination of
perfluoroalkyl halides sometimes happened in this initiation
system, yet their formation mechanisms are not fully under-
stood [5a,9]. Besides we also prepared fluoroalkylated
Scheme 2. Fluoroalkylation of 1a and cyclization of 3a.

H.-P. Cao et al. / Journal of Fluorine Chemistry 127 (2006) 1079–1086
1081
Table 1
Na
S O =NaHCO
2 4
2
CH CN=H
Synthesis of fluoroalkylated aromatic compound 3 by Na2S2O4 ArꢀH1aꢀf þClC4F8Iꢀ!
Entry
3 ArꢀC4F8CL3aꢀf
Product 3
O
2
3
Compound 1
T (8C)
t (h)
Yield (%)
1
2
20
3
2
47
a
20
a
3
4
10
20
0.5
2
40
66
5
20
3
6
20
2
50
a
Not isolated.
Table 2
Synthesis of fluoroalkylated aromatic compound 3 induced by copper powder ArꢀI þ ClC4F8Iꢀ!DMSOArꢀC4F8Cl
Cu
Entry
Compound 1
T (8C)
t (h)
Product 3
Yield (%)
1
100
12
56
2
100
12
57

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H.-P. Cao et al. / Journal of Fluorine Chemistry 127 (2006) 1079–1086
Table 2 (Continued )
Entry
Compound 1
T (8C)
t (h)
Product 3
Yield (%)
69
3
100
10
4
100
10
11
11
80
50
53
5
80
6
80
Table 3
Na
2
S O
2
Cyclization of fluoroalkylated aromatic compound 3 by Na2S2O4 ArꢀC4F8Cl3aꢀf ꢀ!DMSO 4 Product4
Entry
Compound 3
T (8C)
t (min)
Product 4
Yield (%)
85
1
100
15
2
3
4
5
100
100
100
100
15
15
20
15
40
10
40
52

H.-P. Cao et al. / Journal of Fluorine Chemistry 127 (2006) 1079–1086
1083
Table 3 (Continued )
Entry
Compound 3
T (8C)
t (min)
Product 4
Yield (%)
6
100
18
83
7
100
15
76
100
15
62
8
9
100
20
50
10
11
100
100
20
18
65
72
12
100
15
68
aromatics such as Ar(CF2)3I, Ar(CF2)6Cl by the reactions of
I(CF2)3I and I(CF2)6Cl with aromatics, respectively and
attempted to perform the subsequent intramolecular cycliza-
tion. Unfortunately, these attempts only led to the formation of
hydrogenated products [Ar(CF2)nH, n = 3, 6] or sulfinates
[Ar(CF2)nSO2Na, n = 3, 6]. No desired five- or seven-
membered fused compounds were obtained. This might be
largely due to the difference of intramolecular cyclization
between fluorinated porphyrin radicals and aromatic ones.
3. Conclusion
In summary, we described a new intramolecular radical
cyclization of chloro-octafluorobutyl benzenes under modified

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H.-P. Cao et al. / Journal of Fluorine Chemistry 127 (2006) 1079–1086
sulfinatodehalogenation conditions. Further studies on other
intramolecular fluoroalkyl radical substitutions are underway in
our laboratory.
108.87 (m, 2F), 120.13 (m, 2F), 121.44 (m, 2F). MS (ESI): m/
z = 419 [M + H]+. Anal. Calcd. for C16H11F8ClN2: C, 45.90; H,
2.65; N, 6.69. Found: C, 46.01; H, 3.03; N, 6.62.
4. Experimental
4.3. Preparation of 4-chloro-1,1,2,2,3,3,4,4-octafluoro-
aromatic compounds 3g–l [8] from iodoaromatics
4.1. General
A
mixture of 4-chloro-octafluorobutyliodide (1.81 g,
1H NMR and 19F NMR spectra were recorded at 300 and
282 MHz. Chemical shifts were reported in parts per million
5 mmol), 4-iodoanisole (1.17 g, 5 mmol) and copper (1.0 g,
15.6 mmol) in DMSO (10 mL) was stirred at 100 8C for 12 h
under nitrogen. The mixture was filtered. The solid was washed
twice with ether. The filtrate was hydrolyzed with dilute HCl
acid (2N, 20 mL), then was extracted with ether (3ꢁ 20 mL).
The combined extracts were washed with water, dried over
anhydride Na2SO4. After removing ether, the residue was
subjected to column chromatography on silica gel to give 3j as a
white solid.
1
relative to TMS as an internal standard for H NMR and to
CFCl3 as an external standard (positive for up field shifts) for
19F NMR. The solvent for NMR measurement was CDCl3
(unless otherwise noted). DMSO were distilled from CaH2. The
other chemicals used were obtained commercially.
4.2. Preparation of 4-chloro-1,1,2,2,3,3,4,4-octafluoro-
aromatic compounds 3a–f from aromatics
3g: white solid. IR (KBr): 1792, 1133, 772, 740, 701 cmꢀ1
.
1H NMR (300 MHz, CDCl3): d = 7.66 (m, 6H), 7.45 (m, 3H).
19F NMR (282 MHz, CDCl3): d = 69.24 (t, J = 13.7 Hz, 2F),
111.98 (t, J = 14.4 Hz, 2F), 120.81 (t, J = 14.2 Hz, 2F), 122.48
(t, J = 14.2 Hz, 2F). MS (EI, 70 eV): m/z (%) = 388 (29) [M]+,
203 (100). Anal. Calcd. for C16H9F8Cl: C, 49.44; H 2.33.
Found: C, 49.35; H, 2.71.
A
mixture of 4-chloro-octafluorobutyliodide (1.81 g,
5 mmol), 1,4-diamino-benzene (0.54 g, 5 mmol), Na2S2O4
(1.31 g, 7.5 mmol), NaHCO3 (0.63 g, 7.5 mmol) and DMSO
(25 mL) was stirred at room temperature for 3 h under nitrogen.
The mixture was poured into ice water (30 mL). The aqueous
layer was extracted with ether (3ꢁ 30 mL). The combined
extracts were washed with water (3ꢁ 20 mL) and dried over
Na2SO4. After removing ether, the residue was subjected to
column chromatography on silica gel to give 3a as a brown
solid.
3h: colorless oil. IR (film): 1195, 1137, 1083, 776,
767 cmꢀ1
.
1H NMR (300 MHz, CDCl3): d = 8.26 (d,
J = 8.1 Hz, 1H), 8.06 (d, J = 8.1 Hz, 1H), 7.93 (d,
J = 9.6 Hz, 1H), 7.85 (d, J = 7.2 Hz, 1H), 7.59 (m, 3H). 19F
NMR (282 MHz, CDCl3): d = 68.0 (m, 2F), 104.7 (m, 2F),
119.8 (m, 4F). MS (EI, 70 eV): m/z (%) = 364 (4), 362 (13)
[M]+. Anal. Calcd. for C14H7F8Cl: C, 46.37; H, 1.95. Found: C,
46.02; H, 2.08.
3a: brown solid. IR (KBr): 3239, 1490, 1309, 1219, 1195,
1171, 1011, 913 cmꢀ1. H NMR (300 MHz, CDCl3):d = 6.72
1
(m, 2H), 6.60 (dd, J = 0.6, 8.4 Hz, 1H), 3.57 (br, 4H). 19F NMR
(282 MHz, CDCl3): d = 68.25 (t, J = 14.4 Hz, 2F), 109.07 (t,
J = 14.5 Hz, 2F), 120.26 (m, 2F), 121.57 (m, 2F). MS (EI,
70 eV): m/z (%) = 344 (18), 342 (58) [M]+. Anal. Calcd. for
C10H7F8ClN2: C, 35.06; H, 2.06; N, 8.18. Found: C, 35.41; H,
2.07; N, 8.17.
1
3i: yellow oil. H NMR (300 MHz, CDCl3): d = 7.40 (d,
J = 9.0 Hz, 2H), 6.70 (d, J = 9.0 Hz, 2H), 2.99 (s, 6H). 19F
NMR (282 MHz, CDCl3): d = 67.8 (t, J = 13.8 Hz, 2F), 109.2
(t, J = 13.1 Hz, 2F), 119.5 (m, 2F), 121.2 (m, 2F).
3j: colorless oil. IR (film): 1617, 1520, 1311, 1263, 1183,
3d: brown oil. IR (film): 1509, 1188, 1134, 1045, 747 cmꢀ1
.
1137 cmꢀ1 1H NMR (300 MHz, CDCl3): d = 7.55 (d,
.
1H NMR (300 MHz, CDCl3): d = 6.94 (m, 1H), 6.87 (d,
J = 2.9 Hz, 1H), 6.69 (d, J = 8.8 Hz, 1H), 3.87 (br, 5H). 19F
NMR (282 MHz, CDCl3): d = 68.34 (m, 2F), 109.18 (m, 2F),
120.30 (m, 2F), 122.58 (m, 2F). MS (EI, 70 eV): m/z (%) = 357
(9) [M]+, 69 (66). Anal. Calcd. for C11H8F8ClNO: C, 36.94; H,
2.25; N, 3.92. Found: C, 37.02; H, 2.31; N, 3.69.
J = 9.0 Hz, 2H), 7.01 (d, J = 9.0 Hz, 2H), 3.86 (s, 3H). 19F
NMR (282 MHz, CDCl3): d = 68.4 (t, J = 13.3 Hz, 2F), 110.2
(t, J = 14.9 Hz, 2F), 119.9 (m, 2F), 121.7 (m, 2F). MS (EI,
70 eV): m/z (%) = 342 (4) [M]+, 157 (100). Anal. Calcd. for
C11H7F8OCl: C, 38.56; H, 2.06. Found: C, 38.51; H, 2.06.
3k: colorless oil. IR (film): 1516, 1296, 1195, 1135, 752,
3e: yellow oil. IR (film): 3059, 1606, 1513, 1189, 1138,
705 cmꢀ1 1H NMR (300 MHz, CDCl3): d = 7.55 (d,
.
1081 cmꢀ1
.
1H NMR (300 MHz, CDCl3): d = 7.12 (d,
J = 8.1 Hz, 1H), 7.48 (d, J = 7.5 Hz, 1H), 7.37 (t, J = 7.5 Hz,
1H), 7.19 (d, J = 3.3 Hz, 1H), 6.77 (d, J = 0.9 Hz, 1H), 3.82 (s,
3H). 19F NMR (282 MHz, CDCl3): d = 68.06 (m, 2F), 108.89
(m, 2F), 119.87 (m, 2F), 121.01 (m, 2F). MS (EI, 70 eV): m/z
(%) = 365 (26) [M]+, 180 (100). Anal. Calcd. for C13H8F8ClN:
C, 42.70; H, 2.21; N, 3.83. Found: C, 42.95; H, 2.45; N, 3.94.
J = 8.4 Hz, 1H), 7.06 (d, J = 7.5 Hz, 1H), 6.58 (t, J = 7.5 Hz,
1H), 4.75 (s, 1H), 3.34 (t, J = 5.6 Hz, 2H), 2.79 (t, J = 6.5 Hz,
2H), 1.90 (m, 2H). 19F NMR (282 MHz, CDCl3): d = 68.20 (t,
J = 13.0 Hz, 2F), 107.9 (t, J = 13.7 Hz, 2F), 120.23 (m, 2F),
121.52 (t, J = 10.9 Hz, 2F). MS (EI, 70 eV): m/z (%) = 369
(36), 367 (98) [M]+. Anal. Calcd. for C13H10F8ClN: C, 42.47;
H, 2.74; N, 3.81. Found: C, 42.86; H, 2.93; N, 3.80.
3l: colorless oil. IR (film): 1191, 1134, 990, 767, 700 cmꢀ1
.
1H NMR (300 MHz, CDCl3): d = 8.79 (dd, J = 2.1, 6.9 Hz, 1H),
8.71 (d, J = 8.1 Hz, 1H), 8.36 (d, J = 7.5 Hz, 1H), 8.20 (s, 1H),
7.99 (d, J = 7.8 Hz, 1H), 7.74 (m, 4H). 19F NMR (282 MHz,
CDCl3): d = 68.31 (t, J = 12.8 Hz, 2F), 104.94 (t, J = 14.4 Hz,
2F), 119.63 (t, J = 12.5 Hz, 2F), 120.12 (m, 2F). MS (EI,
3f: brown solid. IR (KBr): 1633, 1501, 1187, 1127,
761 cmꢀ1
.
1H NMR (300 MHz, CDCl3): d = 7.46 (d,
J = 7.2 Hz, 2H), 7.32 (m, 2H), 6.72 (m, 3H), 4.19 (br, 2H),
3.62 (br, 2H). 19F NMR (282 MHz, CDCl3): d = 68.20 (m, 2F),

H.-P. Cao et al. / Journal of Fluorine Chemistry 127 (2006) 1079–1086
1085
70 eV): m/z (%) = 412 (46) [M]+, 227 (100). Anal. Calcd. for
C18H9F8Cl: C, 52.38, H, 2.20. Found: C, 52.49; H, 2.12.
CDCl3): d = 111.50 (m, 2F), 125.57 (m, 2F), 139.24 (m, 1F),
167.68 (m, 1F). MS (EI, 70 eV): m/z (%) = 344 (100) [M]+, 345
(22). HRMS-EI: m/z [M]+ calcd. for C16H10F6N2: 344.07482.
Found: 344.07462.
4.4. Typical procedure for the cyclization reaction of 3
4g: white solid. IR (KBr): 1618, 1308, 1239, 1168, 1030,
Under a nitrogen atmosphere, 3a (1.71 g, 5 mmol), Na2S2O4
(4.35 g, 25 mmol), NaHCO3 (2.1 g, 25 mmol) and DMSO
(25 mL) was added to a 50 mL three-necked round bottomed
flask equipped with a magnetic stir bar and a condenser. The
mixture was then heated to 100 8C for 20 min with stirring. The
conversion of 3a was 100%, determined by 19F NMR. After
cooling, the mixture was poured into ice water (30 mL). The
aqueous layer was extracted with ether (3ꢁ 30 mL). The
combinedextractswerewashedwithwater(3ꢁ 20 mL)anddried
over Na2SO4. After removing ether, the residue was subjected to
column chromatography on silica gel to give 4a as a brown solid.
4a: brown solid. IR (KBr): 3226, 1516, 1208, 1124, 753,
676 cmꢀ1. 1H NMR (300 MHz, CDCl3): d = 6.73 (s, 2H), 4.00
(br, 4H). 19F NMR (282 MHz, CDCl3): d = 108.05 (m, 4F),
135.35 (m, 4F). MS (EI, 70 eV): m/z (%) = 306 (100) [M]+, 286
(33). Anal. Calcd. for C10H6F8N2: C, 39.23; H, 1.98; N, 9.15.
Found: C, 39.63; H, 2.11; N, 9.26.
1008, 972, 913, 776 cmꢀ1 1H NMR (300 MHz, CDCl3):
.
d = 8.04 (s, 1H), 7.95 (q, J = 8.4 Hz, 2H), 7.62 (d, J = 6.9 Hz,
2H), 7.50 (m, 3H). 19F NMR (282 MHz, CDCl3): d = 103.18
(m, 2F), 103.54 (m, 2F), 134.86 (m, 4F). MS (EI, 70 eV): m/z
(%) = 353 (17), 352 (100) [M]+. Anal. Calcd. for C16H8F8: C,
54.56; H, 2.29. Found: C, 54.86; H, 2.22.
4h: white solid. IR (KBr): 1281, 1181, 1114, 993, 829,
766 cmꢀ1. 1H NMR (300 MHz, CDCl3): d = 8.14 (m, 4H), 7.68
(t, J = 7.8 Hz, 2H). 19F NMR (282 MHz, CDCl3): d = 103.2 (m,
4F), 127.4 (m, 4F). MS (EI, 70 eV): m/z (%) = 326 (100) [M]+,
257 (41). Anal. Calcd. for C14H6F8: C, 51.55; H, 1.85. Found:
C, 51.87; H, 1.96.
4i: colorless oil. IR (film): 1619, 1261, 1193, 1169, 1014,
944 cmꢀ1
.
1H NMR (300 MHz, CDCl3): d = 7.64 (d,
J = 9.2 Hz, 1H), 6.95 (m, 2H), 3.09 (s, 6H). 19F NMR
(282 MHz, CDCl3): d = 100.4 (m, 2F), 104.0 (t, J = 7.4 Hz, 2F),
134.3 (m, 2F), 134.5 (m, 2F). MS (ESI): m/z = 320 [M + H]+.
HRMS-ESI: m/z [M + H]+ calcd. for C12H10F8N: 320.06855.
Found: 320.06800.
4b: white solid. IR (KBr): 1491, 1248, 1180, 1161, 1077,
1004, 945, 752 cmꢀ1. 1H NMR (300 MHz, CDCl3): d = 7.89 (d,
J = 8.1 Hz, 1H), 7.47 (m, 2H), 7.34 (m, 1H), 3.96 (s, 3H). 19F
NMR (282 MHz, CDCl3): d = 103.44 (m, 2F), 105.44 (m, 2F),
132.04 (m, 2F), 133.00 (m, 2F). MS (EI, 70 eV): m/z (%) = 330
(13), 329 (100) [M]+. Anal. Calcd. for C13H7F8N: C, 47.43; H,
2.14; N, 4.25. Found: C, 47.45; H, 2.19; N, 4.04.
4j: colorless oil. IR (film): 1619, 1297, 1226, 1190, 980,
923 cm-1. 1H NMR (300 MHz, CDCl3): d = 7.78 (d, J = 9.6 Hz,
1H), 7.28 (m, 2H), 3.94 (s, 3H). 19F NMR (282 MHz, CDCl3):
d = 101.5 (m, 2F), 103.6 (m, 2F), 134.5 (m, 4F). MS (EI,
70 eV): m/z (%) = 306 (100) [M]+, 287 (30). Anal. Calcd. for
C11H6F8O: C, 43.16; H, 1.98. Found: C, 42.85; H, 1.94.
4k: white solid. IR (KBr): 1510, 1261, 1191, 1153, 1008,
4c: brown oil. IR (film): 3474, 1310, 1272, 1174, 987,
968 cmꢀ1. 1H NMR (300 MHz, CDCl3): d = 9.10 (br, 1H), 7.12
(t, J = 2.0 Hz, 1H), 6.58 (s, 1H). 19F NMR (282 MHz, CDCl3):
d = 102.73 (m, 2F), 103.92 (m, 2F), 132.67 (m, 4F). MS (EI,
70 eV): m/z (%) = 265 (60) [M]+, 246 (32). HRMS-EI: m/z [M]+
calcd. for C8H3F8N: 265.01377. Found: 265.01474.
954, 815 cmꢀ1 1H NMR (300 MHz, CDCl3): d = 7.89 (d,
.
J = 8.1 Hz, 1H), 7.48 (m, 2H), 7.36 (m, 1H), 3.96 (s, 3H). 19F
NMR (282 MHz, CDCl3): d = 99.57 (m, 2F), 103.61 (m, 2F),
133.92 (m, 2F), 134.47 (m, 2F). MS (EI, 70 eV): m/z (%) = 329
(83) [M]+, 215 (58). Anal. Calcd. for C13H7F8N: C, 47.43; H,
2.14; N, 4.25. Found: C, 47.66; H, 2.29; N, 4.20.
4d: brown solid. IR (KBr): 3381, 1496, 1289, 1222,
986 cmꢀ1. 1H NMR (300 MHz, CDCl3): d = 7.06 (dd, J = 2.4,
9.0 Hz, 1H), 6.92 (d, J = 9.0 Hz, 1H), 5.77 (ddd, J = 4.5, 8.4,
48.9 Hz, 1H), 3.87 (s, 5H). 19F NMR (282 MHz, CDCl3):
d = 103.77 (ddd, J = 7.9, 16.5, 287.1 Hz, 1F), 113.77 (ddd,
J = 12.1, 22.6, 289.3 Hz, 1F), 122.99 (m, 1F), 129.10 (m, 1F),
133.77 (m, 1F), 143.94 (m, 1F), 186.28 (m, 1F). MS (EI,
70 eV): m/z (%) = 303 (100) [M]+, 288 (87). Anal. Calcd. for
C11H8F8NO: C, 43.58; H, 2.66; N, 4.62. Found: C, 44.06; H,
2.81; N, 4.29.
4l: white solid. IR (KBr): 1451, 1235, 1163, 1116, 992, 850,
763, 725 cmꢀ1 1H NMR (300 MHz, CDCl3): d = 8.73 (d,
.
J = 8.4 Hz, 2H), 8.56 (t, J = 4.2 Hz, 1H), 8.21 (m, 1H), 7.79 (m,
4H), 6.45 (m, 1H). 19F NMR: d = 98.06 (m, 1F), 106.02 (m, 1F),
123.20 (m, 1F),128.42 (m, 1F), 133.51 (m, 1F), 142.25 (m, 1F),
180.03 (m, 1F). MS (EI, 70 eV): m/z (%) = 359 (20), 358 (100)
[M]+. Anal. Calcd. for C18H9F7: C, 60.35; H, 2.53. Found: C,
60.53; H, 2.90.
4e: brown solid. IR (KBr): 3510, 1517, 1327, 1272, 1255,
1077, 1066, 1002 cmꢀ1. 1H NMR (300 MHz, CDCl3): d = 6.99
(d, J = 7.5 Hz, 1H), 6.89 (d, J = 7.5 Hz, 1H), 5.30 (d,
J = 14.7 Hz, 1H), 3.38 (m, 2H), 2.79 (t, J = 6.0 Hz, 2H),
1.91 (m, 2H). 19F NMR (282 MHz, CDCl3): d = 119.13 (d,
J = 7.1 Hz, 2F), 127.65 (m, 2F), 140.00 (m, 1F), 169.14 (m, 1F).
MS (EI, 70 eV): m/z (%) = 293 (99) [M]+, 292 (100). Anal.
Calcd. for C13H9F6N: C, 53.25; H, 3.09; N, 4.78. Found: C,
52.97; H, 3.24; N, 4.37.
Acknowledgment
We thank the National Science Foundation of China (Nos.
20272026, D20032010) for financial support of this work.
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