Study the reactions of fluoroalkanesulfonyl azides with N-alkylindoles

Article abstract of DOI:10.1016/j.jfluchem.2004.10.039

The reactions of fluoroalkanesulfonyl azides R_fSO ₂N₃ 1 with N-alkylindoles 2 have been studied in detail. It was found that both solvent and the amount of the azides seriously affected the product distribution. 1 reacted

Full text of DOI:10.1016/j.jfluchem.2004.10.039

Journal of Fluorine Chemistry 126 (2005) 113–120
www.elsevier.com/locate/fluor
Study the reactions of fluoroalkanesulfonyl azides with
N-alkylindoles
*
Ping He, Shi-Zheng Zhu
Key Laboratory of Organofluorine Chemistry, Shanghai Institution of Organic Chemistry,
Chinese Academy of Sciences, 354 Fenglin Lu, Shanghai 200032, China
Received 21 March 2004; accepted 26 October 2004
Available online 7 December 2004
Abstract
The reactions of fluoroalkanesulfonyl azides RfSO2N3 1 with N-alkylindoles 2 have been studied in detail. It was found that both solvent
and the amount of the azides seriously affected the product distribution. 1 reacted with equimolar of 2 in ether or 1,4-dioxane affording 2-(N-
substituted-indolinylidene)fluoroalkane sulfonylimines 3 as major product; While, treatment of 2 with 2 equiv. of 1 in ethanol, an unexpected
product N-substituted-2-fluoroalkanesulfonimino-3-diazo-indolines 4 were obtained in good yield. The reaction mechanism was discussed.
# 2004 Elsevier B.V. All rights reserved.
Keywords: Fluoroalkanesulfonyl azides; N-alkylindoles; Diazo transfer; 1,3-Dipolar cycloaddition; Carbanion process
1. Introduction
[6]. Per (poly) fluroalkanesulfonyl azides RfSO2N3 1 are
more reactive than other nonfluorinated organic azides due
to the strong electron-withdrawing property of the RfSO2
group. However, their reactions are studied rarely. Recently
we systematically studied their reactions with electron-rich
olefin such as enamines, silyl enol ethers, etc. [7], as
continuation of our investigation, the reactions of 1 with N-
alkylindoles have been examined in detail. These reactions
gave 2-(N-substituted-indolinylidene)fluoroalkane sulfony-
limines (3), N-substituted-2-fluoroalkanesulfonimino-3-
diazo-indolines (4) and fluoroalkanesulfonylamide (5), the
distribution of the products are dependent on the reaction
conditions such as solvent, reaction time and molar ratio of
the reactants. Herein we wish to report these results.
As an important nucleus of many alkaloids and pigments,
indole and its derivatives have achieved increased sig-
nificance in medicinal chemistry in recent years [1]. Due to
its special structural character, investigations of their
chemical transformation also gained much attention [2].
Among them, the reactions of sulfonyl azides with indole
and its derivatives were studied extensively. Fusco et al. had
reported that benzensulfonyl azides add to open chain
enamines in such a fashion that the enamine nitrogen and
azide nitrogen are bonded to the same carbon atom in the
product [3] (Scheme 1).
During the past several years Bailey and coworkers have
reported the reaction of arylsulfonyl azides with indole and
alkylindoles and afforded similar results [4,5]. It is well
known that replacement of hydrogen by fluorine in
biologically active molecules often yield analogues with
improved reactivity and selectivity due to the unique
physical and chemical properties of fluorine and C–F bond
2. Results and discussion
The reaction of equimolar fluoroalkanesulfonyl azides 1a
with N-methylindoles 2a was first investigated. It proceeded
smoothly in anhydrous diethyl ether at room temperature,
TLC analysis showed that the azide 1a disappeared within
1 h and three products with close polarities formed. After
removal of solvent, the residue was separated and purified by
* Corresponding author. Tel.: +86 21 641633003525;
fax: +86 21 64166128.
E-mail address: zhusz@mail.sioc.ac.cn (S.-Z. Zhu).
0022-1139/$ – see front matter # 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.jfluchem.2004.10.039

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P. He, S.-Z. Zhu / Journal of Fluorine Chemistry 126 (2005) 113–120
Table 1
Reaction results of fluoroalkanesulfonyl azides 1 with N-alkylindoles 2a
Entry Azides Indoles Time (h) Products and yields (%)b
1
2
3
4
5
6
7
8
9
1a
1a
1b
1b
1c
1c
1d
1e
1e
2a
2b
2a
2b
2a
2b
2a
2a
2b
1
4
4
4
8
8
1
8
8
3aa (76) 4aa (10) 5a (2)
3ab (54) 4ab (20) 5a (10)
3ba (35) 4ba (23) 5b (20)
3bb (33) 4bb (22) 5b (22)
Scheme 1.
3ca (32)
4ca (–)
5c (30)
3cb (30) 4cb (12) 5c (28)
3da (35) 4da (15) 5d (20)
column chromatography over silica gel using petroleum
ether/ether (4:1) as eluant. The first compound 3aa was
isolated in 76% yield. In addition, an unexpected product
4aa was also separated in low yield (10%), accompanying
with small amount of fluoroalkanesulfonylamide 5a (<3%).
New products were fully characterized by spectra
methods and elemental analysis. For instance, the MS
spectrum of 3aa showed its strong molecular ion peak at m/z
3ea (27)
3eb (26) 4eb (–)
4ea (–)
5e (25)
5e (26)
a
1:2 = 1:1, reaction carried out in ether at room temperature.
Isolated yield.
b
decreased obviously, even the corresponding 4ea and 4eb
were not isolated from the system due to the very small
amount but can be seen from the TLC analysis. As
mentioned above, the reaction of 1a with 2a was completed
within 1 h, however, under the same reaction conditions, the
reaction of 1a with N-ethylindole 2b was finished after 4 h
(monitored by TLC). Other azides 1, such as 1b, 1c, 1e,
however, need more reaction time to complete their
reactions.
1
552. Its H NMR consists of five peaks at d 7.55 (m), 7.26
(d), 7.11 (d), 4.30 (s), 3.50 (s), which can be assigned to the
corresponding four Ar–H, the two benzylic protons at the 3
position and the N–CH3, respectively. Meanwhile, a typical
strong absorption at 1552 cmꢀ1 in IR spectrum also
confirmed the existence of C=N functional group. The
mass spectra of 4aa also showed its molecular ion peak, the
mass difference between 3aa and 4aa is 26, which should be
assigned to the additional diazo group (N2). The major
fragment ions observed in spectrum at m/z 235, 207,159 and
132 could be attributed to [M+ ꢀ Rf], [M+ ꢀ Rf ꢀ N2],
[M+ ꢀ RfSO2N] and [M+ ꢀ RfSO2N ꢀ N2] respectively. In
To control the product distribution, some influence
factors were studied in detail. For convenience, the reaction
of fluoroalkanesulfonyl azide 1a and N-methylindole 2a was
chosen as a module reaction. The influence of different
solvents was studied first at room temperature using
equimolar reactants. The results of solvent effects on the
product distribution were summarized in Table 2.
1
its H NMR spectrum, the peak of two benzylic protons at
the 3 position disappeared, while their 19F NMR was similar
to 3aa. A strong absorption at 2153 cmꢀ1 in IR spectrum
was found, which is the typical absorption of C=N+=Nꢀ.
Thus, the molecular structure of compounds 3aa and 4aa
were determined as 2-(N-methyl-indolinylidene)fluoroalk-
ane sulfonylimines and N-methyl-2-fluoroalkanesulfoni-
mino-3-diazo-indolines, respectively (Scheme 2).
From Table 2, it is clear that 1,4-dioxane and Et2O are the
suitable solvent for the formation of product 3aa. Mean-
Table 2
Solvent effects of the product distribution in the reaction of 1a with 2a
Entry
Solvent
T (8C)
Time (h)
Products
and yields (%)a
Other azides 1(b–e) that reacted with 2 gave similar
results. All these results were summarized in Table 1.
Comparing with arylsulfonyl azides, the mild reaction
condition (r.t.) and shorter reaction time (1–8 h) both
confirmed that fluoroalkanesulfonyl azides are more reactive
in these reactions. From Table 1, it was found that when the
azide 1b was used, the yields of 4ba or 4bb were increased
(Table 1, entries 3 and 4). While in the case of the reaction of
azide 1e with 2a or 2b, the yields of 3ea and 3eb were
3aa
4aa
5a
1
2
3
4
5
a
Et2O
20
20
20
20
20
1
87
88
36
93
81
10
9
3
3
CH2Cl2
C2H5OH
1,4-Dioxane
CH3CN
4
0.5
4
32
6
32
1
4
8
11
Determined by 19F NMR.
Scheme 2.

P. He, S.-Z. Zhu / Journal of Fluorine Chemistry 126 (2005) 113–120
115
Table 4
Table 3
Typical results of fluoroalkanesulfonyl azides 1 with N-alkylindoles 2 in
different reaction conditions
Effect of the reactants molar ratio on the products distribution in the reaction
of 1a with 2a
Entry Azides R in 2 Condition
Product Yield
(%)a
Entry
Molar ratio, 1a/2a
Time (h)
Products and
yields (%)a
Sol. molar
ratio
(1/2) T (h)
3aa
4aa
5a
1
2
3
4
5
6
7
a
1
0.5
0.5
0.5
0.5
4
36
20
16
5
32
37
39
44
49
45
44
32
43
45
52
51
55
56
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
1a
1a
1b
1b
1c
1c
1d
1d
1a
1a
1a
1b
1b
1b
1c
1c
1d
1d
2a
2b
2a
2b
2a
2b
2a
2b
2a
2b
2b
2a
2b
2b
2a
2b
2a
2b
1,4-Dioxane
1,4-Dioxane
Et2O
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
1
4
4
4
8
8
1
1
2
2
4
8
8
8
8
8
2
2
3aa
3ab
3ba
3bb
3ca
3cb
3da
3db
4aa
4ab
4ab
4ba
4bb
4bb
4ca
4cb
4da
4db
73
60
35
33
63
51
70
76
81
90
46
52
89
84
59
52
67
89
1.5
2
3
Et2O
1.5
2
0
1,4-Dioxane
1,4-Dioxane
1,4-Dioxane
1,4-Dioxane
Ethanol
4
0
3
4
0
Determined by 19F NMR.
Ethanol
Et2O
while under the same condition, strong polar and protonic
solvent ethanol gave nearly equal amount of 3aa, 4aa and 5a
(entry 3), ethanol was the proper solvent to the formation of
the diazo product 4aa. During our previous study in Et2O,
we found that the molar ratio of the two reactants also
affected the product distribution and the diazo products
could be major product by control of the molar ratios. Then
different molar ratio of the two reactants was investigated at
room temperature in ethanol. The whole reaction process
was followed by 19F NMR and the corresponding results
were summarized in Table 3.
Ethanol
Ethanol
Et2O
Ethanol
Ethanol
Ethanol
Ethanol
a
Isolated yield and based on 2.
From Table 4, it was found that treatment RfSO2N3 1
with equimolar of 2 in 1,4-dioxane at room temperature, 3
were obtained as major products. Meanwhile, by mixing
two equimolar of 1 with 2 in ethanol at room temperature
the major products 4 were obtained in moderate to good
yields within 2–8 h. Compared with the reaction carried out
in Et2O (see Table 1), the yields of 4 were improved
obviously.
It is evident that with the increasing of 1, the proportion of
3aa decreased from 36 to 5%, while the product 4aa
increased from 32 to 44% (Table 3, entries 1–4). To our
surprise, prolonging the reaction time to 4 h, the product 3aa
disappeared and the product 4aa can be selectively formed
(entries 2 and 5). From these results, we could assume that
the products 4 and 5 were formed during the same process
and they might be formed from the transformation of
product 3, which also can be deduced from the TLC analysis.
This point was confirmed during the following studies.
Until now, the controlled reaction conditions to the
formation of the product 3 or 4 are optimized. Some typical
results of the formation of 3 and 4 are selected and
summarized in Table 4.
To the best of our knowledge, the transfer of the diazo
group from arylsulfonyl azides to an active methylene
compound has been known for quite some time [8]. Nearly
all the reported examples have involved the transfer of diazo
group from sulfonyl azides generally under basic reaction
condition [8,9]. However, during the reactions of fluoroalk-
anesulfonyl azides 1 and N-alkylindoles 2 the diazo transfer
reaction to an amidine occurred smoothly in the absence of
Scheme 3.

116
P. He, S.-Z. Zhu / Journal of Fluorine Chemistry 126 (2005) 113–120
base. The products 4 were yellowish stable solid which is
different from the hydrocarbon analogues obtained from the
reaction of arylsulfonyl azides with indoles studied by
Harmon et al. [10]. They found that the corresponding diazo
compounds 8 were light sensitive and difficult to isolate in
pure form, but treated them with PPh3 affording stable
crystalline triphenylphosphine derivatives 9. In addition, the
diazo transfer product was not obtained under the same
conditions using 1,4-dioxane as a solvent instead of ethanol,
i.e., the 2-substituted compounds 6 are the major products
and abnormal 3-substituted compounds 7 are the minor
products in 1,4-dioxane, however, no the corresponding
diazo compounds 8 are formed, which formed only in the
ethanol (Scheme 3).
Scheme 4.
During their studies on the reaction of sulfonyl azides
with indoles, an amino–imino type of tautomeric equili-
brium could be easily observed from the NMR spectra of 6 in
DMSO-d6. However, in our case, the products 3 can dissolve
in DMSO-d6 solution as well as CDCl3, their NMR spectra
shown there is no corresponding amino tautomer exists, the
imino tautomers were the sole type (Scheme 4). These
results are opposite to those reported by Bailey et al. [11] in
the case of 1,3-dimethylindole and are amenable to those
reported by Harmon et al. [12]. They found that in general
electron-withdrawing substituents on the benzenesulfona-
mido group reduce the percentage of amino tautomer in
solution. Thus, the strong electron-withdrawing ability of
the fluorine-containing group perhaps can be used to explain
why only the imino tautomers were found in their NMR
spectra.
Scheme 5.
Scheme 6.

P. He, S.-Z. Zhu / Journal of Fluorine Chemistry 126 (2005) 113–120
117
In our previous study on the fluoroalkanesulfonyl azides
1, the nitrene RfSO2N: formed thermally at 110 8C, thus in
above reactions the nitrene intermediates were not involved.
In the reactions of azides 1 with N-alkylindoles 2, the
triazoline A should be formed first via 1,3-dipolar
cycloaddition process. When the triazoline ring carries an
electron-withdrawing group at the 1-position, it is very
labile. Thus, the triazolines A are not isolated, it
decomposed immediately after their formation in situ
followed by elimination of N2 gas and 1,2-H shift to form
amidines 3. Since the transfer of diazo group from sulfonyl
azides was supposed to involve a carbanion as the reactive
species, the formation of diazo compounds 4 may be
explained well. The formed amidines 3 could be further
reacted with 1 and following with the hydrogen abstraction
to form product 4 and fluoroalkanesulfonamide 5, that is, the
amidines 3 are the key intermediates to the formation of 4
(Scheme 5).
respectively. Elemental analyses were performed by this
institute. All solvents were purified before use. Fluoroalk-
anesulfonyl azides 1 and N-substituted indoles 2 were
prepared according to literature [13,14].
4.1. Typical procedure for the preparation of
2-(N-substituted-indolinylidene)
fluoroalkanesulfonylimines 3
To a 10 mL round-bottom flask containing N-substituted
indoles 2a (2.0 equiv.) in 2 mL 1,4-dioxane or anhydrous
ether was added slowly fluoroalkanesulfonyl azides 1a
(2.0 equiv.) at room temperature within 2 min. Then the
mixture was continuously stirred at room temperature within
1 h until TLC analysis shown the reaction finished. The
solvent was evaporated and the residue was chromato-
graphed on a silica column using petroleum ether/diethyl
ether (4:1) as eluant to give pure product 3aa as a white solid.
This mechanism was further substantiated by the
conversion of amidine 3ba with another equimolar amount
of 1b to diazo compound 4ba in 82% yield. Meanwhile, we
also obtained the compound 4ca by treatment equimolar of
3ca with 1a under the same condition with excellent yield up
to 92%, which was not isolated successfully due to the small
amount of formation in corresponding reaction in Et2O
(Table 1, entry 5). In addition to 4ca, the formation of
another product IRfSO2NH2 5a confirmed the mechanism
again (Scheme 6).
4.1.1. 2-(N-Methyl-indolinylidene)-
(50-iodo-30-oxa-octafluoropentyl)-
sulfonyl imines (3aa)
m.p. 79–80 8C. FT-IR (nmax, cmꢀ1): 1576, 1554 (s, C=N),
1
1499, 1334, 1177, 1135. H NMR d (ppm): 7.80–7.10 (m,
4H, ArH), 4.30 (s, 2H, CH2), 3.50 (s, 3H, CH3). 19F NMR d
(ppm): ꢀ65.2 (t, 2F, ICF2), ꢀ81.7 (t, 2F, CF2O), ꢀ85.8 (m,
2F, OCF2), ꢀ117.3 (s, 2F, SCF2). MS m/z (ion, %): 552 (M+,
49), 425 (M+ ꢀ I, 8), 227 (IC2F4 , 6), 209 (M+ ꢀ Rf, 78), 177
+
+
(ICF2 ,
6),
145
(M+ ꢀ RfSO2,
98),
118
(M+ ꢀ RfSO2 ꢀ HCN, 100). Anal. Calcd. for C13H9F8I-
N2O3S (%): C, 28.26; H, 1.63; N, 5.07; Found (%): C, 28.20;
H, 1.64; N, 5.00.
3. Conclusions
In summary, the reactions of fluoroalkanesulfonyl
azides and N-alkylindoles under mild reaction condition
were studied in detail. By control of the reactant molar
ratio, the 2-(N-substituted-indolinylidene)fluoroalkane sul-
fonylimines 3 and N-substituted-2-fluoroalkanesulfoni-
mino-3-diazo-indolines 4 were obtained selectively in
1,4-dioxane or ethanol in moderate to good yields,
respectively. The obtained products are important synthons
in many synthesis processes, their chemical transformations
are under way.
4.1.2. 2-(N-methyl-indolinylidene)-
(50-chloro-30-oxa-octafluoropentyl)-
sulfonyl imines (3ba)
m.p. 129–130 8C. FT-IR (nmax, cmꢀ1): 1580 (s, C=N),
1384, 1313, 1200, 1167. 1H NMR d (ppm): 7.42–7.12 (m, 4H,
ArH), 4.30 (s, 2H, CH2), 3.50 (s, 3H, CH3). 19F NMR d (ppm):
ꢀ73.7 (s, 2F, ClCF2), ꢀ81.2 (t, 2F, CF2O), ꢀ86.7 (t, 2F,
OCF2), ꢀ116.8 (s, 2F, SCF2). MS m/z (ion, %): 462/460 (M+,
13/34), 425 (M+ ꢀ Cl, 8), 209 (M+ ꢀ Rf, 69), 145
(M+ ꢀ RfSO2, 91), 135 (ClC2F4 , 7), 118 (M+ ꢀ RfSO2 ꢀ
+
HCN, 100). Anal. Calcd. for C13H9ClF8N2O3S (%): C, 33.91;
H, 1.96; N, 6.09; Found (%): C, 33.76; H, 1.96; N, 5.86.
4. Experimental
Melting points were measured in Temp-Melt apparatus
and were uncorrected. 1H and 19F NMR spectra were
recorded in CDCl3 (unless mentioned in text), Bruker AM-
300 instruments with Me4Si and CFCl3 (with upfield
negative) as the internal and external standards, respectively.
IR spectra were obtained with a Nicolet AV-360 spectro-
photometer. Lower resolution mass spectrum or high
resolution mass spectra (HRMS) were obtained on a
Finnigan GC-MS 4021 or a Finnigan MAT-8430 instrument
using the electron impact ionization technique (70 eV),
4.1.3. 2-(N-methyl-indolinylidene)-(10,10,20,20,40,40,50,50-
octafluoro-30-oxa-pentyl) sulfonyl imines (3ca)
m.p. 108–110 8C. FT-IR (nmax, cmꢀ1): 1562 (s, C=N),
1338, 1199, 1180. H NMR d (ppm): 7.46–7.10 (m, 4H,
1
ArH), 5.88 (t–t, J = 52.5 Hz, 3 Hz, 1H, HCF2), 4.31 (s, 2H,
CH2), 3.51 (s, 3H, CH3). 19F NMR d (ppm): ꢀ81.2 (t, 2F,
CF2O), ꢀ88.8 (s, 2F, OCF2), ꢀ117.3 (s, 2F, CF2S), ꢀ137.6
(d, J = 53 Hz, 2F, HCF2). MS m/z (ion, %): 426 (M+, 34), 209
(M+ ꢀ Rf, 45), 177 (ICF2 , 6), 145 (M+ ꢀ RfSO2, 75), 118
+
+
(M+ ꢀ RfSO2 ꢀ HCN, 100), 101 (HC2F4 , 14). Anal. Calcd.

118
P. He, S.-Z. Zhu / Journal of Fluorine Chemistry 126 (2005) 113–120
for C13H10F8N2O3S (%): C, 36.62; H, 2.35; N, 6.57; Found
(%): C, 36.62; H, 2.54; N, 6.31%.
4.1.8. 2-(N-ethyl-indolinylidene)-
perfluorobutylsulfonylimines (3db)
m.p. 48–50 8C. FT-IR (nmax, cmꢀ1): 1569 (s, C=N), 1374,
1317, 1200, 1140, 1046. H NMR d (ppm): 7.44–7.11 (m,
1
4.1.4. 2-(N-ethyl-indolinylidene)-(50-iodo-30-oxa-
octafluoropentyl)-sulfonylimines (3ab)
4H, ArH), 4.31 (s, 2H, CH2), 4.06 (q, J = 7.5 Hz, 2H,
CH2CH3), 1.36 (t, J = 7.5 Hz, 3H, CH2CH3). 19F NMR d
(ppm): ꢀ81.0 (s, 3F, CF3), ꢀ113.6 (t, 2F, CF2S), ꢀ121.3 (s,
2F, CF2), ꢀ126.2 (t, 2F, CF3CF2). MS m/z (ion, %): 442 (M+,
13), 223 (M+ ꢀ Rf, 39), 159 (M+ ꢀ RfSO2, 100), 132
(M+ ꢀ RfSO2 ꢀ HCN, 43). HRMS for C14H11F9N2O2S
Calcd.: 442.03920%; Found: 442.03940%.
m.p. 88–90 8C. FT-IR (nmax, cmꢀ1): 2988, 1552 (s, C=N),
1494, 1331, 1290, 1143, 1089. 1H NMR d (ppm): 7.40–7.12
(m, 4H, ArH), 4.29 (s, 2H, CH2), 4.04 (q, J = 7.2 Hz, 2H,
CH2CH3), 1.36 (t, J = 7.2 Hz, 3H, CH2CH3). 1H NMR
(DMSO-d6) d (ppm): 7.52–7.24 (m, 4H, ArH), 4.34 (s, 2H,
CH2), 4.03 (q, J = 7.2 Hz, 2H, CH2CH3), 1.23 (t, J = 7.2 Hz,
3H, CH2CH3). 19F NMR d (ppm): ꢀ64.7(t, 2F, ICF2), ꢀ81.2
(t, 2F, CF2O), ꢀ85.4 (m, 2F, OCF2), ꢀ116.6 (s, 2F, CF2S).
4.1.9. 2-(N-methyl-indolinylidene)-
(20-isopropoxylcarbonyl-10-difluoromethyl)
MS m/z (ion, %): 566 (M+, 22), 439 (M+ ꢀ I, 4), 227 (IC2F4 ,
+
5), 223 (M+ ꢀ Rf, 50), 177 (ICF2 , 4), 159 (M+ ꢀ RfSO2,
sulfonylimines (3ea)
+
100), 132 (M+ ꢀ RfSO2 ꢀ HCN, 39). Anal. Calcd. for
C14H11F8IN2O3S (%): C, 29.68; H, 1.94; N, 4.95; Found
(%): C, 29.70; H, 1.94; N, 4.92.
m.p. 138–140 8C. FT-IR (nmax, cmꢀ1): 2995, 1763, 1577
(s, C=N), 1381, 1318, 1156, 1100. 1H NMR d (ppm): 7.44–
7.08 (m, 4H, ArH), 5.26 (m, 1H, CH), 4.30 (s, 2H, CH2), 3.49
(s, 3H, CH3), 1.40 (d, J = 6.3 Hz, 6H, 2CH3). 19F NMR d
(ppm): ꢀ109.8 (s, 2F, CF2). MS m/z (ion, %): 346 (M+, 32),
304 (M+ ꢀ C3H6, 13), 209 (M+ ꢀ Rf, 93), 145 (M+ ꢀ
4.1.5. 2-(N-ethyl-indolinylidene)-(50-chloro-30-oxa-
octafluoropentyl)-sulfonyl imines (3bb)
m.p. 106–108 8C. FT-IR (nmax, cmꢀ1): 1569 (s, C=N),
1372, 1317, 1204, 1168. 1H NMR d (ppm): 7.43–7.11 (m, 4H,
ArH), 4.29 (s, 2H, CH2), 4.05 (q, J = 7.2 Hz, 2H, CH2CH3),
1.35 (t, J = 7.2 Hz, 3H, CH2CH3). 19F NMR d (ppm): ꢀ74.0
(s, 2F, ClCF2), ꢀ81.6 (t, 2F, CF2O), ꢀ87.0 (t, 2F, OCF2),
ꢀ117.0 (s, 2F, CF2). MS m/z (ion, %): 476/474 (M+, 9/23),
439 (M+ ꢀ Cl, 5), 223 (M+ ꢀ Rf, 46), 159 (M+ ꢀ RfSO2,
RfSO2N, 100), 118 (M+ ꢀ RfSO2N ꢀ HCN, 89), 43 (C3H7 ,
+
15). Anal. Calcd. for C14H16F2N2O4S (%): C, 48.55; H, 4.62;
N, 8.09; Found (%): C, 48.48; H, 4.56; N, 8.18.
4.1.10. 2-(N-methyl-indolinylidene)-
(20-isopropoxylcarbonyl-10-difluoromethyl)
sulfonylimines (3eb)
100), 135 (ClC2F4 , 27), 80 (M+ ꢀ RfSO2 ꢀ HCN, 100).
m.p. 120–122 8C. FT-IR (nmax, cmꢀ1): 2991, 1765, 1568
(s, C=N), 1374, 1314, 1159, 1097. 1H NMR d (ppm): 7.42–
7.08 (m, 4H, ArH), 5.25 (m, 1H, CH), 4.29 (s, 2H, CH2),
4.02 (q, J = 7.5 Hz, 2H, CH2CH3), 1.40–1.34 (m, 9H,
3CH3). 19F NMR d (ppm): ꢀ109.4 (s, 2F, CF2). MS m/z (ion,
%): 360 (M+, 26), 318 (M+ ꢀ C3H6, 7), 223 (M+ ꢀ Rf, 69),
159 (M+ ꢀ RfSO2N, 100), 132 (M+ ꢀ RfSO2N ꢀ HCN, 32),
+
Anal. Calcd. for C14H11ClF8N2O3S (%): C, 35.41; H, 2.32;
N, 5.90; Found (%): C, 35.31; H, 2.54; N, 5.89.
4.1.6. 2-(N-ethyl-indolinylidene)-(10,10,20,20,40,40,50,50-
octafluoro-30-oxa-pentyl)-sulfonylimines (3cb)
m.p. 90–92 8C. FT-IR (nmax, cmꢀ1): 1568 (s, C=N), 1372,
1319, 1166, 1018. 1H NMR d (ppm): 7.44–7.10 (m, 4H, ArH),
5.88 (t–t, J = 52.8 Hz, 3 Hz, 1H, HCF2), 4.29 (s, 2H, CH2),
4.04 (q, J = 7.5 Hz, 2H, CH2CH3), 1.36 (t, J = 7.5 Hz, 3H,
CH2CH3). 19F NMR d (ppm): ꢀ80.9 (t, 2F, CF2O), ꢀ88.6 (t,
2F, OCF2), ꢀ116.9 (s, 2F, CF2S), ꢀ137.3 (d, J = 53 Hz, 2F,
HCF2). MSm/z(ion,%):440(M+, 34), 223(M+ ꢀ Rf, 45), 159
(M+ ꢀ RfSO2N, 100), 132 (M+ ꢀ RfSO2N ꢀ HCN, 43).
HRMS for C14H12F8N2O3S Calcd.: 440.04354%; Found:
440.04393%.
+
43 (C3H7 , 9). HRMS for C15H18F2N2O4S Calcd.:
360.09498%; Found: 360.09486%.
4.2. Typical procedure for the preparation of
N-substituted-2-fluoroalkanesulfonimino-
3-diazo-indolines 4
To a 10 mL round-bottom flask containing N-substituted
indoles 2 (1.0 equiv.) in 2 mL anhydrous ethanol was added
slowly fluoroalkanesulfonyl azides 1 (2.0 equiv.) at room
temperature within 2 min. Then the mixture was continu-
ously stirred at r.t. within 1–8 h until TLC analysis shown
that the reaction finished. The solvent was evaporated and
the residue was chromatographed on a silica column using
petroleum ether/diethyl ether (4:1) as eluant to give pure
product 4 as a yellowish solid.
4.1.7. 2-(N-methyl-indolinylidene)-
perfluorobutylsulfonylimines (3da)
m.p. 171–173 8C. FT-IR (nmax, cmꢀ1): 1581 (s, C=N),
1504, 1384, 1317, 1163, 1138, 1077. H NMR d (ppm):
7.43–7.11 (m, 4H, ArH), 4.31 (s, 2H, CH2), 3.51 (s, 3H,
CH3). 19F NMR d (ppm): ꢀ80.7 (t, 3F, CF3), ꢀ113.4 (t, 2F,
CF2S), ꢀ120.9 (m, 2F, CF2), ꢀ125.9 (t, 2F, CF3CF2). MS m/
z (ion, %): 428 (M+, 14), 209 (M+ ꢀ Rf, 41), 145
(M+ ꢀ RfSO2N, 55), 118 (M+ ꢀ RfSO2N ꢀ HCN, 100).
Anal. Calcd. for C13H9F9N2O2S (%): C, 36.45; H, 2.10; N,
6.54; Found (%): C, 36.70; H, 2.11; N, 6.41.
1
4.2.1. N-methyl-2-(50-iodo-30-oxa-octafluoropentyl)-
sulfonimino-3-diazo-indolines (4aa)
m.p. 90–92 8C. FT-IR (nmax, cmꢀ1): 2147 (s, C=N+=Nꢀ),
1541 (s, C=N), 1386, 1330, 1297, 1218. 1H NMR d (ppm):

P. He, S.-Z. Zhu / Journal of Fluorine Chemistry 126 (2005) 113–120
119
7.42–7.26 (m, 4H, ArH), 3.63 (s, 3H, CH3). 19F NMR d
(ppm): ꢀ65.0 (t, 2F, ICF2), ꢀ81.6 (t, 2F, CF2O), ꢀ85.8 (m,
2F, OCF2), ꢀ116.9 (s, 2F, CF2S). MS m/z (ion, %): 578 (M+,
(M+, 7/19), 249 (M+ ꢀ Rf, 21), 221 (M+ ꢀ Rf ꢀ N2, 54), 146
(M+ ꢀ RfSO2N ꢀ N2,
100).
Anal.
Calcd.
for
C14H9ClF8N4O3S (%): C, 33.57; H, 1.80; N, 11.19; Found
(%): C, 33.63; H, 1.95; N, 11.31.
23), 451 (M+ ꢀ I, 2), 235 (M+ ꢀ Rf, 24), 227 (IC2F4 , 9), 207
+
(M+ ꢀ Rf ꢀ N2, 61), 177 (ICF2 , 15), 159 (M+ ꢀ RfSO2N,
+
33), 132 (M+ ꢀ RfSO2N ꢀ N2, 100). Anal. Calcd. for
C13H7F8IN4O3S (%): C, 26.99; H, 1.21; N, 9.69; Found
(%): C, 27.27; H, 1.28; N, 9.33.
4.2.6. N-ethyl-2-(10,10,20,20,40,40,50,50-octafluoro-
30-oxa-pentyl)-sulfonimino-3-diazo-indolines (4cb)
m.p. 86–88 8C. FT-IR (nmax, cmꢀ1): 2134 (s, C=N+=Nꢀ),
1
1533 (s, C=N), 1397, 1322, 1210, 1138, 1059. H NMR d
4.2.2. N-methyl-2-(50-chloro-30-oxa-octafluoropentyl)-
sulfonimino-3-diazo-indolines (4ba)
(ppm): 7.42–7.25 (m, 4H, ArH), 5.88 (t–t, J = 52.5 Hz, 3 Hz,
1H, HCF2), 4.17 (q, J = 7.5 Hz, 2H, CH2CH3), 1.36 (t,
J = 7.5 Hz, 3H, CH2CH3). 19F NMR d (ppm): ꢀ81.0 (t, 2F,
CF2O), ꢀ88.6 (m, 2F, OCF2), ꢀ116.6 (s, 2F, CF2S), ꢀ137.3
(d, J = 52.5 Hz, 2F, HCF2,). MS m/z (ion, %): 466 (M+, 24),
249 (M+ ꢀ Rf, 21), 221 (M+ ꢀ Rf ꢀ N2, 47), 146
(M+ ꢀ RfSO2N ꢀ N2, 100). HRMS for C14H10F8N4O3S
Calcd.: 446.03404%; Found: 446.03532%.
m.p. 120–121 8C. FT-IR (nmax
,
cmꢀ1): 2152 (s,
C=N+=Nꢀ), 1544 (s, C=N), 1387, 1329, 1219, 1128. H
NMR d (ppm): 7.42–7.26 (m, 4H, ArH), 3.63 (s, 3H, CH3).
19F NMR d (ppm): ꢀ73.7 (s, 2F, ClCF2), ꢀ81.3 (t, 2F,
CF2O), ꢀ86.7 (t, 2F, OCF2), ꢀ116.8 (s, 2F, CF2S). MS m/z
(ion, %): 488/486 (M+, 11/28), 235 (M+ ꢀ Rf, 28), 207
(M+ ꢀ Rf ꢀ N2, 61), 159 (M+ ꢀ RfSO2N, 32), 135
1
(ClC2F4 , 9), 132 (M+ ꢀ RfSO2N ꢀ N2, 100). Anal. Calcd.
+
4.2.7. N-methyl-2-perfluorobutylsulfonimino-3-diazo-
indolines (4da)
for C13H7ClF8N4O3S (%): C, 32.10; H, 1.44; N, 11.52;
Found (%): C, 31.79; H, 1.68; N, 11.43.
m.p. 140–142 8C. FT-IR (nmax
,
cmꢀ1): 2138 (s,
C=N+=Nꢀ), 1562 (s, C=N), 1435, 1392, 1307, 1218,
1
4.2.3. N-methyl-2-(10,10,20,20,40,40,50,50-octafluoro-
30-oxa-pentyl)-sulfonimino-3-diazo-indolines (4ca)
1137. H NMR d (ppm): 7.41–7.26 (m, 4H, ArH), 3.64 (s,
3H, CH3). 19F NMR d (ppm): ꢀ80.9 (t, 3F, CF3), ꢀ113.4 (t,
2F, CF2S), ꢀ121.3 (s, 2F, CF2), ꢀ126.2 (t, 2F, CF3CF2). MS
m/z (ion, %): 235 (M+ ꢀ Rf, 14), 207 (M+ ꢀ Rf ꢀ N2, 23),
159 (M+ ꢀ RfSO2N, 37), 132 (M+ ꢀ RfSO2N ꢀ N2, 100).
Anal. Calcd. for C13H7F9N4O2S (%): C, 34.36; H, 1.54; N,
12.33; Found (%): C, 34.28; H, 1.60; N, 12.37.
m.p. 114–116 8C. FT-IR (nmax
,
cmꢀ1): 2153 (s,
C=N+=Nꢀ), 1545 (s, C=N), 1388, 1329, 1141. H NMR d
(ppm): 7.46–7.11 (m, 4H, ArH), 5.88 (t–t, J = 52.2 Hz, 3 Hz,
1H, HCF2), 3.60 (s, 3H, CH3). 19F NMR d (ppm): ꢀ81.3 (t,
2F, CF2O), ꢀ88.9 (s, 2F, OCF2), ꢀ117.1 (s, 2F, CF2S),
ꢀ137.6 (d, J = 53 Hz, 2F, HCF2). MS m/z (ion, %): 452 (M+,
26), 235 (M+ ꢀ Rf, 25), 207 (M+ ꢀ Rf ꢀ N2, 48), 159
(M+ ꢀ RfSO2N, 33), 132 (M+ ꢀ RfSO2N ꢀ N2, 100), 101
1
4.2.8. N-ethyl-2-perfluorobutylsulfonimino-3-diazo-
indolines (4da)
+
m.p. 58–60 8C. FT-IR (nmax, cmꢀ1): 2981, 2143 (s,
C=N+=Nꢀ), 1522 (s, C=N), 1460, 1395, 1333, 1216, 1165,
(HC2F4 , 22). Anal. Calcd. for C13H8F8N4O3S (%): C, 34.51;
H, 1.77; N, 12.39; Found (%): C, 34.58; H, 1.90; N, 12.41.
1
1061. H NMR d (ppm): 7.41–7.26 (m, 4H, ArH), 4.19 (q,
4.2.4. N-ethyl-2-(50-iodo-30-oxa-octafluoropentyl)-
sulfonimino-3-diazo-indolines (4ab)
J = 7.2 Hz, 2H, CH2CH3), 1.37 (t, J = 7.2 Hz, 3H, CH2CH3).
19F NMR d (ppm): ꢀ81.0 (t, 3F, CF3), ꢀ113.4 (t, 2F, CF2S),
ꢀ121.3(s, 2F, CF2), ꢀ126.2(t, 2F, CF3CF2). MS m/z (ion, %):
468 (M+, 43), 249 (M+ ꢀ Rf, 32), 221 (M+ ꢀ Rf ꢀ N2, 46),
146 (M+ ꢀ RfSO2N ꢀ N2, 100). Anal. Calcd. for
C14H9F9N4O2S (%): C, 35.90; H, 1.92; N, 11.96; Found
(%): C, 35.86; H, 1.86; N, 12.08.
m.p. 85–86 8C. FT-IR (nmax, cmꢀ1): 2130 (s, C=N+=Nꢀ),
1527 (s, C=N), 1398, 1332, 1291, 1213, 1138. H NMR d
1
(ppm): 7.42–7.26 (m, 4H, ArH), 4.18 (q, J = 7.2 Hz, 2H,
CH2CH3), 1.36 (t, J = 7.2 Hz, 3H, CH2CH3). 19F NMR d
(ppm):ꢀ64.6 (t, 2F, ICF2), ꢀ81.3 (t, 2F, CF2O), ꢀ85.4 (m, 2F,
OCF2), ꢀ116.5 (s, 2F, CF2S). MS m/z (ion, %): 592 (M+, 29),
465 (M+ ꢀ I, 3), 249 (M+ ꢀ Rf, 31), 227 (IC2F4 , 9), 221
+
(M+ ꢀ Rf ꢀ N2, 93), 177 (ICF2 , 24), 146 (M+ ꢀ RfSO2N ꢀ
+
Acknowledgements
N2, 100). Anal. Calcd. for C14H9F8IN4O3S (%): C, 28.38; H,
1.52; N, 9.46; Found (%): C, 28.50; H, 1.62; N, 9.17.
The authors thank the National Natural Science
Foundation of China (nos. 20032010, 20372077) and
Innovation Foundation of Chinese Academy of Science
for financial support.
4.2.5. N-ethyl-2-(50-chloro-30-oxa-octafluoropentyl)-
sulfonimino-3-diazo-indolines (4bb)
m.p. 70–72 8C. FT-IR (nmax, cmꢀ1): 2964, 2155 (s,
C=N+=Nꢀ), 1531 (s, C=N), 1401, 1329, 1175, 1135. 1H NMR
d (ppm): 7.41–7.26 (m, 4H, ArH), 4.18 (q, J = 7.2 Hz, 2H,
CH2CH3), 1.36 (t, J = 7.2 Hz, 3H, CH2CH3). 19F NMR d
(ppm): ꢀ73.7 (s, 2F, ClCF2), ꢀ81.3 (t, 2F, CF2O), ꢀ86.7 (t,
2F, OCF2), ꢀ116.6 (s, 2F, CF2S). MS m/z (ion, %): 502/500
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