Synthesis of 2-aryl-3-arylsulfonylindoles and 2-anilino-3- arylsulfonylindoles from 2-(arylsulfonyl)methylanilines using the aza-Wittig reaction of iminophosphoranes

Article abstract of DOI:10.1055/s-1998-2096

2-(Arylsulfonyl)methyl-N-(triphenylphosphoranylidene)-anilines 5 were prepared starting from 2-(arylsulfonyl)-methylanilines 2. The aza-Wittig reaction of iminophosphoranes 5 with acyl cyanides gave N- [aryl(cyano)methylene]-2-(arylsulfonyl)methylanilines

Full text of DOI:10.1055/s-1998-2096

PAPERS
986
Synthesis of 2-Aryl-3-arylsulfonylindoles and 2-Anilino-3-arylsulfonylindoles from 2-
(Arylsulfonyl)methylanilines Using the Aza-Wittig Reaction of Iminophosphoranes
Masahiko Takahashi,* Daishi Suga
Department of Materials Science, Faculty of Engineering, Ibaraki University, Hitachi, Ibaraki 316, Japan
Fax +81(294)344668; E-mail: takamasa@hit.ipc.ibaraki.ac.jp
Received 18 November 1997; revised 6 January 1998
Abstract: 2-(Arylsulfonyl)methyl-N-(triphenylphosphoranylidene)-
anilines 5 were prepared starting from 2-(arylsulfonyl)methyl-
anilines 2. The aza-Wittig reaction of iminophosphoranes 5
with acyl cyanides gave N-[aryl(cyano)methylene]-2-(arylsulfo-
nyl)methylanilines 6, which were cyclized by sodium hydroxide
to 2-aryl-3-arylsulfonylindoles 7. The iminophosphoranes 5
reacted with phenyl isocyanate to give the corresponding carbodi-
imides 11, which were cyclized in a similar manner to 2-anilino-
3-arylsulfonylindoles 12.
Key words: sulfones, iminophosphoranes, acyl cyanides, aza-
Wittig reaction, indoles
The synthesis of heterocycles using the aza-Wittig reac-
tion of iminophosphoranes is now one of the most useful
methods for preparing nitrogen-containing heterocycles.1
The versatility of the heterocyclic synthesis comes from
the ready accessibility of iminophosphoranes and their
high reactivity towards heterocumulenes and carbonyl
compounds. We are interested in the synthesis of hetero-
cycles using sulfur compounds and have used iminophos-
Scheme 1
phorane-containing sulfur compounds for this purpose.
We obtained 2-substituted 1,3-benzothiazoles from 2-
Table 1. Azides 4 and Iminophosphoranes 5 Prepared
methylsulfanylaniline2 and 2-substituted 1,4-benzothia-
zine-3-thiones3 from 2-(substituted methylsulfanyl)ani-
lines via the corresponding iminophosphoranes. As a con-
tinuation of this study, we chose the iminophosphoranes 5
as the starting sulfur-containing compounds. We report
here the unexpected formation of 2-aryl-3-aryl-sulfo-
nylindoles from 5 and some related results.
Producta
R
R1
Yield
(%)
mp (°C)
4a
4b
4c
5a
5b
5c
H
4-MeC6H4
Ph
4-MeC6H4
4-MeC6H4
Ph
76
87
87
82
95
93
124–126
159–161
154–156
174–175
220–222
240–242
Cl
Cl
H
Cl
Cl
4-MeC6H4
The iminophosphoranes 5 have an active methylene group
adjacent to a sulfonyl group4 and appear to serve as a good
building block for heterocycles (Scheme 1). They can be
easily synthesized from the readily available aryl 2-ni-
trobenzyl sulfones 1.5 2-(Arylsulfonyl)methylanilines
2a–c were obtained by reduction of the nitro group in 1
with tin in hydrochloric acid.6 In a preliminary experi-
ment, 2c (R = Cl, R1 = p-Tol) was diazotized, neutralized
by alkali, and then treated with sodium azide. However,
the product was 5-chloro-3-(p-tolyl)sulfonyl-1H-indazole
(3) instead of the expected azide 4c. Direct addition of so-
dium azide to the diazotized 2 without neutralization by
alkali gave the desired azides 4a–c in 76–87% yield (Ta-
bles 1 and 2). The iminophosphoranes 5a–c were readily
prepared in 82–95% yield from the azides 4 and tri-
phenylphosphane in dichloromethane at 0–5°C to room
temperature (Staudinger reaction1b).
a
Satisfactory microanalyses obtained: C ± 0.28, H ± 0.30, N ± 0.26.
the condensation of the iminophosphorane moiety of 5 with
such ketones was difficult. A report7 about the formation of
2-cyano-1-azadienes by the condensation of iminophos-
phoranes with cinnamoyl cyanide prompted us to use aroyl
cyanides as the substrate. In fact, 5 readily condensed with
aroyl cyanides in refluxing toluene to form 6a–f in 48–74%
yield (Scheme 2 and Tables 3 and 4).
Cyclization of the anions 8 generated by basic treatment
of 6 was expected to give 3-amino-4-phenylsulfonylquin-
oline derivatives 10 through 6-exo-digonal cyclization.8
However, treatment of 6 with sodium hydroxide in warm
DMSO unexpectedly yielded 2-aryl-3-arylsulfonylin-
doles 7a–f in 56–83% yield. Recently, Ichikawa
et al.9 reported that the “disfavored” 5-endo-trigonal
cyclization10 occurred during the nucleophilic addition–
elimination of β,β-difluoro-(o-tosylamino)styrene and
β,β-difluoro-(o-hydroxy)styrene to give 2-fluoroindoles
The preparation of 4-phenylsulfonylquinoline derivatives
by condensation of the iminophosphorane group of 5 with
benzil or methyl phenylglyoxalate followed by cycliza-
tion in the presence of a base was unsuccessful, because

SYNTHESIS
July 1998
987
Table 2. MS, IR, and 1H NMR Data of Azides 4 and Iminophosphoranes 5
Product
4a
MS
m/z (%)
IR (KBr)
1H NMR (CDCl3/TMS)
δ
ν (cm–1)
287 (M+, 7), 194 (50), 180 (28), 132 (28),
104 (100)
2070, 1590, 1480, 1440, 1400, 1280,
1145, 1120, 1080
2.41 (s, 3H), 4.37 (s, 2H), 6.97–7.53 (m,
8H)
4b
307 (M+, 10), 214 (46), 180 (40), 138
(31), 102 (69), 77 (100)
2100, 1410, 1290, 1145, 1130, 1080
4.33 (s, 2H), 6.90–7.70 (m, 8H)
4c
321 (M+, 8), 228 (35), 214 (22), 194 (19),
138 (23), 91 (100)
2070, 1590, 1480, 1395, 1290, 1240,
1130
2.43 (s, 3H), 4.29 (s, 2H), 6.91–7.57 (m,
7H)
5a
521 (M+, 4), 366 (100), 212 (2), 183 (25),
152 (2), 108 (5)
1580, 1480, 1445, 1430, 1345, 1295,
1270, 1105, 1080
2.22 (s, 3H), 4.94 (s, 2H), 6.21–7.54
(23H)
5b
541 (M+, 6), 400 (100), 214 (8), 183 (41),
108 (8)
1570, 1460, 1330, 1295, 1110, 1010
4.90 (s, 2H), 6.10–7.70 (m, 23H)
5c
555 (M+, 6), 400 (100), 214 (9), 183 (45),
152 (5), 108 (8)
1580, 1465, 1340, 1305, 1295, 1105
2.25 (s, 3H), 4.87 (s, 2H), 6.10–7.43 (m,
22H)
and 2-fluorobenzo[b]furans, respectively. These types of
reactions seem to be the same as our method of prepara-
tion of indoles 7. However, the formation of 7 may also be
explained by a 2,3-sigmatropic rearrangement of the an-
ion 8 to the next intermediate 9 followed by aromatization
upon elimination of hydrogen cyanide (Scheme 2).
Carbodiimide formation from iminophosphoranes and
isocyanates followed by intramolecular nucleophilic cy-
clization is a useful methodology for the synthesis of five-
membered nitrogen heterocycles such as pyrazoles, 1,3-
oxazoles, imidazoles, 1,3,4-oxadiazoles, 1,3,4-thiadiaz-
oles, and 1,3,4-triazoles and has been well-reviewed.1d,g
However, studies on the preparation of a pyrrole ring by
such a cyclization process are limited.11 We realized that
cyclization by attack of a sulfone-stabilized carbanion at
the carbodiimide moiety produces indoles. The imino-
phosphoranes 5a–c were treated with phenyl isocyanate in
refluxing dichloromethane to give carbodiimides 11a–c in
66–98% yield (Scheme 3 and Tables 5 and 6). 5-exo-Trig-
Scheme 2
Table 3. Nitriles 6 and Indoles 7 Prepared
Producta
R
R1
R2
Yield (%) mp (°C)
6a
6b
6c
6d
6e
6f
7a
7b
7c
7d
7e
7f
H
H
4-MeC6H4 Ph
4-MeC6H4 4-MeC6H4
49
64
61
67
74
48
74
83
81
66
56
74
115–118
162–164
197–199
156–158
170–171
170–172
204–205
227–228
189–190
215–216
173–175
220–221
Cl
Cl
Cl
Cl
H
Ph
Ph
Ph
4-MeC6H4
4-MeC6H4 Ph
4-MeC6H4 4-MeC6H4
4-MeC6H4 Ph
H
4-MeC6H4 4-MeC6H4
Cl
Cl
Cl
Cl
Ph
Ph
Ph
4-MeC6H4
4-MeC6H4 Ph
4-MeC6H4 4-MeC6H4
a
Satisfactory microanalyses obtained: C ± 0.32, H ± 0.28, N ± 0.28.
Compounds 7a–c, 7e, and 7f contained occluded water to an extent
of 0.5 H2O, 1 H2O, and 0.25 H2O, respectively.
Scheme 3

SYNTHESIS
Papers
Table 4. MS, IR, and 1H NMR Data of Nitriles 6 and Indoles 7
988
Product
6a
MS
m/z (%)
IR (KBr)
1H NMR (CDCl3/TMS)
δ
ν (cm–1)
374 (M+, 7), 219 (100), 165 (6), 116
(14)
2210, 1600, 1565, 1450, 1315, 1290, 1255,
1160, 1130, 1085
2.29 (s, 3H), 4.60 (s, 2H), 6.94–7.98 (m,
13H)
6b
6c
388 (M+, 10), 233 (100), 218 (3), 116
(10)
2200, 1590, 1550, 1310, 1285, 1245, 1180,
1160, 1125, 1080
2.32 (s, 3H), 2.52 (s, 3H), 4.61 (s, 2H),
6.94–7.87 (m, 12H)
394 (M+, 12), 253 (100), 218 (15), 190
(4), 165 (4), 150 (8)
2200, 1585, 1440, 1315, 1300, 1280, 1155,
1130, 1080
4.53 (s, 2H), 7.10–8.00 (m, 13H),
6d
6e
408 (M+, 12), 267 (100), 232 (14), 150
(5), 123 (9)
2220, 1595, 1445, 1320, 1285, 1190, 1135,
1085
2.48 (s, 3H), 4.55 (s, 2H), 7.08–7.89 (m,
12H)
408 (M+, 12), 253 (100), 208 (17), 150
(7), 123 (9)
2200, 1590, 1300, 1280, 1245, 1130, 1080 2.30 (s, 3H), 4.55 (s, 2H), 6.94–7.96 (m,
12H)
6f
422 (M+, 13), 267 (100), 232 (12), 150
(5), 123 (7)
2200, 1585, 1555, 1475, 1405, 1310, 1280,
1180, 1130, 1080
2.32 (s, 3H), 2.48 (s, 3H), 4.53 (s, 2H),
6.97–7.85 (m, 11H)
7a
347 (M+, 100), 283 (10), 267 (14), 208
(27), 165 (15), 139 (8)
3250, 1595, 1535, 1475, 1440, 1395, 1285,
1160, 1130, 1080
2.30 (s, 3H), 7.08–8.23 (m, 13H), 8.82 (br
s, 1H)
7b
7c
361 (M+, 100), 297 (7), 281 (11), 222
(17), 207 (6), 139 (6)
3320, 1600, 1500, 1450, 1395, 1300, 1160,
1130, 1080
2.32 (s, 3H), 2.43 (s, 3H), 7.10–8.23 (m,
12H), 8.67 (br s, 1H)
367 (M+, 100), 303 (10), 267 (29), 242
(29), 199 (14), 191 (20)
3250, 1570, 1440, 1385, 1300, 1130, 1065
7.23–7.63 (m, 12H), 8.29 (s, 1H), 8.96 (br
s, 1H)
7d
7e
381 (M+, 100), 281 (12), 256 (15), 241
(7), 204 (8), 125 (6)
3260, 1610, 1575, 1495, 1445, 1390, 1300,
1160, 1135, 1085
2.40 (s, 3H), 7.19–7.68 (m, 11H), 8.26 (s,
1H), 8.83 (br s, 1H)
381 (M+, 100), 317 (10), 281 (27), 242 3250, 1440, 1390, 1295, 1130, 1080
(25), 191 (12), 139 (12)
2.32 (s, 3H), 7.08–7.56 (m, 11H), 8.28 (s,
1H), 8.53 (br s, 1H)
7f
395 (M+, 100), 295 (20), 281 (10), 256 3250, 1600, 1495, 1445, 1410, 1390, 1300, 2.32 (s, 3H), 2.41 (s, 3H), 7.10–7.55 (m,
(19), 204 (12), 139 (11)
1135, 1085
10H), 8.25 (s, 1H), 8.83 (br s, 1H)
Table 5. Carbodiimides 11 and Indoles 12 Prepared
Wojciechowski and Makosza synthesized 2-alkyl-3-aryl-
sulfonylindoles by the condensation of 2 with trialkyl
orthoformate.6 They also prepared 2-unsubstituted 3-phe-
nylsulfonylindoles via the vicarious substitution of m-iso-
cyanatonitrobenzene with chloromethyl phenyl sulfone.13
In contrast to these methods, we could introduce aryl
groups and an anilino group into the C-2 position of the 3-
arylsulfonylindoles. Thus, we have shown that iminophos-
phoranes 5 are useful building blocks for 2-aryl- and 2-
anilino-3-arylsulfonylindoles which are otherwise inacces-
sible and, furthermore, a rarely known class of indoles.11
Producta
R
R1
Yield
(%)
mp (°C)
11a
11b
11c
12a
12b
12c
H
4-MeC6H4
Ph
4-MeC6H4
4-MeC6H4
Ph
66
98
97
83
72
68
114–117
133–135
133–135
164–166
168–170
229–230
Cl
Cl
H
Cl
Cl
4-MeC6H4
a
Satisfactory microanalyses obtained: C ± 0.24, H ± 0.13, N ± 0.31.
Compound 12b contained one mole of occluded MeOH.
Melting points were determined using a MRK MEL-TEMP II and are
uncorrected. IR spectra were recorded on a JASCO A-102 spectro-
1
photometer. Mass and H NMR spectra were taken with a JEOL JMS
onal cyclization of 11 to 2-anilino-3-arylsulfonylindoles
12a–c was accomplished in 68–83% yield upon treatment
with sodium hydroxide in dimethyl sulfoxide at room
temperature (Tables 5 and 6).
DX-300 spectrometer and a JEOL GSX-400 spectrometer, respec-
tively. Microanalyses were performed with a YANACO CHN-Coder
MT-5.
Aryl 2-Nitrobenzyl Sulfones 1a–c:
The reaction of iminophosphorane 5b with carbon
disulfide12 in refluxing toluene gave the dimer 14 in 68%
yield, probably through further condensation of the inter-
mediate isothiocyanate 13 with the starting 5b (Scheme
3).
14
Compound 1a (R = H, R1 = p-Tolyl) was prepared by stirring a mix-
ture of sodium p-toluenesulfinate (8.9 g, 50 mmol) and commercially
available 2-nitrobenzyl bromide (10.8 g, 50 mmol) in DMSO
(100 mL) at r.t. for 1 h followed by pouring the mixture into ice-water
(500 mL). The sulfones 1b (R = Cl, R1 = Ph) and 1c (R = Cl, R1 = p-

SYNTHESIS
July 1998
989
Table 6. MS, IR, and 1H NMR Data of Carbodiimides 11 and Indoles 12
Product
11a
MS
m/z (%)
IR (KBr)
1H NMR (CDCl3/TMS)
δ
ν (cm–1)
362 (M+, 9), 207 (100), 180 (1), 132 (2) 2100, 1575, 1480, 1300, 1245, 1205,
1130, 1085
2.39 (s, 3H), 4.52 (s, 2H), 7.06–7.55 (m,
13H)
11b
382 (M+, 19), 241 (83), 206 (100), 102
(4)
2150, 1570, 1485, 1305, 1240, 1220,
1160, 1130, 1085
4.50 (s, 2H), 7.05–7.74 (m, 13H)
11c
396 (M+, 14), 241 (65), 206 (100), 102
(5)
2130, 1595, 1485, 1319, 1250, 1160,
1140, 1090
2.42 (s, 3H), 4.46 (s, 2H), 7.03–7.71 (m,
12H)
12a
362 (M+, 100), 298 (8), 223 (9), 207
(36), 206 (41), 180 (7)
3360, 1630, 1605, 1575, 1520, 1505,
1480, 1465, 1375, 1280
2.36 (s, 3H), 7.02–7.88 (m, 13H), 8.20 (br
s, 1H), 8.40 (br s, 1H)
12b
382 (M+, 100), 318 (5), 282 (3), 257 (9),
242 (16), 206 (38)
3500, 3340, 1625, 1600, 1570, 1500,
1460, 1365, 1265, 1145
6.99–8.01 (m, 13H), 8.28 (br s, 1H), 8.39
(br s, 1H)
12c
396 (M+, 100), 332 (7), 257 (9), 241
(20), 206 (41)
3360, 1630, 1600, 1580, 1495, 1460,
1370, 1270, 1145, 1125
2.39 (s, 3H), 6.98–7.90 (m, 12H), 8.19 (br
s, 1H), 8.40 (br s, 1H)
5
Tolyl) were prepared according to the literature from 4-chloroni-
trobenzene and aryl chloromethyl sulfones.
due was recrystallized from CHCl3/hexane to give light tan plates
(4a) or light tan needles (4b and 4c).
2-Aminobenzyl Aryl Sulfones 2a–c:
2-(Arylsulfonyl)methyl-N-(triphenylphosphoranylidene)anilines
5a–c; General Procedure:
The sulfone 2c (R = Cl, R1 = p-Tolyl) was prepared according to the
6
literature by reduction of the corresponding aryl 2-nitrobenzyl sul-
To a cooled (0–5°C) and stirred solution of Ph3P (7.86 g, 30 mmol) in
CH2Cl2 (150 mL) was added a solution of 4 (30 mmol) in CH2Cl2 (150
mL) under N2 . The mixture was stirred at 0–5°C for 1 h and then slow-
ly warmed to r.t. The solvent was removed in vacuo and the residue was
treated with benzene to precipitate the product, which was collected by
filtration and recrystallized from benzene/hexane to give a white pow-
der (5a) or from CHCl3/hexane to give white needles (5b and 5c).
fone with tin in HCl. Sulfones 2a (R = H, R1 = p-Tolyl) and 2b (R =
Cl, R1 = Ph) were prepared similarly.
Compound 2a: yield: 87%; white powder; mp 140–141°C.
IR (KBr): ν = 3470, 3380, 1620, 1595, 1575, 1490, 1275, 1135 cm–1.
+
MS: m/z (%) = 261 (M , 6), 106 (100).
Anal. Calcd for C14H15NO2S (261.3): C, 64.34; H, 5.79; N, 5.36.
Found: C, 64.39; H, 5.78; N, 5.43.
N-[Aryl(cyano)methylene]-2-(arylsulfonyl)methylanilines 6a–f;
General Procedure:
A mixture of 5 (4.0 mmol) and aroyl cyanide (4.0 mmol) in anhyd
toluene (50 mL) was refluxed for 20 h under N2. After cooling, the
precipitate (unreacted 5) was filtered off and the filtrate was evaporat-
ed. In the cases of 6c and 6e, the resulting solid residue was recrystal-
lized from CHCl3/hexane to give the products as yellow needles. In
the other cases, the resulting oily residue was chromatographed on
silica gel with CHCl3 as eluent to give a solid product, which was
recrystallized from CHCl3/hexane to give 6 as yellow needles.
Compound 2b: yield: 90%; white powder; mp 131–133°C.
IR (KBr): ν = 3440, 3360, 1630, 1575, 1480, 1400, 1280, 1140 cm–1.
+
MS: m/z (%) = 281 (M , 7), 140 (100).
Anal. Calcd for C13H12NO2SCl (281.8): C, 55.42; H, 4.29; N, 4.97.
Found: C, 55.36; H, 4.29; N, 4.93.
5-Chloro-3-(p-tolyl)sulfonyl-1H-indazole (3):
A solution of NaNO2 (520 mg, 7.5 mmol) in H2O (3 mL) was added
to a stirred solution of 2c (1.48 g, 5.0 mmol) in 4 M HCl (250 mL) at
0–5°C. After stirring for 30 min at the same temperature, the mixture
was neutralized with 10% aq NaOH solution. The resulting precipi-
tate was collected by filtration, then dissolved in CHCl3.. The CHCl3
solution was dried (MgSO4), filtered and the solvent was evaporated.
The residue obtained was recrystallized from EtOAc/hexane to give 3
(1.35 g, 88%) as a white powder; mp 242–244°C.
2-Aryl-3-arylsulfonylindoles 7a–f; General Procedure:
To a stirred solution of 6 (1.0 mmol) dissolved in warm DMSO
(3 mL) was added powdered NaOH (200 mg, 5.0 mmol). The mixture
was stirred at 80–90°C for 1 h. After cooling, the mixture was neu-
tralized with 10% NH4Cl solution (ca. 50 mL) [Caution! The evolu-
tion of HCN began at pH 8–9]. The resulting precipitate was collected
by filtration and dissolved in CHCl3. The CHCl3 solution was dried
(MgSO4) and the solvent was removed in vacuo. The residue was re-
crystallized from CHCl3/hexane to give 7 as a white powder.
IR (KBr): ν = 3260, 1585, 1470, 1315, 1140 cm–1.
MS: m/z (%) = 306 (M+, 55), 242 (43), 155 (15), 139 (22), 91 (100).
Anal. Calcd for C14H11N2O2SCl (306.8): C, 54.81; H, 3.61; N, 9.13.
Found: C, 54.65; H, 3.62; N, 9.37.
′
N-[2-(Arylsulfonylmethyl)phenyl]N -phenylcarbodiimides 11a–
c; General Procedure:
Aryl 2-Azidobenzyl Sulfones 4a–c; General Procedure:
To a stirred solution of 5 (4.0 mmol) in CH2Cl2 (50 mL) was added
phenyl isocyanate (480 mg, 4.0 mmol) at r.t. under N2. After the mix-
ture was refluxed for 12 h, the solvent was removed in vacuo. The res-
idue was washed with hexane and then recrystallized from CH2Cl2/hex-
ane to give white needles (11a and 11b) or a white powder (11c).
A solution of NaNO2 (5.18 g, 75 mmol) in H2O (25 mL) was added
dropwise to a stirred solution of 2 (50 mmol) in 4 M HCl (250 mL) at
0–5°C. After stirring the mixture at the same temperature for 30 min,
a solution of NaN3 (3.25 g, 50 mmol) in H2O (50 mL) was slowly
added to the mixture. During the addition, a vigorous foam was
formed. The stirring was continued for 30 min below 5°C, and then
for 5 h at r.t. The mixture was extracted with CHCl3, the organic layer
was dried (MgSO4), and the solvent was removed in vacuo. The resi-
2-Anilino-3-arylsulfonylindoles 12a–c; General Procedure:
To a stirred solution of 11 (1.0 mmol) dissolved in warm DMSO
(3 mL) was added powdered NaOH (200 mg, 5.0 mmol). After stir-

SYNTHESIS
Papers
990
ring at r.t. for 30 min, the mixture was neutralized with 10% aq NH4Cl
solution (ca. 50 mL). The resulting precipitate was collected by filtra-
tion and dissolved in CHCl3. The solution was dried (MgSO4) and
evaporated in vacuo to give an oily product. In the case of 12a, the
residue was purified by column chromatography on silica gel with
CHCl3/EtOAc as eluent to give a brown oil, which took a long time
to crystallize. The products 12b and 12c were obtained by the addition
of a small amount of MeOH to the oily residue followed by collection
of the resulting precipitate by filtration. Recrystallization from MeOH
gave a white powder (12a) or white plates (12b and 12c).
c) Eguchi, S.; Matsushita, Y.; Yamashita, K. Org. Prep. Proced.
Int. 1992, 24, 209.
d) Molina, P.; Vilaplana, M. J. Synthesis 1994, 1197.
e) Eguchi, S.; Okano, T. J. Syn. Org. Chem., Jpn. 1993, 51, 203.
f) Iino, Y.; Nitta, M. J. Syn. Org. Chem., Jpn. 1990, 48, 681.
g) Wamhoff, H.; Richardt, G.; Stölben, S. Adv. Heterocycl.
Chem. 1995, 64, 159.
(2) Takahashi, M.; Ohba, M. Heterocycles 1995, 41, 455.
(3) Takahashi, M.; Ohba, M. Heterocycles 1995, 41, 2263.
(4) Simpkins, N. S. Sulphones in Organic Synthesis; Pergamon
Press: Oxford, 1993.
′
N,N -Bis[4-chloro-2-(phenylsulfonylmethyl)phenyl]carbodiim-
(5) Makosza, M.; Goliñski, J.; Baran, J. J. Org. Chem. 1984, 49,
1488.
ide (14):
A mixture of 5b (1.63 g, 3.0 mmol) and excess CS2 (1.0 mL) in anhyd
toluene (40 mL) was refluxed for 20 h under N2. After cooling, the
solvent was removed in vacuo and benzene was added to the residue
to give the precipitate, which was collected by filtration and recrystal-
lized from CH2Cl2/hexane to afford 14 (360 mg, 68%) as a white
powder; mp 186–188°C.
(6) Wojciechowski, K.; Makosza, M. Synthesis 1986, 651.
(7) Trione, C.; Toledo, L. M.; Kuduk, S. D.; Fowler, F. W.; Grier-
son, D. S. J. Org. Chem. 1993, 58, 2075.
(8) Lorente, A.; Gámez, P.; Contreras, M. M. Heterocycles 1994,
38, 113.
(9) Ichikawa, J.; Wada, Y.; Okauchi, T.; Minami, T. J. Chem. Soc.,
Chem. Commun. 1997, 1537.
IR (KBr): ν = 2100, 1475, 1300, 1125 cm–1.
MS: m/z (%) = 570 (M+, 11), 429 (26), 287 (90), 252 (50), 166 (41),
77 (100).
(10) Berry, M. B.; Craig, D.; Jones, P. S.; Rowlands, G. J. J. Chem.
Soc., Chem. Commun. 1997, 2141, and references cited therein.
(11) Sundberg, R. J. In Comprehensive Heterocyclic Chemistry, Vol.
4; Katritzky, A. R.; Rees, C. W., Eds.; Pergamon Press: Oxford,
1984; p 313.
1H NMR (CDCl3): δ = 4.45 (s, 4 H), 7.03–7.74 (m, 16 H).
Anal. Calcd for C27H20N2O4S2Cl2 (571.5): C, 56.75; H, 3.53; N, 4.90.
Found: C, 56.49; H, 3.54; N, 5.02.
(12) Molina, P.; Alajarin, M.; Arques, A. Synthesis 1982, 596.
(13) Wojciechowski, K.; Makosza, M. Tetrahedron Lett. 1984, 25,
4793.
(1) Reviews of chemistry of iminophosphoranes:
a) Barluenga, J.; Palacios, F. Org. Prep. Proced. Int. 1991, 23,
1.
(14) Shriner, R. L.; Greenlee, S. O. J. Org. Chem. 1939, 4, 242.
b) Gololobov, Y. G.; Zhmurova, I. N.; Kasukhin, L. F. Tetrahe-
dron 1981, 37, 437.