PAPER
Hydrodediazoniation of Dry Arenediazonium o-Benzenedisulfonimides
2389
4
-Butylbenzenediazonium o-Benzenedisulfonimide (1b)
for 20 min until dissolution of the salt and completion of the reac-
tion (absence of azo coupling with 2-naphthol). TLC (petroleum
Yield: 85%; dp 96–97 °C.
1
ether–Et O, 8.5:1.5), GC and GC–MS analyses of the reaction mix-
ture showed the presence of the title nitrobenzene (3g) as the only
2
H NMR (CD CN): d = 0.94 (t, J = 7.2 Hz, 3 H), 1.31–1.42, 1.58–
3
1
7
.70 (2 × m, 1:1, 4 H), 2.87 (t, J = 7.4 Hz, 2 H), 7.65–7.74 (m, 4 H),
.74 (d, J = 8.8 Hz, 2 H), 8.38 (d, J = 8.8 Hz, 2 H).
product. The reaction mixture was poured into Et O–sat. aq NaCl
2
(
200 mL, 1:1). The aqueous solution was separated and extracted
Anal. Calcd for C H N O S (379.4): C, 50.65; H, 4.52; N, 11.07;
S, 16.90. Found: C, 50.75; H, 4.58; N, 11.02; S, 16.85.
1
6
17
3
4
2
with Et O (100 mL). The combined organic extracts were washed
2
with sat. aq NaCl (2 × 100 mL), dried (Na SO ), and evaporated un-
2
4
der reduced pressure. The crude residue was column chromato-
2
-Phenylbenzenediazonium o-Benzenedisulfonimide (1c)
graphed (petroleum ether–Et O, 8.5:1.5) to provide the pure (TLC,
2
Yield: 97%; dp 101–102 °C.
1
1
GC, GC–MS, H NMR) title compound 3g in 100% yield (1.23 g)
(MS: m/z = 123 [M ]). Structure of this compound was confirmed
by comparison of its MS and H NMR spectra and retention time,
+
H NMR (CD CN): d = 7.36–7.43, 7.65–7.68, 7.73–7.96, 8.24–
3
1
8
.28, 8.56–8.61 (5 × m, 3:4:4:1:1, 13 H).
by co-injection, with those of an authentic sample (Aldrich) of ana-
lytical purity. The aqueous layer and aqueous washings were col-
lected and evaporated under reduced pressure. The residue was
Anal. Calcd for C H N O S (399.4): C, 54.13; H, 3.28; N, 10.52;
S, 16.05. Found: C, 54.19; H, 3.27; N, 10.55; S, 16.08.
1
8
13
3
4 2
1
virtually pure (determined by H NMR) o-benzenedisulfonimide (4,
4
-Phenoxybenzenediazonium o-Benzenedisulfonimide (1e)
1c
2
.06 g, 94%); mp 192–194 °C (toluene) (lit. mp 192–194 °C).
Yield: 96%; dp 141–142 °C.
1
When the molar ratio hydrogen peroxide/1g was 1:1 (entry 8), the
reaction slowed down (60 min) and 3g was obtained in the same
yield (100%).
H NMR (CD CN): d = 7.05–7.06 (m, 2 H), 7.25 (d, J = 9.3 Hz, 2
3
H), 7.31–7.35, 7.43–7.48, 7.91–8.01 (3 × m, 1:2:4, 7 H), 8.36 (d,
J = 9.3 Hz, 2 H).
All the arenes 3 were prepared according to the above procedure.
Reaction conditions, yields of 3a–o and yields of the recovered o-
benzenedisulfonimide (4) are reported in Table 1.
Anal. Calcd for C H N O S (415.4): C, 52.04; H, 3.15; N, 10.11;
S, 15.43. Found: C, 52.14; H, 3.18; N, 10.08; S, 15.48.
1
8
13
3
5 2
4
-Acetylbenzenediazonium o-Benzenedisulfonimide (1h)
Collateral Proofs
Proof A
A suspension of 1g in THF was refluxed for 24 h, in the absence of
hydrogen peroxide (2). A test of azo coupling with 2-naphthol was
positive and GC and GC–MS analyses of the reaction mixture
showed only traces of nitrobenzene (3g).
Yield: 95%; dp114–115 °C.
1
H NMR (CD CN): d = 2.68 (s, 3 H), 7.68–7.75 (m, 4 H), 8.30, 8.60
2 × d, 1:1, J = 8.9 Hz, 4 H).
3
(
Anal. Calcd for C H N O S (365.4): C, 46.02; H, 3.03; N, 11.50;
S, 17.55. Found: C, 45.95; H, 3.03; N, 11.45; S, 17.60.
1
4
11
3
5 2
Proofs B
2
-Methyl-5-Nitrobenzenediazonium o-Benzenedisulfonimide
B-1: Reaction 9, carried out in the presence of 1,3-dinitrobenzene
(
1k)
(0.42 g, 2.5 mmol), strongly slowed down and came to completion
Yield: 97%; dp 125–126 °C.
only after 10 h. Usual work-up afforded 3g in only 65% yield (0.80
g). When 1,3-dinitrobenzene was used in 5 mmol amount (0.84 g)
with respect to 1g, the reaction was further slowed down (azo cou-
pling with 2-naphthol was still positive after 24 h). Usual work up
afforded only tars, containing traces of 3g.
1
H NMR (CD CN): d = 2.83 (s, 3 H), 7.47–8.57 (m, 5 H), 8.79 (dd,
3
J3,4 = 8.8 Hz, J4,6 = 2.2 Hz, 1 H), 9.22 (d, J4,6 = 2.2 Hz, 1 H).
Anal. Calcd for C H N O S (382.4): C, 40.84; H, 2.64; N, 14.65;
S, 16.77. Found: C, 40.78; H, 2.68; N, 14.59; S, 16.79.
1
3
10
4
6 2
B-2: Under the conditions of proof B-1, the reaction 4 was incom-
plete even after 24 h and yield of 3d was only 22% (0.24 g).
3
,5-Dimethoxybenzenediazonium o-Benzenedisulfonimide (1l)
Yield: 93%; dp 90–91 °C.
1
H NMR (CD CN): d = 3.73 (s, 6 H), 6.22 (t, J = 2.0 Hz, 1 H), 6.78
Proofs C
3
(
d, J = 2.0 Hz, 2 H), 7.91–8.05 (m, 4 H).
C-1 A mixture of 4-nitrobenzenediazonium o-benzenedisulfon-
imide (1g, 3.68 g, 10 mmol), iodoacetic acid (0.93 g, 5 mmol) and
hydrogen peroxide (2, 30 wt.% in H O; 2.32 g, 20 mmol) in anhyd
THF (10 mL) was gently refluxed, under vigorous stirring. The re-
action was slowed down and came to completion after 4 h (absence
of azo coupling with 2-naphthol). Column chromatography (petro-
Anal. Calcd for C H N O S (383.4): C, 43.86; H, 3.42; N, 10.96;
S, 16.72. Found: C, 43.94; H, 3.48; N, 11.01; S, 16.77.
1
4
13
3
6 2
2
Mesitylenediazonium o-Benzenedisulfonimide (1n)
Yield: 98%; dp 105–106 °C.
leum–Et O, 9.9:0.1) of the crude residue obtained after the usual
2
1
H NMR (CF COOD): d = 2.13 (s, 3 H), 2.28 (s, 6 H), 6.98 (s, 2 H),
work up, afforded 4-iodonitrobenzene (0.87 g, 35%) {MS: m/z =
3
+
16
1
7
.50–7.63 (m, 4 H).
249 [M ]; mp 175–176 °C, from EtOH (lit. mp 174 °C); H NMR
was data identical to that of an authentic sample (Aldrich)} and 3g
Anal. Calcd for C H N O S (365.4): C, 49.30; H, 4.14; N, 11.50;
S, 17.55. Found: C, 49.40; H, 4.09; N, 11.42; S, 17.63.
1
5
15
3
4 2
(0.80 g, 65%).
C-2: When 20 mmol12b of iodoacetic acid (3.72 g) were used for 10
mmol of 1g, the reaction time was 60 min and 4-iodonitrobenzene
and 3g were obtained in 77% (1.92 g) and 15% (0.18 g) yields, re-
spectively.
CAUTION! In our laboratory there was no case of sudden decom-
position during the preparation, purification and handling of salts 1.
Nevertheless it must be born in mind that all diazonium salts in the
dry state are potentially explosive. Therefore they must be carefully
stored and handled.
C-3: Under the conditions of proof C-1, the reaction of 4-methoxy-
benzenediazonium o-benzenedisulfonimide (1d) came to comple-
tion after 24 h and afforded 4-iodoanisole (0.76 g, 32%) {MS:
Nitrobenzene (3g); Typical Procedure
+
16
1
In entry 9 of Table 1, hydrogen peroxide (2, 30 wt.% in H O; 2.32
m/z = 234 [M ]; mp 51–52 °C, from EtOH (lit. mp 51–52 °C); H
NMR data was identical to that of an authentic sample (Aldrich)}
and 3d (0.36 g, 33%).
2
g, 20 mmol) was added to a suspension of 4-nitrobenzenediazonium
o-benzenedisulfonimide (1g, 3.68 g, 10 mmol) in anhyd THF (10
mL) and the mixture was gently refluxed, under vigorous stirring,
Synthesis 2004, No. 14, 2386–2390 © Thieme Stuttgart · New York