3
452 J . Org. Chem., Vol. 64, No. 10, 1999
Barbero et al.
arenediazonium o-benzenedisulfonimides 1 with tet-
raalkylammonium halides 2a -c in anhydrous acetoni-
trile and in the presence or absence of copper. The notable
collection of homogeneous data has given the possibility
of arriving at a reasonable interpretation of the mecha-
nisms of the halodediazoniations carried out in acetoni-
trile, with and without copper. Further investigations are
in progress concerning the hypothesized role of the anion
of o-benzenedisulfonimide (9) as an electron transfer
agent.
(3.53 g). For analytical purposes, a sample was crystallized
1
as described for 1q: dp 142-143 °C; H NMR (CF
3
COOD) δ
7
.60-7.80 and 8.60-9.25 ppm (2 m, 4:3). Anal. Calcd for
12 7 5 8 2
C H N O S
: C,34.87; H, 1.71; N, 16.95; S, 15.48. Found: C,
3
4.79; H, 1.73; N, 16.89; S, 15.44.
Ha lod ed ia zon ia tion s Ca r r ied Ou t in th e Absen ce of
a n Electr on Tr a n sfer Ca ta lyst. Rep r esen ta tive P r oce-
d u r es. Br om oben zen e (4a ). In entry 7 (Table 1) tetrabuty-
lammonium bromide (2b; 8.06 g, 25 mmol) was added in one
portion, under vigorous stirring, to a suspension of dry
benzenediazonium o-benzenedisulfonimide (1a ; 3.23 g, 10
mmol) in anhydrous MeCN (20 mL), maintained at room
temperature (∼20 °C). The reaction mixture was put into an
oil bath previously warmed at 60 °C. During the first 20-30
min a slow evolution of nitrogen was observed and at the same
time the salt dissolved. The resultant red-brown solution was
warmed for a further 15 min. Completion of the reaction was
confirmed by absence of azo coupling with 2-naphthol. GC and
GC-MS analyses of the reaction mixture showed bromobenzene
Exp er im en ta l Section
All of the reactions were performed in oven-dried glassware.
Column chromatography and TLC were performed on Merck
silica gel 60 (70-230 mesh ASTM) and GF 254, respectively,
eluting with petroleum ether-methylene chloride (9:1, v/v),
unless otherwise noted. Petroleum ether refers to the fraction
boiling in the range 40-70 °C and is abbreviated as PE.
Details for reactions 1-92 and yields of the pure (GC, GC-
MS, TLC, NMR) isolated halides are listed in Table 1. With
two only exceptions, identical physical and spectral data and
retention times, by co-injection, for the resultant pure halides
(
4a ) as major product and small amounts of three byproducts,
+
i.e., acetanilide, MS m/z 135 (M ), O-phenyl-o-benzenedisul-
fonimide, and N-phenyl-o-benzenedisulfonimide, each with MS
+
m/z 295 (M ). The solution was cooled and poured into Et
2
O-
water (200 mL, 1:1). The aqueous layer, containing MeCN and
a suspension of a fine white solid substance, was separated
3
-5 and the corresponding commercially available samples
and extracted again with Et
extracts were washed several times with water (4 × 50 mL)
to eliminate all the MeCN, dried over Na SO , and evaporated
under reduced pressure. The crude residue was column
Cl (9:1, v/v), to afford
2
O (80 mL). The combined organic
of analytical purity were observed. Only 2-phenylsulfonylchlo-
robenzene (3q) and 2-phenylsulfonylbromobenzene (4q) are not
commercially available. Structures of the two products ob-
tained in this research were confirmed by comparison of their
physical and spectroscopic data with those reported in the
literature.
2
4
chromatographed, eluting with PE-CH
2
2
the pure (GC, GC-MS, TLC, NMR) title compound 4a as a
+
colorless oil (1.30 g, 83% yield); MS m/z 156, 158 (M ). Identical
All the reagents and the reference compounds, i.e., chlorides
physical and spectral data and retention time, by co-injection,
for the product and an authentic sample of analytical purity
were observed. The aqueous layer and the aqueous washings
containing MeCN were collected and evaporated under reduced
3
, bromides 4, and iodides 5, were purchased from the Aldrich
Chemical Co.
o-Benzenedisulfonimide (7) was prepared according to the
4
literature procedure, starting from o-benzenedisulfonyl chlo-
pressure. The residue was dissolved in CHCl
3
(6 mL). By
7
ride and NH
3
gas, via ammonium o-benzenedisulfonimide and
addition of Et O (24 mL) to the solution, a white precipitate
2
+
16
its conversion using Dowex 50X8 resin (H ). Dry arenedia-
of tetrabutylammonium o-benzenedisulfonimide (6b ) was
zonium o-benzenedisulfonimides 1a -p ,s were prepared as
formed. It was gathered by filtration: mp 108.5-109.5 °C
1
,17,18
described previously by us.
The crude salts were virtually
1
(
3
CHCl
3
-PE); H NMR (CDCl
3
) δ 0.65-1.05, 1.05-1.85, 2.85-
pure and could be used in the next halodediazoniations,
without further crystallization.
.35, and 7.30-7.75 ppm (4 m, 12:16:8:4). Anal. Calcd for
: C, 57.36; H, 8.76; N, 6.09; S, 13.89. Found: C,
7.46; H, 8.67; N, 6.03; S, 13.99. Compound 6b was then
22 40 2 4 2
C H N O S
5
Dr y 2-P h en ylsu lfon ylben zen ed ia zon iu m o-Ben zen e-
d isu lfon im id e (1q). According to the procedure previously
passed through a 30 g column of Dowex 50X8 ion exchange
resin (Fluka), eluting with water (about 50 mL). After removal
of the water under reduced pressure, virtually pure (NMR)
o-benzenedisulfonimide (7) was recovered in 68% yield (1.49
1
reported, diazotization of 2-phenylsulfonylaniline (2.33 g, 10
mmol) was carried out with isopentyl nitrite (1.29 g, 11 mmol)
in the presence of o-benzenedisulfonimide (7; 2.63 g, 12 mmol)
in glacial AcOH (60 mL) at 0-5 °C. The virtually pure (NMR,
dp) title compound 1q was obtained in 92% yield (4.26 g). For
analytical purposes, a sample was purified by dissolution in
1
g); mp 192-194 °C (toluene) (lit. mp 192-194 °C). The filtrate
was evaporated under reduced pressure. The resultant residue
was virtually pure (NMR) tetrabutylammonium bromide (2b;
hot anhydrous acetonitrile and precipitation with anhydrous
3
.30 g, 41%, calculated on the amount of 2b put in the
reaction).
To separate the three byproducts, in a parallel test the
1
Et
NMR (CF
). Anal. Calcd for C18
2
O, after cooling: dp (decomposition point) 131-132 °C; H
3
COOD) δ 7.10-8.18 and 8.28-8.65 ppm (2 m, 12:
: C, 46.64; H, 2.83; N, 9.07;
1
13 3 6 3
H N O S
aqueous layer and the aqueous washings containing MeCN
were evaporated and the residue was column chromato-
S, 20.75. Found: C, 46.53; H, 2.89; N, 8.97; S, 20.76.
Dr y 2,4-Din itr oben zen ed ia zon iu m o-Ben zen ed isu lfon -
im id e (1r ). Diazotization of 2,4-dinitroaniline (1.84 g, 10
mmol) was carried out as above with isopentyl nitrite (1.29 g,
graphed. Elution with CHCl
3
afforded 0.02 g (∼1%) of aceta-
nilide (identical to an authentic sample of commercial origin)
and 0.04 g (∼1%) of O-phenyl-o-benzenedisulfonimide. The
following elution with MeCOMe afforded 0.06 g (∼2%) of
N-phenyl-o-benzenedisulfonimide. Structures of the last two
byproducts were confirmed by comparison with the authentic
samples previously prepared.1
1
1 mmol) in the presence of o-benzenedisulfonimide (7; 2.63
g, 12 mmol) in glacial AcOH (60 mL) at 0-5 °C. The virtually
pure (NMR, dp) title compound 1r was obtained in 85% yield
(
16) Hendrickson, J . B.; Okano, S.; Bloom, R. K. J . Org. Chem. 1969,
4, 3434.
17) Barbero, M.; Degani, I.; Dughera, S.; Fochi, R.; Perracino, P.
Synthesis, in press.
18) Caution! In our laboratory was no case of sudden decomposition
Comparable yields of 4a and 7 were obtained when 35 mmol
(11.27 g) of 2b was used (entry 8). Entries 17, 21, 26, 31, 34,
3
(
3
7, 40, 43, 48, 52, 55, 58, and 69 were performed according to
the above procedure. In entries 62, 75, 81, 84, and 90 the molar
ratio 1:2b was 1:1. While the last entry was carried out at 60
°C, the first four entries occurred at room temperature.
2-Ch lor on itr oben zen e (3n ). In entry 60 (Table 1) benzyl-
triethylammonium chloride (TEBA, 2a ; 2.27 g, 10 mmol) was
added in one portion, under vigorous stirring, to a suspension
of dry 2-nitrobenzenediazonium o-benzenedisulfonimide (1n ;
(
during the preparation, purification, and handling of salts 1. Neverthe-
less 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.
(19) Daasbjerg, K.; Lund, H. Acta Chem. Scand. 1992, 46, 157.
(20) Citterio, A.; Arnoldi, A. Synth. Commun. 1981, 11, 639.
(21) Bartsch, R. A.; Yang, I. W. Tetrahedron Lett. 1979, 2503.
(22) Perumal, S.; Chandrasekaran, R.; Vijayabaskar, V.; Wilson, D.
3
.68 g, 10 mmol) in anhydrous MeCN (20 mL), maintained at
A. Magn. Reson. Chem. 1995, 33, 779.
room temperature (∼20 °C). A rapid evolution of nitrogen took