Synthesis of o-sulfamidotriazobenzenes from 1,1′- sulfonylbis(benzotriazole)

Article abstract of DOI:10.1021/jo0705723

(Chemical Equation Presented) Easily accessible 1,1′- sulfonylbis(benzotriazole) (Bt₂SO₂, 1) reacts with secondary amines at room temperature to afford (i) the corresponding o-sulfamidotriazobenzenes 2a-d (53-75%) via concurrent subs

Full text of DOI:10.1021/jo0705723

benzotriazolylmethyl phenethyl ether 5 and benzylmagnesium
bromide at 110 °C gave N-benzyl-N′-phenethyl-o-phenylene-
diamine 6 (Scheme 1) via a single nitrogen atom extrusion in
low (10%) yield;5 N-(benzotriazol-1-ylmethyl)-N-methylpyrro-
lidinium iodide 7 and ethylmagnesium iodide gave a mixture
of unsymmetrically substituted o-phenylenediamines6 (10-40%)
(Scheme 1) and 1-(N-phenylacetimidoyl)benzotriazole 8 and its
propionimidoyl analogue produced corresponding o-phenylene-
diamines in such reactions.7
Synthesis of o-Sulfamidotriazobenzenes from
1,1′-Sulfonylbis(benzotriazole)
Alan R. Katritzky,*,† Levan Khelashvili,† Khanh N. B. Le,†
Prabhu P. Mohapatra,† and Peter J. Steel‡
Center for Heterocyclic Compounds, Department of Chemistry,
UniVersity of Florida, GainesVille, Florida 32611-7200, and
Chemistry Department, UniVersity of Canterbury,
Christchurch, New Zealand
katritzky@chem.ufl.edu
SCHEME 1
ReceiVed March 22, 2007
Later, ring opening of benzotriazoles with electron-donating
substituents and via loss of a nitrogen molecule afforded
rearranged heterocycles: quinazolines from 2-(benzotriazol-1-
yl)enamines8 and benzoheterocycles and ortho-substituted anilines
from N-(R-alkoxyalkyl)benzotriazoles.9 Ring fragmentation of
the diarylbenzotriazolylmethane anion occurred at 20 °C.10 Acid-
catalyzed tandem benzotriazole ring opening/ammonia extrusion
of 3-(benzotriazol-1-yl)-1,4-diaryl-1-buten-4-ols gave benzo[a]-
phenazines.11 Intramolecular benzotriazole ring opening-ring
closure without elimination of nitrogen is preparatively useful
for nitrogen-containing fused heterocyclic systems: pyrazolo-
[5,1-b]benzimidazoles,12 tetrazolo[1,5-e][1,2,5]-triazepines,13 and
1,2,4-triazolo[1,5-a]quinoxalines.14
Easily accessible 1,1′-sulfonylbis(benzotriazole) (Bt2SO2, 1)
reacts with secondary amines at room temperature to afford
(i) the corresponding o-sulfamidotriazobenzenes 2a-d (53-
75%) via concurrent substitution of the first and ring opening
of the second benzotriazolyl group and (ii) N-sulfonylben-
zotriazoles 3b,c,e,f (7-73%). 1-(Morpholine-4-sulfonyl)-1H-
benzotriazole 3c reacts with piperidine, pyrolidine, and
N-methylpiperazine under microwave irradiation (120 W)
at 120 °C for 10 min to give the unsymmetrical sulfamides
4a-c (80-90%).
Recently, Zieglar and Subramanian et al. reported the base-
catalyzed ring opening of benzotriazoles with electron-
withdrawing substituents.15 1-[(Nonafluorobutane)sulfonyl]-1H-
benzotriazole (BtNf, 9) with a variety of phenols and naphthols
in the presence of a base afforded ortho-substituted azobenzenes
(2) (a) Graebe, C.; Ullmann, F. Liebigs Ann. Chem. 1896, 291, 16. (b)
Ullmann, F. Liebigs Ann. Chem. 1904, 332, 82.
Benzotriazole is a useful synthetic auxiliary: it is easily
introduced, activates molecules toward numerous transforma-
tions, and can be removed readily at the end of the reaction
sequence.1 However, in some reactions cleavage of the triazole
ring occurs. The century old classical Graebe-Ullmann syn-
thesis of carbazoles from 1-arylbenzotriazoles occurs at 360 °C
via loss of a nitrogen molecule.2 Pyrolysis of N-vinylbenzot-
riazoles at 500-700 °C gave N-phenylketenimines.3 Recently
photodecomposition of tris(benzotriazol-1-yl)methane in ben-
zene gave phenanthridine.4 Our group encountered benzotriazole
ring opening under milder conditions nearly two decades ago;
(3) Maquestiau, A.; Beugnies, D.; Flammang, R.; Katritzky, A. R.; Sole-
iman, M.; Davis, T.; Lam, J. N. J. Chem. Soc., Perkin Trans. II 1988, 1071.
(4) Androsov, D. A.; Neckers, D. C. J. Org. Chem. 2007, 72, 1148.
(5) (a) Katritzky, A. R.; Rachwal, S.; Rachwal, B. J. Org. Chem. 1989,
54, 6022. (b) Katritzky, A. R.; Rachwal, S.; Rachwal, B. J. Chem. Soc.,
Perkin Trans. 1 1990, 1717.
(6) Katritzky, A. R.; Hughes, C. V.; Rachwal, S. J. Heterocycl. Chem.
1989, 26, 1579.
(7) Katritzky, A. R.; Rachwal, S.; Offerman, R. J.; Najzanek, Z.; Yagoub,
A. K.; Zhang, Y. Chem. Ber. 1990, 123, 1545.
(8) Katritzky, A. R.; Yang, B.; Jiang, J.; Steel, P. J. J. Org. Chem. 1995,
60, 246.
(9) Katritzky, A. R.; Zhang, G.; Jiang, J.; Steel, P. J. J. Org. Chem. 1995,
60, 7625.
(10) Katritzky, A. R.; Lan, X.; Lam, J. N. Chem. Ber. 1991, 124, 1431.
(11) Katritzky, A. R.; El, R. F. A.; Matsukawa, Y.; Steel, P. J.; Denisenko,
S. N. Heterocycles 1999, 51, 2335.
(12) Katritzky, A. R.; Wang, Z.; Lang, H.; Steel, P. J. Khim. Geterotsikl.
Soedin. 1996, 775.
(13) Katritzky, A. R.; Fan, W. Q.; Greenhill, J. V.; Steel, P. J. J. Org.
Chem. 1991, 56, 1299.
(14) Katritzky, A. R.; Huang, T.-B.; Denisko, O. V.; Steel, P. J. J. Org.
Chem. 2002, 67, 3118.
† University of Florida.
‡ University of Canterbury.
(1) (a) Katritzky, A. R.; Kirichenko, K. ARKIVOC 2006, iV, 119. (b)
Katritzky, A. R.; Suzuki, K.; Wang, Z. Synlett 2005, 1656. (c) Katritzky,
A. R.; Manju, K.; Singh, S. K.; Meher, N. K. Tetrahedron 2005, 61, 2555.
(d) Katritzky, A. R.; Rogovoy, B. V. Chem. Eur. J. 2003, 9, 4586. (e)
Katritzky, A. R.; Lan, X.; Yang, J. Z.; Denisko, O. V. Chem. ReV. 1998,
98, 409.
10.1021/jo0705723 CCC: $37.00 © 2007 American Chemical Society
Published on Web 06/21/2007
J. Org. Chem. 2007, 72, 5805-5808
5805

SCHEME 2
TABLE 1. Reaction of Bt2SO2 1 with Secondary Amines
SCHEME 3
10 (47-94%) (Scheme 2).15a This was successfully extended
to a mono-triazole-fused phthalocyaninato zinc complex.15b
Base-catalyzed reactions of BtNf with active methylene com-
pounds afforded R-functionalized N-arylhydrazones 11 (72-89%)
(Scheme 2);15c reactions with alkyl triphenylphosphoranylidenes
and methylenetriphenylphosphorylidene gave phenylazometh-
ylenetriphenylphosphoranes 12 and bis-phenylazomethylenet-
riphenylphosphorane 13, respectively.15d
Herein, we report that Bt2SO2 (1) with diverse secondary
amines involves substitution of one benzotriazolyl group
together with ring opening of the second by two molecules of
the same amine to give novel o-sulfamidotriazobenzenes 2 as
the major products along with the expected N-sulfonylbenzot-
riazoles 3 as the minor products.
Synthesis of 1,1′-Sulfonylbis(benzotriazole). Reaction of
1-trimethylsilanyl-1H-benzotriazole (2 mol) with sulfuryl chlo-
ride in toluene at 0-25 °C for 24 h affords 1,1′-sulfonylbis-
(benzotriazole) (Bt2SO2, 1) (97%) (Scheme 3),16 fully charac-
terized by its NMR and elemental analyses. The detailed
molecular structure of 1 was established by X-ray diffraction
analysis (see the Supporting Information). The molecule pos-
sesses a crystallographic 2-fold rotation axis.
Unexpected Reactivity of 1,1′-Sulfonylbis(benzotriazole)
(1). Reaction of 1 equiv of 1,1′-sulfonylbis(benzotriazole) (Bt2-
SO2, 1) with 3 equiv of pyrrolidine in acetonitrile at rt for 5 h
gave (E)-N-(2-(pyrrolidin-1-yldiazenyl)phenyl)pyrrolidine-1-sul-
fonamide 2a in 55% yield (Table 1). The expected product
1-(pyrrolidine-1-sulfonyl)-1H-benzotriazole 3a was not obtained.
The product 2a was purified by column chromatography, using
silica gel and a mixture of hexanes and ethyl acetate as the
eluent, and characterized by 1H and 13C NMR and satisfactory
a Isolated yields of pure products. b No reaction at rt, refluxed for 12 h.
(15) (a) Mico, X. A.; Ziegler, T.; Subramanian, L. R. Angew. Chem..
Int. Ed. 2004, 43, 1400. (b) Mico, X. A.; Vagin, S.; Subramanian, L. R.;
Ziegler, T.; Hanak, M. Eur. J. Org. Chem. 2005, 4328. (c) Anwar, M. U.;
Tragl, S.; Ziegler, T.; Subramanian, L. R. Synlett 2006, 627. (d) Mico, X.
A.; Bombarelli, R. G.; Subramanian, L. R.; Ziegler, T. Tetrahedron Lett.
2006, 47, 7845.
CHN elemental analysis. The 1H NMR spectrum of 2a showed
the disappearance of the characteristic Bt signals in the aromatic
region, indicating the loss of one of the benzotriazolyl groups
during the reaction. Also a different set of signals appeared for
the phenyl group protons of the other ring opened Bt moiety.
(16) Purygin, P. P.; Ivanov, I. P.; Laletina, Z. P.; Selezneva, E. S. Khim.
Farm. Zh. 1983, 17, 1319.
5806 J. Org. Chem., Vol. 72, No. 15, 2007

SCHEME 4
The NH group of 2a appears downfield at δ 7.81 ppm (singlet)
as a result of H-bonding to the neighboring N atom. The 13C
NMR spectrum of 2a showed eight signals corresponding to
the product. Further the detailed molecular structure of (E)-N-
(2-(pyrrolidin-1-yldiazenyl)phenyl)pyrrolidine-1-sulfonamide 2a
was established unambiguously by X-ray diffraction analysis
(see the Supporting Information). In view of the novelty of the
o-sulfamidotriazobenzene structure and the mechanism of its
formation, we reacted 1 equiv of Bt2SO2 (1) with 3 equiv of
piperidine, morpholine, and diethylamine in acetonitrile at rt
for 5 h to give (E)-N-(2-(piperidin-1-yldiazenyl)phenyl)piperi-
dine-1-sulfonamide (2b), (E)-N-(2-(morpholinodiazenyl)phenyl)-
morpholine-4-sulfonamide (2c), and (E)-N-(2-(diethylamino-1-
yldiazenyl)phenyl)diethylamine-1-sulfonamide (2d) (53%, 63%,
and 75%, respectively) along with 1-(piperidine-1-sulfonyl)-
1H-benzotriazole (3b), 1-(morpholine-4-sulfonyl)1H-benzotria-
zole (3c), and 1-(diethylamine-1-sulfonyl)-1H-benzotriazole (3d)
(7%, 11%, and 0%, respectively) (Table 1). The structure of 2c
was confirmed by X-ray crystallography but the crystals were
all highly twinned and hence the data did not refine to a level
suitable for publication. We tried the experiments with a larger
excess of secondary amines, but the yields of products 2a-d
and 3b,c were not increased. However, the yield of 3c was
increased to 45% when the reaction was heated at 80 °C for 24 h.
Bt2SO2 (1) did not react with methylphenyl amine or di-p-
tolylamine at rt; however, refluxing in acetonitrile for 12 h
produced 1-(methylphenylamine-1-sulfonyl)-1H-benzotriazole
(3e) and 1-(di-p-tolylamine-4-sulfonyl)-1H-benzotriazole (3f)
(70% and 73%, respectively) (Table 1). These results suggest
that alkylaryl amines or diaryl amines do not give benzotriazole
ring-opened products whereas dialkyl amines easily give o-
sulfamidotriazobenzenes at rt. This difference in reactivity may
be due to a large difference in nucleophilicity between the alkyl
and aryl amines.
SCHEME 5
o-Sulfamidotriazobenzenes 2 combine the features of both a
triazine and a sulfamide group. Many triazines are known to
display potent antitumor activity.21 Sulfamides on the other hand
are of interest as (i) components stable to enzymatic hydrolysis
in peptidomimetics,22 (ii) active components in epinephrine
analogues,23 (iii) agonists of the 5-HT1D receptor (regulating
serotonin levels),24 and (iv) HIV protease inhibitors.25
We utilized the byproduct N-sulfonylbenzotriazoles 3 for the
synthesis of unsymmetrical sulfamides. Thus reaction of 1-(mor-
pholine-4-sulfonyl)-1H-benzotriazole (3c) with pyrrolidine, pi-
peridine, and N-methylpiperazine under microwave irradiation
(120 W) at 120 °C for 10 min gave novel 4-(pyrrolidine-1-
sulfonyl)morpholine (4a) and known 4-(piperidine-1-sulfonyl)-
morpholine26 (4b) and 4-(4-methylpiperazine-1-sulfonyl)-
morpholine27 (4c) in 90%, 88%, and 80% yields, respectively
(18) (a) Skelly, J. K.; Farrington, M. German Patent DE75-2517991,
1975; Chem. Abstr. 1976, 85, 27384. (b) Garner, R.; Bolliger, H. R. German
Patent DE72-2244610, 1973; Chem. Abstr. 1973, 79, 460004.
(19) Ege, G.; Beisiegel, E. Ann. Chem. 1972, 763, 46.
A possible mechanism for the formation of o-sulfamidotria-
zobenzenes 2 is outlined in Scheme 4: Bt2SO2 (1) exists in
equilibrium with the diazonium betaine structure 1′.17 Two
molecules of amine attack a single molecule of 1 at different
positionssat the diazo group of 1′ assisted by the electron-
withdrawing sulfone group, and at the sulfur atom with
elimination of a benzotriazole (BtH) moiety. This leads to
product 2 after a proton shift (Scheme 4). A similar mechanism
of ring opening was proposed for the reactions of BtNf (9).15
o-Sulfamidotriazobenzenes of type 2 were unknown; how-
ever, closely related o-sulfonamidotriazobenzenes have been
used as color formers.18 o-Sulfonamidotriazobenzenes 16 have
been prepared by ring cleavage of cyclic triazosulfones 15;19
diazotization of 14 gave the intermediate 15 (Scheme 5).20
(20) Ullmann, F.; Gross, C. Chem. Ber. 1911, 43, 2694.
(21) (a) Manolov, I.; Machulla, H.-J.; Momekov, G. Pharmazie 2006,
61, 511. (b) Vernin, G.; Julliard, M.; Siv, C.; Metzger, J. An. Quim., Ser.
C 1981, 77, 75. (c) Sieh, D. H.; Wilbur, D. J.; Michejda, C. J. J. Am. Chem.
Soc. 1980, 102, 3883 and references cited therein.
(22) Dougherty, J. M.; Probst, D. A.; Robinson, R. E.; Moore, J. D.;
Klein, T. A.; Snelgrove, K. A.; Hanson, P. R. Tetrahedron 2000, 56, 9781.
(23) Acheson, R. M.; Bite, M. G.; Kemp, J. E. G. J. Med. Chem. 1981,
24, 1300.
(24) Castro, J. L.; Baker, R.; Guiblin, A. R.; Hobbs, S. C.; Jenkins, M.
R.; Russell, M. G. N.; Beer, M. S.; Stanton, J. A.; Scholey, K.; Hargreaves,
R. J.; Graham, M. I.; Matassa, V. G. J. Med. Chem. 1994, 37, 3023.
(25) (a) Backbro, K.; Lowgren, S.; Osterlund, K.; Atepo, J.; Unge, T.;
Hulten, J.; Bonham, N. M.; Schaal, W.; Karlen, A.; Hallberg, A. J. J. Med.
Chem. 1997, 40, 898. (b) Hulten, J.; Bonham, N. M.; Nillroth, U.; Hansson,
T.; Zucarello, G.; Bouzide, A.; Aqvist, J.; Classon, B.; Danielson, U. H.;
Karlen, A.; Kvarnstro¨m, I.; Samuelsson, B.; Hallberg, A. J. Med. Chem.
1997, 40, 885.
(26) Vandi, A.; Moeller, T.; Audrieth, L. F. J. Org. Chem. 1961, 26,
1136.
(17) Himbert, G.; Regitz, M. Liebigs Ann. Chem. 1973, 1505.
J. Org. Chem, Vol. 72, No. 15, 2007 5807

Z ) 4, T ) -180 °C, µ(Mo KR) ) 0.231 mm-1, Dcalcd
)
TABLE 2. Reaction of 3c with Secondary Amines
1.426 g‚cm-3, 2θmax 55° (CCD area detector, Mo KR radiation),
GOF ) 0.96, wR(F2) ) 0.087 (all 1044 data), R ) 0.030 (936 data
with I > 2σI).
(E)-N-(2-(Piperidin-1-yldiazenyl)phenyl)piperidine-1-sulfona-
mide (2b): white crystal (53%); mp 74-76 °C (hexanes/dichlo-
1
romethane); H NMR (CDCl3) δ 7.73 (br s, 1H), 7.54 (d, J )
8.0 Hz, 1H), 7.46 (d, J ) 7.8 Hz, 1H), 7.10 (t, J ) 7.3 Hz, 1H),
7.02 (t, J ) 7.4 Hz, 1H), 3.80 (br s, 4H), 3.26-3.10 (m, 4H), 1.73
(br s, 6H), 1.58-1.34 (m, 6H); 13C NMR (CDCl3) δ 138.4, 132.1,
126.1, 123.7, 119.1, 116.2, 47.0, 25.2, 24.1, 23.5. Anal. Calcd for
C16H25N5O2S: C, 54.68; H, 7.17; N, 19.93. Found: C, 54.64; H,
7.26; N, 19.75.
(E)-N-(2-(Morpholinodiazenyl)phenyl)morpholine-4-sulfona-
mide (2c): white crystal (63%); mp 123-125 °C (hexanes/
1
dichloromethane); H NMR (CDCl3) δ 7.70 (br s, 1H), 7.57 (d, J
) 8.2 Hz, 1H), 7.49 (d, J ) 8.1 Hz, 1H), 7.17 (t, J ) 7.4 Hz, 1H),
7.07 (t, J ) 7.7 Hz, 1H), 3.88 (d, J ) 4.8 Hz, 4H), 3.82 (d, J ) 4.7
Hz, 4H), 3.62 (t, J ) 4.0 Hz, 4H), 3.21 (t, J ) 4.3 Hz, 4H); 13C
NMR (CDCl3) δ 137.9, 132.0, 127.1, 124.2, 119.4, 116.9, 66.1,
46.3. Anal. Calcd for C14H21N5O4S: C, 47.31; H, 5.96; N, 19.70.
Found: C, 47.57; H, 5.99; N, 19.67.
(E)-N-(2-(Diethylamino-1-yldiazenyl)phenyl)diethylamine-1-
sulfonamide (2d): white crystal (75%); mp 54-56 °C (hexanes/
1
dichloromethane); H NMR (CDCl3) δ 7.82 (br s, 1H), 7.46 (t, J
) 8.0 Hz, 2H), 7.08 (t, J ) 7.2 Hz, 1H), 7.00 (t, J ) 7.2 Hz, 1H),
3.78 (q, J ) 6.3 Hz, 4H), 3.26 (q, J ) 7.0 Hz, 4H), 1.28 (br s, 6H),
1.05 (t, J ) 7.0 Hz, 6H); 13C NMR (CDCl3) δ 138.8, 131.8, 125.6,
123.5, 118.6, 116.2, 42.0, 13.5. Anal. Calcd for C14H25N5O2S: C,
51.35; H, 7.70; N, 21.39. Found: C, 51.51; H, 7.78; N, 21.30.
1-(Piperidine-1-sulfonyl)-1H-benzotriazole (3b): white crystal
(10%); mp 50-52 °C (hexanes); 1H NMR (CDCl3) δ 8.12 (d, J )
8.3 Hz, 1H), 8.79 (d, J ) 8.3 Hz, 1H), 7.63 (t, J ) 8.1 Hz, 1H),
7.48 (t, J ) 8.1 Hz, 1H), 3.43 (t, J ) 5.4 Hz, 4H), 1.55 (m, 6H);
13C NMR (CDCl3) δ 144.8, 132.5, 129.7, 125.4, 120.2, 112.2, 48.1,
24.8, 23.0. Anal. Calcd for C11H14N4O2S: C, 49.61; H, 5.30; N,
21.04. Found: C, 49.66; H, 5.27; N, 21.02.
1-(Morpholine-4-sulfonyl)-1H-benzotriazole (3c): white crystal
(14%); mp 135-137 °C (hexanes); 1H NMR (CDCl3) δ 8.15 (d, J
) 8.4 Hz, 1H), 7.97 (d, J ) 8.4 Hz, 1H), 7.65 (t, J ) 8.1 Hz, 1H),
7.51 (t, J ) 8.1 Hz, 1H), 3.77 (t, J ) 4.8 Hz, 4H), 3.44 (t, J )
4.8 Hz, 4H); 13C NMR (CDCl3) δ 144.7, 132.5, 130.1, 125.6, 120.4,
111.9, 65.7, 46.9. Anal. Calcd for C10H12N4O3S: C, 44.77; H, 4.51;
N, 20.88. Found: C, 45.14; H, 4.44; N, 20.81.
a Isolated yields of pure products.
(Table 2). Products 4a-c were purified by flash column chro-
matography, using silica gel and a mixture of hexanes and ethyl
acetate as the eluent, and characterized by their spectral properties.
In summary, the reaction of Bt2SO2 (1) with secondary amines
at room temperature provides the first entry to novel o-
sulfamidotriazobenzenes 2 in good yields by a convenient
straightforward one-step method. Byproduct N-sulfonylbenzo-
triazoles 3 enable the preparation of unsymmetrical sulfamides
4 in high yields.
Benzotriazole-1-sulfonic acid N-methyl N-phenylamide (3e):
pink crystal (70%); mp 74-76 °C (hexanes); 1H NMR (CDCl3) δ
8.10 (d, J ) 8.3 Hz, 1H), 7.53 (d, J ) 8.3 Hz, 1H), 7.41-7.44 (m,
2H), 7.25-7.28 (m, 3H), 7.11-7.08 (m, 2H), 3.59 (s, 3H);
13C NMR (CDCl3) δ 144.6, 139.3, 132.8, 129.7, 129.5, 128.9, 127.0,
125.4, 120.1, 112.1, 40.8. Anal. Calcd for C13H12N4O2S: C, 54.15;
H, 4.19; N, 19.43. Found: C, 54.07; H, 4.06; N, 19.81.
Benzotriazole-1-sulfonic acid N,N-di-p-tolylamide (3f): white
needles (73%); mp 125-127 °C (hexanes); 1H NMR (CDCl3)
δ 8.02 (dd, J ) 7.4, 1.6 Hz, 1H), 7.53 (dd, J ) 7.4, 1.5 Hz, 1H),
7.39 (td, J ) 7.0, 1.2 Hz, 2H), 7.34 (td, J ) 7.0, 1.2 Hz, 2H), 7.22
(d, J ) 8.4 Hz, 4H), 7.02 (d, J ) 8.4 Hz, 4H), 2.20 (s, 6H);
13C NMR (CDCl3) δ 144.7, 138.8, 137.4, 132.7, 130.2, 129.6, 127.9,
125.3, 120.0, 112.4, 21.0; HRMS-FAB m/z [M + Na]+ calcd for
C20H18N4O2SNa 401.1043, found 401.1053.
Experimental Section
1,1′-Sulfonylbis(benzotriazole) (1) was prepared by a slight
modification of a previously published procedure.16
General Procedure for the Preparation of 2a-d and 3b,c,e.
To 1,1-sulfonylbenzotriazole (1 g, 3.3 mmol) in anhydrous aceto-
nitrile (15 mL) was added dropwise amine (9.9 mmol, 3 equiv)
with stirring at rt for 5 h. The mixture after removal of the solvent
was subjected to column chromatography (5-20% ethyl acetate in
hexanes) to give pure products 2a-d and 3b,c,e,f.
(E)-N-(2-(Pyrrolidin-1-yldiazenyl)phenyl)pyrrolidine-1-sul-
fonamide (2a): white crystals (55%); mp 109-111 °C (hexanes/
dichloromethane); 1H NMR (CDCl3) δ 7.81 (s, 1H), 7.57 (dd, J )
8.0, 1.4 Hz, 1H), 7.43 (dd, J ) 7.8, 1.4 Hz, 1H), 7.08 (td, J ) 7.4,
1.5 Hz, 1H), 7.01 (td, J ) 7.8, 1.5 Hz, 1H), 3.95 (br s, 2H), 3.63
(br s, 2H), 3.29 (t, J ) 6.9 Hz, 4H), 2.06 (br s, 4H), 1.75-1.69 (m,
4H); 13C NMR (CDCl3) δ 139.1, 131.8, 125.6, 123.8, 119.1, 115.8,
48.3, 25.6. Anal. Calcd for C14H21N5O2S: C, 51.99; H, 6.54; N,
21.65. Found: C, 52.16; H, 6.58; N, 21.44.
Acknowledgment. We thank William Lewis for assistance
with the X-ray crystallography.
Crystal data for 2a: C14H21N5O2S, MW 323.42, monoclinic,
space group P21/c, a ) 10.1479(3) Å, b ) 10.2295(3) Å, c )
14.7132(4) Å, â ) 99.468(1)°, V ) 1506.54(7) Å,3 F(000) ) 688,
Supporting Information Available: Characterization data and
details for the crystal structure of 1 and 2a. This material is available
free of charge via the Internet at http://pubs.acs.org.
(27) Ciba, Ltd., Patent BE 621190; Chem. Abstr. 1963, 59, 62444.
5808 J. Org. Chem., Vol. 72, No. 15, 2007
JO0705723