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Z.-Q. Hu, C.-F. Chen / Tetrahedron 62 (2006) 3446–3454
ppm relative to internal TMS, J in Hertz). Mass spectra were
obtained by EI and MALDI-TOF techniques. Elemental
analyses were performed on a Vario ELIII and Carlo Erba
1106 analytical instrument. Solvents were dried and
distilled before use according to standard procedures.
N-Phenyl-2-aminobenzenesulfonamide23 was prepared
according to the published procedure.
4.1.4. Compound 2. Following the method described above
for 1, 2 was obtained in 54% yield by the reaction of 2,6-
pyridinedicarboxylic acid with 6. Mp 256–258 8C. 1H NMR
(CDCl3): d 11.37 (s, 2H), 10.65 (s, 2H), 8.49 (d, JZ7.8 Hz,
2H), 8.27 (d, JZ7.3 Hz, 2H), 8.18 (t, JZ7.8 Hz, 1H), 7.83
(d, JZ8.0 Hz, 2H), 7.76 (d, JZ8.0 Hz, 2H), 7.64–7.55 (m,
4H), 7.33 (t, JZ7.5 Hz, 2H), 7.18 (t, JZ7.6 Hz, 2H), 6.96
(t, JZ7.1 Hz, 2H), 3.66 (s, 6H). 13C NMR (DMSO-d6): d
166.9, 161.2, 161.1, 147.9, 140.4, 137.7, 137.6, 135.0,
134.8, 134.6, 134.0, 130.7, 129.8, 129.3, 129.1, 129.0,
125.4, 125.2, 125.1, 125.0, 124.95, 124.89, 124.4, 121.1,
118.4, 52.2; MALDA-TOF MS: m/z 766.3 [MCNa]C;
elemental analysis calcd (%) for C35H29N5O10S2: C 56.52,
H 3.93, N 9.42; found: C 56.54, H 3.92, N 9.33.
4.1.1. Compound 5. To a solution of methyl anthranilate
(1 mmol) and Et3N (1.2 mmol) in CH2Cl2 (10 mL) at 0 8C,
2-nitrobenzenesulfonyl chloride (1.2 mmol) in CH2Cl2
(5 mL) was added dropwise. The reaction mixture was stirred
at room temperature for 10 h and then washed with 2 N HCl
and water. The organic phase was dried over anhydrous
MgSO4 and then concentrated. The crude product was purified
by flash chromatography (1:1 DCM/petroleum ether) to give
the product 5 as a white solid (218 mg, 65%). Mp 143–144 8C.
1H NMR (CDCl3): d 11.18 (s, 1H), 8.16 (m, 1H), 7.98 (d, JZ
8.0 Hz, 1H), 7.83–7.78 (m, 2H), 7.74–7.69 (m, 2H), 7.49 (t,
JZ8.0 Hz, 1H), 7.08 (t, JZ7.8 Hz, 1H), 3.93 (s, 3H). 13C
NMR (CDCl3): d 167.9, 148.2, 139.3, 134.5, 134.2, 132.9,
132.4, 131.6, 131.3, 125.4, 123.2, 117.9, 116.3, 52.8; EI-MS:
m/z 336 [M]C; elemental analysis calcd (%) for
C14H12N2O6S: C 50.00, H 3.60, N 8.33; found: C 50.03, H
3.60, N 8.24.
4.1.5. Compound 7. To a solution of N-phenyl-2-amino-
benzenesulfonamide (1 mmol) and DMAP (1.2 mmol) in
CH2Cl2 (10 mL) at 0 8C was added 2-nitrobenzenesulfonyl
chloride (1.2 mmol) in CH2Cl2 (5 mL). The reaction mixture
was refluxed for 10 h and then washed with 2 N HCl and
water. The organic phase was dried over anhydrous MgSO4
and then concentrated. The crude product was purified byflash
chromatography (1:1 DCM/petroleum ether) to give desired
product 7 as a white solid (294 mg, 68%). Mp 138–140 8C. 1H
NMR (CDCl3):d 8.44–8.41 (m, 1H), 7.78–7.75 (m, 2H), 7.67–
7.65 (m, 1H), 7.49 (d, JZ8.3 Hz, 1H), 7.41–7.38 (m, 1H),
7.34–7.26 (m, 5H), 6.64–6.57 (m, 2H), 4.88 (broad, 2H). 13C
NMR (CDCl3): d 148.2, 147.1, 136.1, 135.1, 132.8, 132.7,
132.66, 132.1, 132.0, 131.3, 130.6, 129.1, 124.3, 117.4, 117.0,
116.7; MALDA-TOF MS: m/z 432.4 [MKH]K; elemental
analysiscalcd(%)forC18H15N3O6S2:C49.88,H3.49, N9.69;
found: C 49.75, H 3.49, N 9.75.
4.1.2. Compound 6. A mixture of compound 5 (1 mmol)
dissolved in CH3OH (15 mL) and 10% Pd/C (10 mg) was
stirred at ambient temperature under an atmosphere of
hydrogen for 10 h. The reaction mixture was filtered through
Celite and CH3OH was evaporated to afford 6 as a white solid
in quantitative yield. The product was pure and used without
1
further purification. Mp 164–165 8C. H NMR (CDCl3): d
4.1.6. Compound 8. A mixture of compound 7 (1 mmol)
dissolved in CH3OH (25 mL) and 10% Pd/C (15 mg) was
stirred at ambient temperature under an atmosphere of
hydrogen for 10 h. The reaction mixture was filtered
through Celite and CH3OH was evaporated to afford 8 as
a white solid in quantitative yield. The product was pure and
used without further purification. Mp 162–164 8C. 1H NMR
(CDCl3): d 7.49 (d, JZ8.2 Hz, 2H), 7.38–7.15 (m, 7H),
6.70–6.61 (m, 4H), 4.86 (broad, 4H). 13C NMR (CDCl3): d
146.4, 135.6, 133.8, 132.0, 131.3, 130.2, 128.9, 119.0,
117.4, 116.7; MALDA-TOF MS: m/z 404.3 [MCH]C;
elemental analysis calcd (%) for C18H17N3O4S2: C 53.58, H
4.25, N 10.41; found: C 53.38, H 4.31, N 10.21.
10.85 (s, 1H), 7.91 (d, JZ8.0 Hz, 1H), 7.71 (d, JZ8.0 Hz,
1H), 7.62 (d, JZ8.3 Hz, 1H), 7.42 (t, JZ7.8 Hz, 1H), 7.23 (t,
JZ8.5 Hz, 1H), 7.00 (t, JZ7.7 Hz, 1H), 6.71–6.65 (m, 2H),
4.88 (broad, 2H), 3.88 (s, 3H). 13C NMR (CDCl3): d 168.3,
145.5, 148.5, 140.4, 134.5, 134.4, 131.1, 130.1, 122.6, 120.3,
118.4, 117.6, 117.2, 115.7, 52.5; EI-MS: m/z 306 [M]C;
elemental analysis calcd (%) for C14H14N2O4S: C 54.89, H
4.61, N 9.14; found: C 54.72, H 4.65, N 9.13.
4.1.3. Compound 1. A solution of 2,6-pyridinedicarboxylic
acid N-oxide (1 mmol) in excess SOCl2 was refluxed for 2 h,
SOCl2 was then removed by reduced pressure. The acid
chloride obtained was dissolved in anhydrous CH2Cl2
(10 mL), and added dropwisely over a period of 10 min to a
solution of 6 (1 mmol) and Et3N (3 mmol) in CH2Cl2 (10 mL)
at 0 8C. The mixture was stirred at room temperature for 4 h.
The organic phase was washed with 2 N HCl twice, and dried
over anhydrous Na2SO4. The solvent was removed and the
residuewaspurifiedbyflashchromatography(20:1DCM/EA)
to give desired product 1 as a white solid (342 mg, 45%). Mp
268–270 8C. 1H NMR (DMSO-d6): d 13.11 (s, 2H), 10.78 (s,
2H), 8.61 (d, JZ8.0 Hz, 2H), 8.14 (d, JZ8.0 Hz, 2H), 8.03 (d,
JZ7.8 Hz, 2H), 7.96 (t, JZ7.9 Hz, 1H), 7.79–7.72 (m, 4H),
7.56–7.41 (m, 6H), 7.07 (t, JZ7.4 Hz, 2H), 3.48 (s, 6H). 13C
NMR (DMSO-d6): d 167.3, 167.2, 157.9, 157.8, 140.8, 138.6,
138.4, 134.5, 134.4, 134.3, 134.1, 131.6, 131.0, 129.9, 129.7,
129.6, 128.9, 126.5, 126.4, 125.6, 123.8, 119.2, 116.7, 52.1;
MALDA-TOF MS: m/z 758.3 [MKH]C; elemental analysis
calcd (%) for C35H29N5O11S2: C 55.33, H 3.85, N 9.22; found:
C 55.33, H 3.97, N 8.92.
4.1.7. Compound 4. Following the method described for 1,
compound 4 was obtained as a white solid in 71% yield by
the reaction of 2,6-pyridinedicarboxylic acid with 8. MpO
1
300 8C. H NMR (CDCl3): d 12.70 (s, 2H), 8.98 (d, JZ
8.2 Hz, 2H), 8.42 (d, JZ7.7 Hz, 2H), 8.22 (t, JZ7.7 Hz,
1H), 7.71 (t, JZ7.9 Hz, 2H), 7.61–7.50 (m, 3H), 7.40–7.35
(m, 4H), 7.17 (t, JZ7.7 Hz, 2H). 13C NMR (CDCl3): d
160.8, 147.8, 140.5, 136.9, 136.0, 134.3, 132.3, 131.2,
129.6, 126.9, 124.8, 123.5, 121.3; EI-MS: m/z 534 [M]C;
elemental analysis calcd (%) for C25H18N4O6S2: C 56.17, H
3.39, N 10.48; found: C 55.96, H 3.36, N 10.39.
4.2. X-ray crystallographic study
Data were collected using a Rigaku RAXIS-RAPID Imaging
Plate diffractometer with graphite monochromated Mo Ka