1168
V. Padmavathi, K. Mahesh, P. Thriveni and T. V. Ramana Reddy
Vol 44
Table 3 (continued)
Compound
1H NMR (ꢀ, ppm)
13C NMR (ꢀ, ppm)
5a
5b
3.46 (s, 3H, -OCH3), 4.72 (s, 2H, SO2-CH2), 4.85 (s, 2H,
CH2-SO2), 7.38-7.93 (m, 10H, Ar-H), 9.72 (bs, 1H, NH)
-
-
2.34 (s, 3H, Ar-CH3), 3.36 (s, 3H, -OCH3), 4.68 (s, 2H, SO2-
CH2), 4.78 (s, 2H, CH2-SO2), 7.32-7.84 (m, 9H, Ar-H), 9.68
(bs, 1H, NH)
5c
6a
3.48 (s, 3H, -OCH3), 4.79 (s, 2H, SO2-CH2), 4.91 (s, 2H,
CH2-SO2), 7.40-7.94 (m, 9H, Ar-H), 9.78 (bs, 1H, NH)
-
3.51 (s, 3H, -OCH3), 4.68 (s, 2H, SO2-CH2), 7.62-7.82 (m,
10H, Ar-H)
53.8 (-OCH3), 60.2 (SO2-CH2), 146.1 (C-5), 158.7 (C-4),
164.4 (C=O), 128.6, 129.2, 129.8, 130.2, 132.4, 133.1,
134.6, 134.9 (aromatic carbons)
21.8 (Ar-CH3), 52.8 (-OCH3), 57.2 (SO2- CH2), 148.7 (C-5),
159.4 (C-4), 164.2 (C=O), 127.9, 128.7, 129.7, 130.4, 131.2,
131.8, 132.6, 133.1 (aromatic carbons)
6b
6c
2.32 (s, 3H, Ar-CH3), 3.48 (s, 3H, -OCH3), 4.56 (s, 2H, SO2-
CH2), 7.64-7.89 (m, 9H, Ar-H)
53.8 (-OCH3), 59.2 (SO2-CH2), 147.2 (C-5), 156.6 (C-4),
162.2 (C=O), 127.6, 128.3, 128.9, 129.6, 131.5, 132.6,
133.4, 134.8 (aromatic carbons)
3.53 (s, 3H, -OCH3), 4.59 (s, 2H, SO2-CH2), 7.38-7.92 (m,
9H, Ar-H)
1
acetate trihydrate (0.272 g, 2 mmol) was dissolved in methanol
(20 ml) and the residue (NaCl) was filtered off. Compound 1
(0.254 g, 1 mmol) in methanol (10 ml) was added to the filtrate
and the contents were heated on a water bath for 3-5 hours. The
reaction mixture was concentrated, cooled and poured onto
crushed ice. The solid obtained was collected by filtration, dried
and recrystallized from ethanol.
5 were due to phenylhydrazone moiety. The H NMR
spectrum of 5a displayed three singlets at 4.85 (CH2-SO2),
4.72 (SO2-CH2-CO2Me) and 3.46 ppm (OCH3). When 5
was subjected to cyclocondensation with phosphorus
trichloride in anhydrous diethyl ether in the presence of
triethylamine at -5 to 10°C, (2,5-diphenyl-2H-[1,2,3]-
diazaphosphole-4-sulfonyl)acetic acid methyl ester (6)
was obtained (Scheme I and Table 1). The absence of the
NH band and the presence of bands around 1730-1735
(CO2Me), 1335-1345, 1140-1150 (SO2) and 1580-1600
cm-1 (C=N) in the IR spectra indicates the formation of 6
(4-Phenyl[1,2,3]selenadiazole-5-sulfonyl)acetic acid methyl
ester (3). General Procedure. The semicarbazone 2 (0.936 g, 3
mmol) was dissolved in glacial acetic acid (20 ml) and warmed
gently with stirring until a clear solution was obtained. Selenium
dioxide (0.332 g, 3 mmol) was then added in portions over a
period of 30 mins. with stirring. The contents were stirred at 60-
70°C until the evolution of gas ceased and the deposited selenium
was removed by filtration. The filtrate was poured onto crushed
ice and the collected solid was washed with cold water and
saturated sodium bicarbonate solution. The crude material was
purified by column chromatography (silica gel, 60-120 mesh,
hexane: ethyl acetate, 2:0.5) affording the titled compound.
(4-Phenyl[1,2,3]thiadiazole-5-sulfonyl)acetic acid methyl
ester (4). General Procedure. To a well cooled (0°C) solution of
semicarbazone 2 (0.936 g, 3 mmol) in dichloromethane (20 ml),
an excess of thionyl chloride (3 ml) was added in portions while
stirring. The mixture was then allowed to reach room
temperature over 2-3 hours. Excess reagent was decomposed
with cold saturated sodium carbonate solution. The organic layer
was separated, washed with water and dried over anhydrous
Na2SO4. Evaporation of the solvent in vacuo produced a residue,
which was purified by column chromatography (silica gel, 60-
120 mesh, hexane: ethyl acetate, 2:1).
1
(Table 2). The H NMR spectrum of 6a showed a singlet
at 4.68 ppm for methylene protons and another singlet at
3.51 ppm for methoxy protons of carbomethoxy group.
The structure of the compounds 3, 4 and 6 was further
confirmed by 13C NMR spectra (Table 3).
EXPERIMENTAL
Melting points were determined in open capillaries on a Mel-
Temp apparatus and are uncorrected. The purity of the
compounds was checked by TLC (silica gel H, BDH, ethyl
acetate-hexane, 0.5:2). The IR spectra were recorded on a
Thermo Nicolet IR 200 FT-IR spectrometer as KBr pellets and
the wave numbers were given in cm-1. The H NMR spectra
1
were recorded in CDCl3/DMSO-d6 on a Varian EM-360
spectrometer (300 MHz). The 13C NMR spectra were recorded
in CDCl3/DMSO-d6 on a Varian VXR spectrometer operating at
75.5 MHz. All chemical shifts are reported in ꢀ (ppm) using
TMS as an internal standard. The microanalyses were performed
on Perkin-Elmer 240C elemental analyzer. The starting
compound phenacylsulfonylacetic acid methyl ester (1) was
prepared by the literature procedure [11].
(1-Phenyl-ethanonephenylhydrazone)sulfonylacetic acid
methyl ester (5). General Procedure. To compound 1 (1.27 g,
5 mmol) dissolved in methanol (15 ml), phenylhydrazine (0.72
g, 5 mmol) was added and refluxed for 2-3 hours. Then the
reaction mixture was concentrated and cooled (0°C). The solid
was collected by filtration, washed with water, dried and
recrystallized from ethanol.
(1-Phenyl-ethanonesemicarbazone)sulfonylacetic acid
methyl ester (2). General Procedure. A mixture of
semicarbazide hydrochloride (0.134 g, 1.2 mmol) and sodium
(2,5-Diphenyl-2H-[1,2,3]diazaphosphole-4-sulfonyl)acetic
acid methyl ester (6). General Procedure. Phosphorus tri-
Padmavathi, Venkatapuram
