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SREENIVASA et al., Orient. J. Chem., Vol. 35(1), 157-166 (2019)
General procedure for the synthesis of
compounds 6a-e
133.29, 129.12, 128.29, 127.405, 61.22, 52.77,
45.95, 18.56. IR (KBr): δ = 1665.8 (CO), 1321.4
(S = O asymmetric), 1169.3 (S = O symmetric).
LCMS m/z: cal. 421.12; found 422.21(M+1).
An equimolar mixture of N-(2,6-dimethy
lphenyl)-2-(piperazin-1-yl)acetamide 4 (0.001 mol)
and different substituted benzene sulfonyl chlorides
5a-e (0.001 mol) in methylene dichloride were stirred
for about 8 h in presence of triethylamine at 25oC.
The completion of the reaction was checked byTLC.
Then it was poured into ice-cold water and extracted
with MDC. The organic layer was washed with brine
solution, dried over anhydrous sodium sulphate and
concentratedunderreducedpressuretogetpiperazine
sulphonamide derivatives 6a-e in high yield.
N-(2,6-dimethylphenyl)-2-(4-((4-nitrophenyl)
sulfonyl)piperazin-1-yl)acetamide 6c
Colour: white solid,Yield: 89, m.p:176-177
oC. 1H NMR (400 MHz, CDCl3, TMS): δ = 8.38-8.36
(d, J = 8Hz, 2H; Ar-H), 8.21 (s, 1H, NH), 7.95-7.92
(d, J = 12Hz, 2H, Ar-H), 7.07-7.02 (m, 3H, Ar-H), 3.22
(s, 2H, CH2), 3.16 (s, 4H, CH2), 2.79 (s, 4H, CH2),
2.12 (s, 6H, CH3).13C NMR (100 MHz, CDCl3, TMS):
δ = 167.35, 150.36, 141.7, 134.14, 133.18, 128.87,
127.47, 124.45, 61.19, 52.75, 45.95, 18.53.IR (KBr):
δ = 1659.4 (CO), 1312.1(S = O asymmetric), 1163.5
(S = O symmetric). LCMS m/z: cal. 432.15; found
433.24 (M+1).
General procedure for the synthesis of
compounds 8a-e
To a solution of N-(2,6-dimethylphenyl)-2-
(piperazin-1-yl)acetamide 4 in acetonitrile, different
substituted benzyl chlorides 7a-e (0.001 mol) were
slowly added drop wise in presence of K2CO3 (0.003
mol). Reaction mixture was stirred for 10 h at 25oC
and completion of reaction was checked by TLC.
Reaction mixture was poured into ice-cold water
and extracted with methylene dichloride.The organic
layers was washed with brine solution, dried over
anhydrous sodium sulphate and concentrated to get
alkylated piperazine derivatives 8a-e in good yield.
2-(4-((4-bromophenyl)sulfonyl)piperazin-1-yl)-N-
(2,6-dimethylphenyl) acetamide 6d
Colour:white solid,Yield:90, m.p:184-185
oC. 1H NMR (400 MHz, CDCl3, TMS):δ = 8.27 (s, 1H,
NH), 7.65-7.63 (d, J = 8Hz, 2H, Ar-H), 7.57-7.55
(d, J = 8Hz, 2H, Ar-H), 7.05-7.00 (m, 3H, Ar-H),
3.15 (s, 2H, CH2), 3.04 (s, 4H, CH2), 2.71-2.69
(t, J = 8Hz, 4H, CH2), 2.11 (s, 6H, CH3). 13C NMR
(100 MHz, CDCl3,TMS):δ = 167.73, 135.05, 134.55,
133.37, 132.50, 129.80, 128.26, 128.14, 127.36,
61.19, 52.72, 45.94, 18.58.IR (KBr):δ = 1650.0 (CO),
1315.9 (S = O asymmetric), 1159.7 (S = O symmetric).
LCMS m/z: cal. 465.07; found 468.16 (M+1).
N-(2,6-dimethylphenyl)-2-(4-((4-methoxyphenyl)
sulfonyl)piperazin-1-yl)acetamide 6a
Colour: white solid,Yield: 91, m.p:180-181
oC. 1H NMR (400 MHz, CDCl3, TMS): δ = 8.28 (s,
1H, NH), 7.68-7.66 (t, J = 8Hz, 2H, Ar-H), 7.07-6.97
(m, 5H, Ar-H), 3.84 (s, 3H, OCH3), 3.17 (s, 2H,
CH2), 3.06 (s, 4H, CH2), 2.75-2.72 (t, J = 12Hz, 4H,
CH2), 2.13 (s, 6H, CH3). 13C NMR (100 MHz, CDCl3,
TMS): δ = 167.78, 163.22, 135.02, 133.32, 129.89,
128.27, 127.37, 126.92, 114.34, 61.20, 55.62, 52.80,
46.06, 18.5. IR (KBr): δ = 1662.2 (CO), 1322.2
(S = O asymmetric), 1170.3 (S = O symmetric).
LCMS m/z: cal. 417.17; found 418.25 (M+1).
N-(2,6-dimethylphenyl)-2-(4-tosylpiperazin-1-yl)
acetamide 6e
Colour:white solid,Yield:87, m.p:170-171
oC. 1H NMR (400 MHz, CDCl3, TMS):δ = 8.29 (s, 1H,
NH), 7.62-7.61 (d, J = 4Hz, 2H, Ar-H), 7.32-7.31
(d, J = 4Hz, 2H, Ar-H), 7.07-7.05 (m, 3H, Ar-H),
3.167-3.162 (d, J = 2Hz, 2H, CH2), 3.05 (s, 4H, CH2),
2.73-2.72 (s, 4H, CH2), 2.12 (s, 6H, CH3). 13C NMR
(100 MHz, CDCl3,TMS):δ = 167.73, 143.97, 135.05,
134.55, 133.37, 132.47, 129.20, 128.26, 127.77,
127.36, 61.19, 52.72, 45.94, 18.58. IR (KBr): δ =
1649.1 (C = O), 1342.5 (S = O asymmetric), 1140.1
(S = O symmetric), 2918.89 (Ar-H). LCMS m/z: cal.
401.18; found 402.26 (M+1).
2-(4-((4-chlorophenyl)sulfonyl)piperazin-1-yl)-N-
(2,6-dimethylphenyl)acetamide 6b
Colour :white solid,Yield:90, m.p:188-189
oC. 1H NMR (400 MHz, CDCl3, TMS):δ = 8.26 (s, 1H,
NH), 7.68-7.66 (d, J = 8Hz, 2H, Ar-H), 7.51-7.49
(d, J = 8Hz, 2H, Ar-H), 7.07-7.02 (m, 3H, Ar-H), 3.18
(s, 2H, CH2), 3.08 (s, 4H, CH2), 2.76-2.73 (t, J = 12Hz,
4H, CH2), 2.13 (s, 6H, CH3). 13C NMR (100MHz,
CDCl3, TMS): δ = 167.60, 139.67, 135.03, 134.05,
2-(4-(4-bromobenzyl)piperazin-1-yl)-N-(2,6-
dimethylphenyl) acetamide 8a
Colour: white solid,Yield: 92, m.p:130-131oC.