HETEROCYCLES

Paper | Regular issue | Vol. 83, No. 4, 2011, pp. 777-787
Received, 30th December, 2010, Accepted, 21st February, 2011, Published online, 2nd March, 2011.
DOI: 10.3987/COM-10-12133

■ Synthesis of 3-Alkanesulfonyl-4(1H)-quinolinones from 3-Alkanesulfonyl-4-alkylsulfanylquinolines

Leszek Skrzypek,* Andrzej Maślankiewicz, and Kinga Suwińska

Department of Organic Chemistry, The Medical University of Silesia, Jagiellońska 4, 41-200 Sosnowiec, Poland

Abstract

3-Alkanesulfonyl-4-alkylsulfanylquinolines (4) were transformed to 3-alkanesulfonyl-4(1H)-quinolinones (5) and (6). 1H-Derivatives 5 were obtained by acidic hydrolysis of compounds 4. 1-Alkyl derivatives 6 were prepared in three ways: a) via 1-alkylquinolinium salts 7 followed by their acidic hydrolysis to 6; b) in one-pot reactions of compounds 4 with alkyl bromides under Phase Transfer Catalysis (PTC) conditions; or c) by alkylation of 1H-derivatives 5 with alkyl bromides under PTC conditions.

INTRODUCTION
The discovery of strong antimicrobial 4(1H)-quinolinones inspired broad and intensive study on the structure-activity relationship of 4(1H)-quinolinone derivatives.1-3 It is well documented that N-alkyl derivatives are more potent than their N-H parent structures.1-5 The same trends were observed for 3-alkylsulfinyl-4(1H)-quinolinones acting as antihypertensive agent5 and for 3-sulfamoyl-4(1H)-quinolinones with antihypertensive,5,7 or phosphordiesterase-5 inhibitory6 activity.
N-Alkyl-4(1H)-quinolinones were synthesized mainly by cyclisation of the benzene derivatives,1-7 by hydrolysis of N-alkylquinolinium salts 8,9 or by N-alkylation of 4(1H)-quinolinones.1-3
The easy access to the title 4-alkylsulfanyl-3-alkanesulfonylquinolines 4 from 4-chloro-3-quinolinesulfonyl chloride10 (Scheme 1) prompted us to a study on the transformation of compounds 4 to 3-alkanesulfonyl-4(1H)-quinolinones 5 and 6 (Schemes 2-4).

RESULTS and DISCUSSION
First experiments on the purification of 4-alkylsulfanyl-3-alkanesulfonylquinolines (4) by recrystallization from aqueous ethanolic solutions revealed an instability in the compounds 4, which partially decomposed to 4-quinolinones 5 accompanied by volatile odorous thioderivatives. Hydrolysis of compounds 4 was performed for preparative purposes in boiling 1% hydrochloric acid for 1 h to give 1,4-dihydro-4-oxo-3-alkanesulfonylquinolines 5a-e as sole products.

We then turned to the synthesis of N-alkyl derivatives 6 via quinolinium salts 7 applying our previous methodology.9 For this purpose, compounds 4 were heated with dimethyl or diethyl sulfate which led to N-alkylquinolinium salts 7. Due to instability of salts 7 crude alkylation products were subjected directly to hydrolysis, and N-alkyl derivatives 6a, b, f, g, h, i were obtained as sole products in good yields (70-90%).

Hoping to extend the set of alkanesulfonyl derivatives 4, it was attempted to alkylate compound 4a at α-alkanesulfonyl carbon using the PTC conditions described for aryl benzylsulfones or sulfonamides.11 Unexpectedly, the reaction gave the N-alkyl-4-quinolinones 6b and 6e or 6c and 6e in the presence of methylene chloride (Table, entries 2 and 4), but N-alkyl-4-quinolinones 6b, c, d, j were obtained as sole products in the absence of methylene chloride and using an excess of alkyl bromide (Scheme 4).
Due to the sensitivity of compounds 4 toward hydrolysis and the rigorous conditions of N-alkylation of compounds 4, we assumed that the hydrolysis of 4-methylsulfanylquinolines 4 to 4(1H)-quinolinones 5 is the first step in the reaction sequences involved under PTC conditions. To confirm this assumption, 4(1H)-quinolinones 5a, b were isolated from reaction performed under the PTC conditions in the absence of alkylating agents. Then, compounds 5a, b were subjected to N-alkylation under the PTC conditions and 1-ethyl-4(1H)-quinolinones 6c, g were obtained in good yields. 4-Quinolinone 5a did not react with methylene chloride under the PTC conditions.
In order to explain the formation of methylthiomethyl derivative 6e, 3-methanesulfonyl-4-methylsulfanyl- quinoline (4a) was subjected to the reaction with methylene chloride under the PTC conditions. The reaction gave only traces of 6e. However, the same reaction performed in the presence of potassium bromide (2 molar equivalents) produced compound 6e (~40%). This suggests that bromide anion activated the methylene chloride molecule to form bromomethylene derivatives (CH2BrCl or CH2Br2), which then reacted with sodium methanethiolate to give methylthiomethyl halogenide (X=Br or Cl). The latter acted as an alkylating agent toward the quinolinone 5a anion (see Scheme 3).

X-Ray analysis
Products obtained by the hydrolysis of compounds 4 may formally exist as the 1,4-dihydro-4-oxo or 4-hydroxy tautomer, as it was observed for 4(1H)-quinolinone derivatives with a strong electron-withdrawing group, like 4-hydroxy- or 4-mercapto-3-quinolinesulfonic acids.12,13
Therefore, in order to evaluate tautomeric preferences of hydrolysis products of compounds 4, n-propyl derivative 5c was subjected to X-ray examination. It was proved that compound 5c exists as the 4-oxo form in the solid state with hydrogen atom located at the N1 atom (Figure 1a).
Molecules in crystal form 1D polymer via bifurcated N-H···O1(O2) hydrogen bonds (Figure 1b). Two molecules related by center of symmetry are arranged in “dimers”, in which the quinolone aromatic rings are parallel one to each other and are separated by 3.527 Å indicating π-π interaction (Figure 1c). There are also one C-H··· π·and one C=O···π interactions to the quinolone aromatic rings with distances to the ring 2.895 and 3.286 Å, respectively (Figure 1d).

CONCLUSIONS
Both functions of compounds 4 were engaged in reactions with alkylating agents under the PTC conditions. They participated, on one hand, in nucleophilic substitution of the 4-alkylsulfanyl substituent with hydroxy anion to form, after tautomerization the 4-oxo function of 5, which was then alkylated at the endocyclic nitrogen atom to afford the final N-alkyl-3-alkanesulfonyl-4(1H)-quinolinones 6. Taking into account the easy access to the title 3-alkanesulfonyl-4-alkylsulfanylquinolines 4 and the one-pot synthesis of 6 from compounds 4, the present study opens a unique route to the title compounds 6 and is therefore more general and more convenient than previous findings concerning the preparation of 3-methanesulfonyl-1-methyl-4(1H)-quinolinone (6a) derivatives by cyclizations or oxidation of the respective 3-thioderivatives.7

EXPERIMENTAL
Melting points were taken in open capillary tubes and are uncorrected. All NMR spectra were recorded on a Bruker AVANCE 400 spectrometer operating at 400.22 MHz for 1H nuclei, in deuterochloroform or in hexadeuterodimethyl sulfoxide solutions with tetramethylsilane (δ 0.0 ppm) as internal standard.
EI MS spectra were determined on a Finnigan MAT 95 spectrometer at 70 eV. TLC analyses were performed employing Merck’s aluminium oxide 60 F254 neutral (type E) plates and using chloroform as an eluent.
3-Alkanesulfonyl-4-alkylsulfanylquinolines 4 were prepared as described previously.10 In the same way were prepared 3-(1-propanesulfonyl)-4-methylsulfanylquinoline (4d) (82% from salt 3a, R=Me) and 3-(1-propanesulfonyl)-4-propylsulfanylquinoline (4e) (90% from salt 2) required for this paper.

3-(1-Propanesulfonyl)-4-methylsulfanylquinoline (4d):
Oil. MS (EI, 70 eV): m/z (%) = 281 (M+, 100). 1H NMR (CDCl3) δ: 1.04 (t, J=7.5 Hz, 3H, CH3), 1.78-1.84 (m, 2H, CH2CH3), 3.66-3.70 (m, 2H, SO2CH2), 7.77-7.81 (m, 1H, H6), 7.91-7.95 (m, 1H, H7), 8.23-8.25 (m, 1H, H8), 8.70-8.73 (m, 1H, H5), 9.48 (s, 1H, H2). Anal. Calcd for C13H15NO2S2: C 55.49, H 5.37, N 4.98. Found: C 55.79, H 5.67, N 5.12.
3-(1-Propanesulfonyl)-4-propylsulfanylquinoline (4e):
Mp 66-67 oC. MS (EI, 70 eV): m/z (%) = 309 (M+, 51), 1H NMR (CDCl3) δ: 1.01-1.05 (m, 6H, 2 x CH3), 1.68-1.73 (m, 4H, 2x CH2), 3.05-3.08 (m, 2H, SCH2), 3.66-3.70 (m, 2H, SO2CH2), 7.75-7.79 (m, 1H, H6), 7.92-7.94 (m, 1H, H7), 8.22-8.24 (m, 1H, H8), 8.71-8.73 (m, 1H, H5), 9.48 (s, 1H, H2). Anal. Calcd for C15H19NO2S2: C 58.22, H 6.19, N 4.53. Found: C 58.41, H 6.41, N 4.30.

Hydrolysis of 3-alkanesulfonyl-4-alkylsulfanylquinolines (4) to 3-alkanesulfonyl-4(1H)-quinolinones (5)
A mixture of 3-alkanesulfonyl-4-alkylsulfanylquinolines (4) (1.5 mM), 8 mL of 1% HCl aq. and 2 mL of EtOH was kept at the boiling state for 1 h. The mixture was cooled down to rt. The solid was filtered off and recrystallized from aqueous EtOH to give 3-alkanesulfonyl-4(1H)-quinolinones 5.
3-Methanesulfonyl-4(1H)-quinolinone (5a):
mp 319-320 oC. MS (EI, 70 eV): m/z (%) = 223 (M+, 100). 1H NMR (DMSO-d6), δ: 3.26 (s, 3H, SO2CH3), 7.48-7.52 (m, 1H, H6),7.70-7.72 (m, 1H, H8), 7.78-7.81 (m, 1H, H7), 8.18-8.20 (m, 1H, H5), 8.53 (s, 1H, H2), 12.69 (s, 1H, NH). Anal. Calcd for C10H9NO3S: C 53.80, H 4.06, N 6.27, S 14.36. Found: C 54.04, H 4.36, N 6.40, S 14.51.
3-Ethanesulfonyl-4(1H)-quinolinone (5b):
mp 216-217 oC. MS (EI, 70 eV): m/z (%) = 237 (M+, 100). 1H NMR (DMSO-d6), δ: 1.12 (t, J=7.3 Hz, 3H, CH2CH3), 3.41 (q, J=7.3 Hz, 2H, CH2CH3), 7.48-7.52 (m, 1H, H6),7.70-7.72 (m, 1H, H8), 7.78-7.80 (m, 1H, H7), 8.17-8.19 (m, 1H, H5), 8.50 (s, 1H, H2), 12.71 (s, 1H, NH). Anal. Calcd for C11H11NO3S: C 55.68, H 4.67, N 5.90, S 13.51. Found: C 55.47, H 4.88, N 6.11, S 13.72.
3-(1-Propanesulfonyl)-4(1H)-quinolinone (5c):
mp 206-209 oC. MS (EI, 70 eV): m/z (%) = 251 (M+, 79), (M-SO2CH2CH2CH3 +1, 100). 1H NMR (DMSO-d6), δ: 0.94 (t, J=7.5 Hz, 3H, CH2CH2CH3), 1.54-1.64 (m, 2H, CH2CH2CH3), 3.40-3.44 (m, 2H, CH2CH2CH3), 7.48-7.52 (m, 1H, H6) 7.70-7.72 (m, 1H, H8), 7.77-7.82 (m, 1H, H7), 8.17-8.19 (m, 1H, H5). 8.51 (s, 1H, H2), 12.71 (s, 1H, NH). Anal. Calcd for C12H13NO3S: C 57.35, H 5.21, N 5.57, S 12.76. Found: C 57.64, H 5.09, N 5.50, S 12.97.
3-(1-Methylethanesulfonyl)-4(1H)-quinolinone (5d):
mp 295-296 oC. MS (EI, 70 eV): m/z (%) = 251 (M+, 82), 191(M-SO2, 100). 1H NMR (DMSO-d6), δ: 1.20 (d, 6H, J=7.3 Hz, (CH3)2), 3.81-3.91 (m, 1H. CH), 7.48-7.51 (m, 1H, H6), 7.71-7.73 (m, 1H, H8), 7.78-7.81 (m, 1H, H7), 8.16-8.18 (m, 1H, H5), 8.59 (s, 1H, H2), 12.71 (s, 1H, NH). Anal. Calcd for C12H13NO3S: C 57.35, H 5.21, N 5.57, S 12.76. Found: C 57.47, H 5.55, N 5.32, S 12.81.
3-(Propene-3-sulfonyl)-4(1H)-quinolinone (5e):
mp 224-226 oC. MS (EI, 70 eV): m/z (%) = 249 (M+, 43), (M- SO2CH2CH=CH2, 100). 1H NMR (DMSO-d6), δ: 4.22 (d, J=7.6 Hz, 2H, CH2CH=CH2), 5.21-5.27 (m, 2H, CH2CH=CH2), 5.66-5.77 (m, 1H, CH2CH=CH2), 7.48-7.52 (m, 1H, H6) 7.70-7.72 (m, 1H, H8), 7.80-7.82 (m, 1H, H7), 8.18-8.20 (m, 1H, H5). 8.47 (s, 1H, H2), 12.72 (s, 1H, NH). Anal. Calcd for C12H11NO3S: C 57.82, H 4.45, N 5.62, S 12.86. Found: C 57.68, H 4.59, N 5.38, S 12.65.
3-Phenylmethanesulfonylquinolinone (5f):
mp 283-285 oC. MS (EI, 70 eV): m/z (%) = 299 (M+, 22), 91 (CH2Ph, 100). 1H NMR (DMSO-d6), δ: 4.78 (s, 2H, CH2Ph), 7.20-7.22 (m, 2H, Harom), 7.27-7.29 (m, 3H, Harom), 7.51-7.55 (m, 1H, H6) 7.69-7.71 (m, 1H, H8), 7.78-7.82 (m, 1H, H7), 8.24-8.26 (m, 2H, H5 and H2). 12.74 (s, 1H, NH). Anal. Calcd for C16H13NO3S: C 64.20, H 4.38, N 4.68, S 10.71. Found: C 64.36, H 4.62, N 4.70, S 11,01.

Alkylation of 3-alkanesulfonyl-4-alkylsulfanylquinolines 4 to 3-alkanesulfonyl-1-alkyl-4-alkylsulfanyl-quinolinium salts 7 and hydrolysis of salts 7 to 3-alkanesulfonyl-1-alkyl-4(1H)-quinolinones 6
3-Alkanesulfony-4-alkylsulfanylquinoline 4 (1 mM) was dissolved in 0.7 mL of freshly distilled dialkyl sulfate and kept at 100 ºC for 2 h (dimethyl sulfate) or 24 h (diethyl sulfate). The mixture was cooled down to rt and triturated three times with dry Et2O (4 mL) followed by decantation. The residue was kept at rt under vacuum to give quinolinium salt 7 as syrupy semi-solid material. Due to instability of quinolinium methyl (or ethyl) sulfate 7, they could not be isolated in a pure state, and crude salts 7 were used directly for the preparation of compounds 6.
For purpose of hydrolysis, salt 7 (ca. 1 mM) was dissolved in water (8 mL) and refluxed for 1 h. The mixture was then cooled down to rt. The solid was filtered off, washed with cold water and dried on air. It was recrystallized from EtOH to give 3-alkanesulfonyl-1-alkyl-4(1H)-quinolinones 6.

Reaction of 3-alkanesulfonyl-4-alkylsulfanylquinolines 4 performed under the PTC conditions
a) In the absence of CH2Cl2
4-Methylsulfanylquinoline 4 (1 mM) was suspended with stirring in a mixture of 50% aqueous NaOH (2 mL), tetrabutylammonium bromide (50 mg), HMPA (0.2 mL) and then alkyl bromide (11-20 mM) was added. The mixture was stirred for 6 h up to 72 h at rt or at appropriate temperature (for details – see Table). The mixture was then cooled down to rt and diluted with water (20 mL) to precipitate solid, which was filtered off, washed with cold water and dried on air. It was recrystallized from EtOH to give 3-alkanesulfonyl-1-alkyl-4(1H)-quinolinone 6.
b) In the presence of CH2Cl2
The reaction performed in the presence of CH2Cl2 (2 mL) and using the 2 mM of alkyl bromide led to a mixture of 3-alkanesulfonyl-­1-alkyl-4(1H)-quinolinone 6b or 6c and 1-methylthiomethyl derivative 6e. The mixture was separated by column chromatography (aluminium oxide / CH2Cl2).
The same reaction carried out without alkyl bromide but with addition of KBr (240 mg, ca. 2 mM) led to 1-methylthiomethyl derivative 6e (38%). Acidification of aqueous layer afforded non-alkylated 4(1H)-quinolinones 5a (27%).
c) Hydrolysis of 3-alkanesulfonyl-4-alkylsulfanylquinolines 4 to 3-alkanesulfonyl-4(1H)-quinolinones 5.
A mixture of 3-alkanesulfonyl-4-alkylsulfanylquinolines 4a or 4b (1.5 mM), 50% aqueous NaOH (2 mL), tetrabutylammonium bromide (50 mg), HMPT (0.2 mL) and benzene (1.5 mL) was refluxed with stirring for 3 h. The mixture was cooled down to rt. The precipitated solid was filtered off to give ca. 40% of non-converted substrate 4. The filtrate was transfered into a separatory funnel, and the aqueous layer was separated. This solution was then acidified with 10% HCl aq. to precipitate 3-alkanesulfonyl-4(1H)-quinolinones (5a, 37%, or 5b, 39%).

Alkylation of 3-alkanesulfonyl-4(1H)-quinolinones 5 to 3-alkanesulfonyl-1-alkyl-4(1H)-quinolinones 6
3-Alkanesulfonyl-4(1H)-quinolinones 5a or 5b were subjected to alkylation under the PTC conditions mentioned above (procedure a for compounds 4). N-Alkyl derivative 6c or 6g was isolated as described above. For details, see Table – entry 9 and 10.

3-Methanesulfonyl-1-methyl-4(1H)-quinolinone (6a):
mp 215-216 oC. MS (EI, 70 eV): m/z (%) = 237 (M+, 95), 173 (M-SO2 100). 1H NMR (CDCl3), δ: 3.36 (s, 3H, SO2CH3), 3.95 (s, 3H, NCH3), 7.51-7.56 (m, 2H, H6, H8), 7.79-7.81 (m, 1H, H7), 8.44 (s, 1H, H2), 8.49-8.52 (m, 1H, H5). Anal. Calcd for C11H11NO3S: C 55.68, H 4.67, N 5.90, S 13.51. Found: C 55.80, H 4.41, N 6.02, S 13.87.
1-Ethyl-3-methanesulfonyl-4(1H)-quinolinone (6b):
mp 184-185 oC. MS (EI, 70 eV): m/z (%) = 251 (M+, 100), 187 (M-SO2, 77). 1H NMR (CDCl3), δ: 1.58 (t, J=7.2 Hz, 3H, CH2CH3), 3.36 (s, 3H, CH3), 4.32 (q, J=7.2 Hz, 2H, CH2CH3), 7.49–7.54 (m, 1H, H6), 7.51–7.56 (m, 1H, H8), 7.76–7.81 (m, 1H, H7), 8.46 (s, 1H, H2), 8.50–8.52 (m, 1H, H5). Anal. Calcd for C12H13NO3S: C 57.35, H 5.21, N 5.57, S 12.76. Found: C 57.67, H 5.26, N 5.69, S 13.03.
3-Methanesulfonyl-1-propyl-4(1H)-quinolinone (6c):
mp 167-169 oC. MS (EI, 70 eV): m/z (%) = 265 (M+, 100), 201 (M-SO2, 59). 1H NMR (CDCl3), δ: 1.06 (t, J=7.2 Hz, 3H, CH2CH2CH3), 1.92–2.00 (m, 2H, CH2CH2CH3), 3.37 (s, 3H, CH3), 4.20 (t, J=7.2 Hz, 2H, CH2CH2CH3), 7.50–7.55 (m, 2H, H6, H8), 7.75-7.80 (m, 1H, H7), 8.42 (s, 1H, H2), 8.50–8.53 (m, 1H, H5). Anal. Calcd for C13H15NO3S: C 58.85, H 5.70, N 5.28. Found: C 58.53, H 5.50, N 5.31.
3-Methanesulfonyl-1-(2-propyl)-4(1H)-quinolinone (6d):
mp 198-199 oC. MS (EI, 70 eV): m/z (%) = 265 (M+,100), 201 (M-SO2, 48). 1H NMR (CDCl3), δ: 1.64 (d, J=6.4 Hz, 6H, (CH3)2), 3.38 (s, 3H, CH3), 4.95–5.01 (m, 1H, CH(CH3)2), 7.50–7.53 (m, 1H, H6), 7.66–7.68 (m, 1H, H8), 7.77–7.81 (m, 1H, H7), 8.53–8.56 (m, 1H, H5), 8.58 (s, 1H, H2). Anal. Calcd for C13H15NO3S: C 58.85, H 5.70, N 5.28. Found: C 58.71, H 5.90, N 5.42.
3-Methanesulfonyl-1-methylthiomethyl-4(1H)-quinolinone (6e):
mp 223-224 oC. MS (EI, 70 eV): m/z (%) = 283 (M+, 48), 236 (M-SO2, 100). 1H NMR (CDCl3), δ: 2.23 (s, 3H, SCH3), 3.37 (s, 3H, SO2CH3), 5.24 (s, 2H, CH2SCH3), 7.53–7.57 (m, 1H, H6), 7.58–7.61 (m, 1H, H8), 7.78–7.82 (m, 1H, H7), 8.47 (s, 1H, H2), 8.50–8.52 (m, 1H, H5). Anal. Calcd for C12H13NO3S2: C 50.87, H 4.62, N 4.94, S 22.63. Found: C 51.03, H 4.40, N 4.80, S 22.03.
3-Ethanesulfonyl-1-methyl-4(1H)-quinolinone (6f):
mp 157-159 oC. MS (EI, 70 eV): m/z (%) = 251 (M+, 17) 158 (M- SO2CH2CH3, 100). 1H NMR (CDCl3) δ: 1.41 (t, J=7.3 Hz, 3H CH2CH3), 3.65 (q, J=7.3 Hz, 2H, CH2 CH3), 3.94 (s, 3H, CH3), 7.51-7.54 (m, 2H, H6, H8), 7.78-7.81 (m,1H, H7), 8.39 (s, 1H, H2), 8.46-8.47 (m, 1H, H5). Anal. Calcd for C12H13NO3S: C 57.35, H 5.21, N 5.57, S 12.76. Found: C 57.16, H 5.10, N 5.65, S 12.97.
3-Ethanesulfonyl-1-ethyl-4(1H)-quinolinone (6g):
mp 116-118 oC. MS (CI, 70 eV): m/z (%) = 265 (M+ +1, 100).1H NMR (CDCl3), δ: 1.29 (t, J= 7,4 Hz, 3H, SO2CH2CH3), 1.57 (t, J=7.3 Hz, 3H, NCH2CH3), 3.58 (q, J= 7,4 Hz, 2H, SO2CH2CH3), 4.32 (q, J=7.3 Hz, 2H, NCH2CH3), 7.49-7.55 (m, 2H, H6, H8), 7.77-7.80 (m,1H, H7), 8.42 (s, 1H, H2), 8.49-8.50 (m, 1H, H5). Anal. Calcd for C13H15NO3S: C 58.85, H 5.70 ,N 5.28, S 12.08. Found: C 58.57, H 5.56, N 5.33, S 12.00.
3-(1-Propanesulfonyl)-1-methyl-4(1H)-quinolinone (6h):
mp 141-142 oC. MS (EI, 70 eV): m/z (%) = 265 (M+, 1.2), 159 (M- SO2CH2CH2CH3, 100). 1H NMR (CDCl3), δ: 1.01 (t, J=7,4 Hz, 3H, CH2CH2CH3), 1.71-1.79 (m, 2H, CH2CH2CH3), 3.48-3.51 (m, 2H, CH2CH2CH3), 3.93 (s, 3H, CH3), 7.48-7.51 (m, 2H, H6, H8), 7.76-7.79 (m, 1H, H7), 8.39 (s, 1H, H2), 8.41-8.43 (m, 1H, H5). Anal. Calcd for C13H15NO3S: C 58.85, H 5.70, N 5.28. Found: C 58.63, H 5.40, N 5.29.
1-Ethyl-3-(1-propanesulfonyl)-4(1H)-quinolinone (6i):
mp 66–69 oC. MS (CI, 70 eV): m/z (%) = 279 (M+ +1, 100). 1H NMR (CDCl3) δ: 1.04 (t, J=7.4 Hz, 3H, CH2CH2CH3), 1.57 (t, J=7,3 Hz, 3H2, 3H, CH2-CH3), 1.75-1.81 (m, 2H, CH2CH2CH3), 3 52-3.55 (m, 2H, CH2CH2CH3), 4 31 (t, J=7.3 Hz, 2H, CH2CH3), 7.50-7.55 (m, 2H, H6, H8), 7.77-7.80 (m,1H, H7), 8.42 (s, 1H, H2), 8.49-8.51 (m, 1H, H5). Anal. Calcd for C14H17NO3S: C 60.19, H 6.13, N 5.01. Found: C 60.33, H 6.29, N 4.88.
1-Hexyl-3-methanesulfonyl-4(1H)-quinolinone (6j):
mp 83-84 oC. MS (EI, 70 eV): m/z (%) = 307 (M+, 100). 1H NMR (CDCl3), δ: 0.82 (t, J=7.6 Hz, 3H, CH3), 1.25-1.47 (m, 8H, (CH2)4), 3.34 (s, 3H, SO2CH3), 4.02 (t, J=7.6 Hz, 2H, NCH2), 7.47-7.52 (m, 2H, H6, H8), 7.74-7.78 (m, 1H, H7), 8.40 (s, 1H, H2), 8.47-8.50 (m, 1H, H5). Anal. Calcd for C16H21NO3S: C 62.52, H 6.89, N 4.56. Found: C 62.70, H 7.11, N 4.60.

X-Ray structure analysis
The diffraction data were collected with a KappaApexII diffractometer using graphite monochromated Mo Kα radiation. The structure was solved and refined using the programs SHELXS14 and SHELXL15 respectively. Crystals of 1,4-dihydro-4-oxo-3-(1-propanesulfonyl)quinoline (5c) were obtained by slow evaporation of aqueous ethanol solution at room temperature. Crystal data for 5c: C12H13NO3S, M = 251.29, crystal size 0.50 x 0.35 x 0.10 mm, monoclinic, space group P21/c (No. 14), a = 12.0856(7), b = 7.6792(5), c = 12.4887(5) Å, β = 98.846(4)°, V = 1145.3(1) Å3, Z = 4, Dc = 1.457 g/cm3, F000 = 528, MoKα radiation, λ= 0.71073 Å, T = 100(2)K, 2θ max = 55.0º, 8985 reflections collected, 2548 unique (Rint = 0.034). Final GooF = 1.12, R = 0.067, wR = 0.1367, R indices based on 2027 reflections with I > 2σ(I) (refinement on F2), 159 parameters, 0 restraints. Lp and absorption corrections applied, µ = 0.278 mm-1.
Crystallographic data for compound 5c have been deposited with Cambridge Crystallographic Data Centre (CCDC deposition number 805112). Copies of the data can be obtained upon request from CCDC, 12 Union road, Cambridge CB2 1EZ, UK).

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