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5H), 3.01–2.89 (m, 2H), 2.88–2.67 (m, 2H), 2.39 (s, 3H), 2.16 (s,
3H); 13C NMR (CDCl3, 50 MHz) d (ppm) 207.5, 144.8, 135.2,
135.1, 130.6, 129.8 (2C), 126.7 (2C), 124.7, 123.0, 122.7, 121.9,
119.3, 113.7, 42.6, 38.0, 21.5, 18.7; FTIR nmax/cmꢁ1 3106, 2921,
1706, 1370, 1169, 1129, 752, 702, 607, 534; m/z (E/I): 341 (M+,
100%), 298 (45), 284 (48), 186 (25), 155 (47), 144 (77), 115 (16), 91
(49), 65 (139). Found: C, 66.68; H, 5.87; N, 4.15. Calc. for
4-(3,5-Dibromo-4-methoxyphenyl)butan-2-one (4e). Accord-
ing to general procedure the crude ketone was puried by
chromatography using a diethyl ether–hexane mixture (1 : 9) as
1
eluent to give 4e. Yield: 53 mg (79%); colourless oil. H NMR
(CDCl3, 200 MHz) d (ppm) 7.32 (s, 2H), 3.85 (s, 3H), 2.90–2.65
(m, 4H), 2.16 (s, 3H); 13C NMR (CDCl3, 100 MHz) d (ppm) 206.9,
152.3, 139.8, 132.5 (2C), 117.9 (2C), 60.5, 44.5, 30.0, 28.1; FTIR
nmax/cmꢁ1 2928, 1773, 1422, 1259, 993, 737; m/z (E/I): 336 (M+,
100%), 278 (87), 266 (18), 214 (42), 185 (11), 118 (11). Found: C,
39.37; H, 3.84. Calc. for C11H12Br2O2: C, 39.32; H, 3.60.
C
19H19NO3S: C, 66.84; H, 5.61; N, 4.10.
4-[4-(Allyloxy)-3-methoxyphenyl]butan-2-one (4k). According
to general procedure the crude ketone was puried by chro-
matography using a diethyl ether–dichloromethane mixture
(1 : 99) as eluent to give 4k. Yield: 54 mg (78%); colourless oil.
1H NMR (200 MHz, CDCl3) d (ppm) 6.79 (d, J ¼ 8.1 Hz, 1H), 6.71
(d, J ¼ 2.0 Hz, 1H), 6.68 (dd, J ¼ 8.1, 2.0 Hz, 1H), 6.13–6.01 (m,
1H), 5.38 (dq, J ¼ 17.3, 1.5 Hz, 1H), 5.26 (dq, J ¼ 10.5, 1.5 Hz,
1H), 4.58 (dt, J ¼ 5.4, 1.5 Hz, 2H), 3.85 (s, 3H), 2.88–2.79 (m, 2H),
2.78–2.70 (m, 2H), 2.13 (s, 3H); 13C NMR (CDCl3, 50 MHz)
d (ppm) 208.1, 149.3, 146.2, 134.0, 133.4, 119.9, 117.8, 113.5,
111.9, 69.9, 55.8, 45.3, 30.1, 29.3; FTIR nmax/cmꢁ1 2925, 1713,
1512, 1139, 1020, 803; m/z (E/I): 234 (M+, 88%), 193 (100), 161
(25), 151 (15), 133 (61), 119 (79), 102 (21), 91 (36), 77 (21). Found:
C, 71.22; H, 7.84. Calc. for C14H18O3: C, 71.37; H, 7.74.
4-(4-Isocyanophenyl)butan-2-one (4f). According to general
procedure the crude ketone was puried by chromatography
using a diethyl ether–hexane mixture (4 : 6) as eluent to give 4f.
1
ꢀ
Yield: 47 mg (90%); light yellow solid, mp 44–46 C. H NMR
(CDCl3, 200 MHz) d (ppm) 7.55 (d, J ¼ 8.1 Hz, 2H), 7.29 (d, J ¼
8.1 Hz, 2H), 3.04–2.86 (m, 2H), 2.85–2.68 (m, 2H), 2.15 (s, 3H);
13C NMR (CDCl3, 50 MHz) d (ppm) 206.8, 146.7, 132.1 (2C),
129.1 (2C), 118.9, 109.8, 44.0, 29.9, 29.4; FTIR nmax/cmꢁ1 2962,
2228, 1708, 1376, 1167, 827, 560; m/z (E/I): 173 (M+, 100%), 130
(96), 116 (51), 103 (32), 89 (21), 77 (19). Found: C, 76.01; H,
6.60; N, 7.97. Calc. for C11H11NO: C, 76.28; H, 6.40; N, 8.09.
4-(3-Nitrophenyl)butan-2-one (4g).35 According to general
procedure the crude ketone was puried by chromatography
using an ethyl acetate–hexane mixture (4 : 6) as eluent to give
4g. Yield: 60 mg (78%). 1H NMR (CDCl3, 200 MHz) d (ppm) 8.13–
7.95 (m, 2H), 7.62–7.3 (m, 2H), 3.06–2.92 (m, 2H), 2.90–2.78 (m,
2H), 2.17 (s, 3H).
4-[4-(Benzyloxy)-3-methoxyphenyl]butan-2-one (4l). Accord-
ing to general procedure the crude ketone was puried by
chromatography using
a
diethyl ether–dichloromethane
mixture (1 : 99) as eluent to give the known36 ketone 4l. Yield:
40 mg (71%). 1H NMR (CDCl3, 400 MHz) d (ppm) 7.46–7.40 (m,
2H), 7.39–7.33 (m, 2H), 7.32–7.26 (m, 1H), 6.79 (d, J ¼ 8.1 Hz,
1H), 6.74 (d, J ¼ 2.0 Hz, 1H), 6.65 (dd, J ¼ 8.1, 2.0 Hz, 1H), 5.13
(s, 2H), 3.88 (s, 3H), 2.87–2.79 (m, 2H), 2.77–2.71 (m, 2H), 2.13
(s, 3H); 13C NMR (CDCl3, 100 MHz) d (ppm) 208.2, 149.5, 146.4,
137.3, 134.2, 128.5, 127.7, 127.2, 120.0, 114.1, 112.1, 71.1, 55.9,
45.3, 30.1, 29.3.
4-(2-Phenyl-1,3-thiazol-4-yl)butan-2-one (4h). According to
general procedure the crude ketone was puried by chroma-
tography using a diethyl ether–hexane mixture (4 : 6) as eluent
1
to give 4h. Yield: 40 mg (86%); colourless oil. H NMR (CDCl3,
200 MHz) d (ppm) 8.01–7.82 (m, 2H), 7.50–7.37 (m, 3H), 6.92 (s,
1H), 3.28–3.01 (m, 2H), 3.00–2.85 (m, 2H), 2.19 (s, 3H); 13C NMR
(CDCl3, 50 MHz) d (ppm) 207.9, 167.8, 156.6, 133.6, 129.9, 128.9
(2C), 126.4 (2C), 113.7, 42.8, 30.0, 25.5; FTIR nmax/cmꢁ1 2918,
1713, 1356, 1159, 1003, 764, 690; m/z (E/I): 231 (M+, 6%), 188
(100), 158 (12), 78 (20). Found: C, 67.39; H, 5.91; N, 5.90. Calc.
for C13H13NOS: C, 67.50; H, 5.66; N, 6.06.
2-Benzylcyclopentanone (4m).28 According to general proce-
dure the crude ketone was puried by chromatography using
a diethyl ether–hexane mixture (3 : 97) as eluent to give the
commercially available ketone 4m. Yield: 38 mg (66%).
4-(1-Benzothien-2-yl)butan-2-one (4i). According to general
procedure the crude ketone was puried by chromatography
using a diethyl ether–hexane mixture (2 : 8) as eluent to give 4i.
Two steps synthesis of zingerone 7.19
To a solution of vanillin (0.5 g, 3.3 mmol) in 2 mL of acetone was
added gradually 2.5 M aqueous sodium hydroxide (2 mL) at
room temperature. The mixture was stirred for 48 h and then
diluted with 2.0 M aqueous hydrochloric acid (5 mL) and EtOAc
(10 mL). The organic and aqueous layers were separated, and
the aqueous layer was extracted with EtOAc (3ꢂ 20 mL). The
combined extracts were washed with brine (10 mL), dried
(MgSO4), ltrated and concentrated in vacuo. Purication by
silica gel column chromatography using an ethyl ether–hexane
mixture (6 : 4) as eluent afforded the known20 (3E)-4-(4-hydroxy-
3-methoxyphenyl)but-3-en-2-one (6) intermediate (0.56 g, 89%
yield). m/z (E/I): 192 (M+, 92%), 177 (100), 145 (81), 117 (37), 89
(26), 77 (18).
1
Yield: 36 mg (85%); colourless oil. H NMR (CDCl3, 200 MHz)
d (ppm) 7.77 (dd, J ¼ 6.9, 1.6 Hz, 1H), 7.68 (dd, J ¼ 6.6, 2.1 Hz,
2H), 7.38–7.21 (m, 2H), 7.03 (s, 1H), 3.20 (t, J ¼ 7.2 Hz, 2H), 2.89
(t, J ¼ 7.2 Hz, 2H), 2.19 (s, 3H); 13C NMR (CDCl3, 50 MHz)
d (ppm) 207.0, 144.6, 140.0, 139.2, 124.2, 123.6, 122.8, 122.1,
121.1, 44.5, 30.1, 24.6; FTIR nmax/cmꢁ1 2914, 1712, 1354, 1097,
813, 749, 484; m/z (E/I): 204 (M+, 51%), 161 (100), 147 (59), 128
(20), 115 (12). Found: C, 70.45; H, 5.90. Calc. for C12H12OS: C,
70.55; H, 5.92.
4-{1-[(4-Methylphenyl)sulfonyl]-1H-indol-3-yl}butan-2-one
(4j). According to general procedure the crude ketone was
puried by chromatography using a diethyl ether–hexane
mixture (4 : 6) as eluent to give 4j. Yield: 64 mg (91%); colourless
oil. 1H NMR (CDCl3, 200 MHz) d (ppm) 7.98 (d, J ¼ 8.3 Hz, 1H),
7.74 (d, J ¼ 8.4 Hz, 2H), 7.48 (d, J ¼ 8.3 Hz, 1H), 7.37–7.13 (m,
Then compound 6 (0.3 mmol) was reduced as reported above
for other arylidene acetones. Aer 7 h the mixture was cooling
down and water (10 mL) was added. The mixture was extracted
with three 10 mL portions of EtOAc. The combined extracts were
33714 | RSC Adv., 2020, 10, 33706–33717
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