RSC Advances
Paper
d 8.38–8.35 (m, 2H), 8.16–8.14 (m, 2H), 7.88 (d, J ¼ 15.6 Hz, 1H),
6.95 (d, J ¼ 15.6 Hz, 1H), 3.87 (s, 3H); HRMS (ESI) m/z calcd for
(E)-Ethyl 4-(4-ethoxyphenyl)-4-oxobut-2-enoate (9d). Yellow
solid (40%), mp: 54.4–55.7 ꢁC. 1H NMR (400 MHz, CDCl3)
d 8.03–7.97 (m, 2H), 7.92 (d, J ¼ 15.6 Hz, 1H), 6.99–6.93 (m, 2H),
6.87 (d, J ¼ 15.6 Hz, 1H), 4.30 (q, J ¼ 7.2 Hz, 2H), 4.13 (q, J ¼
C
22H17N2O10 [2M ꢀ H] 469.0883, found 469.0875 [2M ꢀ H].
(E)-Methyl 4-(4-bromophenyl)-4-oxobut-2-enoate (8p). Yellow
solid (46%). Mp: 77.8–79.0 ꢁC. 1H NMR (400 MHz, CDCl3) d 7.87
(d, J ¼ 15.6 Hz, 1H), 7.87–7.85 (m, 2H), 7.67–7.65 (m, 2H), 6.90
(d, J ¼ 15.6 Hz, 1H), 3.85 (s, 3H); 13C NMR (125 MHz, DMSO-d6)
d 188.50, 165.33, 136.60, 135.01, 132.12, 131.50, 130.84, 128.36,
52.27; HRMS (ESI) m/z calcd for C11H9BrO3Na [M + Na]
290.9633, found 290.9616 [M + Na].
6.8 Hz, 2H), 1.46 (t, J ¼ 6.8 Hz, 3H), 1.35 (t, J ¼ 7.2 Hz, 3H); 13
C
NMR (125 MHz, DMSO-d6) d 187.15, 165.02, 163.28, 136.90,
131.40, 130.88, 128.84, 114.72, 63.75, 60.94, 14.44, 14.02; HRMS
(ESI) m/z calcd for C14H16O4Na [M + Na] 271.0946, found
271.0953 [M + Na].
(E)-Ethyl 4-(2-methoxyphenyl)-4-oxobut-2-enoate (9e). Yellow
1
solid (41%), mp: 50.1–51.5 ꢁC. H NMR (500 MHz, DMSO-d6)
(E)-Methyl 4-(furan-2-yl)-4-oxobut-2-enoate (8q). Yellow solid
(44%). Mp: 90.7–92.8 ꢁC. 1H NMR (400 MHz, CDCl3) d 7.77 (d, J
¼ 15.6 Hz, 1H), 7.70–7.69 (m, 1H), 7.39–7.38 (m, 1H), 6.99 (d, J ¼
15.6 Hz, 1H), 6.63–6.62 (m, 1H), 3.85 (s, 3H); 13C NMR (125
MHz, DMSO-d6) d 175.46, 165.27, 151.97, 149.73, 136.10, 130.72,
121.68, 113.29, 52.24; HRMS (ESI) m/z calcd for C9H7O4 [M ꢀ H]
179.0362, found 179.0350 [M ꢀ H].
d 7.66 (d, J ¼ 15.5 Hz, 1H), 7.64–7.57 (m, 2H), 7.24–7.22 (m, 1H),
7.10–7.07 (m, 1H), 6.57 (d, J ¼ 15.5 Hz, 1H), 4.22 (q, J ¼ 7.0 Hz,
2H), 1.26 (t, J ¼ 7.0 Hz, 3H); 13C NMR (125 MHz, DMSO-d6)
d 190.62, 165.11, 158.65, 140.68, 134.76, 130.10, 129.32, 126.81,
120.83, 112.70, 60.91, 56.00, 13.97; HRMS (ESI) m/z calcd for
C
13H14O4Na [M + Na] 257.0790, found 257.0778 [M + Na].
(E)-Methyl 4-oxopent-2-enoate (8r). White solid (41%). Mp:
61.9–63.2 ꢁC. 1H NMR (400 MHz, CDCl3) d 7.02 (d, J ¼ 16.0 Hz,
1H), 6.65 (d, J ¼ 16.0 Hz, 1H), 3.81 (s, 3H), 2.35 (s, 3H); HRMS
(ESI) m/z calcd for C6H7O3 [M ꢀ H] 127.0412, found 127.0392 [M
ꢀ H].
(E)-Ethyl 4-(3-methoxyphenyl)-4-oxobut-2-enoate (9f). Yellow oil
(40%). 1H NMR (500 MHz, DMSO-d6) d 7.93 (d, J ¼ 15.5 Hz, 1H),
7.68–7.62 (m, 1H), 7.55–7.47 (m, 2H), 7.30–7.28 (m, 1H), 6.73 (d,
J ¼ 15.5 Hz, 1H), 4.25 (q, J ¼ 7.0 Hz, 2H), 3.85 (s, 3H), 1.28 (t, J ¼
7.0 Hz, 3H); 13C NMR (125 MHz, DMSO-d6) d 188.99, 164.88,
159.61, 137.42, 136.74, 131.65, 130.22, 121.52, 120.32, 112.82,
61.00, 55.39, 13.98; HRMS (ESI) m/z calcd for C13H14O4Na [M +
Na] 257.0790, found 257.0793 [M + Na].
(E)-Methyl 4-cyclohexyl-4-oxobut-2-enoate (8s). White solid
(43%). Mp: 52.3–54.6 ꢁC. 1H NMR (400 MHz, CDCl3) d 7.19 (d, J
¼ 16.0 Hz, 1H), 6.71 (d, J ¼ 16.0 Hz, 1H), 3.81 (s, 3H), 2.61–2.55
(m, 1H), 1.89–1.68 (m, 5H), 1.42–1.17 (m, 5H); 13C NMR (125
MHz, DMSO-d6) d 202.32, 165.59, 138.83, 129.68, 52.19, 47.97,
27.68, 25.37, 24.88; HRMS (ESI) m/z calcd for C11H16O3Na [M +
Na] 219.0997, found 219.1006 [M + Na].
(E)-Ethyl
4-(2,5-dimethoxyphenyl)-4-oxobut-2-enoate
(9g).
Yellow solid (42%). Mp: 66.2–67.5 ꢁC. 1H NMR (500 MHz,
DMSO-d6) d 7.68 (d, J ¼ 15.5 Hz, 1H), 7.22–7.17 (m, 2H), 7.11–
7.10 (m, 1H), 6.57 (d, J ¼ 15.5 Hz, 1H), 4.22 (q, J ¼ 7.0 Hz, 2H),
3.84 (s, 3H), 3.75 (s, 3H), 1.26 (t, J ¼ 7.0 Hz, 3H); 13C NMR (125
MHz, DMSO-d6) d 190.18, 165.10, 153.15, 153.02, 140.61, 129.35,
127.08, 120.76, 114.33, 113.77, 60.90, 56.46, 55.57, 13.96; HRMS
(ESI) m/z calcd for C14H16O5Na [M + Na] 287.0895, found
287.0895 [M + Na].
(E)-Methyl 4-cyclopropyl-4-oxobut-2-enoate (8t). Yellow oil
(37%). 1H NMR (400 MHz, DMSO-d6) d 7.13 (d, J ¼ 16.0 Hz, 1H),
6.79 (d, J ¼ 16.0 Hz, 1H), 3.76 (s, 3H), 2.56–2.51 (m, 1H), 1.06–
0.95 (m, 4H); 13C NMR (125 MHz, DMSO-d6) d 199.42, 165.61,
139.62, 129.80, 52.15, 19.44, 11.76; HRMS (ESI) m/z calcd for
C8H10O3Na [M + Na] 177.0528, found 177.0520 [M + Na].
(E)-Ethyl 4-(4-methoxyphenyl)-4-oxobut-2-enoate (9a). Yellow
(E)-Ethyl
4-(3,4-dimethoxyphenyl)-4-oxobut-2-enoate
(9h).
Yellow solid (43%). Mp: 92.6–94.7 ꢁC. 1H NMR (400 MHz,
DMSO-d6) d 8.00 (d, J ¼ 15.6 Hz, 1H), 7.79–7.77 (m, 1H), 7.52–
7.51 (m, 1H), 7.13–7.10 (m, 1H), 6.72 (d, J ¼ 15.6 Hz, 1H), 4.24 (q,
J ¼ 7.2 Hz, 2H), 3.88 (s, 3H), 3.84 (s, 3H), 1.28 (t, J ¼ 7.2 Hz, 3H);
13C NMR (125 MHz, DMSO-d6) d 187.09, 165.06, 154.08, 149.04,
136.75, 130.93, 129.04, 124.38, 111.01, 110.41, 60.95, 55.89,
55.57, 14.03; HRMS (ESI) m/z calcd for C14H16O5Na [M + Na]
287.0895, found 287.0878 [M + Na].
1
solid (46%), mp: 41.2–42.7 ꢁC. H NMR (500 MHz, DMSO-d6)
d 8.06–8.05 (m, 2H), 7.99 (d, J ¼ 15.5 Hz, 1H), 7.11–7.10 (m, 2H),
7.05–7.03 (m, 1H), 6.69 (d, J ¼ 15.5 Hz, 1H), 4.18–4.16 (m, 2H),
3.88 (s, 3H), 3.28–3.24 (m, 2H), 1.37 (s, 9H); 13C NMR (125 MHz,
DMSO-d6) d 187.14, 165.00, 163.95, 136.81, 131.36, 130.91,
129.00, 114.33, 60.93, 55.66, 13.99; HRMS (ESI) m/z calcd for
C
13H14O4Na [M + Na] 257.0790, found 257.0792 [M + Na].
(E)-Ethyl 4-oxo-4-phenylbut-2-enoate (9b). Yellow oil (46%). H
1
(E)-Ethyl 4-(benzo[d][1,3] dioxol-5-yl)-4-oxobut-2-enoate (9i).
Yellow solid (45%). Mp: 90.8–93.0 ꢁC. 1H NMR (500 MHz,
DMSO-d6) d 7.93 (d, J ¼ 15.5 Hz, 1H), 7.75–7.73 (m, 1H), 7.51–
7.50 (m, 1H), 7.09–7.08 (m, 1H), 6.69 (d, J ¼ 15.5 Hz, 1H), 6.18 (s,
2H), 4.24 (q, J ¼ 7.0 Hz, 2H), 1.28 (t, J ¼ 7.0 Hz, 3H); 13C NMR
(125 MHz, DMSO-d6) d 186.88, 164.97, 152.45, 148.29, 136.74,
131.12, 130.79, 126.22, 108.30, 107.64, 102.36, 60.95, 14.01; MS-
ESI (m/z): 249.13 [M + Na].
(E)-Ethyl 4-(2,3-dihydrobenzofuran-5-yl)-4-oxobut-2-enoate (9j).
Yellow solid (44%). Mp: 57.7–59.4 ꢁC. 1H NMR (500 MHz,
DMSO-d6) d 7.96–7.89 (m, 3H), 6.92–6.90 (m, 1H), 6.69 (d, J ¼
15.5 Hz, 1H), 4.67 (t, J ¼ 9.0 Hz, 2H), 4.24 (q, J ¼ 7.0 Hz, 2H), 3.26
(t, J ¼ 9.0 Hz, 2H), 1.28 (t, J ¼ 7.0 Hz, 3H); 13C NMR (125 MHz,
NMR (500 MHz, DMSO-d6) d 8.05–8.03 (m, 2H), 7.95 (d, J ¼
15.5 Hz, 1H), 7.75–7.69 (m, 1H), 7.63–7.56 (m, 2H), 6.73 (d, J ¼
15.5 Hz, 1H), 4.25 (q, J ¼ 7.0 Hz, 2H), 1.28 (t, J ¼ 7.0 Hz, 3H); 13
C
NMR (125 MHz, DMSO-d6) d 189.15, 164.85, 136.64, 136.02,
134.01, 131.57, 128.99, 128.78, 60.98, 13.95; HRMS (ESI) m/z calcd
for C11H10O3Na [M + Na] 213.0528, found 213.0538 [M + Na].
(E)-Ethyl 4-oxo-4-(p-tolyl) but-2-enoate (9c). Yellow oil (43%).
1H NMR (500 MHz, DMSO-d6) d 7.96–7.92 (m, 3H), 7.40–7.38 (m,
2H), 6.71 (d, J ¼ 15.5 Hz, 1H), 4.25 (q, J ¼ 7.0 Hz, 2H), 2.41 (s,
3H), 1.28 (t, J ¼ 7.0 Hz, 3H); 13C NMR (125 MHz, DMSO-d6)
d 188.51, 164.92, 144.77, 136.74, 133.58, 131.30, 129.60, 128.96,
60.97, 21.23, 13.98; HRMS (ESI) m/z calcd for C13H14O3Na [M +
Na] 241.0841, found 241.0840 [M + Na].
4770 | RSC Adv., 2017, 7, 4763–4775
This journal is © The Royal Society of Chemistry 2017