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The Journal of Organic Chemistry
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60.2, 43.6, 34.4, 24.9, 14.5. HRMS (ESI) m/z calcd. for C13H20NO4 [M+H]+
254.1387, found 254.1384.
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Ethyl
5,5-dimethyl-2-oxo-4-(phenethylamino)-2,5-dihydrofuran-3-carboxylate
(3l). Following the same experimental procedure of 3a with 2l (28 mg, 0.25 mmol),
3c (69 mg, 91%, silica gel, petroleum ether : ethyl acetate = 2: 1, V/V) was obtained
as yellow liquid. 1H NMR (400 MHz, CDCl3) δ 8.77 (s, 1H), 7.34 (t, J = 7.2 Hz, 2H),
7.30 – 7.25 (m, 1H), 7.20 (d, J = 7.0 Hz, 2H), 4.30 (q, J = 7.1 Hz, 2H), 3.68 (q, J =
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6.8 Hz, 2H), 2.96 (t, J = 7.0 Hz, 2H), 1.51 (s, 6H), 1.35 (t, J = 7.1 Hz, 3H). C{1H}
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NMR (101 MHz, CDCl3) δ 179.2, 167.2, 166.5, 136.8, 129.0, 128.8, 127.3, 85.6,
79.1, 60.2, 46.1, 36.9, 24.8, 14.4. HRMS (ESI) m/z calcd. for C17H22NO4 [M+H]+
304.1543, found 304.1546.
Ethyl
4-(isobutylamino)-5,5-dimethyl-2-oxo-2,5-dihydrofuran-3-carboxylate
(3m). Following the same experimental procedure of 3a with 2m (18 mg, 0.25 mmol),
3m (55 mg, 87%, silica gel, petroleum ether : ethyl acetate = 2: 1, V/V) was obtained
as brown solid, m.p. 128–130 ºC. 1H NMR (400 MHz, CDCl3) δ 8.77 (s, 1H), 4.25 (q,
J = 7.1 Hz, 2H), 3.19 (t, J = 6.5 Hz, 2H), 1.85 (h, 1H), 1.56 (s, 6H), 1.30 (t, J = 7.1
Hz, 3H), 0.98 (d, J = 6.7 Hz, 6H); 13C{1H} NMR (101 MHz, CDCl3) δ 179.5, 167.3,
166.9, 85.3, 79.1, 60.2, 51.8, 29.3, 25.0, 19.8, 14.5. HRMS (ESI) m/z calcd. for
C13H22NO4 [M+H]+ 256.1543, found 256.1541.
Ethyl 5,5-dimethyl-2-oxo-4-(phenylamino)-2,5-dihydrofuran-3-carboxylate (3n).
Following the same experimental procedure of 3a with 2n (23 mg, 0.25 mmol) in 3
day reaction time, 3n (40 mg, 58%, silica gel, petroleum ether : ethyl acetate = 4: 1,
V/V) was obtained as brown solid, m.p. 119–121 ºC. 1H NMR (400 MHz, CDCl3) δ
10.26 (s, 1H), 7.47 – 7.43 (m, 3H), 7.32 – 7.29 (m, 2H), 4.37 (q, J = 7.1 Hz, 2H), 1.40
(t, J = 7.1 Hz, 3H), 1.36 (s, 6H). 13C{1H} NMR (101 MHz, CDCl3) δ 179.2, 167.1,
166.7, 135.8, 87.2, 80.4, 60.6, 26.0, 14.5. HRMS (ESI) m/z calcd. for C15H18NO4
[M+H]+ 276.1230, found 276.1232.
Ethyl
4-((4-methoxyphenyl)amino)-5,5-dimethyl-2-oxo-2,5-dihydrofuran-3-
Carboxylate (3o). Following the same experimental procedure of 3a with 2o (31 mg,
0.25 mmol) in 3 day reaction time, 3o (47 mg, 61%, silica gel, petroleum ether : ethyl
acetate = 4: 1, V/V) was obtained as brown solid, m.p. 156–158 ºC. 1H NMR (400
MHz, CDCl3) δ 10.10 (s, 1H), 7.21 (d, J = 8.7 Hz, 2H), 6.92 (d, J = 8.9 Hz, 2H), 4.36
(q, J = 7.1 Hz, 2H), 3.85 (s, 3H), 1.39 (t, J = 7.1 Hz, 3H), 1.36 (s, 6H). 13C{1H} NMR
(101 MHz, CDCl3) δ 179.7, 167.1, 166.7, 159.9, 130.1, 128.1, 114.3, 87.0, 80.4, 60.5,
55.6, 26.0, 14.5. HRMS (ESI) m/z calcd. for C16H20NO5 [M+H]+ 306.1336, found
306.1336.
Ethyl
4-((2-bromophenyl)amino)-5,5-dimethyl-2-oxo-2,5-dihydrofuran-3-carboxylate (3p).
Following the same experimental procedure of 3a with 2p (43 mg, 0.25 mmol) in 3
day reaction time, 3p (55 mg, 62%, silica gel, petroleum ether : ethyl acetate = 4: 1,
V/V) was obtained as yellow solid, m.p. 118–120 ºC. H NMR (400 MHz, CDCl3) δ
10.12 (s, 1H), 7.71 (d, J = 7.8 Hz, 1H), 7.43 (d, J = 4.1 Hz, 2H), 7.37 – 7.30 (m, 1H),
4.39 (q, J = 7.1 Hz, 2H), 1.41 (t, J = 7.1 Hz, 3H), 1.37 (s, 6H). C{1H} NMR (101
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MHz, CDCl3) δ 179.1, 166.9, 166.4, 135.4, 133.6, 131.0, 130.7, 128.1, 124.3, 88.5,
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