General Papers
ARKIVOC 2016 (vi) 79-91
Me), 4.16 (1H, d, J HH 4.00 Hz, H3), 5.64 (1H, s, NH), 6.47 (1H, d, JHH 4.10 Hz, H2), 7.00
(1H, t, JHH 4.52 Hz, thiophene CH), 7.08 (1H, d, JHH 3.15 Hz, thiophene CH), 7.15 (1H, s,
NH), 7.30 (1H, d, J 5.09 Hz, thiophene CH); 13C NMR (100 MHz, CDCl3): δ C 16.5 (Me),
29.5 (Me), 55.7 (C3), 80.8 (C2), 114.0 (C4), 125.9, 126.2, 127.1, 142.5, 169.5 (C5), 172.9
(C=O), 194.6 (C=O); HRMS (ESI+): m/z (M+H)+ calcd for C12H14NO3S: 252.06889; found:
252.06908.
trans-6,6-Dimethyl-2-(5-methylfuran-2-yl)-4-oxo-2,3,4,5,6,7-hexahydro-1-benzofuran-3-
carboxamide (7i). Yellow solid, yield 80%, 231 mg, mp 143-145 °C; IR (νmax, cm-1): 621, 665,
781, 879, 1020, 1070, 1251, 1388, 1591 (C=C), 1614 (C=O), 1683 (C=O), 2920, 2964, 3175,
1
3383; H NMR (400 MHz, CDCl3): δH 1.11 (6H, s, Me), 2.26 (3H, s, Me), 2.32 (2H, d, JHH
1.60 Hz, H5), 2.35 (2H, d, JHH 1.20 Hz, H7), 4.25 (1H, d, JHH 6.0 Hz, H3), 5.53 (1H, s, NH),
5.94 (1H, dq, JHH 3.60, 0.40 Hz, furan CH), 6.34 (1H, d, JHH 3.2 Hz, furan CH), 6.35 (1H, d,
JHH 6.0 Hz, H2), 7.84 (1H, s, NH); 13C NMR (100 MHz, CDCl3): δC 13.9, 28.6, 28.8, 34.5,
38.3, 48.7, 51.1 (C3), 81.3 (C2), 106.9, 110.3, 111.0, 149.2, 154.1, 171.9 (C7a), 178.2 (C=O),
196.2 (C=O); HRMS (ESI+): m/z (M+H)+ calcd for C16H20NO4: 290.13868; found: 290.13923.
Ethyl
trans-3-carbamoyl-5,5'-dimethyl-2,3-dihydro-[2,2'-bifuran]-4-carboxylate
(7j).
Yellow solid, yield 67%, 186 mg, mp 133-135 °C; IR (νmax, cm-1): 653, 796, 962, 1124, 1217,
1
1319, 1381, 1635 (C=C), 1654 (C=O), 1678 (C=O), 2918, 2985, 3165, 3352; H NMR (400
MHz, CDCl3): δH 1.32 (3H, t, JHH 7.20 Hz, Me), 2.23 (3H, s, Me), 2.27 (3H, s, 5.84 (1H, s,
NH), Me), 4.14 (1H, d, JHH 5.60 Hz, H3´),4.23 (2H, q, JHH 7.20 Hz, –OCH2-),5.92 (1H, d,
JHH 3.20 Hz, furan CH), 6.08 (1H, d, JHH 5.60 Hz, H2´),6.28 (1H, d, JHH 3.20 Hz, furan CH),
13
6.95 (1H, s, NH); C NMR (100 MHz, CDCl3): δC 13.9 (Me), 14.6(Me), 15.3(Me), 52.1, 60.6,
78.6, 102.0, 106.7, 110.4, 149.8, 153.7, 166.8 (C=O), 169.8 (C5´), 173.3 (C=O); HRMS (ESI+):
m/z (M+Na)+ calcd for C14H17NO5Na: 302.09989; found: 302.10051.
trans-4-Acetyl-5,5'-dimethyl-2,3-dihydro-[2,2'-bifuran]-3-carboxamide (7k). Pale yellow
solid, yield 70%, 174 mg, mp 150-152 °C; IR (νmax, cm-1): 663, 796, 900, 943, 1213, 1392, 1595
1
(C=C), 1672 (C=O), 1681 (C=O), 2848, 2918, 3153, 3327; H NMR (400 MHz, CDCl3): δH
2.26 (3H, s, Me), 2.29 (3H, s, Me), 2.37 (3H, d, JHH 0.8 Hz, Me), 4.24 (1H, d, JHH 5.2 Hz,
H3´),5.70 (1H, s, NH), 5.91 (1H, dq, JHH 3.2, 0.8 Hz, furan CH), 6.11 (1H, d, JHH 5.2 Hz,
13
H2´),6.26 (1H, d, JHH 3.2 Hz, furan CH), 7.14 (1H, s, NH); C NMR (100 MHz, CDCl3): δC
13.9 (Me), 16.5 (Me), 29.6 (Me), 52.0, 78.4, 106.7, 110.5, 114.7, 149.6, 153.8, 169.9 (C5´),
173.1 (C=O), 194.5 (C=O); HRMS (ESI+): m/z (M+Na)+ calcd for C13H15NO4Na: 272.08932;
found: 272.08976.
trans-6,6-Dimethyl-4-oxo-2-(thiophen-3-yl)-2,3,4,5,6,7-hexahydrobenzofuran-3-
carboxamide (7l). Colorless solid, yield 36%, 104 mg, mp 148-150 °C; IR (νmax, cm-1): 700,
965, 1095, 1212, 1618 (C=C), 1675 (C=O), 1703 (C=O), 2920, 2983, 3194, 3362; 1H NMR (400
MHz, CDCl3): δH 1.14 (6H, s), 2.32 (2H, s), 2.42 (2H, s), 4.00 (1H, d, JHH 6.0 Hz, H3), 5.94
(1H, s, NH), 6.50 (1H, d, JHH 6.0 Hz, H2), 7.01 (1H, dd, JHH 4.8, 0.8 Hz, thiophene CH), 7.28
(1H, d, JHH 7.2 Hz, thiophene CH), 7.35 (1H, dd, JHH 5.2, 4.8 Hz, thiophene CH), 7.80 (1H, s,
NH); 13C NMR (100 MHz, CDCl3): δC 28.3, 28.6, 34.2, 38.1, 50.9, 51.8, 84.1, 109.6, 122.2,
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