NMR (75 MHz, CDCl3) d 176.4, 168.3, 136.8, 135.8, 133.0, 128.6,
126.6, 126.4, 89.5, 84.1, 65.1, 30.5, 30.2; MS (ESI) m/z: 321 (M +
H)+. HRMS: calcd for C21H21O3 321.1491; found 321.1497.
8.3 Hz, 1H), 6.91 (dd, J = 1.5, 8.3 Hz, 1H), 6.19 (s, 1H), 5.16 (s,
2H), 3.84 (s, 2H), 2.40 (s, 3H); 13C NMR (75 MHz, CDCl3) d 170.4,
135.3, 134.6, 130.3, 128.7, 123.7, 120.2, 110.4, 101.5, 67.1, 33.9,
21.4; MS (ESI) m/z: 280 (M + H)+. HRMS: calcd for C18H18NO2
280.1334; found 280.1330.
(E)-Ethyl 2-((4S,5S)-4-hydroxy-5-phenyldihydrofuran-2(3H)-
ylidene)acetate (3d)
◦
Yield (220 mg, 89%); White solid; m.p. 78–81 C; [a]2D4 = +7.5
(S,E)-Benzyl 2-(4-(tert-butoxycarbonylamino)dihydrofuran-
2(3H)-ylidene)acetate (3i)
(c = 0.04, CHCl3); IR (KBr): 3364, 2092, 1685, 1521, 1163, 750,
632 cm-1; 1H NMR (300 MHz, CDCl3) d 7.31–7.42 (m, 5H), 5.46
(s, 1H), 5.31 (m, 1H), 4.51 (s, 1H), 4.12 (q, J = 6.9 Hz, 2H), 3.61
(d, J = 18.6 Hz, 1H), 3.12 (dd, J = 1.2, 18.6 Hz, 1H), 1.28 (t, J =
6.9 Hz, 3H); 13C NMR (75 MHz, CDCl3) d 168.0, 129.0, 126.0,
91.7, 87.8, 71.3, 59.5, 39.8, 29.6, 25.5, 14.4; MS (ESI) m/z: 271 (M
+ Na)+. HRMS: calcd for C14H16O4Na 271.0946; found 271.0953.
◦
Yield (286 mg, 86%); White solid; m.p. 76–78 C; [a]2D4 = +10.65
(c = 0.84, CHCl3); IR (KBr): 3230, 2910, 1688, 1611, 1555, 1148,
1033, 925, 866, 788, 664 cm-1;1H NMR (300 MHz, CDCl3) d 7.29–
7.34 (m, 5H), 5.4 (s, 1H), 5.1 (s, 2H), 4.66–4.70 (m, 1H), 4.3–4.41
(bs, 1H), 4.17–4.29 (m, 2H), 3.11–3.27 (m, 2H), 1.42 (s, 9H); 13C
NMR (75 MHz, CDCl3) d 174.3, 168.0, 128.4, 127.9, 91.1, 65.3,
49.4, 37.0, 29.6, 28.2; MS (ESI) m/z: 356 (M + Na)+. HRMS:
calcd for C18H23NO5Na 356.1473; found 356.1459.
(2R,3S,E)-tert-Butyl 5-(2-(benzyloxy)-2-oxoethylidene)-2-(furan-
2-yl)-3-methylpyrrolidine-1-carboxylate (3e)
Yield (321 mg, 81%); Pale yellow solid; m.p. 88–90 ◦C; [a]D24 -19.8
(c 0.9, CHCl3); IR (KBr): 3356, 2978, 2934, 1736, 1684, 1514,
(R,E)-Benzyl 2-(5-((4-methoxybenzyloxy)methyl)dihydrofuran-
2(3H)-ylidene)acetate (3j)
1
1450, 1280, 1045, 908, 615 cm-1; H NMR (300 MHz, CDCl3) d
7.25–7.36 (m, 6H), 6.53 (d, J = 5.3 Hz, 1H), 6.36 (d, J = 5.7 Hz,
1H), 5.4 (s, 1H), 5.3 (d, J = 3.0 Hz, 1H), 5.04 (q, J = 12.3 Hz,
2H), 3.95–4.0 (m, 1H), 3.77–3.88 (m, 1H), 3.03–3.10 (m, 1H), 1.43
(s, 9H), 1.27 (d, J = 6.9 Hz, 3H); 13C NMR (75 MHz, CDCl3)
d 169.0, 140.3, 135.9, 132.9, 128.5, 128.1, 124.4, 82.6, 66.6, 59.9,
51.6, 47.9, 28.2, 18.7; MS (ESI) m/z: 420 (M + Na)+. HRMS:
calcd for C23H27NO5Na 420.1786; found 420.1766.
Yield (323 mg, 88%). Colorless oil; [a]2D4 -14.7 (c 0.09, CHCl3);
IR (KBr): 2930, 1698, 1634, 1511, 1244, 1097, 1025, 816, 738,
694 cm-1; 1H NMR (300 MHz, CDCl3) d 7.17–7.33 (m, 8H), 6.79–
6.84 (m, 2H), 5.32 (s, 1H), 5.08 (s, 1H), 4.50–4.57 (m, 1H), 4.46
(s, 2H), 3.78 (s, 3H), 3.44–3.54 (m, 2H), 3.18–3.29 (m, 1H), 2.94–
3.06 (m, 1H), 2.07–2.27 (m, 1H), 1.85–1.97 (m, 1H); 13C NMR
(75 MHz, CDCl3) d 176.9, 168.3, 159.2, 136.8, 129.3, 128.4, 113.8,
89.3, 82.7, 73.1, 70.9, 65.1, 55.2, 30.4, 25.7; MS (ESI) m/z: 391 (M
+ Na)+. HRMS: calcd for C22H24O5Na 391.1521; found 391.1528.
(R,E)-Benzyl 2-(5-(furan-2-yl)dihydrofuran-2(3H)-ylidene)acetate
(3f)
Yield (227 mg, 80%); colorless oil; HPLC analysis on a Dai-
cel chiralpak OD-H column: 95 : 5 hexane–i-PrOH, flow rate
0.5 mL min-1, l = 254 nm: tmajor = 29.99 min, tminor = 33.63 min;
[a]2D4 -70.8 (c 0.9, CHCl3); IR (KBr): 3064, 3033, 2953, 2362, 2334,
1730, 1703, 1641, 1499, 1352, 1208, 1107, 1029, 878, 823, 743,
698 cm-1; 1H NMR (300 MHz, CDCl3) d 7.38 (t, J = 1.5 Hz, 1H),
7.23–7.34 (m, 5H), 6.32 (d, J = 1.5 Hz, 2H), 5.33–5.38 (m, 2H),
5.10 (s, 2H), 3.35–3.47 (m, 1H), 3.07–3.20 (m, 1H), 2.31–2.39 (m,
2H); 13C NMR (75 MHz, CDCl3) d 175.9, 168.2, 164.8, 151.5,
143.2, 136.7, 135.1, 129.7, 128.4, 127.8, 110.3, 108.8, 89.7, 77.6,
66.9, 65.1, 30.6, 29.6, 27.9; MS (ESI) m/z: 307 (M + Na)+. HRMS:
calcd for C17H16O4Na 307.0946; found 307.0957.
(S,E)-Benzyl 2-(6-(tosyloxymethyl)piperidin-2-ylidene)acetate
(3k)
Yield (352 mg, 85%); colorless oil; [a]2D4 -40.0 (c 0.06, CHCl3); IR
(KBr): 2921, 2853, 1740, 1648, 1599, 1453, 1360, 1233, 1165, 959,
818, 779, 747, 694, 667 cm-1; 1H NMR (300 MHz, CDCl3) d 8.72
(bs, 1H), 7.80 (d, J = 7.9 Hz, 2H), 7.20–7.31 (m, 7H), 5.06 (q, J =
12.8 Hz, 2H), 4.42 (s, 1H), 3.99–4.02 (m, 1H), 3.82–3.86 (m, 1H),
3.58–3.63 (m, 1H), 2.43 (s, 3H), 2.26–2.32 (m, 2H), 1.90–1.95 (m,
1H), 1.74–1.79 (m, 1H), 1.25–1.63 (m, 6H); 13C NMR (75 MHz,
CDCl3) d 169.8, 161.6, 144.9, 129.9, 128.4, 128.0, 127.3, 82.1, 72.0,
64.2, 50.0, 43.4, 29.1, 25.0, 21.7, 18.4; MS (ESI) m/z: 416 (M +
H)+. HRMS: calcd for C22H26NO5S 416.1531; found 416.1520.
(E)-Benzyl 2-(benzofuran-2(3H)-ylidene)acetate (3g)
Yield (218 mg, 82%); Colorless oil; IR (KBr): 3447, 3058, 1735,
1612, 1191, 955, 741, 697 cm-1; 1H NMR (300 MHz, CDCl3) d 7.46
(d, J = 7.8 Hz, 1H), 7.39 (d, J = 7.8 Hz, 1H), 7.10–7.24 (m, 7H),
6.59 (s, 1H), 5.17 (s, 2H), 3.83 (s, 2H); 13C NMR (75 MHz, CDCl3)
d 168.7, 128.5, 128.2, 123.9, 122.7, 120.7, 110.0, 105.2, 67.0, 34.6;
MS (ESI) m/z: 289 (M + Na)+. HRMS: calcd for C17H14O3Na
289.0840; found 289.0853.
(S,E)-Benzyl 2-(5-(tert-butoxycarbonylamino)tetrahydro-2H-
pyran-2-ylidene)acetate (3l)
Yield (284 mg, 82%); colorless oil; [a]2D4 = +1.6 (c = 0.04, CHCl3); IR
(KBr): 3440, 3365, 2937, 1694, 1613, 1528, 1380, 1247, 1172, 1086,
1015, 948, 630 cm-1; 1H NMR (300 MHz, CDCl3) d 7.25–7.35 (m,
5H), 6.38 (s, 1H), 5.05–5.15 (m, 2H), 4.24–4.31 (m, 1H), 3.67 (d, J =
5.1 Hz, 2H), 3.37–3.46 (m,1H), 2.94–3.07 (m, 1H), 2.27–2.38 (m,
1H), 1.88–2.06 (m, 1H), 1.53(s, 9H); 13C NMR (75 MHz, CDCl3) d
168.5, 158.2, 151.9, 128.4, 127.6, 96.1, 82.6, 66.6, 64.9, 63.7, 62.3,
44.1, 30.6, 28.0, 23.6; MS (ESI) m/z: 348 (M + H)+. HRMS: calcd
for C19H26NO5 348.1844; found 348.1850.
(E)-Benzyl 2-(5-methylindolin-2-ylidene)acetate (3h)
Yield (234 mg, 84%); Yellow solid; m.p. 84–87 ◦C; IR (KBr):
3369, 2887, 1730, 1584, 1431, 1209, 792, 725, 644 cm-1; 1H NMR
(300 MHz, CDCl3) d 8.52 (bs, 1H), 7.30–7.33 (m, 6H), 7.15 (d, J =
This journal is
The Royal Society of Chemistry 2011
Org. Biomol. Chem., 2011, 9, 7913–7920 | 7917
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