PAPER
Simple Synthesis of Tetrahydrofurans
1193
4b
MS (EI): m/z (rel. intensity) = 332 (6), 304 (6), 289 (3), 234 (2), 205
(18), 192 (34), 177 (14), 150 (10), 135 (100).
All data are consistent with those described in the literature.8a
Anal. Calcd for C21H32O3 (332.235): C, 75.86; H, 9.70. Found: C,
76.10; H, 9.91.
4c
Oil.
IR (neat): 2926, 2855, 1682, 1597, 1581, 1448, 1366, 1217, 1069,
1002, 702, 662 cm–1.
4g
trans-Isomer
Oil.
1H NMR (200 MHz, CDCl3): d = 7.92–8.00 (m, 2 H), 7.43–7.64 (m,
3 H), 4.13–4.24 (m, 1 H), 3.95–4.08 (m, 1 H), 3.81–3.95 (m, 1 H),
3.56–3.69 (m, 1 H), 2.26–2.41 (m, 1 H), 2.06–2.23 (m, 1 H), 1.07–
1.85 (m, 16 H), 0.80–0.92 (m, 3 H).
13C NMR (50 MHz, CDCl3): d = 200.5, 136.8, 133.2, 128.7, 128.4,
82.0, 67.5, 51.5, 35.0, 31.9, 31.9, 29.6, 29.5, 29.5, 29.3, 26.3, 22.7,
14.1.
Described in the literature,8b but some data are moderately consis-
tent.
IR (neat): 2972, 2870, 1670, 1601, 1575, 1511, 1458, 1420, 1371,
1310, 1262, 1223, 1171, 1117, 1090, 1028, 848, 612, 604, 514 cm–1.
1H NMR (500 MHz, CDCl3): d = 7.93–7.97 (m, 2 H), 6.94–6.98 (m,
2 H), 4.17–4.26 (m, 1 H), 4.01–4.06 (m, 1 H), 3.88 (s, 3 H), 3.85–
3.92 (m, 1 H), 3.49–3.57 (m, 1 H), 2.26–2.35 (m, 1 H), 2.17–2.25
(m, 1 H), 1.32 (d, J = 6.1 Hz, 3 H).
MS (EI): m/z (rel. intensity) = 302 (8), 259 (5), 175 (56), 162 (48),
148 (22), 105 (100), 77 (20).
Anal. Calcd for C20H30O2 (302.458): C, 79.42; H, 10.10. Found: C,
79.27; H, 10.09.
13C NMR (125 MHz, CDCl3): d = 198.8, 163.7, 130.7, 129.9, 113.9,
78.3, 67.6, 55.5, 52.7, 31.8, 20.0.
HRMS (EI): m/z calcd for C13H16O3: 220.10994; found: 220.11029.
4d
Oil.
MS (EI): m/z (rel. intensity) = 220 (5), 192 (5), 177 (21), 164 (5),
152 (12), 135 (100).
IR (neat): 3062, 2980, 2891, 1756, 1725, 1682, 1596, 1580, 1448,
1363, 1279, 1228, 1177, 1091, 1001, 858, 771, 742, 699, 584 cm–1.
1H NMR (200 MHz, CDCl3): d = 7.95–8.06 (m, 2 H), 7.27–7.72 (m,
8 H), 4.57 (dd, J = 2.4, 8.2 Hz, 1 H), 4.25 (dd, J = 3.6, 8.2 Hz, 1 H),
4.16–4.37 (m, 1 H), 4.09 (q, J = 7.1 Hz, 2 H), 2.00–2.34 (m, 2 H),
1.11 (t, J = 7.1 Hz, 3 H).
cis-Isomer
Oil.
IR (neat): 3425, 2975, 1716, 1672, 1601, 1575, 1512, 1460, 1421,
1379, 1310, 1258, 1233, 1172, 1114, 1085, 1027, 845, 606, 515
cm–1.
1H NMR (200 MHz, CDCl3): d = 7.91–7.99 (m, 2 H), 6.91–7.00 (m,
2 H), 4.41–4.56 (m, 1 H), 3.98–4.24 (m, 2 H), 3.88 (s, 3 H), 3.85–
3.90 (m, 1 H), 2.48–2.68 (m, 1 H), 1.94–2.11 (m, 1 H), 0.94 (d, J =
6.5 Hz, 3 H).
13C NMR (50 MHz, CDCl3): d = 199.1, 171.1, 140.9, 136.0, 133.2,
128.7, 128.4, 128.3, 128.0, 125.5, 89.5, 67.9, 61.4, 56.0, 30.0, 13.8.
HRMS (ESI): m/z calcd for C20H20O4Na: 347.1254; found:
347.1242.
Anal. Calcd for C20H20O4: C, 74.06; H, 6.22. Found: C, 70.88; H,
5.87.
13C NMR (50 MHz, CDCl3): d = 197.2, 163.5, 130.7, 130.5, 113.9,
76.4, 67.1, 55.5, 49.4, 28.0, 17.4.
HRMS (EI): m/z calcd for C13H16O3: 220.10994; found: 220.10903.
4e
Oil.
MS (EI): m/z (rel. intensity) = 220 (10), 205 (5), 192 (48), 177 (33),
161 (9), 150 (5), 135 (100).
IR (neat): 2937, 2873, 1670, 1600, 1576, 1511, 1454, 1420, 1360,
1310, 1263, 1221, 1170, 1062, 1028, 842, 759, 701, 612, 514 cm–1.
1H NMR (200 MHz, CDCl3): d = 7.75–7.84 (m, 2 H), 7.19–7.38 (m,
5 H), 6.82–6.91 (m, 2 H), 5.23 (d, J = 7.3 Hz, 1 H), 4.19–4.32 (m, 1
H), 4.01–4.15 (m, 1 H), 3.84 (s, 3 H), 3.81–3.95 (m, 1 H), 2.22–2.54
(m, 2 H).
Stereochemistry was established according to COSY and NOE
spectra.
4h
Oil.
IR (neat): 2938, 1670, 1600, 1575, 1511, 1421, 1360, 1313, 1262,
1227, 1171, 1057, 1030, 841, 705, 611, 514 cm–1.
1H NMR (200 MHz, CDCl3): d = 7.82–7.91 (m, 2 H), 7.21–7.27 (m,
1 H), 6.86–6.95 (m, 4 H), 5.49 (d, J = 6.8 Hz, 1 H), 4.16–4.28 (m, 1
H), 3.91–4.12 (m, 2 H), 3.85 (s, 3 H), 2.23–2.56 (m, 2 H).
13C NMR (50 MHz, CDCl3): d = 198.2, 163.6, 141.7, 130.8, 129.6,
128.4, 127.6, 125.9, 113.7, 83.3, 68.6, 55.5, 54.5, 32.3.
MS (EI): m/z (rel. intensity) = 282 (9), 254 (100), 176 (12), 135 (93),
108 (34).
Anal. Calcd for C18H18O3 (282.339): C, 76.57; H, 6.43. Found: C,
76.46; H, 6.56.
13C NMR (50 MHz, CDCl3): d = 197.5, 163.7, 144.9, 130.8, 129.3,
126.7, 124.7, 124.5, 113.8, 79.5, 68.3, 55.5, 54.5, 31.8.
MS (EI): m/z (rel. intensity) = 288 (23), 260 (55), 227 (13), 176 (14),
153 (7), 135 (100), 111 (10), 108 (23), 92 (11), 77 (16).
4f
Oil.
Anal. Calcd for C16H16O3S (288.082): C, 66.64; H, 5.59; S, 11.12.
Found: C, 66.63; H, 5.65; S, 11.17.
IR (neat): 2926, 2855, 1673, 1601, 1576, 1511, 1465, 1420, 1367,
1310, 1261, 1231, 1171, 1032, 842, 612, 513 cm–1.
1H NMR (200 MHz, CDCl3): d = 7.90–8.00 (m, 2 H), 6.91–7.00 (m,
2 H), 4.09–4.24 (m, 1 H), 3.91–4.07 (m, 1 H), 3.88 (s, 3 H), 3.80–
3.91 (m, 1 H), 3.50–3.65 (m, 1 H), 2.04–2.38 (m, 2 H), 1.10–1.71
(m, 16 H), 0.78–0.92 (m, 3 H).
13C NMR (50 MHz, CDCl3): d = 199.0, 163.6, 130.6, 129.8, 113.8,
82.1, 67.6, 55.5, 51.1, 35.0, 32.0, 31.9, 29.6, 29.5, 29.3, 29.3, 26.3,
22.7, 14.1.
4i
Oil.
IR (neat): 3061, 3029, 2946, 2872, 1686, 1656, 1608, 1575, 1494,
1450, 1359, 1177, 1110, 1061, 980, 762, 699, 567, 485 cm–1.
1H NMR (200 MHz, CDCl3): d = 7.24–7.54 (m, 11 H), 6.82 (d, J =
12.7 Hz, 1 H, Z isomer), 6.66 (d, J = 16.1 Hz, 1 H, E isomer), 6.10
(d, J = 12.8 Hz, 1 H, Z isomer), 5.08 (d, J = 7.2 Hz, 1 H, E isomer),
Synthesis 2006, No. 7, 1190–1194 © Thieme Stuttgart · New York