Molecules 2013, 18
11115
(±)-cis-2,4,5,6-Tetrahydro-4-(2-methoxyphenyl)-1-methyl-1H-benzo[f]isochromene (cis-7c). IR (film):
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3063, 2960, 2936, 2836, 1599, 1491, 1462, 756, 736 cm−1. H-NMR (300 MHz, CDCl3) δ: 1.41 (d,
J = 6.9 Hz, 3H), 1.77–1.87 (m, 1H), 1.94–2.05 (m, 1H), 2.67 (t, J = 7.9 Hz, 2H), 2.76–2.78 (m, 1H),
3.83–3.87 (m, 1H), 3.87 (s, 3H), 3.98 (dd, J = 10.8, 3.3 Hz, 1H), 5.70 (s, 1H), 6.91–6.97 (m, 2H),
7.08–7.16 (m, 2H), 7.21–7.27 (m, 1H), 7.29–7.38 (m, 3H). 13C-NMR (75 MHz, CDCl3) δ: 18.5, 24.4,
28.0, 28.8, 55.6, 70.2, 73.0, 110.9, 120.7, 122.1, 126.4, 127.6, 128.5, 129.3, 131.8, 133.7, 134.0, 135.8,
157.9. LRMS m/z (rel. int.): 306 (M+·, 25), 264 (17), 245 (13), 231 (10), 199 (11), 141 (17), 135 (100).
HRMS [ESI(+)] calcd. for [C21H22O2+Na+] 329.1517, found 329.1494.
(±)-trans-2,4,5,6-Tetrahydro-4-(2-methoxyphenyl)-1-methyl-1H-benzo[f]-isochromene (trans-7c). IR
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(film): 3060, 3018, 2959, 2929, 2835, 1599, 1587, 1489, 1462, 756, 736 cm−1. H-NMR (300 MHz,
CDCl3) δ: 1.26 (d, J = 7.0 Hz, 3H), 1.81–2.04 (m, 2H), 2.62–2.81 (m, 3H), 3.54 (dd, J = 11.2, 2.6 Hz,
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1H), 3.81–3.95 (m, 1H), 3.90 (s, 3H), 5.75 (s, 1H), 6.86–6.96 (m, 2H), 7.11–7.39 (m, 6H). C-NMR
(75 MHz, CDCl3) δ: 18.2, 25.8, 28.1, 28.3, 55.6, 66.1, 71.5, 110.8, 119.7, 122.3, 126.3, 126.7, 127.6, 129.3,
129.6, 132.3, 132.8, 133.7, 136.3, 158.3. LRMS m/z (rel. int.): 306 (M+·, 32), 264 (18), 245 (16), 231
(8), 199 (11), 141 (19), 135 (100). HRMS [ESI(+)] calcd. for [C21H22O2+Na+] 329.1517, found 329.1511.
Prins cyclization of 1a and 2d. The reaction was performed following the general procedure, but using 1a
(0.096 g, 0.51 mmol), 2d (0.060 mL, 0.41 mmol), CH2Cl2 (5 mL), I2 (0.0065, 0.025 mmol). A mixture
of 7d and 12d (cis:trans:12d = 4.2:2.5:1, 0.12 g, 0.43 mmol, 84%) was obtained as a colorless viscous
oil. This mixture was subjected to another flash column chromatography (1% AcOEt in hexanes).
Partially pure samples could be obtained for characterization separately.
(±)-cis-2,4,5,6-Tetrahydro-1-methyl-4-p-tolyl-1H-benzo[f]isochromene (cis-7d). IR (film): 3058, 3024,
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2954, 2919, 2849, 1272, 1178, 1109, 766, 754 cm−1. H-NMR (200 MHz, CDCl3) δ: 1.43 (d, J = 6.8
Hz, 3H), 1.68–2.05 (m, 2H), 2.35 (s, 3H), 2.67 (t, J = 7.6 Hz, 2H), 2.73–2.78 (m, 1H), 3.88 (dd, J = 10.9,
1.8 Hz, 1H), 3.97 (dd, J = 10.8, 2.8 Hz, 1H), 5.09 (s, 3H), 7.08–7.19 (m, 3H), 7.21–7.29 (m, 3H),
7.30–7.47 (m, 2H). 13C-NMR (50 MHz, CDCl3) δ: 18.7, 21.2, 24.5 28.0, 28.9, 70.0, 80.5, 122.1, 126.5,
126.6, 127.7, 128.6, 129.2, 131.9, 133.1, 133.8, 135.7, 137.7, 138.0. LRMS m/z (rel. int.): 290 (M+·, 18),
276 (14), 275 (72), 257 (8), 247 (25), 229 (10), 215 (8), 203 (13), 171 (9), 155 (11), 128 (29), 127 (22), 119
(93), 91 (88), 65 (51), 43 (100). HRMS [ESI(+)] calcd. for [C21H22O+Na]+ 313.1563, found 313.1535.
(±)-(4R,4aR)-4,4a,5,6-Tetrahydro-1-methyl-4-p-tolyl-2H-benzo[f]isochromene (12d) and (±)-trans-
2,4,5,6-tetrahydro-1-methyl-4-p-tolyl-1H-benzo[f]isochromene (trans-7d). IR (film): 3059, 3020,
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2925, 2873, 1716, 1452, 1273, 1103, 1038, 816, 760 cm−1. H-NMR (200 MHz, CDCl3) δ: 12d:
1.21–1.81 (m, 2H), 1.92 (s, 3H), 2.53 (s, 3H), 2.60–2.87 (m , 3H), 4.10 (d, J = 9.6 Hz, 1H), 4.24 (d,
J = 17.2 Hz, 1H), 4.35 (d, J = 16.6 Hz, 1H), 7.11–7.41 (m, 7H), 7.44 (d, J = 3.0 Hz, 1H), trans-7d:
1.22 (d, J = 6.8 Hz, 3H), 2.34 (s, 3H), 3.50 (dd, J = 11.3, 3.3 Hz, 1H), 3.99 (d, J = 11.3, 3.7 Hz, 1H),
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5.17 (s, 1H). Other signals overlap with the major diastereomer. C-NMR (75 MHz, CDCl3) δ: 12d:
16.6, 21.2, 26.1, 28.3, 40.7, 71.3, 83.3, 125.0, 126.3, 126.5, 126.6, 127.6, 129.1, 128.4, 128.9, 129.1,
132.6, 136.2, 137.7, 137.9, 138.0, 138.1. trans-7d: 17.9, 21.2, 26.0, 28.2, 28.2, 66.7, 78.8, 122.6, 127.0,
127.3, 127.6, 129.2, 129.6, 129.7, 130.2, 132.6, 133.5, 133.7, 134.8, 136.2, 136.3. LRMS m/z (rel. int.):