The Journal of Organic Chemistry
Page 24 of 44
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1.3:1 diastereomeric mixture of compound 16h in 84% yield (288 mg, 0.84 mmol).
Yellowish liquid; Rf (1:10 EtOAc/hexane) 0.3; 1H NMR (600 MHz, CDCl3): δ 8.11–8.08 (m,
4.6H), 7.56–7.49 (m, 4.6H), 5.35 (q, J = 6.6 Hz, 1.3H), 4.95 (q, J = 6.6 Hz, 1H), 4.38–4.32
(m, 4.6H), 3.98 (s, 3H), 3.97 (s, 3.9H), 3.89 (s, 3.9H), 3.87 (s, 3H), 3.73 (s, 2.6H), 3.63 (s,
2H), 2.08 (q, J = 7.8 Hz, 2H), 1.79 (q, J = 7.2 Hz, 2.6H), 1.75 (d, J = 6.6 Hz, 3.9H), 1.56 (d, J
= 6.6 Hz, 3H), 1.40–1.36 (m, 6.9H), 1.02 (t, J = 7.8 Hz, 3H), 0.90 (t, J = 7.2 Hz, 3.9H). 13C
NMR (150 MHz, CDCl3) δ 167.9, 167.9, 151.0, 150.8, 150.1, 150.0, 140.0, 139.3, 129.5,
129.4, 127.7, 127.6, 127.3, 127.3, 126.4, 126.2, 126.2, 126.1, 126.1, 123.1, 123.0, 122.8,
122.8, 119.8, 118.7, 63.5, 62.5, 62.2, 61.4, 61.3, 33.4, 28.4, 27.5, 23.8, 14.3, 14.2, 13.7, 13.2,
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12.9, 12.6. IR (KBr): ν̃ = 3448, 2964, 2936, 1727, 1458, 1419, 1355, 1280, 1234, 1158, 1086,
1039, 969, 778, 749 cmꢀ1. HRMS (ESIꢀTOF) m/z: [M + Na]+ Calcd for C21H26O4Na
365.1729, [M + H]+ Calcd for C21H27O4 343.1909; Found 365.1731, 343.1921.
Ethyl (E)-3-(2-ethylbut-2-en-1-yl)-1,4,6,7-tetramethoxy-2-naphthoate (16i). Annulation
reaction was performed between 15f (219 mg, 1.0 mmol) and 14b (218 mg, 1.2 mmol) with
LiHMDS (3.0 mmol) following the general procedure. Annulation crude product was
purified by column chromatography on silica gel with EtOAc/petroleum ether (1:5) as solvent
to obtain 1:1 diastereomeric mixture of compound 16i in 82% yield (330 mg, 0.82 mmol).
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Yellowish liquid; Rf (1:5 EtOAc/hexane) 0.4; H NMR (600 MHz, CDCl3): δ 7.33 (s, 3H),
7.31 (s, 1H), 5.30 (q, J = 6.6 Hz, 1H), 4.90 (q, J = 6.6 Hz, 1H), 4.36–4.23 (m, 4H), 4.01 (s,
3H), 4.00 (s, 3H), 3.98 (s, 6H), 3.93 (s, 3H), 3.92 (s, 3H), 3.85 (s, 3H), 3.83 (s, 3H), 3.65 (s,
2H), 3.55 (s, 2H), 2.03 (q, J = 7.4 Hz, 2H), 1.75 (q, J = 7.5 Hz, 2H), 1.71 (d, J = 6.8 Hz, 3H),
1.51 (d, J = 6.7 Hz, 3H), 1.36–1.33 (m, 6H), 0.97 (t, J = 7.5 Hz, 3H), 0.86 (t, J = 7.4 Hz, 3H).
13C NMR (150 MHz, CDCl3) δ 168.2, 168.1, 150.8, 150.0, 149.9, 149.7, 149.1, 148.9, 140.2,
139.5, 125.3, 125.2, 124.8, 124.6, 124.5, 124.5, 123.0, 128.9, 119.6, 118.4, 101.8, 101.7,
101.6, 101.6, 63.0, 62.0, 61.8, 61.3, 61.2, 56.1, 56.0, 33.3, 28.4, 27.4, 23.7, 14.3, 14.2, 13.7,
13.2, 12.8, 12.6. IR (KBr): ν̃ = 3448, 2935, 1724, 1507, 1475, 1428, 1332, 1259, 1231, 1207,
1170, 1092, 1039, 1016, 975, 859 cmꢀ1. HRMS (ESIꢀTOF) m/z: [M + H]+ Calcd for C23H31O6
403.2121; Found 403.2139.
Ethyl
4,8-dimethoxy-3-(2-methylallyl)-1-oxo-1,2,3,4-tetrahydronaphthalene-2-
carboxylate (16ja) and Ethyl 1-hydroxy-4,8-dimethoxy-3-(2-methylallyl)-3,4-
dihydronaphthalene-2-carboxylate (16jb). Annulation reaction was performed between
15h (246 mg, 1.5 mmol) and 14a (277 mg, 1.8 mmol) with LiHMDS (4.5 mmol) following
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