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Organic & Biomolecular Chemistry
fied by column chromatography (CHCl3/EtOAc 4 : 1) to give 7 959, 848, 809, 761 cm−1. HRMS (EI): calcd for C17H23O7P [M]+
(13.9 mg, 83%) as a pale yellow powder. Recrystallization from 370.1181; found 370.1194.
hexane/EtOAc (2 : 1) gave an analytical sample of 7 as pale
1,2,4-Trimethoxy-8-(4-methyl-3-penten-1-yl)naphthalene (21)
yellow needles. M.p. 182–184 °C. 1H NMR (400 Hz, CD3OD):
δ = 7.08 (s, 1H), 7.51–7.55 (m, 1H), 7.62–7.66 (m, 1H), 8.12 (d, 5-Bromo-2-methyl-2-pentene (3.30 mL, 24 mmol) was added
J = 8.3 Hz, 1H), 8.34 (d, J = 8.8 Hz, 1H), 8.48 (s, 1H) ppm. 13C slowly to
a stirred suspension of magnesium turnings
NMR (100 Hz, CD3OD): δ = 99.6, 120.6, 121.8, 124.8, 125.5, (654 mg, 27 mmol) in Et2O (49 mL) under argon, and stirring
126.0, 128.6, 137.3, 141.2, 153.0, 154.1 ppm. IR (KBr) ν = 3120, was continued for 20 min, which resulted in the production of
1588, 1505, 1449, 1423, 1354, 1325, 1266, 1179, 1108, 1076, Grignard reagent 25.
823, 755 cm−1. HRMS (EI): calcd for C11H7NO2 [M]+ 185.0477;
found 185.0474.
NiCl2(dppp) (1.10 g, 2.0 mmol) and a solution of 23 (3.02 g,
8.2 mmol) in Et2O (41 mL) were successively added to the
above solution of 25 in Et2O, and the resulting mixture was
stirred at room temperature for 2 h. The reaction was
quenched with 1 M HCl (30 mL) at 0 °C, and the resulting
mixture was extracted with EtOAc (3 × 30 mL). The combined
extracts were washed with saturated aqueous NaHCO3 (2 ×
50 mL) and brine (2 × 50 mL), then dried with Na2SO4. The
mixture was concentrated in vacuo, and the residue was puri-
fied by column chromatography (hexane/EtOAc 20 : 1) to give
5,7,8-Trimethoxynaphthalen-1-yl trifluoromethanesulfonate (22)
Trifluoromethanesulfonic anhydride (0.19 mL, 1.1 mmol) was
added to a stirred solution of 5,7,8-trimethoxy-1-naphthol (24)
(170 mg, 0.73 mmol) in CH2Cl2 (7 mL) containing N,N-diiso-
propylethylamine (0.14 μL, 1.1 mmol) at 0 °C under argon.
After 1 h, the reaction was quenched with water (5 mL) at 0 °C,
and the resulting mixture was extracted with CH2Cl2 (3 ×
5 mL). The combined extracts were washed with brine (2 ×
5 mL), then dried with MgSO4. The mixture was concentrated
in vacuo, and the residue was purified by column chromato-
graphy (hexane/EtOAc 5 : 1) to give 22 (260 mg, 98%) as a pale
brown solid. Recrystallization from hexane/CHCl3 (10 : 1) gave
an analytical sample of 22 as pale gray powders.
M.p. 123–124 °C. 1H NMR (400 Hz, CDCl3): δ = 3.87 (s, 3H),
3.98 (s, 3H), 4.01 (s, 3H), 6.72 (s, 1H), 7.26 (dd, J = 8.5, 7.1 Hz,
1H), 7.32 (d, J = 7.3 Hz, 1H), 8.22 (dd, J = 8.3, 1.5 Hz, 1H) ppm.
13C NMR (100 Hz, CDCl3): δ = 55.9, 57.1, 61.4, 96.1, 118.9 (q,
JCF = 320 Hz), 120.72, 120.73, 121.9, 122.5, 123.3, 134.8, 144.4,
151.0, 152.5 ppm. IR (KBr) ν = 3009, 2942, 2850, 1604, 1419,
1370, 1347, 1234, 1211, 1195, 1128, 1053, 1028, 978, 933, 894,
836, 817, 788, 758 cm−1. HRMS (EI): calcd for C14H13F3O6S
[M]+ 366.0385; found 366.0374.
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21 (2.20 g, 89%) as a yellow oil. H NMR (400 Hz, CDCl3): δ =
1.55 (s, 3H), 1.69 (s, 3H), 2.35 (q, J = 7.6 Hz, 2H), 3.16–3.18 (m,
2H), 3.85 (s, 3H), 3.99 (s, 3H), 4.00 (s, 3H), 5.24–5.28 (m, 1H),
6.68 (s, 1H), 7.21 (d, J = 6.8 Hz, 1H), 7.24–7.27 (m, 1H), 8.08
(dd, J = 8.3, 2.0 Hz, 1H) ppm. 13C NMR (100 Hz, CDCl3): δ =
17.6, 25.7, 31.0, 37.0, 55.8, 57.3, 61.2, 95.5, 120.4, 122.7, 123.1,
124.7, 127.6, 129.8, 131.4, 137.4, 139.1, 149.5, 152.7 ppm. IR
(neat) ν = 2930, 2841, 1616, 1596, 1511, 1456, 1418, 1362, 1204,
1171, 1049, 980, 920, 808, 767, 713 cm−1. HRMS (EI): calcd for
C19H24O3 [M]+ 300.1725; found 300.1714.
5,6,8-Trimethoxy-1,1-dimethyl-1,2,3,4-tetrahydrophenanthrene (20)
p-Toluenesufonic acid monohydrate (217 mg, 1.1 mmol) was
added to a stirred solution of 21 (311 mg, 1.0 mmol) in CH2Cl2
(21 mL) at room temperature, and the mixture was heated at
reflux for 2 h. After cooling to room temperature, the reaction
mixture was diluted with saturated aqueous NaHCO3 (10 mL),
and the resulting mixture was extracted with CHCl3 (3 × 10 mL).
Diethyl(5,7,8-trimethoxynaphthalen-1-yl) phosphate (23)
Sodium hydride (60% dispersion in paraffin liquid, 20.5 mg, The combined extracts were washed with brine (2 × 15 mL), then
0.51 mmol) was added to a stirred solution of 24 (100 mg, dried with MgSO4. The mixture was concentrated in vacuo, and
0.43 mmol) in THF (4 mL) at 0 °C under argon. After 30 min, the residue was purified by column chromatography (hexane/
diethyl chlorophosphate (67.9 µL, 0.47 mmol) was added drop- EtOAc 12 : 1) to give 20 (261 mg, 84%) as a colourless solid.
wise to the mixture at 0 °C, and stirring was continued for Recrystallization from hexane gave an analytical sample of 20 as
1
20 min at the same temperature. The reaction was quenched colourless needles. M.p. 72–73 °C. H NMR (400 Hz, CDCl3): δ =
with water (3 mL) at 0 °C, and the resulting mixture was 1.35 (s, 6H), 1.69–1.72 (m, 2H), 1.79–1.82 (m, 2H), 3.42 (t, J = 6.3
extracted with EtOAc (3 × 10 mL). The combined extracts were Hz, 2H), 3.77 (s, 3H), 3.96 (s, 3H), 3.98 (s, 3H), 6.63 (s, 1H), 7.33
washed with water (2 × 5 mL) and brine (2 × 5 mL), then dried (d, J = 9.3, 1H), 7.98 (d, J = 8.8 Hz, 1H) ppm. 13C NMR (100 Hz,
with Na2SO4. The mixture was concentrated in vacuo, and the CDCl3): δ = 20.4, 30.0, 31.9 (2C), 34.8, 38.8, 55.9, 57.4, 61.2, 95.2,
residue was purified by column chromatography (hexane/ 119.4, 120.4, 123.4, 128.7, 131.0, 140.2, 144.5, 150.3, 152.4 ppm.
1
EtOAc 3 : 1) to give 23 (155 mg, 98%) as a yellow oil. H NMR IR (neat) ν = 2929, 1614, 1512, 1453, 1420, 1409, 1362, 1314,
(400 Hz, CDCl3): δ = 1.26–1.33 (m, 6H), 3.85 (s, 3H), 3.99 (s, 1259, 1203, 1154, 1127, 1071, 1038, 982, 926, 883 cm−1. HRMS
3H), 4.00 (s, 3H), 4.23–4.32 (m, 4H), 6.69 (s, 1H), 7.24 (dd, J = (EI): calcd for C19H24O3 [M]+ 300.1725; found 300.1732.
15.9, 7.6 Hz, 1H), 7.50–7.52 (m, 1H), 8.01 (d, J = 8.8 Hz, 1H)
3-Methoxy-8,8-dimethyl-5,6,7,8-tetrahydrophenanthrene-1,4-
dione (27)
ppm. 13C NMR (100 Hz, CDCl3): δ = 16.6, 16.1, 55.8, 57.2, 61.7,
64.32, 64.39, 95.8, 118.0, 119.2, 122.2, 122.8, 123.6, 145.5,
145.6, 150.2, 152.3 ppm. IR (neat) ν = 3481, 2983, 2935, 2843, A solution of ammonium cerium(IV) nitrate (5.48 g. 1.0 mmol)
1600, 1510, 1456, 1421, 1363, 1267, 1250, 1208, 1056, 1035, in MeCN/H2O (1 : 1, 100 mL) was added to a stirred solution of
660 | Org. Biomol. Chem., 2019, 17, 655–663
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