L. F. Tietze, K. M. Gericke, I. Schuberth
FULL PAPER
1 min, freshly distilled acetaldehyde (0.36 mL, 6.40 mmol) was
added quickly. Stirring was continued at –78 °C for 15 min, and
then the reaction mixture was warmed to 25 °C over 1 h. The reac-
tion mixture was treated with saturated aq. NH4Cl (9 mL), stirred
for 5 min and then poured into H2O (50 mL). Afterwards, the re-
sulting solution was extracted with CH2Cl2 (3ϫ30 mL), and the
combined organic layers were dried (Na2SO4), filtered and concen-
trated under reduced pressure. The crude material was subjected to
silica gel flash chromatography (PE/EtOAc, 4:1 Ǟ 1:1), and the
concentration of the appropriate fractions in vacuo afforded
alcohol rac-19 (450 mg, 98% yield) as a yellow oil which solidified
under high vacuum. Rf = 0.55 (PE/EtOAc, 3:2); m.p. 152 °C. 1H
filtered through a plug of silica gel (CH2Cl2, CH2Cl2/EtOAc, 9:1)
to afford anthraquinone 21 (193 mg, 97% yield) as a yellow solid.
Rf = 0.41 (PE/EtOAc, 1:1); m.p. 188 °C. 1H NMR (300 MHz,
CDCl3): δ = 2.35 (s, 3 H, Ar-CH3), 2.56 (s, 3 H, 2-H3), 3.93 (s, 3
H, C-1-OCH3), 4.03 (s, 3 H, C-8-OCH3), 7.34 (dbr, J = 8.2 Hz, 1
H, 7-H), 7.66 (t, J = 8.3 Hz, 1 H, 6-H), 7.82–7.90 (m, 2 H, 4-H, 5-
H) ppm. 13C NMR (75.5 MHz, CDCl3): δ = 19.15, 31.93, 56.54,
63.56, 118.1, 119.1, 123.2, 124.8, 134.4, 125.5, 134.1, 134.7, 140.5,
143.5, 156.6, 159.6, 181.9, 183.1, 204.2 ppm. IR (KBr): ν = 2954,
˜
1691, 1672, 1586, 1446, 1393, 1322, 1286, 1230 cm–1. UV (CH3CN):
λmax (lg ε) = 219.0 (4.454), 257.0 (4.420), 376.0 (3.747) nm. MS (EI,
70 eV): m/z (%) = 324.1 (28) [M]+, 309.1 (100) [M – CH3]+. HRMS
NMR (300 MHz, CDCl3): δ = 1.68 (d, J = 6.7 Hz, 3 H, 2-H3), 2.55 (EI): calcd. for C19H16O5 324.0998; found 324.0998. C19H16O5
(s, 3 H, Ar-CH3), 3.89 (s, 3 H, OCH3), 4.00 (s, 3 H, OCH3), 4.04
(s, 3 H, OCH3), 4.06 (s, 3 H, OCH3), 5.29 (sbr, 1 H, 1-H), 6.78 (dbr,
J = 7.3 Hz, 1 H, 7Ј-H), 7.36 (dd, J = 7.9, 7.7 Hz, 1 H, 6Ј-H), 7.81
(s, 1 H, 4Ј-H), 7.83 (dd, J = 7.6, 0.9 Hz, 1 H, 5Ј-H) ppm. 13C NMR
(75.5 MHz, CDCl3): δ = 20.84, 24.97, 56.36, 62.63, 63.63, 63.99,
67.59, 104.0, 114.6, 118.8, 118.9, 118.9, 125.6, 126.5, 127.3, 133.5,
(324.33): calcd. C 70.36, H 4.97; found C 69.66, H 5.03.
2-Acetyl-1,8-dihydroxy-3-methylanthraquinone (22): A suspension
of anthraquinone 21 (200 mg, 0.617 mmol) in HOAc (10 mL) was
treated at 25 °C with HBr (15 mL, 33% in HOAc) and stirred at
100 °C for 1.5 h. Afterwards, the mixture was poured into H2O
(250 mL) and extracted with CH2Cl2 (3ϫ75 mL). The combined
organic layers were dried (Na2SO4), filtered and concentrated un-
der reduced pressure. The resulting crude material was filtered
through a plug of silica gel (CH2Cl2) to afford anthraquinone 22
(181 mg, 99% yield) as a yellow solid. Rf = 0.49 (PE/EtOAc, 4:1);
m.p. 203 °C. 1H NMR (300 MHz, CDCl3): δ = 2.41 (s, 3 H, Ar-
CH3), 2.62 (s, 3 H, 2Ј-H3), 7.32 (dd, J = 8.5, 1.1 Hz, 1 H, 7-H),
7.68 (sbr, 1 H, 4-H), 7.70 (t, J = 8.5 Hz, 1 H, 6-H), 7.84 (dd, J =
7.6, 1.0 Hz, 1 H, 5-H), 11.98 (s, 1 H, 8-OH), 12.36 (s, 1 H, 1-OH)
ppm. 13C NMR (75.5 MHz, CDCl3): δ = 20.36, 31.82, 114.2, 115.8,
120.2, 122.2, 124.8, 133.1, 133.5, 136.2, 137.4, 145.6, 159.5, 162.6,
134.1, 147.2, 148.9, 153.9, 157.2 ppm. IR (KBr): ν = 2932, 1621,
˜
1557, 1396, 1453, 1362, 1332, 1316, 1268 cm–1. UV (CH3CN): λmax
(lg ε) = 199.5 (4.342), 227.5 (4.087), 264.0 (4.987), 359.5 (3.743),
377.5 (4.011), 393.0 (3.915), 415.5 (3.753) nm. MS (EI, 70 eV):
m/z (%) = 356.4 (15) [M]+, 341.3 (11) [M – CH3]+. HRMS (EI):
calcd. for C21H24O5 356.1624; found 356.1624. C21H24O5 (356.41):
calcd. C 70.77, H 6.79; found C 70.49, H 6.49.
rac-2-(1-Hydroxyethyl)-1,8-dimethoxy-3-methylanthraquinone (rac-
20): A solution of anthracene rac-19 (450 mg, 1.26 mmol) in 1,4-
dioxane (50 mL) was treated at 25 °C with AgO (782 mg,
6.31 mmol) stirred for 5 min until a suspension was formed. After-
wards, HNO3 (4 , 10 mL) was added dropwise over 5 min until
the AgO was completely dissolved. After being stirred for another
10 min, the reaction mixture was poured into H2O (150 mL) and
extracted with CH2Cl2 (3ϫ75 mL). The combined organic layers
were dried (Na2SO4), filtered and concentrated under reduced pres-
sure. The resulting crude material was filtered through a plug of
silica gel (CH2Cl2/EtOAc, 1:1) to afford anthraquinone rac-20
(407 mg, 99% yield) as a yellow oil which solidified under high
vacuum. Rf = 0.55 (PE/EtOAc, 1:2); m.p. 187 °C. 1H NMR
(300 MHz, CDCl3): δ = 1.59 (d, J = 7.0 Hz, 3 H, 2Ј-H3), 2.48 (s, 3
H, Ar-CH3), 4.00 (s, 3 H, OCH3), 4.01 (s, 3 H, OCH3), 5.24 (q, J
= 7.0 Hz, 1 H, 1Ј-H), 7.31 (dd, J = 8.2, 0.9 Hz, 1 H, 7-H), 7.64 (t,
J = 8.4 Hz, 1 H, 6-H), 7.75 (s, 1 H, 4Ј-H), 7.81 (dd, J = 8.0, 0.9 Hz,
1 H, 5-H) ppm. 13C NMR (75.5 MHz, CDCl3): δ = 20.36, 23.39,
56.52, 63.32, 66.54, 118.0, 118.9, 124.8, 125.5, 134.1, 123.6, 132.72,
181.3, 192.6, 202.5 ppm. IR (KBr): ν = 3057, 1705, 1673, 1622,
˜
1558, 1449, 1374, 1350, 1291, 1268, 1247 cm–1. UV (CH3CN): λmax
(lg ε) = 225.0 (4.496), 255.0 (4.354), 277.0 (4.041), 287.0 (4.035),
428.0 (4.048) nm. MS (EI, 70 eV): m/z (%) = 296.1 (58) [M]+, 281.1
(100) [M – CH3]+. HRMS (EI): calcd. for C17H12O5 296.0685;
found 296.0685. C17H12O5 (296.27): calcd. C 68.92, H 4.08; found
C 68.65, H 3.86.
rac-(2E)-1-(1,8,9,10-Tetramethoxy-3-methylanthracene-2-yl)but-2-
en-1-ol (rac-23): A solution of anthracene 18 (978 mg, 2.50 mmol)
in THF (30 mL) was treated at –78 °C dropwise with nBuLi
(1.20 mL, 3.00 mmol, 2.5 in n-hexane) over 1 min, and stirring
was continued for 1 min. (E)-Crotonaldehyde (1.02 mL, 12.5 mmol)
was added quickly. Stirring was continued at –78 °C for 15 min,
and then the reaction mixture was warmed to 25 °C over 1 h. The
reaction mixture was treated with saturated NH4Cl (20 mL), stirred
for 5 min and then poured into H2O (100 mL). Afterwards, the
resulting solution was extracted with CH2Cl2 (3ϫ50 mL), and the
combined organic layers were dried (Na2SO4), filtered and concen-
trated under reduced pressure. The crude material was subjected to
silica gel flash chromatography (PE/EtOAc, 10:1 Ǟ 4:1), and the
concentration of the appropriate fractions in vacuo afforded
alcohol rac-23 (688 mg, 72% yield) as a yellow foam. Rf = 0.15
134.7, 142.3, 143.6, 158.7, 159.3, 182.6, 183.2 ppm. IR (KBr): ν =
˜
3474, 2983, 2849, 1661, 1583, 1472, 1445, 1315, 1273, 1241 cm–1.
UV (CH3CN): λmax (lg ε) = 220.0 (4.496), 259.5 (4.448), 372.5
(3.786) nm. MS (EI, 70 eV): m/z (%) = 326.1 (38) [M]+, 311.1 (100)
[M – CH3]+, 293.1 (34) [M – CH3 – H2O]+, 281.1 (18) [M –
C2H5O]+. HRMS (EI): calcd. for C19H18O5 326.1154; found
326.1154. C19H18O5 (326.34): calcd. C 69.93, H 5.56; found C
69.66, H 5.38.
1
(PE/EtOAc, 4:1); H NMR (300 MHz, CDCl3): δ = 1.73 (dbr, J =
6.2 Hz, 3 H, 4-H3), 2.55 (s, 3 H, Ar-CH3), 3.89 (s, 3 H, OCH3),
3.92 (s, 3 H, OCH3), 4.03 (s, 3 H, OCH3), 4.05 (s, 3 H, OCH3),
5.52–5.76 (m, 2 H, 1-H, 3-H), 5.94 (ddbr, J = 18.3, 3.7 Hz, 1 H, 2-
H), 6.76 (dbr, J = 7.4 Hz, 1 H, 7Ј-H), 7.35 (dd, J = 8.7, 7.8 Hz, 1 H,
6Ј-H), 7.80–7.85 (m, 2 H, 4Ј-H, 5Ј-H) ppm. 13C NMR (75.5 MHz,
CDCl3): δ = 17.71, 20.87, 56.29, 62.56, 63.49, 63.63, 71.00, 71.17,
71.29, 103.9, 114.5, 118.7, 118.9, 118.9, 125.6, 125.9, 126.6, 127.4,
2-Acetyl-1,8-dimethoxy-3-methylanthraquinone (21): A solution of
anthraquinone rac-20 (200 mg, 0.613 mmol) in CH2Cl2 (20 mL)
was treated at 25 °C with the Dess–Martin periodinane (390 mg,
0.920 mmol) and stirred for 30 min. Afterwards, saturated aq.
NaHCO3 (3 mL) and aq. Na2S2O3 (1 , 3 mL) were added simulta-
neously, and the resulting cloudy reaction mixture was stirred for
30 min until a clear solution was formed. The mixture was poured
into H2O (50 mL) and extracted with CH2Cl2 (3ϫ30 mL). The
combined organic layers were dried (Na2SO4), filtered and concen-
trated under reduced pressure. The resulting crude material was
131.6, 133.8, 134.6, 147.1, 149.0, 154.1, 157.2 ppm. IR (KBr): ν =
˜
3462, 2931, 2834, 1620, 1557, 1515, 1452, 1396, 1359, 1316,
1259 cm–1. UV (CH3CN): λmax (lg ε) = 199.0 (4.379), 228.0 (4.090),
266.0 (4.941), 359.5 (3.710), 377.5 (3.975), 393.5 (3.873), 415.5
4570
www.eurjoc.org
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2007, 4563–4577