PAPER
Synthesis of Uralenol
173
and the mixture was stirred for 20 h at the same temperature. The
resulting mixture was diluted with EtOAc (1.0 L) and washed with
aq 1 M HCl (0.50 L), H2O (0.50 L), and brine (0.50 L). The organic
phase was dried (Na2SO4) and concentrated in vacuo. The residue
was purified by column chlomatography (silica gel, hexane–EtOAc,
2:3) to give a mixture of 8a and 8b (8.43 g, 17.8 mmol, 92%, 76:24)
as a pale yellow amorphous powder. Although pure 8a was obtained
by recrystallization of the mixture of 8a and 8b, it was difficult to
record the spectral data of 8a because 8a was converted into a mix-
ture of 8a and 8b within a short time. Only 1H NMR was available.
1H NMR (400 MHz, CDCl3): δ = 7.59–7.55 (m, 2 H), 7.00 (d,
J = 3.2 Hz, 1 H), 6.97 (d, J = 11.2 Hz, 1 H), 6.72 (d, J = 3.2 Hz, 1
H), 6.50 (s, phenolic OH, 1 H), 5.27 (s, 2 H), 3.51 (s, 3 H), 2.44 (s,
3 H), 2.35 (s, 3 H), 2.33 (s, 3 H).
Urarenol (1)
To a suspension of 11 (7.00 g, 12.0 mmol, 1.00 equiv) in i-PrOH
(120 mL, 0.10 M) was added CBr4 (0.199 g, 0.60 mmol, 0.05 equiv)
at r.t. and the mixture was stirred for 5 h at reflux. After cooling to
r.t., NH4OAc (9.25 g, 120 mmol, 10.0 equiv) was added to the re-
sulting solution and the mixture was stirred for 5 h at 60 °C. After
cooling to r.t., the mixture was concentrated in vacuo, and the resi-
due was recrystallized from MeOH–H2O (85:15) to give 1 as pale
yellow needles; yield: 4.27 g (11.5 mmol, 96%); mp 176–178 °C.
FT-IR (KBr): 3462, 1734, 1653, 1559, 1522, 1457, 1339, 1161
cm–1.
1H NMR (400 MHz, CD3OD): δ = 7.61 (d, J = 2.0 Hz, 1 H), 7.55 (d,
J = 2.0 Hz, 1 H), 6.36 (d, J = 2.0 Hz, 1 H), 6.18 (d, J = 2.0 Hz, 1 H),
5.34–5.39 (m, 1 H), 3.37 (d, J = 7.6 Hz, 2 H), 1.76 (s, 6 H).
13C NMR (75 MHz, CD3OD): δ = 177.5 (C), 165.7 (C), 162.7 (C),
158.4 (C), 148.5 (C), 146.9 (C), 145.9 (C), 137.3 (C), 133.4 (C),
129.6 (CH), 123.9 (C), 123.3 (C), 122.1 (CH), 113.5 (CH), 104.6
(CH), 99.3 (CH), 94.4 (CH), 29.3 (CH2), 25.9 (CH3), 17.9 (CH3).
2-{3-Acetoxy-4-[(2-methylbut-3-en-2-yl)oxy]phenyl}-7-(meth-
oxymethoxy)-4-oxo-4H-chromene-3,5-diyl Diacetate (10a)
To a solution of 8a/8b (8.00 g, 16.9 mmol, 1.00 equiv) in THF (170
mL, 0.10 M) were added pyridine (14 mL, 0.169 mmol, 0.01 equiv),
the mixed carbonate 9 (90 wt%, 10.5 g, 50.7 mmol, 3.00 equiv), and
Pd(PPh3)4 (0.976 g, 0.845 mmol, 0.05 equiv) at 0–5 °C, and the mix-
ture was stirred for 20 h at the same temperature. The resulting mix-
ture was filtered through a Celite pad, and the residue was then
washed with EtOAc (3 × 100 mL). The combined eluents were con-
centrated in vacuo. The residue was purified by column chromatog-
raphy (silica gel, hexane–EtOAc, 1:1) to give a mixture of 10a and
10b (8.40 g, 15.5 mmol, 92%, 10a/10b = 87:13) as a pale yellow
amorphous powder. The mixture was recrystallized from EtOAc–
hexane (1:1) to give the single isomer 10a as a white powder; yield:
7.22 g (13.4 mmol, 79% from 8a/8b); mp 124–125 °C.
Acknowledgment
This work was supported by the Program for Promotion of Basic
and Applied Researches for Innovations in Bio-oriented Industry
(Japan).
Supporting Information for this article is available online at
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FT-IR (KBr): 3446, 2987, 1773, 1633, 1506, 1434, 1365, 1286,
1203, 1076, 1021, 948, 858, 793, 697, 600 cm–1.
References
1H NMR (400 MHz, CDCl3): δ = 7.60 (dd, J = 8.8, 2.0 Hz, 1 H),
7.54 (d, J = 2.0 Hz, 1 H), 7.22 (d, J = 8.8 Hz, 1 H), 7.05 (d, J = 2.4
Hz, 1 H), 6.72 (d, J = 2.4 Hz, 1 H), 6.13 (dd, J = 17.6, 10.8 Hz, 1
H), 5.27 (d, J = 17.6 Hz, 1 H), 5.26 (s, 2 H), 5.22 (d, J = 10.8 Hz, 1
H), 3.50 (s, 3 H), 2.43 (s, 3 H), 2.34 (s, 3 H), 2.33 (s, 3 H), 1.52 (s,
6 H).
13C NMR (75 MHz, CDCl3): δ = 170.3 (C), 169.7 (C), 168.7 (C),
168.1 (C), 161.3 (C), 157.9 (C), 154.0 (C), 150.8 (C), 150.7 (C),
143.4 (CH), 142.4 (C), 133.3 (C), 126.3 (CH), 122.8 (CH), 122.6
(C), 119.5 (CH), 114.4 (CH2), 111.7 (C), 109.7 (CH), 101.5 (CH),
94.5 (CH2), 81.6 (C), 56.4 (CH3), 26.9 (2 × CH3), 21.0 (CH3), 20.5
(2 × CH3).
(1) (a) Yazaki, K.; Sasaki, K.; Tsurumaru, Y. Phytochemistry
2009, 70, 1739. (b) Nomura, T. Yakugaku Zasshi 2001, 121,
535; Chem. Abstr. 2001, 135, 119570. (c) Ren, Y.; Kardono,
L. B. S.; Riswan, S.; Chai, H.; Farnsworth, N. R.; Soejarto,
D. D.; Carcache-Blanco, E. J.; Kinghorn, A. D. J. Nat. Prod.
2010, 73, 949. (d) Huang, Y.-C.; Hwang, T.-L.; Chang, C.-
S.; Yang, Y.-L.; Shen, C.-N.; Liao, W.-Y.; Chen, S.-C.;
Liaw, C.-C. J. Nat. Prod. 2009, 72, 1273. (e) Tabopda, T. K.;
Ngoupayo, J.; Awoussong, P. K.; Mitaine-Offer, A.-C.; Ali,
M. S.; Ngadjui, B. T.; Lacaille-Dubois, M.-A. J. Nat. Prod.
2008, 71, 2068. (f) Meragelman, K. M.; MaKee, T. C.;
Boyd, M. R. J. Nat. Prod. 2001, 64, 546. (g) Conseil, G.;
Decottignies, A.; Jault, J-M.; Comte, G.; Barron, D.;
Goffeau, A.; Pietro, A. D. Biochemistry 2000, 39, 6910.
(h) Jia, S. S.; Ma, C. M.; Wang, J. M. Acta. Pharm. Sin.
1990, 25, 758. (i) Fukai, T.; Wang, Q.-H.; Takayama, M.;
Nomura, T. Heterocycles 1990, 31, 373.
(2) (a) Zheng, Z.-P.; Cheng, K.-W.; Chao, J.; Wu, J.; Wang, M.
Food Chem. 2008, 106, 529. (b) Chen, R. M.; Hu, L. H.; An,
T. Y.; Li, J.; Shen, Q. Bioorg. Med. Chem. 2002, 12, 3387.
(3) Kawamura, T.; Hayashi, M.; Mukai, R.; Terao, J.; Nemoto,
H. Synthesis 2012, 44, 1308.
(4) (a) Kaiho, T.; Miyamoto, M.; Nobori, T.; Katakami, T. Yuki
Gosei Kagaku Kyokaishi 2004, 62, 27. (b) Kaiho, T.;
Yokoyama, T.; Mori, H.; Fujiwara, J.; Nobori, T.; Odaka,
H.; Kamiya, J.; Maruyama, M.; Sugawara, T. Japanese
Patent JP 06-128238, 1994; Chem. Abstr. 1995, 123, 55900.
(5) When acetic anhydride was used as the solvent, the chemical
yield and chemoselectivity of Claisen rearrangement were
dramatically improved; see ref. 3.
2-[3,4-Diacetoxy-5-(3-methylbut-2-enyl)phenyl]-7-(methoxy-
methoxy)-4-oxo-4H-chromene-3,5-diyl Diacetate (11)
A solution of 10a (7.00 g, 13.0 mmol, 1.00 equiv) in Ac2O (130 mL,
0.10 M) and pyridine (3.2 mL, 39.0 mmol, 3.00 equiv) was heated
to 120–130 °C and stirred for 5 h at the same temperature. After
cooling to r.t., the resulting mixture was concentrated in vacuo. The
residue was recrystallized from EtOAc and hexane (2:1) to give 11
as a white powder; yield: 7.19 g (12.4 mmol, 95%); mp 152–154
°C).
FT-IR (KBr): 3503, 2913, 1771, 1621, 1488, 1443, 1372, 1290,
1178, 1079, 1012, 950, 842, 788, 680, 604, 521, 472 cm–1.
1H NMR (400 MHz, CDCl3): δ = 7.57 (d, J = 2.0 Hz, 1 H), 7.53 (d,
J = 2.0 Hz, 1 H), 7.05 (d, J = 2.4 Hz, 1 H), 6.73 (d, J = 2.4 Hz, 1 H),
5.27 (s, 1 H), 5.20–5.25 (m, 1 H), 3.51 (s, 1 H), 3.31 (d, J = 6.8 Hz,
2 H), 2.43 (s, 3 H), 2.34 (s, 3 H), 2.31 (s, 6 H), 1.77 (s, 3 H), 1.71 (s,
3 H).
13C NMR (75 MHz, CDCl3): δ = 170.4 (C), 169.8 (C), 168.3 (2 ×
C), 168.0 (C), 161.6 (C), 158.1 (C), 153.9 (C), 150.9 (C), 143.0 (C),
142.8 (C), 136.6 (C), 134.9 (C), 134.0 (CH), 127.9 (C), 127.2 (CH),
121.5 (CH), 120.5 (CH), 112.0 (C), 110.0 (CH), 101.8 (CH), 94.7
(CH2), 56.6 (CH3), 28.8 (CH2), 25.8 (CH3), 21.2 (CH3), 20.8 (CH3),
20.5 (CH3), 20.4 (CH3), 17.9 (CH3).
(6) Differentiation of C-4′ from C-3′ with migratory group such
as acetyl group has not been reported prior to our result
reported herein. In contrast, selective O-methylation of C-4′
of quercetin via six steps was reported: Li, N.-G.; Shi, Z.-H.;
© Georg Thieme Verlag Stuttgart · New York
Synthesis 2014, 46, 170–174