Notes
J . Org. Chem., Vol. 65, No. 2, 2000 585
2′,4′-Diben zoyloxya cetop h en on e (8b). White solid (2.33 g,
7.60-7.27 (6H, m), 7.01 (2H, d, J ) 9 Hz), 5.38 (2H, s), 3.91
(3H, s). 13C NMR: δC 192.3, 166.0, 164.6, 164.5, 149.9, 134.0,
133.3, 132.7, 130.2, 130.0, 129.4, 128.8, 128.4, 126.2, 124.0, 121.1,
114.3, 68.6, 55.6.
2-Ben zoyloxy-2′,6′-d i(3,4,5-tr im eth oxyben zoyloxy)-a ce-
top h en on e (10e). Colorless needles (467 mg, 68%). 1H NMR:
δH 7.94-7.88 (2H, m), 7.61-7.38 (8H, m), 7.30 (2H, d, J ) 8.2
Hz), 5.21 (2H, s), 3.95-3.93 (18H, m). 13C NMR: δC 194.1, 165.8,
164.1, 153.2, 148.9, 143.4, 133.4, 131.8, 129.8, 129.1, 128.4, 124.6,
123.3, 120.6, 107.8, 69.0, 61.0, 56.4.
1
98%). H NMR: δH 8.24-8.17 (4H, m), 7.98 (1H, d, J ) 8.5 Hz),
7.71-7.49 (6H, m), 7.33-7.22 (2H, m), 2.57 (3H, s).13C NMR:
δC 196.3, 164.9, 164.3, 154.4, 150.3, 134.1, 131.5, 130.4, 129.1,
128.8, 119.6, 117.7, 29.9.
2′,3′,4′-Tr iben zoyloxya cetop h en on e (8c). Colorless needles
(6.02 g, 89%). 1H NMR: δH 8.12-7.89 (7H, m), 7.56-7.24 (10 H,
m), 2.58 (3H, s). 13C NMR: δC 195.7, 163.6, 163.3, 147.3, 143.6,
136.4, 134.0, 130.4, 130.3, 128.7, 128.5, 128.4, 127.9, 127.4, 120.8,
29.8.
2′-(4-Meth oxyben zoyloxy)-a cetop h en on e (8d ). White solid
(3.88 g, 98%). H NMR: δH 8.17 (2H, d, J ) 9 Hz), 7.85 (1H, dd,
J ) 7.7, 1.7 Hz), 7.58 (1H, m), 7.35 (1H, m), 7.23 (1H, dd, J )
8.1, 1.1 Hz), 7.00 (2H, d, J ) 9 Hz), 3.90 (3H, s), 2.54 (3H, s).
13C NMR: δC 197.8, 164.8, 164.2, 149.6, 133.3, 132.5, 131.6, 130.2,
126.1, 124.0, 121.6, 114.1, 55.6, 30.0.
2′-Ben zoyloxy-2-cin n a m oyloxya cetop h en on e (10f). Col-
orless needles (417 mg, 69%). 1H NMR: δH 8.27-8.22 (2H, m),
7.94 (1H, dd, J ) 7.7, 1.7 Hz), 7.78-7.29 (12H, m), 6.50 (1H, d,
J ) 16 Hz), 5.27 (2H, s). 13C NMR: δC 192.6, 166.2, 164.9, 149.7,
146.1, 134.2, 134.0, 130.5, 130.1, 128.9, 128.3, 126.4, 124.0, 117.0,
68.1.
1
2′,6′-Di(3,4,5-tr im eth oxyben zoyloxy)-a cetop h en on e (8e).
White solid (1.53 g, 84%). H NMR: δH 7.51 (1H, d, J ) 8.2 Hz),
7.40 (4H, s), 7.21 (2H, d, J ) 8.2 Hz), 3.94-3.91 (18H, m), 2.47
(3H, s). 13C NMR: δC 198.3, 164.2, 153.2, 148.2, 143.4, 131.0,
128.4, 123.5, 120.6, 107.6, 61.0, 56.4, 31.4.
Gen er a l P r oced u r e for 12: 2-P h en yl-3-ben zoyloxy-4-
oxo-4H-1-ben zop yr a n (3-Ben zoyloxyfla von e) (12a ). To a
suspension of sodium hydride (60% dispersion in oil, washed
three times with dry hexane) (48 mg, 2.0 mmol) in dry tetrahy-
drofuran (10 mL) was added 10a (250 mg, 0.7 mmol) in THF
(10 mL). The reaction mixture was refluxed for 90 min with
stirring, and then the cooled mixture was poured into a mixture
of ice (120 g) and concentrated HCl (2 mL). The crude â-diketone
11a precipitated, was washed with water, and was used in the
following ring closure step without further purification.
To a solution of the crude â-diketone 11a in acetic acid (10
mL) was added, dropwise, concentrated sulfuric acid (0.25 mL).
The reaction mixture was heated at 60 °C for 90 min with
stirring, and the solution was poured over ice (60 g). The
precipitate was filtered, washed with water, and recrystallized
from ethanol to yield the pure 12a (150 mg, 63%) as colorless
needles. 1H NMR: δH 8.28 (1H, dd, J ) 8.1, 1.6 Hz), 8.19 (2H,
m), 7.93 (2H, m), 7.78-7.32 (9H, m). 13C NMR: δC 172.2, 164.0,
156.4, 155.8, 134.1, 133.9, 131.3, 130.6, 130.1, 128.8, 128.7, 128.4,
126.2, 125.3, 123.8, 118.2. HRMS (M + H)+: calcd for C22H14O4,
343.0970; found, 343.0967.
1
Gen er a l P r oced u r e for 9: 2′-Ben zoyloxy-2-br om oa c-
etop h en on e (9a ). To a solution of 8a (5.00 g, 20.8 mmol) in
anhydrous tetrahydrofuran (25 mL) was added PTT (7.80 g, 20.8
mmol) in portions over a period of 10 min. The reaction mixture
was stirred at room temperature for 6 h, poured into water (110
mL), and stirred until a colorless precipitate was formed. The
residue was recrystallized from ethanol to give 9a (5.57 g, 84%)
1
as colorless needles. H NMR: δH 8.24-8.19 (2H, m), 7.89 (1H,
m), 7.68-7.22 (6H, m), 4.41 (2H, s).13C NMR: δC 190.9, 164.9,
149.7, 134.2, 134.1, 130.6, 130.4, 129.0, 128.9, 128.5, 126.3, 124.2,
34.1.
2′,4′-Diben zoyloxy-2-br om oa cetop h en on e (9b). Colorless
needles (547 mg, 75%). 1H NMR: δH 8.25-8.17 (4H, m), 8.01 (1H,
d, J ) 8.3 Hz), 7.69-7.29 (8H, m), 4.42 (2H, s).
2′,3′,4′-Tr iben zoyloxy-2-br om oa cetop h en on e (9c). Color-
less needles (5.25 g, 77%). 1H NMR: δH 8.11-7.91 (7H, m), 7.59-
7.24 (10H, m), 4.45 (2H, s).
2-P h en yl-3,7-d iben zoyloxy-4-oxo-4H-1-ben zop yr a n (3,7-
Diben zoyloxyfla von e) (12b). Colorless solid (274 mg, 59%).
1H NMR: δH 8.33 (1H, d, J ) 8.7 Hz), 8.26-8.19 (4H, m), 7.95
(2H,m), 7.70-7.46 (10H, m), 7.33 (1H, dd, J ) 8.7, 2 Hz). 13C
NMR: δC 171.6, 164.3, 163.8, 156.9, 156.2, 155.2, 134.2, 133.9,
131.4, 130.6, 130.3, 129.9, 128.8, 128.6, 128.3, 127.6, 121.5, 119.7,
111.3. HRMS (M + H)+: calcd for C29H18O6, 463.1182; found,
463.1183.
2′-(4-Meth oxyben zoyloxy)-2-br om oa cetop h en on e (9d ).
1
Colorless needles (1.10 g, 85%). H NMR: δH 8.17 (2H, d, J ) 9
Hz), 7.89 (1H, dd, J ) 7.8, 1.6 Hz), 7.63 (1H, m), 7.42-7.30 (2H,
m), 7.02 (2H, d, J ) 9 Hz), 4.41 (2H, s), 3.91 (3H, s). 13C NMR:
δC 190.9, 164.5, 164.4, 149.8, 134.1, 132.6, 130.6, 128.7, 126.2,
124.2, 121.2, 114.2, 55.7, 34.6.
2′,6′-Di(3,4,5-tr im eth oxyben zoyloxy)-2-br om oa cetop h e-
n on e (9e). Colorless needles (904 mg, 79%). 1H NMR: δH 7.60
(1H, d, J ) 8.2 Hz), 7.39 (4H, s), 7.30 (2H, d, J ) 8.2 Hz), 4.35
(2H, s), 3.99-3.93 (18H, m). 13C NMR: δC 191.3, 164.0, 153.3,
148.6, 143.5, 131.9, 123.2, 120.6, 107.7, 61.1, 56.5, 35.6.
Gen er a l P r oced u r e for 10: 2,2′-Diben zoyloxya cetop h e-
n on e (10a ). A mixture of 9a (1.45 g, 4.55 mmol) and potassium
benzoate (1.10 g, 6.87 mmol) was stirred in acetonitrile (20 mL)
at room temperature for 48 h. The salts were filtered off, and
the solvent was removed under reduced pressure. The residue
was taken up in dichloromethane, washed with aqueous sodium
carbonate, and then washed with water. The solvent was
removed under reduced pressure, and the residue was recrystal-
lized from ethanol to give 10a (1.38 g, 84%) as colorless needles.
1H NMR: δH 8.25-8.19 (2H, m), 8.07-8.01 (2H, m), 7.94 (1H,
dd, J ) 7.7, 1.7 Hz), 7.69-7.34 (8H, m), 7.29 (1H, dd, J ) 8.1,
1.1 Hz), 5.38 (2H, s). 13C NMR: δC 192.3, 165.9, 164.9, 149.7,
134.2, 134.1, 133.3, 130.5, 130.1, 130.0, 129.4, 128.9, 128.7, 128.4,
126.4, 123.9, 68.4.
2,2′,4′-Tr iben zoyloxyacetoph en on e (10b). Colorless needles
(669 mg, 79%). 1H NMR: δH 8.27-8.04 (7H, m), 7.69-7.31 (11H,
m), 5.40 (2H, s). 13C NMR: δC 191.1, 165.9, 164.5, 164.2, 154.9,
150.7, 134.3, 134.1, 133.4, 131.3, 130.5, 130.4, 130.0, 129.4, 129.0,
128.8, 128.5, 126.1, 119.9, 117.7, 68.4.
2,2′,3′,4′-Tetr a ben zoyloxya cetop h en on e (10c). Colorless
needles (3.53 g, 73%). 1H NMR: δH 8.13-7.92 (9H, m), 7.61-
7.23 (13H, m), 5.43 (2H, s). 13C NMR: δC 190.5, 164.8, 163.7,
163.2, 163.0, 148.0, 143.9, 136.3, 134.2, 134.1, 134.0, 133.3, 130.5,
130.3, 130.2, 130.0, 129.3, 128.7, 128.6, 128.4, 128.2, 127.9, 127.7,
127.6, 127.2, 121.3, 68.1.
2-P henyl-3,7,8-tribenzoyloxy-4-oxo-4H-1-benzopyran (3,7,8-
Tr iben zoyloxyfla von e) (12c). Colorless solid (451 mg, 77%).
1H NMR: δH complex spectrum. 13C NMR: δC 171.9, 163.8, 156.8,
147.8, 134.0, 130.6, 130.5, 130.0, 129.6, 128.8, 128.3, 123.8, 120.6.
HRMS (M + H)+: calcd for C36H22O8, 583.1393; found, 583.1384.
2-(4-Meth oxyp h en yl)-3-ben zoyloxy-4-oxo-4H-1-ben zop y-
r a n (3-Ben zoyloxy-4′-m eth oxyfla von e) (12d ). Colorless solid
(357 mg, 75%). 1H NMR: δH 8.30-8.20 (3H, m), 7.93 (2H, d, J )
9 Hz), 7.75-7.40 (6H, m), 6.97 (2H, d, J ) 9 Hz), 3.83 (3H, s).
13C NMR: δC 172.1, 163.9, 162.0, 156.3, 155.7, 133.8, 133.4, 130.6,
130.2, 128.9, 128.7, 126.2, 125.1, 123.8, 122.4, 118.1, 114.3, 55.5.
HRMS (M + H)+: calcd for C23H16O5, 373.1076; found, 373.1078.
2-(3′,4′,5′-Tr im eth oxyp h en yl)-3-ben zoyloxy-5-h yd r oxy-4-
oxo-4H-1-ben zop yr a n (3-Ben zoyloxy-5-h yd r oxy-3′,4′,5′-tr i-
m eth oxyfla von e) (12e). Yellow solid (240 mg, 59%). 1H NMR:
δH 12.06 (1H, s, 5-OH), 8.25-8.19 (2H, m), 7.69-7.46 (4H, m),
7.16 (2H, s), 7.01 (1H, dd, J ) 8.4, 0.7 Hz), 6.82 (1H, dd, J )
8.4, 0.7 Hz), 3.88 (3H, s), 3.75 (6H, s). 13C NMR: δC 176.9, 163.7,
160.8, 157.0, 155.7, 153.3, 141.2, 135.8, 134.4, 131.8, 130.5, 128.9,
128.2, 124.4, 111.4, 110.8, 107.3, 106.0, 61.0, 56.2. HRMS (M +
H)+: calcd for C25H20O8, 449.1236; found, 449.1231.
Gen er a l P r oced u r e for F la von ols: 2-P h en yl-3-h yd r oxy-
4-oxo-4H-1-ben zop yr a n (F la von ol) (13). Compound 12a (150
mg, 0.438 mmol) was hydrolyzed with 5% aqueous sodium
hydroxide solution (2.5 mL) in ethanol (20 mL) at 60 °C for 2 h.
The reaction mixture was poured into a mixture of crushed ice
(60 g) and concentrated HCl (1 mL). It was then extracted with
ethyl acetate and washed with aqueous sodium hydrogen
carbonate and water. The solvent was removed under reduced
pressure, and the residue was recrystallized from aqueous
ethanol to give the flavonol 13 (83 mg, 80%) as colorless needles.
1H NMR (CDCl3): δH 8.27-8.20 (3H, m), 7.73-7.34 (6H, m), 6.97
2-B e n zo y lo x y -2′-(4-m e t h o x y b e n zo y lo x y )-a c e t o p h e -
n on e (10d ). Colorless needles (865 mg, 77%). 1H NMR: δH 8.20
(2H, d, J ) 9 Hz), 8.07 (2H, m), 7.97 (1H, dd, J ) 7.7, 1.6 Hz),