9706
J.P.A. Ferreira et al. / Tetrahedron 69 (2013) 9701e9709
31%; 3e, 30.09 mg, 21% and 3f, which was also obtained in the re-
action of 1e with NBS, 57.99 mg, 42%.
8), 98.7 (C-6), 104.3 (C-10), 109.5 (C-3), 119.1 (C-
a
), 127.5 (C-20, 60),
), 156.9 (C-9),
129.0 (C-30,50), 130.1 (C-40), 134.9 (C-10), 139.5 (C-
b
158.9 (C-5), 159.2 (C-2), 165.0 (C-7), 182.0 (C-4). EI-MS, m/z 388 (18,
ꢃ
ꢃ
4.2.1. (E)-3-Bromo-2-styryl-4H-chromen-4-one (3a). Yellow solid.
Mp 169e170 ꢀC. dH (300.13 MHz, CDCl3) 7.38e7.47 (4H, m, H-6, H-
Mþ
,
81Br), 386 (25, Mþ
,
79Br), 355 (8), 325 (10), 277 (11), 248 (100),
ꢃ
247 (12%); HR-EIMS: Mþ , C19H1581BrO4 requires 388.0125, found
30,40,50), 7.50 (1H, d, J 16.0 Hz, H-
a
), 7.55 (1H, d, J 7.9 Hz, H-8),
7.64e7.69 (2H, m, H-20,60), 7.72 (1H, dt, J 7.9 and 1.8 Hz, H-7), 7.74
(1H, d, J 16.0 Hz, H- ), 8.27 (1H, dd, J 8.0 and 1.8 Hz, H-5); dC
(75.47 MHz, CDCl3) 109.8 (C-3), 117.5 (C-8), 119.1 (C- ), 122.0 (C-10),
388.0108; C19H1579BrO4 requires 386.0155, found 386.0166.
b
4.2.6. (E)-5-Hydroxy-7-methoxy-2-styryl-4H-chromen-4-one
(3f). Pale yellow solid. Mp 180e181 ꢀC. dH (300.13 MHz, CDCl3) 3.89
(3H, s, 7-OCH3), 6.18 (1H, s, H-3), 6.36 (1H, d, J 2.2 Hz, H-6), 6.48 (1H,
d, J 2.2 Hz, H-8), 6.74 (1H, d, J 16.1 Hz, H-
30,40,50), 7.57e7.60 (2H, m, H-20,60), 7.58 (1H, d, J 16.1 Hz, H-
(1H, br s, 5-OH); dC (125.77 MHz, CDCl3), 56.4 (7-OCH3), 93.2 (C-8),
98.5 (C-6), 106.4 (C-10), 109.5 (C-3), 120.2 (C-
), 128.3 (C-20,60),
129.6 (C-30,50), 130.6 (C-40), 135.4 (C-10), 137.9 (C-
), 158.1 (C-9),
a
125.4 (C-6), 126.5 (C-5), 128.1 (C-20,60), 129.1 (C-30,50), 130.3 (C-40),
134.1 (C-7), 134.9 (C-10), 139.6 (C-
b
), 154.7 (C-9), 158.4 (C-2), 172.8
a), 7.39e7.46 (3H, m, H-
ꢃ
ꢃ
(C-4). EI-MS, m/z 328 (22, Mþ
,
81Br), 326 (22, Mþ
,
79Br), 282 (10),
b
), 12.75
247 (100), 218 (12), 191 (11), 189 (12), 165 (4), 127 (24), 109 (7), 101
ꢃ
(3), 92 (10), 77 (9), 63 (6), 51 (4%); HR-EIMS: Mþ , C17H1181BrO2
a
requires 327.9911, found 327.9901; C17H1179BrO2 requires
325.9942, found 325.9927.
b
162.0 (C-5), 162.8 (C-2), 166.2 (C-7), 183.1 (C-4). EI-MS, m/z 293 (42,
ꢃ
ꢃ
Mþ ), 277 (11), 264 (12), 248 (100%). HR-EIMS: Mþ , C18H14O4 re-
quires 294.0890, found 294.0894.
4.2.2. (E)-3-Bromo-2-(4-methoxystyryl)-4H-chromen-4-one
(3b). Yellow solid. Mp 141e142 ꢀC. dH (300.13 MHz, CDCl3) 3.86
(3H, s, 40-OCH3), 6.94 (2H, d, J 8.6 Hz, H-30,50), 7.33 (1H, d, J 16.0 Hz,
4.2.7. (E)-6,8-Dibromo-2-styryl-4H-chromen-4-one
residue. dH (300.13 MHz, CDCl3) 6.35 (1H, s, H-3), 6.81 (d, 1H, J
16.0 Hz, H-
), 7.41e7.45 (m, 3H, H-30,40,50), 7.60e7.63 (m, 2H, H-
20,60), 7.75 (d, 1H, J 16.0 Hz, H-
), 8.02 (d, 1H, J 2.2 Hz, H-7), 8.27 (d,
1H, J 2.2 Hz, H-5); dC (75.47 MHz, CDCl3) 110.3 (C-3), 112.8 (C-8),
118.2 (C-6), 119.4 (C-
), 126.1 (C-10), 127.8 (C-7), 127.9 (C-30,50),
(5a). Yellow
H-a
), 7.40 (1H, ddd, J 8.5, 8.0, and 0.8 Hz, H-6), 7.52 (1H, d, J 8.0 Hz,
), 7.71
H-8), 7.59 (2H, d, J 8.6 Hz, H-20,60), 7.66 (1H, d, J 16.0 Hz, H-
b
a
(1H, ddd, J 8.5, 8.0, and 1.6 Hz, H-7), 8.20 (1H, dd, J 8.0 and 1.6 Hz, H-
b
5); dC (75.47 MHz, CDCl3) 55.3 (40-OCH3), 108.8 (C-3), 114.5 (C-30,50),
116.6 (C-
a
), 117.6 (C-8), 122.0 (C-10), 125.1 (C-6), 126.5 (C-5), 127.7
a
(C-10) 129.6 (C-20,60), 134.0 (C-7), 139.6 (C-
b
), 154.7 (C-9), 158.7 (C-
129.0 (C-20,60), 130.2 (C-40), 134.7 (C-10), 138.8 (C-
b), 139.3 (C-5),
ꢃ
2), 161.5 (C-40), 172.8 (C-4). EI-MS, m/z 358 (32, Mþ
,
81Br), 356 (21,
151.5 (C-9), 162.1 (C-2), 176.4 (C-4). ESIþ-MS, m/z 409 [31, (MþH)þ,
ꢃ
Mþ
,
79Br), 325 (7), 323 (10), 277 (100), 247 (12), 245 (11), 223 (4),
81Br], 407 [31%, (MþH)þ, 79Br].
ꢃ
145 (5%); HR-EIMS: Mþ , C18H1381BrO3 requires 358.0016, found
358.0000; C18H1379BrO3 requires, 356.0048, found 356.0034.
4.3. General procedure for the synthesis of (E)-3-iodo-2-
styryl-4H-chromen-4-ones 6aed
4.2.3. (E)-3-Bromo-2-(4-chlorostyryl)-4H-chromen-4-one
(3c). Orange solid. Mp 154e155 ꢀC. dH (300.13 MHz, CDCl3) 7.43
NaOAc (121 mg, 1.48 mmol) was added to a mixture of tri-
(3H, m, H-6 and H-30,50), 7.46 (1H, d, J 16.0 Hz, H-
a
), 7.54 (1H, d, J
8.4 Hz, H-8), 7.58 (2H, d, J 8.5 Hz, H-20,60), 7.66 (1H, d, J 16.0 Hz, H-
),
7.72 (1H, dt, J 8.4 and 1.6 Hz, H-7), 8.24 (1H, dd, J 8.0 and 1.6 Hz, H-
5); dC (75.47 MHz, CDCl3) 109.8 (C-3), 117.5 (C-8), 120.1 (C- ), 122.0
(C-10), 125.1 (C-30,50), 125.7 (C-6), 126.5 (C-5), 128.1 (C-20,60), 134.6
fluoroacetic acid (0.43
m
L, 5.6ꢂ10ꢁ3 mmol) and trifluoroacetic an-
b
hydride (0.79
m
L, 5.6ꢂ10ꢁ3 mmol) at 0 ꢀC. Then the appropriate 5-
aryl-3-hydroxy-1-(2-hydroxyphenyl)penta-2,4-diene-1-one 1aed
(0.37 mmol) was added and the mixture was stirred at room
temperature for 30 min. After the addition of N-iodosuccinimide
(124.9 mg, 0.56 mmol) the stirring was continued over 24 h. After
that period the reaction mixture was poured into ice (20 g) and
water (20 mL) and brought to pH 5 with an aqueous solution of
NaHCO3. The aqueous layer was extracted with ethyl acetate
(3ꢂ20 mL) and the combined organic fractions were washed with
water (20 mL) and brine (20 mL). After drying over anhydrous so-
dium sulfate, the solvent was evaporated to dryness. Purification
was accomplished by thin layer chromatography using dichloro-
methane as eluent. (E)-3-Iodo-2-styryl-4H-chromen-4-ones 6aed
were recrystallized from ethanol and obtained as yellow to orange
solids in good yields: 6a, 96.91 mg, 70%; 6b, 92.72 mg, 62%; 6c,
92.22 mg, 61%; 6d, 91.50 mg, 59%.
a
(C-7), 134.9 (C-10), 135.6 (C- ), 138.3 (C-40), 154.7 (C-9), 158.4 (C-2),
b
ꢃ
ꢃ
172.8 (C-4). EI-MS, m/z 364 (8, Mþ
,
81Br, 37Cl), 362 (18, Mþ
,
79Br,
ꢃ
37Cl or 81Br, 35Cl), 360 (24, Mþ
,
79Br, 35Cl), 325 (5), 281 (8), 223 (4),
ꢃ
248 (100%); HR-EIMS: Mþ , C17H1081Br37ClO2 requires 363.9433,
found 363.9416;
C
17H1079Br37ClO2 requires 361.9521, found
361.9506; C17H1081Br35ClO2 requires 361.9519, found 361.9504;
C17H1079Br35ClO2 requires 359.9553, found 359.9541.
4.2.4. (E)-3-Bromo-2-(4-nitrostyryl)-4H-chromen-4-one
(3d). Orange solid. Mp 184e185 ꢀC. dH (500.13 MHz, CDCl3) 7.47
(1H, dt, J 7.6 and 0.9 Hz, H-6), 7.58 (1H, dd, J 8.1 and 0.9 Hz, H-8),
7.65 (1H, d, J 15.8 Hz, H-a), 7.76 (1H, d, J 15.8 Hz, H-b), 7.77 (1H, ddd,
J 8.1, 7.6, and 1.5 Hz, H-7), 7.81 (2H, dd, J 8.8 Hz, H-20,60), 8.27 (1H,
dd, J 8.0 and 1.5 Hz, H-5), 8.31 (2H, d, J 8.8 Hz, H-30,50); dC
4.3.1. (E)-3-Iodo-2-styryl-4H-chromen-4-one (6a). Yellow solid. Mp
174e176 ꢀC. dH (300.13 MHz, CDCl3) 7.40e7.46 (4H, m, H-6 and H-
(75.47 MHz, CDCl3) 111.6 (C-3), 117.6 (C-8), 122.0 (C-10), 123.5 (C-
a),
124.4 (C-30,50), 125.8 (C-6), 126.6 (C-5), 128.6 (C-20,60), 134.5 (C-7),
30,40,50), 7.56 (1H, d, J 15.8 Hz, H-
a
), 7.57 (1H, dd, J 8.0 and 1.1 Hz, H-
8), 7.66 (2H, d, J 8.4 Hz, H-20,60), 7.71 (1H, d, J 15.8 Hz, H-
), 7.73 (1H,
dt, J 8.0 and 1.7 Hz, H-7), 8.24 (1H, dd, J 8.0 and 1.7 Hz, H-5); dC
(75.47 MHz, CDCl3) 89.9 (C-3), 117.3 (C-8), 120.4 (C-10), 123.4 (C- ),
136.4 (C-
b
), 141.0 (C-10), 148.3 (C-40), 154.9 (C-9), 157.2 (C-2), 172.7
b
ꢃ
ꢃ
(C-4). EI-MS, m/z 373 (24, Mþ
,
81Br), 371 (28, Mþ
,
79Br), 325 (7), 323
ꢃ
(10), 248 (100), 250 (11), 223 (5), 125 (5%); HR-EIMS: Mþ
,
a
C
17H1081BrNO4 requires 372.9763, found 372.9745; C17H1079BrNO4
requires 370.9793, found 370.9779.
125.5 (C-6), 126.7 (C-5), 128.1 (C-20,60), 129.1 (C-30,50), 130.3 (C-40),
134.1 (C-7), 134.8 (C-10), 140.2 (C-
b), 155.1 (C-9), 160.0 (C-2), 174.3
ꢃ
(C-4); EI-MS, m/z 374 (18, Mþ ), 247 [100, (MꢁI)þ], 218 (10),189 (13),
ꢃ
4.2.5. (E)-3-Bromo-5,7-dimethoxy-2-styryl-4H-chromen-4-one
(3e). Yellow solid. Mp 179e181 ꢀC. dH (300.13 MHz, CDCl3) 3.82
(3H, s, 7-OCH3), 3.83 (3H, s, 5-OCH3), 6.38 (1H, d, J 2.3 Hz, H-8), 6.55
127 (12%); HRMS (EI): Mþ , C17H11IO2 requires 373.9804, found
373.9805.
(1H, d, J 2.3 Hz, H-6), 7.43 (1H, d, J 16.2 Hz, H-
H-20,60), 7.61 (1H, d, J 16.2 Hz, H-
), 7.63 (2H, dd, J 8.8 and 1.8 Hz, H-
30,50); dC (125.77 MHz, CDCl3) 55.8 (5-OCH3), 58.9 (7-OCH3), 92.8 (C-
a
), 7.43 (2H, d, J 8.8 Hz,
4.3.2. (E)-3-Iodo-2-(4-methoxystyryl)-4H-chromen-4-one
(6b). Orange solid. Mp 156e157 ꢀC. dH (300.13 MHz, CDCl3) 3.88
(3H, s, 40-OCH3), 6.98 (2H, d, J 8.5 Hz, H-30,50), 7.32 (1H, d, J 15.9 Hz,
b