C. Soldi, A. V. Moro, M. G. Pizzolatti, C. R. D. Correia
FULL PAPER
solved in dioxane (15 mL) inside a sealed tube. The mixture was
heated at 180 °C for 5 h. After this time, the reaction mixture was
cooled to room temperature and filtered, and the filter cake was
washed with ethyl acetate (30 mL). The crude product was purified
by flash chromatography (hexanes/ethyl acetate, 50:50) to provide
aldehyde 32 (65 %) as a yellowish solid. 1H NMR (250 MHz,
(E)-6-(2,4-Dimethoxystyryl)-4-methoxy-2H-pyran-2-one (10): 63%
yield. 1H NMR (250 MHz, CDCl3): δ = 3.81 (s, 3 H), 3.84 (s, 3 H),
3.87 (s, 3 H), 5.45 (d, J = 2.0 Hz, 1 H), 5.88 (d, J = 2.0 Hz, 1 H),
6.45 (d, J = 2.2 Hz, 1 H), 6.50 (dd, J = 8.5, 2.2 Hz, 1 H), 6.61 (d,
J = 16.0 Hz, 1 H), 7.41 (d, J = 8.5 Hz, 1 H), 7.69 (d, J = 16.0 Hz,
1 H) ppm. 13C NMR (62.5 MHz, CDCl3): δ = 55.40, 55.43, 55.8,
CDCl3): δ = 3.89 (s, 3 H), 5.76 (d, J = 2.2 Hz, 1 H), 6.69 (d, J = 88.0, 98.4, 100.0, 105.2, 117.1, 117.4, 129.6, 131.3, 159.4, 159.9,
2.2 Hz, 1 H), 9.55 (s,1 H) ppm. 13C NMR (62.5 MHz, [D6]DMSO):
162.0, 164.4, 171.3 ppm. HRMS calcd. for C16H16O5 288.0998;
found 288.0993.
δ = 57.5, 95.1, 113.1, 154.2, 161.7, 169.5, 184.8 ppm. IR (KBr): ν
˜
= 1731, 1697, 1336, 1256 cm–1. MS (EI): m/z = 154 [M]+, 125, 69,
(E)-4-Methoxy-6-(3,4,5-trimethoxystyryl)-2H-pyran-2-one (30):[17]
Obtained as a yellow solid (81%) which decomposed at 185 °C. 1H
NMR (250 MHz, CDCl3): δ = 3.83 (s, 3 H), 3.87 (s, 3 H), 3.90 (s,
6 H), 5.50 (d, J = 2.2 Hz, 1 H), 5.95 (d, J = 2.2 Hz, 1 H), 6.48 (d,
J = 16.1 Hz, 1 H), 6.73 (s, 2 H), 7.42 (d, J = 16.1 Hz, 1 H) ppm.
13C NMR (50 MHz, [D6]DMSO): δ = 56.4, 56.9, 60.6, 89.1, 101.5,
105.6, 119.3, 131.2, 135.0, 139.2, 153.6, 158.9, 163.1, 171.3 ppm.
59, 53.
4-Methoxy-6-vinyl-2H-pyran-2-one (33): To a solution of methyltri-
phenylphosphonium iodide (0.55 g, 1.37 mmol) in dry THF
(15 mL) under argon at 0 °C was added nBuLi (1.37 mmol). The
reaction mixture was stirred at 0 °C for 1 h, and then at –78 °C, a
solution of aldehyde 32 (0.152 g, 1 mmol) in THF (10 mL) was
added. The reaction was slowly warmed to room temperature and
then stirred for 2 h. After this time, a saturated NaCl solution was
added, and the mixture was extracted with ethyl acetate
(3ϫ20 mL). The combined organic phases were dried with MgSO4,
filtered, and the solvent was evaporated under reduced pressure.
The crude residue was purified by flash chromatography (hexanes/
ethyl acetate, 70:30) to give olefin 33 (51%) as an amorphous, white
IR (film): ν = 1705, 1642, 1550, 1252, 1126 cm–1. MS (EI): m/z =
˜
318 [M]+, 303, 243, 148, 69. HRMS: calcd. for C17H18O6 318.1103;
found 318.1098.
(E)-6-[2-(Benzo[d][1,3]dioxol-5-yl)vinyl]-4-methoxy-2H-pyran-2-one
1
(4):[1b] 57% yield. H NMR (250 MHz, CDCl3): δ = 3.82 (s, 3 H),
5.47 (d, J = 2.0 Hz, 1 H), 5.89 (d, J = 2.0 Hz, 1 H), 5.99 (s, 2 H),
6.40 (d, J = 16.0 Hz, 1 H), 6.80 (d, J = 8.0 Hz, 1 H), 6.97 (d, J =
8.0 Hz, 1 H), 7.00 (s, 1 H), 7.41 (d, J = 16.0 Hz, 1 H) ppm. 13C
NMR (62.5 MHz, CDCl3): δ = 55.9, 89.5, 100.7, 101.4, 105.9,
108.6, 116.8, 123.5, 129.7, 135.5, 148.3, 148.9, 158.8, 164.1,
1
solid. H NMR (250 MHz, CDCl3): δ = 3.80 (s, 3 H), 5.49 (d, J =
2.2 Hz, 1 H), 5.54 (dd, J = 9.7, 1.7 Hz, 1 H), 5.86 (d, J = 2.2 Hz,
1 H), 6.14 (dd, J = 17.2, 1.7 Hz, 1 H), 6.25 (dd, J = 17.2, 9.7 Hz,
1 H) ppm. 13C NMR (62.5 MHz, CDCl3): δ = 55.9, 89.4, 101.4,
171.1 ppm. IR (film): ν = 1722, 1635, 1553, 1257, 1031 cm–1. MS
˜
(EI): m/z = 272 [M]+, 201, 115, 89, 69, 39. HRMS: calcd. for
121.6, 128.0, 158.0, 163.8, 170.8 ppm. IR (KBr): ν = 1716, 1561,
˜
1253 cm–1. MS (EI): m/z = 152 [M]+, 124, 81, 69, 59, 55. HRMS:
C15H12O5 272.0685; found 272.0682.
calcd. for C8H8O3 152.0473; found 152.0471.
(E)-6-(4-Hydroxystyryl)-4-methoxy-2H-pyran-2-one (28):[20] Ob-
tained as a white solid (63 %), m.p. 159–160 °C. 1H NMR
(200 MHz, [D6]DMSO): δ = 3.82 (s, 3 H), 5.59 (d, J = 1.7 Hz, 1
H), 6.22 (d, J = 1.7 Hz, 1 H), 6.77 (d, J = 16.5 Hz, 1 H), 6.78 (d,
J = 8.5 Hz, 2 H), 7.24 (d, J = 16.5 Hz, 1 H), 7.52 (d, J = 8.5 Hz,
2 H), 9.91 (br., 1 H) ppm. 13C NMR (50 MHz, [D6]DMSO): δ =
56.8, 88.6, 100.6, 116.3, 116.6, 126.7, 129.8, 134.9, 159.4 (2 C),
163.2, 171.5 ppm. IR (KBr): ν˜ = 3231, 1694, 1547, 1454, 1252,
1033 cm–1. MS (EI): m/z = 244 [M]+, 216, 173, 145, 127, 115, 69,
43. HRMS: calcd. for C14H12O4 244.0736; found 244.0739.
Procedure for the Heck Arylation of Olefin 33: To a 10-mL tube
were added Pd(OAc)2 (5 mol-%, 1.5 mg), sodium acetate (35.6 mg,
0.39 mmol, 3 equiv.), and olefin 33 (20.0 mg, 0.13 mmol). Acetoni-
trile (0.5 mL) was added, and the tube was filled with an atmo-
sphere of carbon monoxide. After 10 min, the arenediazonium salt
(0.156 mmol, 1.2 equiv.) was added to the resulting suspension. The
reaction was heated at 60 °C for 3 h. After this time, the crude
reaction mixture was filtered through a plug of silica, and the fil-
trate was concentrated under reduced pressure. The product was
purified by flash chromatography (hexanes/ethyl acetate, 50:50) to
provide the corresponding Heck adduct as a homogeneous material
by TLC.
(E)-4-Methoxy-6-styryl-2H-pyran-2-one (9):[19] 25 % yield. 1H
NMR (250 MHz, CDCl3): δ = 3.84 (s, 3 H), 5.50 (d, J = 2.0 Hz, 1
H), 5.95 (d, J = 2.0 Hz, 1 H), 6.60 (d, J = 16.0 Hz, 1 H), 7.31–7.43
(m, 3 H), 7.47–7.55 (m, 3 H) ppm. 13C NMR (62.5 MHz, CDCl3):
δ = 55.9, 88.8, 101.3, 118.6, 127.4, 128.9, 129.4, 135.2, 135.7, 158.6,
(E)-4-Methoxy-6-(4-methoxystyryl)-2H-pyran-2-one (8):[19] Ob-
tained as a yellow solid (96 %), m.p. 152–153 °C. 1H NMR
(250 MHz, CDCl3): δ = 3.82 (s, 3 H), 3.83 (s, 3 H), 5.47 (d, J =
2.0 Hz, 1 H), 5.89 (d, J = 2.0 Hz, 1 H), 6.45 (d, J = 16.0 Hz, 1
H), 6.90 (d, J = 8.7 Hz, 2 H), 7.43–7.48 (m, 3 H) ppm. 13C NMR
(62.5 MHz, CDCl3): δ = 55.3, 55.9, 88.3, 100.5, 114.3, 116.3, 128.0,
163.9, 171.0 ppm. IR (KBr): ν = 1714, 1641, 1533, 1253, 1153 cm–1.
˜
MS (EI): m/z = 228 [M]+, 200, 185, 157, 129, 103, 77, 69.
(E)-6-(4-Fluorostyryl)-4-methoxy-2H-pyran-2-one (34): Obtained as
a white solid (55 %), m.p. 134–135 °C. 1H NMR (250 MHz,
CDCl3): δ = 3.83 (s, 3 H), 5.50 (d, J = 2.0 Hz, 1 H), 5.94 (d, J =
2.0 Hz, 1 H), 6.50 (d, J = 16.0 Hz, 1 H), 7.07 (t, J = 8.5 Hz, 2 H),
7.43–7.51 (m, 3 H) ppm. 13C NMR (125 MHz, CDCl3): δ = 55.9,
88.9, 101.3 (d, J = 0.9 Hz), 116.0 (d, J = 21.7 Hz), 118.4 (d, J =
2.5 Hz), 129.2 (d, J = 8.2 Hz), 131.4 (d, J = 3.5 Hz), 134.5 (d, J =
1.0 Hz), 158.4 (d, J = 0.9 Hz), 163.3 (d, J = 249.0 Hz), 163.9,
129.0, 135.4, 159.1, 160.7, 164.2, 171.2 ppm. IR (film): ν = 1706,
˜
1522, 1410, 1256, 1150 cm–1. MS (EI): m/z = 258 [M]+, 230, 215,
187, 159, 115, 89, 69.
(E)-6-(3,4-Dimethoxystyryl)-4-methoxy-2H-pyran-2-one (7):[1b] Ob-
tained as a yellow solid (89 %), m.p. 158–159 °C. 1H NMR
(250 MHz, CDCl3): δ = 3.82 (s, 3 H), 3.91 (s, 3 H), 3.92 (s, 3 H),
5.47 (s, 1 H), 5.91 (s, 1 H), 6.45 (d, J = 15.8 Hz, 1 H), 6.87 (d, J =
8.3 Hz, 1 H), 7.02 (s, 1 H), 7.08 (d, J = 8.3 Hz, 1 H), 7.45 (d, J =
15.8 Hz, 1 H) ppm. 13C NMR (62.5 MHz, CDCl3): δ = 55.8 (2 C),
55.9, 88.4, 100.5, 109.3, 111.2, 116.5, 121.6, 128.2, 135.7, 149.2,
171.0 ppm. IR (KBr): ν = 1721, 1555, 1255, 1157 cm–1. MS (EI):
˜
m/z = 246 [M]+, 218, 174, 146, 101, 69. HRMS: calcd. for
C14H11FO3 246.0692; found 246.0706.
(E)-6-(4-Chlorostyryl)-4-methoxy-2H-pyran-2-one (29):[21] Obtained
as a white solid (86 %), m.p. 151–152 °C. 1H NMR (250 MHz,
CDCl3): δ = 3.83 (s, 3 H), 5.50 (d, J = 1.7 Hz, 1 H), 5.95 (d, J =
1.7 Hz, 1 H), 6.55 (d, J = 16.0 Hz, 1 H), 7.32–7.48 (m, 5 H) ppm.
150.4, 158.9, 164.1, 171.2 ppm. IR (KBr): ν = 1710, 1635, 1546,
˜
1516, 1255, 1143, 1030 cm–1. MS (EI): m/z = 288 [M]+, 245, 217,
115, 69. HRMS: calcd. for C16H16O5 288.0998; found 288.1009.
3614
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Eur. J. Org. Chem. 2012, 3607–3616