Y. Yang et al. / Tetrahedron: Asymmetry 13 (2002) 2689–2692
2691
(s, 2H). 13C NMR (50 MHz, CDCl3): 56.1, 111.6,
118.3, 122.2, 125.2, 127.8,131.0, 134.0, 135.2, 139.9,
147.1, 151.6, 154.9, 188.5, 190.5.
ature of the acid solution at 5°C for 1 h. Then the
diazonium solution was added dropwise into the boil-
ing mixture of water (10 mL), H2SO4 (10 mL) and
Na2SO4 (15 g). The solution was continuously boiled
for 5 min and then allowed to cool to rt. After it was
stored overnight in a refrigerator, the solid was
filtrated and recrystallized from ethyl acetate to afford
6 as a yellow solid (497 mg, 84%). Mp 102–103°C. MS
(EI): 412 (M+, 26) 390(38), 350(98), 304(87), 221(43),
4.3. (2-Nitro-2%-methoxy-4,4%-diacrylic acid ethyl
ester)diphenyl ether, 4
Monoethyl malonate (1.523 g, 11.54 mmol) was added
to a solution of compound 3 (1.74 g, 5.77 mmol) in
pyridine (15 mL) and piperidine (0.25 mL). The mix-
ture was heated under reflux at 120°C for 6 h, and
then the solvent was evaporated. The crude product
was dissolved in ethyl acetate and the resulting solu-
tion was washed with 5% sodium bicarbonate and
water, dried over Na2SO4. The solvent was distilled off
and the residue was purified by flash chromatography
using petroleum ether and ethyl acetate (3:1, v/v) as
eluent. Compound 5 was obtained as a white solid
(1.93 g, 81%). Mp 136–138°C. MS (EI): 441 (M+, 55),
396(39), 304(63), 287(39), 221(100). 1H NMR (200
MHz, CDCl3): 1.29 (t, J=6.5 Hz, 3H), 1.31 (t, J=6.5
Hz, 3H), 3.78 (s, 3H), 4.23 (q, J=6.5 Hz, 2H), 4.25
(q, J=6.5 Hz, 2H), 6.36 (d, J=15.6 Hz, 1H), 6.38 (d,
J=15.6 Hz, 1H), 6.82 (dd, J=8, 2.2 Hz, 1H), 7.07(d,
J=8 Hz, 1H), 7.09 (d, J=8.4 Hz, 1H), 7.12 (d, J=2.2
Hz, 1H), 7.59 (dd, J=8.4, 2 Hz, 1H), 7.61(d, J=15.6
Hz, 1H), 7.63 (d, J=15.6 Hz, 1H), 8.09 (d, J=2 Hz,
1H). 13C NMR (50 MHz, CDCl3): 14.2, 56.0, 60.6,
112.0, 118.5, 118.7, 119.7, 121.6, 121.9, 124.9, 129.3,
132.8, 133.1, 140.0, 141.1, 143.3, 144.4, 151.3, 152.0,
166.1, 166.5.
1
167(25), 44(100). H NMR (200 MHz, CDCl3): 1.31 (t,
J=6.2 Hz, 3H), 1.32 (t, J=6.2 Hz, 3H) 3.85 (s, 3H),
4.25 (q, J=6.2 Hz, 2H), 4.27 (q, J=6.2 Hz, 2H), 6.47
(d, J=15 Hz, 1H), 6.49 (d, J=15 Hz, 1H), 6.81(d,
J=8.3 Hz, 1H), 7.01(d, J=8.3 Hz, 1H), 7.03 (dd,
J=8.3, 2 Hz, 1H), 7.05 (dd, J=8.3, 1.7 Hz, 1H),7.18
(d, J=1.7 Hz, 1H), 7.21(d, J=2 Hz, 1H), 7.24 (d,
J=15 Hz, 1H), 7.26 (d, J=15 Hz, 1H).
4.6. (2,2%-Dimethoxy-4,4%-diacrylic acid ethyl
ester)diphenyl ether, 7
A mixture of compound 6 (300 mg, 0.74 mmol), MeI
(0.5 mL) and anhydrous potassium carbonate (300
mg) in acetone (5 mL) was heated under reflux for 6
h. After general work up, the crude products were
dissolved in water and then extracted with ethyl ace-
tate (3×10 mL). The combined organic layer was
washed with brine and dried over Na2SO4. The solvent
was distilled off and the residue was purified by flash
chromatography using petroleum ether and ethyl ace-
tate (3:1, v/v) as eluent. The product 7 was obtained
as white solid (296 mg, yield 94%). Mp 80–81°C. MS
(EI): 426 (M+, 36), 381(22), 354(56), 337(41), 323(82),
4.4. (2-Amino-2%-methoxy-4,4%-diacrylic acid ethyl
ester)diphenyl ether, 5
1
167(100). H NMR (200 MHz, CDCl3): 1.29 (t, J=6.1
To the suspension of compound 4 (1 g, 2.25 mmol) in
50 mL boiling H2O was added Fe (1.26 g, 22.5 mmol)
and FeSO4 (340 mg, 2.25 mmol). The reaction mixture
was heated under reflux for 3 h, filtered through
Celite, and washed thoroughly with CH2Cl2. The
aqueous phase was extracted with CH2Cl2, dried over
Na2SO4, and evaporated in vacuo. The residue was
purified by flash chromatography using CH2Cl2 and
MeOH (30:1, v/v) as eluent to afford 5 as slightly
yellow solid (850 mg, 92%). Mp 92–94°C. MS (EI):
411 (M+,53), 368(49), 353(20), 339(21), 313(32),
285(33), 190(38), 155(45), 57(100). 1H NMR (200
MHz, CDCl3): 1.30 (t, J=6.2 Hz, 3H), 1.32 (t, J=6.2
Hz, 3H), 3.78 (s, 3H), 3.97(br, 2H), 4.24 (q, J=6.2
Hz, 2H), 4.26 (q, J=6.2 Hz, 2H), 6.35 (d, J=15.6 Hz,
1H), 6.37 (d, J=15.6 Hz, 1H), 6.76 (d, J=8.3 Hz,
1H), 7.04 (d, J=8.5 Hz, 1H),7.06 (dd, J=8.3, 2 Hz,
1H), 7.08 (d, J=1.5 Hz, 1H),7.11(d, J=2 Hz, 1H)
7.54 (dd, J=8.3, 1.5 Hz, 1H), 7.55 (d, J=15.6 Hz,
1H), 7.57 (d, J=15.6 Hz, 1H).
Hz, 6H), 3.85 (s, 6H), 4.23 (q, J=6.1 Hz, 4H), 6.47
(d, J=15 Hz, 2H), 6.81(d, J=8 Hz, 2H), 7.06 (dd,
J=8, 1.4 Hz, 2H), 7.18 (d, J=1.4 Hz, 2H), 7.25 (d,
J=15 Hz, 2H).
4.7. (2,2%-Dimethoxy-4,4%-dipropenyl alcohol)diphenyl
ether, 8
To a suspension of LiAlH4 (80 mg, 2.118 mmol) in
dry THF (50 mL), AlCl3 (95 mg, 0.706 mmol) was
added portionwise at rt. After stirring for 10 min, a
solution of compound 7 (300 mg, 0.706 mmol) in dry
THF was added dropwise to the mixture. The reaction
mixture was stirred at rt for 0.5 h. Then the reaction
was quenched with ice-water, extracted with ethyl ace-
tate and the combined organic layers were washed
with brine, dried over Na2SO4. The solvent was dis-
tilled off and the residue was purified by flash chro-
matography using petroleum ether and ethyl acetate
(2:1, v/v) as eluent. Compound 8 was obtained as a
white solid (227 mg, 94%). Mp 96–97°C. MS (EI): 342
4.5. (2-Hydroxy-2%-methoxy-4,4%-diacrylic acid ethyl
ester)diphenyl ether, 6
1
(M+, 5), 251(26), 219(63), 191(78), 182(100). H NMR
(200 MHz, CDCl3): 3.83 (s, 6H), 4.29 (d, J=5.5 Hz,
4H), 6.47 (dt, J=15, 5.5 Hz, 2H), 6.81(d, J=8.3 Hz,
2H), 7.08 (dd, J=8.3, 1.6 Hz, 2H), 7.17 (d, J=1.6 Hz,
2H), 7.24 (d, J=15 Hz, 2H).
Under salt–ice bath cooling, compound 5 (600 mg,
1.44 mmol) was added into H2SO4 (5 mL, 6 N), after
a few minutes, sodium nitrite (100 mg, 1.44 mmol) in
water (2.5 mL) was added drop-wise, keep the temper-