B. T. Lee et al. / Tetrahedron 60 (2004) 7391–7396
7395
To a Schlenk flask equipped with a reflux condenser was
added catalyst 1 (478 mg, 0.581 mmol), 1,1,1-trichloro-
ethane (25.0 mL, 21.0 equiv.) and methyl acrylate (5)
(960 mg, 11.2 mmol). The reaction was heated to 75 8C
under N2 atm. for 2 h. The reaction was concentrated and
purified by silica gel chromatography (pentanes/Et2O, 50:1)
to give compound 13 (2.23 g, 10.2 mmol, 91% yield) as a
colorless oil. Compound 13: 1H NMR (CDCl3, 400 MHz): d
4.63 (1H, dd, J¼7.6, 4.2 Hz), 3.82 (3H, s), 3.27 (1H, dd, J¼
15.0, 7.6 Hz), 2.75 (1H, dd, J¼15.0, 4.2 Hz), 2.21 (3H, s).
13C NMR (CDCl3, 100 MHz): d 169.7, 86.9, 53.7, 53.6,
52.4, 37.9. IR (NaCl, thin film): 2993, 2949, 1753, 1438,
1275, 1168, 1086, 985 cm21. Anal. calcd for C6H9Cl3O2: C,
32.83; H, 4.13. Found: C, 32.97; H, 3.91.
0.22 mmol, 76% yield) as a yellow oil. The spectral data
obtained for 15 were identical to an authentic sample
obtained from Aldrich Chemical Co.
4.1.10. 3,3-Dichloro-5-phenyl-dihydro-furan-2-one (16).
To a round-bottom flask equipped with a reflux condenser
was added compound 8 (26.0 mg, 0.088 mmol) and HCl
(1 M aq., 1 mL). The reaction was stirred at 100 8C for 72 h.
After cooling to rt the reaction mixture was extracted with
ether and the organic layer was dried over MgSO4, filtered,
and concentrated to give analytically pure lactone 16
(18 mg, 0.078 mmol, 89% yield) as a colorless oil. Com-
1
pound 16: H NMR (CDCl3, 400 MHz): d 7.47–7.35 (5H,
m), 5.62 (1H, dd, J¼10.1, 5.1 Hz), 3.45 (1H, dd, J¼14.2,
5.1 Hz), 2.93 (1H, dd, J¼14.2, 10.1 Hz). 13C NMR (CDCl3,
100 MHz): d 167.5, 135.6, 129.7, 129.2, 125.9, 82.1, 78.9,
52.6. IR (NaCl, thin film): 3031, 2911, 2848, 1797, 1325,
1199, 1174, 1036, 960 cm21. Anal. calcd for C10H8Cl2O2:
C, 51.98; H, 3.49. Found: C, 51.67; H, 3.42.
4.1.6. 4-(4-Methoxy-phenyl)-but-3-en-2-one (17). To a
Schlenk flask equipped with a reflux condenser was
added catalyst 1 (92 mg, 0.11 mmol), 1,1,1-trichloroethane
(4.4 mL, 20 equiv.) and p-methoxystyrene (3) (300 mg,
2.32 mmol). The reaction was heated to 75 8C under N2 atm.
for 2 h. The reaction was concentrated and purified by silica
gel chromatography (two successive columns; pentanes/
Et2O, 3:2) to give enone 17 (E:Z .20:1, 270 mg,
1.53 mmol, 69% yield) as a white solid. Compound 17
(data for the trans isomer is given): 1H NMR (CDCl3,
400 MHz): d 7.49 (2H, d, J¼8.4 Hz), 7.47 (1H, d, J¼
16.4 Hz), 6.91 (2H, d, J¼8.8 Hz), 6.60 (1H, d, J¼16.4 Hz),
3.83 (3H, s), 2.35 (3H, s), 13C NMR (CDCl3, 100 MHz): d
198.2, 161.6, 143.2, 130.0, 127.1, 125.1, 114.5, 55.6, 27.5.
IR (NaCl, thin film): 3011, 2960, 2930, 2855, 1678, 1610,
1525, 1511, 1186, 1036 cm21. These spectral data are in
agreement with the reported literature values for trans-17.15
4.1.11. 5-Hydroxy-3-methyl-5H-furan-2-one (18). To a
round-bottom flask equipped with a reflux condenser was
added compound 10 (50 mg, 0.23 mmol) and HCl (6 M aq.,
2.3 mL). The reaction was stirred at 100 8C for 48 h. After
cooling to rt the reaction mixture was extracted with ether
and the organic layer was dried over MgSO4, filtered, and
concentrated. Purification by silica gel chromatography
(Et2O) gave pure compound 18 (24 mg, 0.21 mmol, 91%
yield) as a white solid. The spectral data obtained for
compound 18 were identical to the reported literature data.16
4.1.12. 5-Hydroxy-3,5-dimethyl-5H-furan-2-one (19). To
a round-bottom flask equipped with a reflux condenser was
added compound 11 (80 mg, 0.34 mmol) and HCl (1.2 M
aq., 2 mL). The reaction was stirred at 100 8C for 72 h. The
water was removed by a lyophilization and the reaction
mixture was purified by silica gel chromatography (CH2Cl2/
MeOH, 20:1) to provide pure 19 (28 mg, 0.22 mmol, 65%
yield) as a white solid. The spectral data obtained for
compound 19 were identical to the reported literature
data.17
4.1.7. 3-Phenyl-propenal (14). To a round-bottom flask
equipped with a reflux condenser was added compound 6
(70 mg, 0.31 mmol), H2O (2 mL), and AgNO3 (255 mg,
1.50 mmol). The reaction was stirred at 100 8C for 72 h.
After cooling to rt the reaction mixture was extracted with
pentanes and the organic layer was concentrated. Purifi-
cation by silica gel chromatography (pentanes/Et2O, 5:1)
gave trans-cinnamaldehyde (14) (26 mg, 0.19 mmol, 63%
yield) as a yellow oil. The spectral data obtained for 14 was
identical to an authentic sample obtained from Aldrich
Chemical Co.
4.1.13. 2,4,4-Trichloro-3-methyl-pentanoic acid ethyl
ester (20). To a heavy walled reaction tube was added
Cl2Ru(PPh3)3 (37 mg, 0.039 mmol), ethyl crotonate
4.1.8. Alternative hydrolysis. To a heavy walled reaction
tube was added compound 6 (70 mg, 0.31 mmol), and
H2SO4 (10% aq., 1.0 mL). The tube was sealed with a
Teflone screw cap and heated to 180 8C (oil bath temp) for
6.5 h. The reaction was partitioned between Et2O and
H2O. The organic layer was separated, concentrated, and
purified by silica gel chromatography (pentanes/Et2O, 10:1)
to give trans-cinnamaldehyde (14) (31 mg, 0.24 mmol, 77%
yield) as a yellow oil.
(110 mg,
0.964 mmol),
and
1,1,1-trichloroethane
(1.50 mL, 18.5 equiv.). The tube was sealed under N2 with
a Teflone screw cap and heated to 130 8C (oil bath
temperature) for 65 h. The reaction was concentrated and
purified by silica gel chromatography (hexanes/Et2O, 10:1)
to give 199 mg of a colorless oil containing a mixture of the
diastereomeric ester 20 (86% wt/wt, 171 mg, 0.690 mmol,
72% yield, dr¼1.1:1) and a regioisomeric product (14% wt/
wt, 28.0 mg, 0.11 mmol, 12% yield, data not shown).
Compound 20: 1H NMR (CDCl3, 400 MHz), Major
diastereomer: d 4.83 (1H, d, J¼5.2 Hz), 4.22 (2H, m),
2.76 (1H, qd, J¼9.2, 5.2 Hz), 2.25 (3H, s), 1.48 (3H, d,
J¼9.6 Hz), 1.31 (3H, t, J¼7.2 Hz). Minor diastereomer: d
5.04 (1H, d, J¼3.6 Hz), 4.22 (2H, m), 3.08 (1H, qd, J¼9.2,
3.6 Hz), 2.19 (3H, s), 1.34 (3H, d, J¼9.2 Hz), 1.29 (3H, t,
J¼7.2 Hz). 13C NMR (CDCl3, 100 MHz) taken as a
diastereomeric mixture: d 162.8, 87.0, 64.8, 57.7, 57.2,
56.6, 54.0, 51.7, 50.1, 31.8, 29.8, 9.2, 9.0, 7.41, 7.40.
4.1.9. 4-Phenyl-but-3-en-2-one (15). To a round-bottom
flask equipped with a reflux condenser was added
compound 7 (70 mg, 0.29 mmol), H2O (3.0 mL), and
AgNO3 (250 mg, 1.47 mmol). The reaction was stirred at
100 8C for 16 h. After cooling to rt the reaction mixture was
extracted with pentanes and the organic layer was
concentrated. Purification by silica gel chromatography
(pentanes/Et2O, 5:1) gave enone 15 (E:Z .10:1, 32 mg,