8784 J . Org. Chem., Vol. 66, No. 26, 2001
Kita et al.
1
0.36 mmol of C6F5OH), and CH2Cl2 (1.2 mL, 1 mL). The eluent
for SiO2 column chromatography was hexane-AcOEt (3/1).
Yellowish oil; IR (KBr) 1755, 1732, 1532, 1296 cm-1; 1H NMR
(CDCl3) δ 1.49 (s, 3H), 1.91-2.05 (m, 2H), 2.54-2.59 (m, 1H),
2.71-2.74 (m, 1H), 3.81 (s, 3H), 5.49-5.55 (m, 1H), 6.91 (d,
2H, J ) 8.9 Hz), 7.32 (d, 2H, J ) 8.9 Hz), 8.17 (d, 2H, J ) 8.9
Hz), 8.27 (d, 2H, J ) 8.9 Hz); 13C NMR (CDCl3) δ 26.3, 26.6,
33.0, 51.0, 55.2, 75.8, 114.1, 123.5, 127.4, 131.0, 133.2, 134.7,
150.7, 158.5, 163.9, 213.4. Anal. Calcd for C20H19NO6: C, 65.03;
H, 5.19; N, 3.79; O, 25.99. Found: C, 64.81; H, 5.21; N, 3.78;
O, 26.2.
1728, 1522 cm-1; H NMR (CDCl3) δ 1.30 (s, 3H), 2.01-2.18
(m, 3H), 2.51-2.59 (m, 1H), 5.15 (d, 1H, J ) 17.0 Hz), 5.17 (d,
1H, J ) 11.0 Hz), 5.46 (t, 1H, J ) 9.0 Hz), 5.89 (dd, 1H, J )
11.0, 17.0 Hz), 8.23-8.32 (m, 4H); 13C NMR (CDCl3) δ 23.5,
25.0, 30.8, 49.8, 76.3, 114.6, 123.5, 131.0, 134.8, 140.2, 150.7,
163.8. Anal. Calcd for C15H15NO5: C, 62.28; H, 5.23; N, 4.84;
O, 27.65. Found: C, 62.21; H, 5.26; N, 4.85; O, 27.68.
tr a n s-3-Met h yl-2-oxo-3-(t r im et h ylsilylet h yn yl)cyclo-
p en tyl 4-Nitr oben zoa te (6b). By the same procedure as for
3a , 6b (42.0 mg, 69%) was obtained from 5b (60.4 mg, 0.168
mmol), Al(OC6F5)3 (0.168 mmol prepared from 0.168 mmol of
Me3Al and 0.504 mmol of C6F5OH), and CH2Cl2 (0.7 mL, 1 mL).
The eluent for SiO2 column chromatography was hexane-
AcOEt (15/1). White crystals; mp 99-101 °C; IR (KBr) 2164,
1769, 1732 cm-1; 1H NMR (CDCl3) δ 0.15 (s, 9H), 1.43 (s, 3H),
1.95-2.02 (m, 1H), 2.14-2.21 (m, 1H), 2.28-2.34 (m, 1H),
2.58-2.60 (m, 1H), 5.63 (t, 1H, J ) 9.0 Hz), 8.22 (d, 2H, J )
8.7 Hz), 8.29 (d, 2H, J ) 8.7 Hz); 13C NMR (CDCl3) δ 0.37,
23.6, 25.0, 34.2, 42.4, 75.5, 88.1, 105.8, 123.6, 131.1, 134.7,
150.8, 163.8, 207.7. Anal. Calcd for C18H21NO5Si: C, 60.14;
H, 5.89; N, 3.90; O, 22.26; Si; 7.81. Found: C, 59.98; H, 5.93;
N, 3.89; O, 22.16; Si, 8.04.
cis-3-Meth yl-2-oxo-3-vin ylcyclop en tyl 4-Nitr oben zoa te
(8a ). By the same procedure as for 3a , 8a (94.1 mg, 94%) was
obtained from 7a (100 mg, 0.346 mmol) and Al(OC6F5)3 (0.350
mmol prepared from 0.350 mmol of Me3Al and 1.05 mmol of
C6F5OH), and CH2Cl2 (2.5 mL, 1 mL). The eluent for SiO2
column chromatography was hexane-AcOEt (10/1). Light
yellowish crystals; mp 78-81 °C (hexane-AcOEt); IR (KBr)
1755, 1732, 1532 cm-1; 1H NMR (CDCl3) δ 1.27 (s, 3H), 1.76-
1.88 (m, 1H), 1.93-2.08 (m, 1H), 2.28-2.36 (m, 1H), 2.48-
2.57 (m, 1H), 5.15 (d, 1H, J ) 18.0 Hz), 5.21 (d, 1H, J ) 11.0
Hz), 5.45 (dd, 1H. J ) 8.0, 11.0 Hz), 5.79 (dd, 1H, J ) 11.0,
18.0 Hz), 8.24 (d, 2H, J ) 8.5 Hz), 8.30 (d, 2H, J ) 8.5 Hz);
13C NMR (CDCl3) δ 23.7, 25.8, 31.1, 50.3, 75.9, 115.1, 123.5,
cis-3-Met h yl-2-oxo-3-p h en ylcyclop en t yl 4-Nit r ob en -
zoa te (3c). By the same procedure as for 3a , 3c (49.9 mg, 99%)
was obtained from 2c (50.4 mg, 0.15 mmol), Al(OC6F5)3 (0.150
mmol prepared from 0.15 mmol of Me3Al and 0.45 mmol of
C6F5OH), and CH2Cl2 (1.5 mL, 1 mL). The eluent for SiO2
column chromatography was hexane-AcOEt (5/1). Light yel-
lowish oil; IR (KBr) 1755, 1732, 1539, 1267, 1123, 1107 cm-1
;
1H NMR (CDCl3) δ 1.52 (s, 3H), 1.91-2.08 (m, 2H), 2.55-2.78
(m, 2H), 5.53 (dd, 1H, J ) 10.1, 8.2 Hz), 7.27-7.42 (m, 5H),
8.17 (d, 2H, J ) 9.2 Hz), 8.26 (d, 2H, J ) 9.2 Hz); 13C NMR
(CDCl3) δ 26.3, 26.5, 33.1, 51.8, 75.8, 123.5, 126.3, 127.1, 128.8,
131.0, 134.8, 141.6, 150.7, 164.0, 213.5. Anal. Calcd for C19H17
-
NO5: C, 67.25; H, 5.05; N, 4.13; O, 23.58. Found: C, 67.05; H,
5.14; N, 4.04; O, 23.77.
tr a n s-3-Meth yl-2-oxo-3-p h en ylcyclop en tyl 4-Nitr oben -
zoa te (3d ). By the same procedure as for 3a , 3d (47.7 mg,
95%) was obtained from 2d (50.2 mg, 0.15 mmol), Al(OC6F5)3
(0.150 mmol prepared from 0.15 mmol of Me3Al and 0.45 mmol
of C6F5OH), and CH2Cl2 (1.5 mL, 1 mL). The eluent for SiO2
column chromatography was hexane-AcOEt (5/1). Light yel-
lowish crystals; mp 102-104 °C (hexane-AcOEt); IR (KBr)
1
1755, 1732, 1532, 1267, 1134 cm-1; H NMR (CDCl3) δ 1.53
(s, 3H), 2.11-2.59 (m, 4H), 5.55 (dd, 1H, J ) 10.0, 8.5 Hz),
7.26-7.40 (m, 5H), 8.27 (d, 2H, J ) 8.9 Hz), 8.32 (d, 2H, J )
8.9 Hz); 13C NMR (CDCl3) δ 25.0, 26.3, 33.0, 50.5, 76.9, 123.5,
125.7, 127.0, 128.8, 131.0, 134.8, 142.9, 150.7, 163.8, 212.5.
Anal. Calcd for C19H17NO5: C, 67.25; H, 5.05; N, 4.13; O, 23.58.
Found: C, 67.05; H, 5.14; N, 4.04; O, 23.71.
131.0, 134.8, 139.5, 150.7, 163.9, 212.6. Anal. Calcd for C15H15
NO5: C, 62.28; H, 5.23; N, 4.84; O, 27.65. Found: C, 62.21; H,
5.26; N, 4.85; O, 27.88.
-
cis-3-Meth yl-2-oxo-3-(tr im eth ylsilyleth yn yl)cyclop en -
tyl 4-Nitr oben zoa te (8b). By the same procedure as for 3a ,
8b (29.3 mg, 55%) was obtained from 7b (53.1 mg, 0.148
mmol), Al(OC6F5)3 (0.148 mmol prepared from 0.15 mmol of
Me3Al and 0.444 mmol of C6F5OH), and CH2Cl2 (0.8 mL, 0.7
mL). The eluent for SiO2 column chromatography was benzene-
AcOEt (3/1). White crystals; mp 146-148 °C; IR (KBr) 2161,
1765, 1728 cm-1; 1H NMR (CDCl3) δ 0.16 (s, 9H), 1.43 (s, 3H),
1.77-1.85 (m, 1H), 2.20-2.60 (m, 1H), 2.43-2.55 (m, 2H), 5.44
(dd, 1H, J ) 8.0, 11.0 Hz), 8.25 (d, 2H, J ) 9.0 Hz), 8.31 (d,
2H, J ) 9.0 Hz); 13C NMR (CDCl3) δ -0.1, 23.2, 26.3, 34.0,
43.6, 75.1, 88.0, 105.3, 123.5, 131.1, 134.7, 150.8, 163.9, 207.7.
Anal. Calcd for C18H21NO5Si: C, 60.14; H, 5.89; N, 3.90; O,
22.26; Si; 7.81. Found: C, 59.99; H, 5.88; N, 3.88; O, 22.20; Si,
8.05.
tr a n s-2-Acetyl-2-p h en ylcyclop en tyl 4-Nitr oben zoa te
(3e) a n d cis-2-Acetyl-2-p h en ylcyclop en tyl 4-Nitr oben -
zoa te (3f). From 2e: by the same procedure as for 3a , 3e (47.8
mg, 48%) and 3f (18.0 mg, 18%) were obtained from 2e (100
mg, 0.283 mmol), Al(OC6F5)3 (0.283 mmol prepared from 0.283
mmol of Me3Al and 0.85 mmol of C6F5OH), and CH2Cl2 (1.8
mL, 1 mL). The eluent for SiO2 column chromatography was
hexane-AcOEt (10/1). From 2f: by the same procedure as for
3a , 3e (39.8 mg, 40%) and 3f (46.3 mg, 46%) were obtained
from 2f (100 mg, 0.283 mmol), Al(OC6F5)3 (0.283 mmol
prepared from 0.283 mmol of Me3Al and 0.85 mmol of C6F5-
OH)), and CH2Cl2 (1.8 mL, 1 mL). Da ta for 3e: colorless
crystals; mp 149-151 °C (hexane-AcOEt); IR (KBr) 1725,
1
1705, 1532, 1275, 1121, 1105 cm-1; H NMR (CDCl3) δ 1.62-
2.05 (m, 3H), 1.99 (s, 3H), 2.39-2.59 (m, 3H), 6.21 (d, 1H, J )
5.5 Hz), 7.21-7.32 (m, 5H), 7.63 (d, 2H, J ) 8.9 Hz), 8.09 (d,
2H, J ) 8.9 Hz); 13C NMR (CDCl3) δ 21.5, 25.2, 31.5, 69.6,
79.9, 123.3, 127.5, 127.6, 128.8, 130.2, 135.8, 137.5, 150.2,
163.8, 207.5. Anal. Calcd for C20H19NO5: C, 67.98; H, 5.42; N,
3.96; O, 22.64. Found: C, 67.83; H, 5.44; N, 3.97; O, 22.76.
Da ta for 3f: colorless needles; mp 149-151 °C (hexane-
Syn t h esis of (S)-(+)-Sp or och n ol A (1) (Sch em e 5).
(-)-(1R)-2-Meth yl-3-[4-(m eth oxy)p h en yl]cyclop en t-2-en e-
1-ol (12). BH3‚Me2S (2 M in THF, 3.1 mL, 6.20 mmol) was
added dropwise to a solution of (S)-5,5-diphenyl-2-methyl-3,4-
propan-1,3,2-oxazaborolidine (1.72 g, 6.21 mmol) in THF (40
mL) at 0 °C under N2. After 30 min of stirring, a solution of
the enone 11 (1.26 g, 6.23 mmol) in THF (20 mL) was added
slowly to the resulting mixture. After 30 min of stirring, MeOH
was added to the mixture. The solvent was removed in vacuo.
The residue was purified by SiO2 column chromatography
using hexane-AcOEt (2/1) as the eluent to give 12 (1.28 g,
92%; HPLC analysis 94% ee by CHIRALCEL OD, hexane/i-
PrOH ) 99/1, flow rate 1.0 mL/min), which was recrystalized
in hexane to give optically pure 12 (731 mg, 59%). Light
yellowish crystals; mp 66-68 °C (hexane-AcOEt); IR (KBr)
3400-3200, 1514, 1248, 1036 cm-1; 1H NMR (CDCl3) δ 1.68-
1.79 (m, 1H), 1.74 (s, 1H), 1.91 (s, 3H), 2.32-2.44 (m, 1H),
2.61-2.80 (m, 2H), 3.81 (s, 3H), 4.72 (brs, 1H), 6.89 (d, 2H,
J ) 8.9 Hz), 7.26 (d, 2H, J ) 8.9 Hz); 13C NMR (CDCl3) δ 12.9,
32.6, 33.9, 55.2, 82.2, 113.5, 128.9, 130.3, 134.9, 137.5, 158.4;
[R]15D -25.9 (c 1.05, CHCl3); HPLC analysis >99% ee (CHIRAL-
CEL OD; hexane/i-PrOH ) 99/1; flow rate 1.0 mL/min; tR 84.3
AcOEt); IR (KBr) 1725, 1715, 1530, 1277 cm-1 1H NMR
;
(CDCl3) δ 1.57-1.62 (m, 1H), 1.86-1.98 (m, 2H), 1.91 (s, 3H),
2.20-2.37 (m, 2H), 2.71-2.83 (m, 1H), 6.17 (d, 1H, J ) 5.2
Hz), 7.30-7.43 (m, 5H), 8.14 (d, 2H, J ) 9.1 Hz), 8.30 (d, 2H,
J ) 9.1 Hz); 13C NMR (CDCl3) δ 20.6, 27.3, 31.6, 33.2, 68.5,
81.2, 123.7, 126.3, 127.7, 129.2, 130.7, 135.3, 138.8, 150.7,
163.9, 205.7. Anal. Calcd for C20H19NO5: C, 67.98; H, 5.42; N,
3.96; O, 22.64. Found: C, 67.83; H, 5.44; N, 3.97; O, 22.66.
tr a n s-3-Meth yl-2-oxo-3-vin ylcyclop en tyl 4-Nitr oben -
zoa te (6a ). By the same procedure as for 3a , 6a (82.4 mg,
82%) was obtained from 5a (100 mg, 0.346 mmol), Al(OC6F5)3
(0.35 mmol prepared from 0.35 mmol of Me3Al and 1.05 mmol
of C6F5OH), and CH2Cl2 (2.5 mL, 1 mL). The eluent for SiO2
column chromatography was hexane-AcOEt (10/1). White
crystals; mp 107-109 °C (hexane-AcOEt); IR (KBr) 1755,