2280
M. Tanaka et al. / Tetrahedron 60 (2004) 2271–2281
(39), 207 (16), 169 (46), 115 (49), 73 (100); EI(þ)HRMS
calcd for C17H21O2Br (Mþ): 336.0725. Found: 336.0750
(Mþ).
4.4.2. Compound 17d. IR (neat) 3435 (br), 2932,
1
1718 cm21; H NMR (CDCl3) d 7.18–7.38 (m, 5H), 6.31
(d, J¼16.2 Hz, 1H), 6.28 (d, J¼16.2 Hz, 1H), 4.68 (m, 1H),
3.70 (m, 1H), 2.60 (br s, 1H), 2.25 (d, J¼13.6 Hz, 1H), 2.22
(d, J¼13.6 Hz, 1H), 1.30–2.00 (m, 16H), 1.10 (s, 3H), 1.07
(s, 3H); EIMS m/z 370 (Mþ, 3), 279 (8), 241 (13), 199 (10),
149 (100); EI(þ)HRMS calcd for C24H34O3 (Mþ):
370.2508. Found: 370.2610 (Mþ). The enantiomeric excess
of 17f prepared from 17d was determined to be 32% ee by
HPLC.
4.3.7. Compound 14d. A colorless oil; IR (neat) 3435 (br),
1
2930, 1713 cm21; H NMR (CDCl3) d 7.25 (d, J¼7.5 Hz,
2H), 7.10 (d, J¼7.5 Hz, 2H), 6.25–6.40 (m, 2H), 4.67 (m,
1H), 3.68 (m, 1H), 2.52–2.60 (m, 2H), 2.33 (s, 3H), 2.20–
2.30 (m, 3H), 1.40–1.85 (m, 18H); EIMS m/z 370 (Mþ, 13),
258 (37), 198 (100), 182 (28); EI(þ)HRMS calcd for
C24H34O3 (Mþ): 370.2508. Found: 370.2517 (Mþ).
4.4.3. Compound 17e. IR (neat) 3445 (br), 2971,
1
4.3.8. Compound 14f. A colorless oil; 63% ee [HPLC
retention time (tR), 13 and 15 min]; IR (neat) 2925,
1725 cm21; H NMR (CDCl3) d 7.18–7.39 (m, 5H), 6.31
(d, J¼16.5 Hz, 1H), 6.29 (d, J¼16.5 Hz, 1H), 4.73 (m, 1H),
3.72 (m, 1H), 2.21–2.28 (m, 2H), 1.60–2.05 (m, 7H), 1.15–
1.22 (m, 6H), 1.10 (s, 3H), 1.06 (s, 3H); EIMS m/z 330 (Mþ,
14), 272 (12), 241 (28), 198 (64), 181 (66), 129 (94), 91
(100); EI(þ)HRMS calcd for C21H30O3 (Mþ): 330.2195.
Found: 330.2159 (Mþ). The enantiomeric excess of 17f
prepared from 17e was determined to be 28% ee by HPLC.
1
1737 cm21; H NMR (CDCl3) d 7.24 (d, J¼8.1 Hz, 2H),
7.10 (d, J¼8.1 Hz, 2 h), 6.34 (d, J¼15.9 Hz, 1H), 6.29 (dd,
J¼15.9, 7.3 Hz, 1H), 3.62 (s, 3H), 2.51 (m, 1H), 2.32 (s,
3H), 2.18–2.31 (m, 3H), 1.40–1.70 (m, 8H); EIMS m/z 272
(Mþ, 41), 198 (100), 183 (24); EI(þ)HRMS calcd for
C18H24O2 (Mþ): 272.1776. Found: 272.1695 (Mþ).
4.4. Methyl 2-{2-[(1E)-2-phenylvinyl]-1,2-
dimethylcyclopentyl}acetate (17f)
4.4.4. Methyl 2-{2-[(1E)-2-phenylvinyl]-1,2-dimethyl-
cyclohexyl}acetate (18f). Compounds 18a and 18f were
prepared from 16 in a manner similar to that described for
the preparation of 17f. Compound 18a: 12%; a colorless oil;
IR (neat) 3446 (br), 2935, 1723 cm21; 1H NMR (CDCl3) d
7.17–7.39 (m, 5H), 6.51 (d, J¼16.3 Hz, 1H), 6.33 (d,
J¼16.3 Hz, 1H), 4.11–4.15 (m, 2H), 3.72–3.82 (m, 2H),
2.50 (d, J¼13.2 Hz, 1H), 2.28 (d, J¼13.2 Hz, 1H), 1.90 (m,
1H), 1.50–1.75 (m, 8H), 1.13 (s, 3H), 1.11 (s, 3H); EIMS
m/z 316 (Mþ, 16), 213 (14), 55 (100); EI(þ)HRMS calcd for
C20H28O3 (Mþ): 316.2038. Found: 316.2027 (Mþ). Com-
BF3·OEt2 (0.72 mL, 6.0 mmol) was added dropwise to a
stirred solution of 15 (150 mg, 1.0 mmol), benzaldehyde
(127 mg, 1.2 mmol), and ethylene glycol (0.28 mL,
5.0 mmol) in CH2Cl2 (7 mL) at room temperature. After
being stirred overnight, the solution was diluted with 5%
aqueous NaHCO3, extracted with EtOAc, washed with
brine, and dried over MgSO4. Removal of the solvent
afforded an oily residue, which was purified by column
chromatography on silica gel. The fraction eluted with 20%
EtOAc in hexane afforded the ring-cleaved product 17a
(121 mg, 40%) as a colorless oil. Compound 17a: IR (neat)
3440 (br), 2961, 1730 cm21; 1H NMR (CDCl3) d 7.18–7.38
(m, 5H), 6.31 (d, J¼16.2 Hz, 1H), 6.28 (d, J¼16.2 Hz, 1H),
4.13–4.16 (m, 2H), 3.76–3.79 (m, 2H), 2.26 (d, J¼13.9 Hz,
1H), 2.25 (d, J¼13.9 Hz, 1H), 1.67–1.96 (m, 7H), 1.10 (s,
3H), 1.06 (s, 3H); EIMS m/z 302 (Mþ, 30), 241 (61), 199
(75), 129 (100); EI(þ)HRMS calcd for C19H26O3 (Mþ):
302.1882. Found: 302.1840 (Mþ). Solvolysis of 17a with
K2CO3 in MeOH afforded 17f (85%) as a colorless oil.
1
pound 18f: a colorless oil; IR (neat) 2933, 1728 cm21; H
NMR (CDCl3) d 7.15–7.37 (m, 5H), 6.50 (d, J¼16.5 Hz,
1H), 6.29 (d, J¼16.5 Hz, 1H), 3.57 (s, 3H), 2.44 (d,
J¼13.3 Hz, 1H), 2.23 (d, J¼13.3 Hz, 1H), 1.43–1.70 (m,
8H), 1.10 (s, 3H), 1.07 (s, 3H); EIMS m/z 286 (Mþ, 64), 255
(20), 213 (23), 154 (47), 149 (99), 91 (100); EI(þ)HRMS
calcd for C19H26O2 (Mþ): 286.1933. Found: 286.1951
(Mþ).
4.4.5. Compound 18c. IR (neat) 3435 (br), 2935,
1
1722 cm21; H NMR (CDCl3) d 7.18–7.40 (m, 5H), 6.51
Compound 17f: IR (neat) 2957, 1735 cm21
;
1H NMR
(d, J¼16.3 Hz, 1H), 6.32 (d, J¼16.3 Hz, 1H), 4.54 (m, 1H),
3.52 (m, 1H), 2.51 (d, J¼12.8 Hz, 1H), 2.24 (m, 1H), 1.95–
2.10 (m, 3H), 1.20–1.70 (m, 14H), 1.11–1.13 (m, 6H);
EIMS m/z 370 (Mþ, 49), 316 (9), 272 (56), 254 (26), 212
(64), 184 (100); EI(þ)HRMS calcd for C24H34O3 (Mþ):
370.2508. Found: 370.2489 (Mþ). The enantiomeric excess
of 18f prepared from 18c was determined to be 34% ee by
HPLC (column; CHIRALPAK AD, eluent; 1% isopropanol
in hexane, flow rate, 0.5 mL/min, detection; UV 254 nm,
retention time (tR); 20 and 23 min).
(CDCl3) d 71.5–7.38 (m, 5H), 6.31 (d, J¼16.2 Hz, 1H),
6.28 (d, J¼16.2 Hz, 1H), 3.64 (s, 3H), 2.23 (d, J¼13.6 Hz,
1H), 2.20 (d, J¼13.6 Hz, 1H), 1.60–2.00 (m, 6H), 1.11 (s,
3H), 1.03 (s, 3H); EIMS m/z 272 (Mþ, 32), 198 (34), 143
(69), 129 (100); EI(þ)HRMS calcd for C18H24O2 (Mþ):
272.1776. Found: 272.1765 (Mþ).
4.4.1. Compound 17c. IR (neat) 3447 (br), 2938,
1
1723 cm21; H NMR (CDCl3) d 7.18–7.38 (m, 5H), 6.31
(d, J¼16.2 Hz, 1H), 6.28 (d, J¼16.2 Hz, 1H), 4.55 (m, 1H),
3.52 (m, 1H), 2.26 (d, J¼13.9 Hz, 1H), 2.24 (d, J¼13.9 Hz,
1H), 1.15–2.10 (m, 13H), 1.10 (s, 3H), 1.06 (s, 3H); EIMS
m/z 356 (Mþ, 21), 258 (33), 234 (73), 198 (99), 129 (100);
EI(þ)HRMS calcd for C23H32O3 (Mþ): 356.2351. Found:
356.2354 (Mþ). The enantiomeric excess of 17f prepared
from 17c was determined to be 6% ee by HPLC [column;
CHIRALPAK AS, eluent; 0.03% isopropanol in hexane,
flow rate, 0.5 mL/min, detection; UV 254 nm, retention
time (tR); 33 and 38 min].
4.5. 2-[(1S,2S)-2-(Hydroxymethyl)cyclohexyl]-N-[2-(1H-
indol-3-yl)ethyl]acetamide (19)
Ozone gas was bubbled into a solution of 5d (220 mg,
0.62 mmol, 61% de) in MeOH (10 mL) and CH2Cl2
(10 mL) at 278 8C, and the reaction was monitored by
TLC. NaBH4 (70 mg, 1.84 mmol) was added portionwise to
the solution at 278 8C. After being stirred at 278 8C for 2 h,
the mixture was gradually warmed to 0 8C and diluted with