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P. Mayo, W. Tam / Tetrahedron 58 (2002) 9513–9525
(933 mg, 6.19 mmol) was added to a flame-dried flask
containing alcohol 3b (287 mg, 2.61 mmol) and imidazole
(269 mg, 3.95 mmol) in DMF (3.5 mL) and the reaction was
stirred for 24 h. After quenching with water (5 mL), the
reaction mixture was extracted into CH2Cl2/hexanes (1:9)
(4£5 mL), and the combined organic layers were washed
with water (10 mL), brine (10 mL) and dried (MgSO4). The
solvent was removed by rotary evaporation and the crude
product was purified by column chromatography
(EtOAc/hexanes¼1:19) to give 3d (397 mg, 1.77 mmol,
68%) as a colorless oil: Rf 0.31 (hexanes); IR (neat): 3070
(m), 2957 (s), 2931 (s), 2886 (s), 2858 (s), 1472 (m), 1463
isomer (cis-18a) d 166.0, 165.3, 144.45, 140.3, 139.1, 127.7,
127.4, 115.6, 51.9, 50.0, 49.8, 44.2, 37.8, 18.6, 21.9; Anal.
calcd for C17H26O4Si: C, 63.32; H, 8.13. Found C, 63.05; H,
8.46.
4.4.2. Cyclopentene (18b) (Table 1, entry 3). A solution of
Ru-catalyst 4 (7.1 mg, 0.0086 mmol) in THF (0.3 mL) was
added to a flame-dried vial containing a solution of
norbornadiene 1b (44.0 mg, 0.177 mmol) and allyltri-
methylsilane 7a (28 mL, 0.176 mmol) in THF (1 mL) via
cannula and rinsed with THF (2£0.2 mL). The reaction was
stirred at room temperature for 3 h. The solvent was
removed by rotary evaporation and the crude product was
purified by column chromatography (hexanes) to give an
inseparable mixture the cis and trans isomers (43:57,
measured by 1H NMR) of cyclopentene 18b (51.4 mg,
0.141 mmol, 80%) as a clear, transparent liquid. Rf 0.49
(hexanes); IR (neat): 3083 (w), 3009 (w), 2955 (s), 2894
(m), 1712 (w), 1648 (m), 1611 (m), 1443 (w), 1418 (m),
(m), 1368 (m), 1256 (s), 1161 (m), 1123 (s), 1103 (m) cm21
;
1H NMR (CDCl3, 400 MHz): d 6.29 (dd, 1H, J¼5.6,
3.0 Hz), 5.96 (dd, 1H, J¼5.6, 2.9 Hz), 4.45 (dt, 1H, J¼7.9,
3.2 Hz), 2.85 (br s, 1H), 2.74 (m, 1H), 1.93 (ddd, 1H,
J¼15.6, 7.9, 3.8 Hz), 1.35 (m, 1H), 1.20 (d, 1H, J¼8.2 Hz),
0.85 (s, 9H), 0.77 (dt, 1H, J¼11.9, 3.2 Hz), 0.04 (s, 3H),
0.03 (s, 3H). 13C NMR (CDCl3, 100 MHz): d 137.5, 132.0,
72.7, 48.5, 47.2, 42.6, 37.1, 25.9, 18.1, 24.6, 24.7. HRMS
calcd for C13H24SiO: m/z 224.1596, found m/z 224.1598.
1248 (s), 1151 (m), 1096 (m) cm21 1H NMR (CDCl3,
;
400 MHz): d 5.50–5.73 (m, 2H), 5.03–5.17 (m, 3H), 3.62–
3.69 (m, 0.43H), 3.23–3.36 (m, 1.57H), 2.57 (t, 0.43H,
J¼8.4 Hz), 2.54 (t, 0.57H, J¼8.4 Hz), 1.56–1.68 (m,
1.43H), 1.42–1.51 (m, 1.57H), 0.03 (s, 3.9H), 0.02 (s,
5.1H); 13C NMR (CDCl3, 100 MHz): major isomer (trans-
18b) d 139.3, 130.0, 129.2, 128.6, 125.8, 116.8, 53.3, 52.3,
37.2, 22.8, 21.9; minor isomer (cis-18b) d 139.3, 128.5,
128.3, 128.0, 125.9, 116.9, 53.3, 46.6, 37.3, 18.7, 21.7.
Anal. calcd for C13H20Br2Si: C, 42.87; H, 5.54. Found C,
42.55; H, 5.80.
4.3.8. endo-Bicyclo[2.2.1]hept-5-en-2-yl acetate (3e).
Acetic anhydride (0.40 mL, 4.2 mmol) was added to a
flame-dried flask containing alcohol 3b (323 mg,
2.93 mmol), pyridine (0.7 mL, 8.65 mmol) and dimethyl-
aminopyridine (10 mg, 0.819 mmol) in CH2Cl2 (1 mL). The
reaction mixture was stirred for 20 h. After quenching with
water (5 mL), the aqueous layer was extracted with CH2Cl2
(4£5 mL) and the combined organic layers were washed
with saturated CuSO4 (5 mL), water (5 mL), brine (5 mL),
and dried (MgSO4). The solvent was removed by rotary
evaporation and the crude product was purified by column
chromatography (EtOAc/hexanes¼1:9) to give 3e (348 mg,
2.29 mmol, 78%) as a colorless oil. Spectral data identical to
those reported in the literature.38
4.4.3. Cyclopentene (18c) (Table 1, entry 4). A solution of
Ru-catalyst 4 (4.4 mg, 0.0053 mmol) in THF (1 mL) was
added to a flame-dried vial containing norbornadiene 1c
(23.3 mg, 0.985 mmol) and allyltrimethylsilane 7a (16 mL,
0.101 mmol) via cannula and rinsed with THF (2£0.5 mL).
The reaction was stirred at room temperature for 27 h. The
solvent was removed by rotary evaporation and the crude
product was purified by column chromatography (hexanes)
to give an inseparable mixture of the cis and trans isomers
(50:50, measured by 1H NMR) of cyclopentene 18c
(25.6 mg, 0.0730 mmol, 74%) as a clear, transparent liquid.
Rf 0.78 (hexanes); IR (neat): 2949 (m), 2891 (w), 1653 (s),
4.4. Ru-catalyzed ROM–CM reactions
4.4.1. Cyclopentene (18a) (Table 1, entry 1). A solution of
Ru-catalyst 4 (8.1 mg, 0.0098 mmol) in THF (1 mL) was
added to a flame-dried vial containing norbornadiene 1a
(43.6 mg, 0.209 mmol) and allyltrimethylsilane 7a (30 mL,
0.189 mmol) via cannula and rinsed with THF (2£0.5 mL).
The reaction was stirred at room temperature for 24 h. The
solvent was removed by rotary evaporation and the crude
product was purified by column chromatography
(EtOAc/hexanes¼1:9) to give an inseparable mixture of
the cis and trans isomers (38:62, measured by 1H NMR) of
cyclopentene 18a (59.9 mg, 0.186 mmol, 89%) as a clear,
transparent liquid. Rf 0.55 (EtOAc/hexanes¼1:4); IR (neat):
3082 (w), 3005 (m), 2954 (s), 2898 (m), 1605 (br, s), 1636
1
1559 (m), 1248 (s), 1145 (w), 1036 (w) cm21; H NMR
(CDCl3, 400 MHz): d 5.72–5.83 (m, 1H), 5.14–5.33 (m,
2H), 4.85–4.96 (m, 2H), 3.68 (t, 0.5H, J¼9.0 Hz), 3.38–
3.48 (m, 1.5H), 2.10–2.21 (m, 1H), 1.68 (dd, 0.5H, J¼13.7,
9.3 Hz), 1.50 (dd, 0.5H, J¼12.5, 0.7 Hz), 1.45 (dd, 0.5H,
J¼12.4, 0.8 Hz), 1.39 (s, 0.5H), 1.38 (br s, 0.5H), 1.34 (ddd,
0.5H, J¼13.8, 6.2, 1.5 Hz), 0.172 (s, 4.5H), 0.170 (br s, 9H),
0.16 (s, 4.5H), 0.02 (s, 4.5H), 20.01 (s, 4.5H); 13C NMR
(CDCl3, 100 MHz): d 159.1, 158.3, 156.3, 156.1, 144.54,
144.50, 134.7, 134.2, 125.3, 123.8, 113.3, 113.2, 58.1, 57.9,
57.3, 51.8, 40.7, 40.6, 22.7, 18.8, 1.52, 1.48, 1.4, 21.5,
21.8. Anal. calcd for C19H38Si3: C, 65.06; H, 10.92. Found
C, 65.42; H, 10.67.
1
(br, s), 1436 (s), 1248 (br, s), 1197 (s), 1132 (s) cm21; H
NMR (CDCl3, 400 MHz): d 5.85 (ddd, 0.38H, J¼10.2, 8.0,
2.3 Hz), 5.81 (ddd, 0.62H, J¼10.2, 8.0, 2.4 Hz), 5.42–5.33
(m, 1H), 5.17–5.25 (m, 1H), 5.11 (m, 0.62H), 5.07 (m,
0.38H), 5.05 (m, 0.62H), 5.02 (m, 0.38H), 3.84–3.91 (m,
0.38H), 3.733 (s, 3H), 3.731 (s, 1.14H), 3.727 (s, 1.86H),
3.54–3.61 (m, 1.62H), 2.43–2.52 (m, 1H), 1.49–1.65 (1,
1.38H), 1.40–1.45 (m, 1.62H), 0.00 (s, 3.42H), 20.03 (s,
5.58H); 13C NMR (CDCl3, 100 MHz): major isomer (trans-
18a) d 166.0, 165.4, 144.53, 140.1, 139.3, 128.8, 128.6,
115.5, 51.8, 49.85, 49.82, 44.2, 37.8, 22.7, 22.1; minor
4.4.4. Cyclopentene (18d) (Table 1, entry 2). A solution of
Ru-catalyst 4 (7.4 mg, 0.0090 mmol) in THF (1 mL) was
added to a flame-dried vial containing norbornadiene 1a
(37.3 mg, 0.179 mmol) and styrene 7b (22 mL, 0.192 mmol)
via cannula and rinsed with THF (2£0.5 mL). The reaction
was stirred at room temperature for 21 h. The solvent was