Barbero et al.
25.0 (CH2), 19.7 (CH3), -3.0 (CH3). MS: m/z 231 (M+ - CH3,
5), 217 (M+ - COH, 10), 135 (SiMe2Ph, 100). Anal. Calcd for
C15H22OSi: C, 73.11; H, 9.00. Found: C, 73.41; H, 9.31.
(c) 4-[(Dimethylphenylsilyl)methyl]-3-propylpent-4-
enal (10c). Colorless oil. IR (neat, cm-1): 1715, 1630, 1245,
1110. 1H NMR (CDCl3): δ 9.48 (1H, t, J ) 2.1 Hz), 7.58-7.27
(5H, m), 4.70 (1H, s), 4.66 (1H, s), 2.43-2.27 (3H, m), 1.77 (2H,
s), 1.57-1.13 (4H, m), 0.86 (3H, t, J ) 7.1 Hz), 0.37 (3H, s),
0.36 (3H, s). 13C NMR (CDCl3): δ 202.7 (C), 148.2 (C), 138.7
(C), 133.7 (CH), 129.1 (CH), 127.8 (CH), 109.0 (CH2), 47.3
(CH2), 40.8 (CH), 35.9 (CH2), 24.4 (CH2), 20.2 (CH2), 14.1 (CH3),
-2.6 (CH3), -2.8 (CH3). MS: m/z 274 (M+, 3), 259 (M+ - CH3,
5), 245 (M+ - CHO, 7), 139 (M+ - SiMe2Ph, 10), 135 (SiMe2-
Ph, 100). Anal. Calcd for C17H26OSi: C, 74.39; H, 9.55.
Found: C, 74.68; H, 9.86.
Sı´ntesis of Methylenecycloheptanones. To a stirred
solution of enones 12a-d (3 mmol) in dry toluene (15 mL) is
added EtAlCl2 (1.8 M, 3 mmol) at 0 °C under nitrogen. The
mixture is stirred at this temperature for 1 h, and then
saturated solution of NaHCO3 (2 mL) is added. Extraction
(Et2O), drying (MgSO4), and chromatography gave the follow-
ing compounds.
(a) 4-Methylenecycloheptanone (13a). Colorless oil. IR
(neat, cm-1): 1730, 1630. 1H NMR (CDCl3): δ 4.82 (1H, s),
4.78 (1H, s), 2.58 (2H, t, J ) 6.2 Hz), 2.52 (2H, t, J ) 6.5 Hz),
2.33-2.45 (4H, m), 1.83-1.73 (2H, m). 13C NMR (CDCl3): δ
215.1 (CdO), 139.5 (C), 112.6 (CH2), 43.3 (CH2), 43.1 (CH2),
38.2 (CH2), 31.8 (CH2), 24.2 (CH2). MS: m/z 124 (M+, 19). Anal.
Calcd for C8H12O: C, 77.38; H, 9.74. Found: C, 77.72; H, 9.99.
(b) 3-Methyl-4-methylenecycloheptanone (13b). Color-
less oil. IR (neat, cm-1): 1735, 1650. 1H NMR (CDCl3): δ 4.81
(1H, s), 4.78 (1H, s), 2.49-2.21 (5H, m), 2.01-1.80 (4H, m),
1.30 (3H, d, J ) 7.4 Hz). 13C NMR (CDCl3): δ 212.7 (CdO),
145.0 (C), 111.1 (CH2), 49.8 (CH), 43.8 (CH2), 41.2 (CH2), 39.8
(CH2), 26.4 (CH2), 20.8 (CH3). MS: m/z 138 (M+, 12), 123 (M+
- CH3, 10). Anal. Calcd for C9H14O: C, 78.21; H, 10.21.
Found: C, 78.59; H, 10.48.
(c) 4-Methylene-3-propylcycloheptanone (13c). Color-
less oil. IR (neat, cm-1): 1728, 1632. 1H NMR (CDCl3): δ 4.83
(1H, s), 4.77 (1H, s), 2.55-2.20 (5H, m), 1.70-1.50 (4H, m),
1.39-1.21 (4H, m), 0.90 (3H, t, J ) 7.0 Hz). 13C NMR
(CDCl3): δ 213.9 (CdO), 139.1 (C), 111.9 (CH2), 51.9 (CH2),
48.9 (CH2), 43.3 (CH), 35.8 (CH2), 35.4 (CH2), 24.9 (CH2), 20.4
(CH2), 13.4 (CH3). MS: m/z 166 (M+, 20). Anal. Calcd for
C11H18O: C, 79.46; H, 10.91. Found: C, 79.81; H, 11.21.
(d) 4-Methylene-3-phenylcycloheptanone (13d). Color-
less oil. IR (neat, cm-1): 1730, 1630. 1H NMR (CDCl3): δ 7.53-
7.27 (5H, m), 4.88 (1H, s), 4.85 (1H, s), 3.83 (1H, dd, J ) 7.9
and 7.7 Hz), 2.98 (1H, dd, J ) 16.2 and 7.9 Hz), 2. 83 (1H, dd,
J ) 16.2 and 7.7 Hz), 2.66-2.48 (4H, m), 1.71-1.56 (2H, m).
13C NMR (CDCl3): δ 208.0 (CdO), 147.1 (C), 142.2 (C), 129.0
(CH), 127.6 (CH), 126.1 (CH), 110.2 (CH2), 49.7 (CH2), 47.5
(CH), 43.1 (CH2), 29.6 (CH2), 21.9 (CH2). MS: m/z 200 (M+,
20), 77 (Ph, 14). Anal. Calcd for C14H16O: C, 83.96; H, 8.05.
Found: C, 84.29; H, 8.38.
135 (SiMe2Ph, 100). Anal. Calcd for C17H24OSi: C, 74.94; H,
8.88. Found: C, 75.28; H, 9.21.
(b) [1R*,2R*]-2-Methyl-4-methylene-1-[2-(dimethyl-
phenylsilyl)-2-propenyl]cyclopentan-1-ol (14b). Colorless
oil. IR (neat, cm-1): 3400, 1650, 1240, 1090. 1H NMR
(CDCl3): δ 7.59-7.37 (5H, m), 5.92 (1H, d, J ) 2.9 Hz), 5.71
(1H, d, J ) 2.9 Hz), 4.84-4.82 (2H, m), 2.74-2.67 (1H, m),
2.43 (1H, d, J ) 14.1 Hz), 2.43 (1H, d, J ) 14.1 Hz), 2.30 (1H,
d, J ) 14.1 Hz), 2.07-1.89 (3H, m), 1.33-1.29 (1H, s, OH),
0.87 (3H, d, J ) 7.0 Hz), 0.45 (3H, s), 0.43 (3H, s). 13C NMR
(CDCl3): δ 148.6 (C), 147.1 (C), 138.3 (C), 133.9 (CH), 131.3
(CH2), 129.1 (CH), 127.9 (CH), 107.2 (CH2), 82.0 (C), 44.3 (CH2),
44.2 (CH), 41.2 (CH2), 38.7 (CH2), 15.8 (CH3), -2.2 (CH3), -2.5
(CH3). MS: m/z 271 (M+ - CH3, 7), 151 (M+ - SiMe2Ph, 12),
135 (SiMe2Ph, 100). Anal. Calcd for C18H26OSi: C, 75.46; H,
9.15. Found: C, 75.78; H, 9.36.
(c) [1R*,2S*]-2-Methyl-4-methylene-1-[2-(dimethyl-
phenylsilyl)-2-propenyl]cyclopentan-1-ol (15b). Colorless
oil. IR (neat, cm-1): 3400, 1650, 1240, 1090. 1H NMR
(CDCl3): δ 7.59-7.37 (5H, m), 5.92 (1H, d, J ) 2.9 Hz), 5.68
(1H, d, J ) 2.9 Hz), 4.85 (1H, s with fine couplings), 4.81 (1H,
s with fine couplings), 2.61 (1H, d, J ) 13.7 Hz), 2.45 (1H, dd,
J ) 16.4 and 8.1 Hz ), 2.25 (1H, ddd, J ) 16.4, 4, 9 and 2.3
Hz), 2.15 (1H, d, J ) 13.7 Hz), 2.14-2.10 (2H, m), 1.90-1.80
(1H, m), 1.06 (1H, s, OH), 0.90 (3H, d, J ) 6.7 Hz), 0.43 (6H,
s). 13C NMR (CDCl3): δ 148.9 (C), 147.4 (C), 138.4 (C), 134.0
(CH), 131.0 (CH2), 129.1 (CH), 127.9 (CH), 106.6 (CH2), 81.0
(C), 46.7 (CH2), 44.8 (CH2), 43.0 (CH), 38.7 (CH2), 12.4 (CH3),
-2.2 (CH3), -2.3 (CH3). MS: m/z 271 (M+ - CH3, 7), 151 (M+
- SiMe2Ph, 12), 135 (SiMe2Ph, 100).
(d) [1R*,4S*]-4-Methyl-3-methylene-1-[2-(dimethyl-
phenylsilyl)-2-propenyl]cyclopentan-1-ol (14d) and [1R*,-
4R*] (15d). Colorless oils. Chromatography gave the alcohols
as a mixture. (14d) IR (neat, cm-1): 3560, 1650, 1240, 1090.
1H NMR (CDCl3): δ 7.56-7.27 (5H, m), 5.92-5.89 (1H, m),
5.71-5.69 (1H, m), 4.85-4.78 (2H, m), 2.72-2.67 (1H, m), 2.45
(1H, d, J ) 10.6 Hz), 2.49-2.19 (3H, m), 1.77 (1H, ddd, J )
12.9, 7.4 and 2.4 Hz), 1.33-1.15 (2H, m), 1.04 (3H, d, J ) 6.7
Hz), 0.43 (6H, s). 13C NMR (CDCl3): δ 155.5 (C), 147.2 (C),
138.2 (C), 133.9 (CH), 131.3 (CH2), 129.1 (CH), 127.9 (CH),
105.4 (CH2), 79.3 (C), 47.6 (CH2), 47.2 (CH2), 46.6 (CH2), 36.3
(CH), 20.2 (CH3), -2.3 (CH3), -2.4 (CH3). MS: m/z 286 (M+,
16), 271 (M+ - CH3, 97), 194 (M+ - Ph - CH3, 19), 135 (SiMe2-
1
Ph, 29). (15d) H NMR (CDCl3): δ 7.56-7.27 (5H, m), 5.92-
5.89 (1H, m), 5.71-5.69 (1H, m), 4.85-4.78 (2H, m), 2.45 (2H,
d, J ) 10.6 Hz), 2.49-2.19 (4H, m), 1.98 (1H, dd, J ) 13.0 and
8.9 Hz), 1.33-1.15 (2H, m), 1.09 (3H, d, J ) 6.8 Hz), 0.43 (6H,
s). 13C NMR (CDCl3): δ 155.5 (C), 147.1 (C), 138.2 (C), 133.9
(CH), 131.5 (CH2), 129.1 (CH), 127.9 (CH), 105.4 (CH2), 79.2
(C), 48.7 (CH2), 47.5 (CH2), 47.1 (CH2), 36.3 (CH), 18.6 (CH3),
-2.5 (CH3).
(e)
[1R*,4S*]-4-Ethyl-3-methylene-1-[2-(dimethyl-
phenylsilyl)-2-propenyl]cyclopentan-1-ol (14i) and [1R*,-
4R*] (15i). Colorless oils. Chromatography gave the alcohols
as a mixture. (14i) IR (neat, cm-1): 3560, 1650, 1240, 1090.
1H NMR (CDCl3): δ 7.59-7.27 (5H, m), 5.91-5.88 (1H, m),
5.72-5.67 (1H, m), 4.85 (1H, s with fine couplings), 4.80 (1H,
s with fine couplings), 2.49-2.15 (3H, m), 2.41 (2H, s), 1.92
(1H, ddd, J ) 13.2, 8.8 and 1.2 Hz), 1.71-1.55 (2H, m), 1.33-
1.15 (2H, m), 0.86 (3H, t, J ) 7.4 Hz), 0.43 (3H, s), 0.42 (3H,
s). 13C NMR (CDCl3): δ 154.0 (C), 147.0 (C), 138.2 (C), 133.9
(CH), 131.6 (CH2), 129.1 (CH), 127.9 (CH), 106.1 (CH2), 78.9
(C), 47.7 (CH2), 46.5 (CH2), 44.4 (CH2), 43.4 (CH), 28.1 (CH2),
12.1 (CH3), -2.4 (CH3), -2.5 (CH3). M. S. m/z 285 (M+-CH3,
5), 165 (M+-SiMe2Ph, 7), 135 (SiMe2Ph, 100). (15i): 1H NMR
(CDCl3): δ 7.59-7.27 (5H, m), 5.91-5.88 (1H, m), 5.72-5.67
(1H, m), 4.85 (1H, s with fine couplings), 4.80 (1H, s with fine
couplings), 2.49-2.15 (3H, m), 2.41 (2H, s), 1.79 (1H, ddd, J
) 13.0, 7.7 and 2.6 Hz), 1.71-1.55 (2H, m), 1.33-1.15 (2H,
m), 0.85 (3H, t, J ) 7.3 Hz), 0.43 (3H, s), 0.42 (3H, s). 13C NMR
(CDCl3): δ 154.3 (C), 147.2 (C), 138.2 (C), 133.9 (CH), 131.3
(CH2), 129.1 (CH), 127.7 (CH), 106.0 (CH2), 79.3 (C), 47.4 (CH2),
Allylsilane-Terminated Cyclizations. EtAlCl2 (2 mmol,
1.8 M) was added slowly to a solution of 7 (2 mmol) in DCM
(8 mL), under nitrogen. After stirring at 0 °C for 0.5 h, brine
was added (5 mL) and the mixture extracted with ether, dried,
and evaporated. Purification by flash chromatography gave the
products 14 and 15.
(a) 1-[2-(Dimethylphenylsilyl)-2-propenyl]-3-methyl-
enecyclopentan-1-ol (14a). Colorless oil. IR (neat, cm-1):
1
3585, 1665, 1550, 1240, 1090. H NMR (CDCl3): δ 7.57-7.27
(5H, m), 5.91 (1H, d, J ) 2.2 Hz), 5.70 (1H, d, J ) 2.2 Hz),
4.89-4.80 (2H, m), 2.51-2.39 (1H, m), 2.46 (2H, s), 2.36-2.22
(1H, m), 2.29 (1H, d, J ) 16.6 Hz), 2.15 (1H, d, J ) 16.6 Hz),
1.65-1.57 (2H, m), 1.22 (1H, s), 0.43 (6H, s). 13C NMR
(CDCl3): δ 150.4 (C), 147.1 (C), 138.2 (C), 133.9 (CH), 131.4
(CH2), 129.0 (CH), 127.7 (CH), 106.8 (CH2), 80.9 (C), 47.0 (CH2),
46.4 (CH2), 39.3 (CH2), 30.2 (CH2), -2.4 (CH3). MS: m/z 257
(M+ - CH3, 7), 195 (M+ - Ph, 30), 137 (M+ - SiMe2Ph, 68),
6882 J. Org. Chem., Vol. 70, No. 17, 2005