4:1 endo:exo). Mp 98–100 °C; vmax (KBr disc) 2998, 2955, 2895,
1614, 1408, 1329, 1243, 1161, 1119, 1079, 1069, 835 cm−1; H
(250 MHz) 7.60–7.20 (4H, m, Ar–H), 6.00–5.80 (1H, m, 4-H),
5.50–5.20 (1H, m, 5-H), 3.20–3.10 (0.2H, m, 3-H exo), 3.10–3.00
(0.8H, m, 3-H endo), 1.80–1.30 (2H, m, 6-H2), 1.03 (0.6H, d,
J = 7.4 Hz, 3-CH3 exo), 0.97 (2.4H, d, J = 7.2 Hz, 3-CH3 endo),
0.22 [7.2H, s, OSi(CH3)3 endo], 0.20 [7.2H, s, Si(CH3)3 endo], 0.12
[1.8H, s, Si(CH3)3 exo], 0.08 [1.8H, s, OSi(CH3)3 exo], −0.30 [7.2H,
s, Si(CH3)3 endo], −0.01 [1.2H, s, Si(CH3)3 exo]; 19F (235 MHz)
−62.52; m/z (EI) 487 (M+ − H, 2%), 415 [M+ − Si(SiMe3)3, 17%],
312 (30), 262 (37), 147 (28), 73 (100). Repeated flash column
chromatography (eluting petrol) gave the endo diastereoisomer as
a single isomer. H (300 MHz) 7.51 (2H, d, J = 8.4 Hz, Ar–H), 7.46
(2H, d, J = 8.4 Hz, Ar–H), 5.95 (1H, m, 4-H), 5.58 (1H, m, 5-H),
3.10 (1H, m, 3-H), 1.40 (2H, m, 6-H2), 0.98 (3H, d, J = 7.4 Hz, 3-
CH3), 0.22 [9H, s, OSi(CH3)3], 0.20 [9H, s, Si(CH3)3], −0.30 [9H, s,
Si(CH3)3]; C (75 MHz) 150.59, 136.82, 127.06 (q, 2JC–F = 31.95 Hz
s, Si(CH3)3 exo], −0.16 [6.48H, Si(CH3)3 endo], −0.26 [6.48H, s,
Si(CH3)3 endo], −0.27 [2.52H, s, Si(CH3)3 exo]; C (50 MHz)
157.86, 140.18, 138.86, 133.52, 132.21, 131.34, 130.97, 129.73,
129.50, 113.16, 112.98, 87.50, 86.45, 55.31, 55.25, 51.85, 50.89,
45.30, 44.58, 34.22, 33.4, 30.96, 2.55, 2.46, 0.94, 0.14, −0.13,
−0.37; m/z (EI) 448 (M+, 1%), 209 (20), 73 (100); HRMS (EI):
Found M+, 448.2113; C22H40O2Si4 requires M, 448.2105.
2,2-Bistrimethylsilyl-3-[4′-(trifluoromethyl)phenyl]-3-tri-
methylsilyloxy-2-silabicyclo[2.2.1]hept-5-ene 5cy. Reaction of
4-trifluoromethylbenzoyltris(trimethylsilyl)silane 2c with cyclopen-
tadiene gave the title compound as a mixture of diastereoisomers
(85%, 4:1 endo:exo). vmax 3062, 2955, 2896, 1926, 1794, 1614,
1445, 1406, 1326, 1250, 1168 cm−1; H (250 MHz) 7.51 (1.6H, d,
J = 8.2 Hz, Ar–H endo), 7.40 (1.6H, d, J = 8.2 Hz, Ar–H endo),
7.35 (0.4H, d, J = 8.2 Hz, Ar–H exo), 7.27 (0.4H, d, J = 8.2 Hz,
Ar–H exo), 6.30 (0.2H, dd, J = 8.3, 3.6 Hz, 5-H exo), 6.15 (0.8H,
dd, J = 8.3, 3.6 Hz, 5-H endo), 5.94 (0.2H, dd, J = 8.3, 3.2 Hz, 6-H
exo), 5.79 (0.8H, dd, J = 8.3, 3.2 Hz, 6-H endo), 3.31 (0.2H, m, 4-
H exo), 3.05 (0.8H, m, 4-H endo), 2.35 (2H, m, 7-H2), 2.05 (0.8H,
m, 6-H endo), 2.01 (0.2H, m, 1-H exo), 0.32 [7.2H, s, –OSi(CH3)3
endo], 0.14 [1.8H, s, OSi(CH3)3 exo], −0.07 [1.8H, s, Si(CH3)3 exo],
−0.16 [7.2H, s, Si(CH3)3 endo], −0.30 [9H, s, Si(CH3)3]; C (63 MHz)
152.85, 151.14, 141.03, 139.39, 129.54 (q, J = 32.4 Hz, C–CF3 exo),
128.20 (q, J = 32.4 Hz, C–CF3 endo), 125.80(q, J = 3.6 Hz, C–C–CF3
exo) 124.72 (q, J = 3.7 Hz, C–C–CF3 endo), 124.24 (q, J = 272.3 Hz,
CF3 endo) 123.80 (q, J = 272.4 Hz, CF3 exo), 86.82, 84.51, 51.53,
50.93, 45.62, 44.79, 34.21, 30.95, 2.5, 2.14, 0.86, 0.03, −0.36, −0.61;
19F (235 MHz) −62.69; m/z (CI, NH3) 487 (MH+, 2%), 466 (MH+ −
F, 3%), 405 (24), 397 (30), 203 (57), 147 (20), 90 (58), 73 (100).
3
F3C–C), 126.02, 125.32, 124.60 (q, JC–F = 3.75 Hz, F3C–C–CH),
1
124.49 (q, JC–F = 269.93 Hz, CF3), 122.69, 119.10, 79.09, 42.97,
16.52, 8.26, 3.45, 0.66, −1.10.
2-Methyl-1-bistrimethylsilyl-2-trimethylsilyloxy-3-methyl-
silacyclohex-4-ene 5ex. Reaction of acetyltris(trimethylsilyl)-
silane 4e with E-1,3-pentadiene gave the title compound as a
mixture of diastereoisomers (ca. 21%, 2:1 endo:exo), along
with other inseparable components. H (200 MHz) 5.80–5.20 (2H,
m, CH), 2.60–2.50 (0.33H, m, 3-H exo), 2.26–2.20 (0.67H, m,
3-H endo), 1.70–1.10 (2H, m, 6-H2), 1.53 (1H, s, 2-CH3 exo), 1.34
(2H, s, 2-CH3 endo), 1.09 (1H, d, J = 6.8 Hz, 3-CH3 exo), 1.00
(2H, d, J = 7.2 Hz, 3-CH3 endo), 0.16–0.13 [5 × 9H, s, Si(CH3)3];
C (100 MHz) 135.00, 125.78, 45.62, 43.48, 30.70, 23.34, 16.48,
14.92, 8.86, 7.98, 3.54, 0.38, 0.23; m/z (EI) 285 [M+ − Si(CH3)3,
7%], 207 (61), 183 (29),147 (72), 133 (58), 73 (100).
2,2-Bistrimethylsilyl-3-tert-butyl-3-trimethylsilyloxy-2-sila-
bicyclo[2.2.1]hept-5-ene 5fy. Reaction of trimethylacetyltris(tri-
methylsilyl)silane 2f with cyclopentadiene gave the title compound
as a mixture of diastereoisomers (70%, 6:1 endo:exo).
2,2-Bis(trimethylsilyl)-3-phenyl-3-trimethylsilyloxy-2-
silabicyclo[2.2.1]hept-5-ene 5ay. Reaction of benzoyltris(tri-
methylsilyl)silane 2a with cyclopentadiene gave the title compound
as a mixture of diastereoisomers (0.433 g, 68%, 3:1 endo:exo).
Mp 88–89 °C; vmax (CHCl3) 3050, 2948, 2878, 1599, 1500, 1250,
1169, 1041, 1021, 838 cm−1; H (400 MHz) 7.40–7.05 (5H, m,
Ar–H), 6.32 (0.25H, dd, J = 5.4, 3.3 Hz, 5-H exo), 6.11 (0.75H,
dd, J = 5.4, 3.3 Hz, 5-H endo), 5.86 (0.25H, dd, J = 5.4, 3.3 Hz,
6-H exo), 5.77 (0.75H, dd, J = 5.4, 3.3 Hz, 6-H endo), 3.40 (0.25H,
m, 4-H, exo), 3.30 (0.75H, m, 4-H, endo), 2.45 (0.25H, m, 7-HH
exo), 2.35 (1.75H, m, 7-H2 endo and 7-HH exo), 2.02 (0.75H, m,
1-H endo), 1.95 (0.25H, m, 1-H exo), 0.28 [6.75H, s, OSi(CH3)3
endo], 0.21 [2.25H, s, OSi(CH3)3 exo], −0.16 [2.25H, s, Si(CH3)3
exo], −0.18 [6.75H, s, Si(CH3)3 endo], −0.28 [6.75H, s, Si(CH3)3
endo], −0.29 [2.25H, s, Si(CH3)3 exo]; C (100 MHz) 148.11,
146.46, 140.37, 139.07, 129.89, 129.51, 127.84, 127.75, 126.10,
125.66, 87.07, 84.45, 51.54, 50.66, 45.44, 44.56, 34.15, 30.86, 2.44,
0.89, 0.06, −0.33, −0.59; m/z (EI) 418 (M+, 2%), 403 (M+ − CH3,
1%), 345 (M+ − SiMe3, 16%), 337 (50), 147 (42), 135 (21), 117
(21), 73 (100).
vmax (thin film) 3051, 2945, 2887, 1621, 1500, 1212, 1153, 1042,
1021, 822 cm−1; H (250 MHz) 6.31 (0.14H, dd, J = 5.3, 3.2 Hz,
5-H), 6.09 (0.86H, dd, J = 5.4, 3.2 Hz, 5-H), 5.90 (0.14H, dd,
J = 5.3, 3.2 Hz, 6-H), 5.65 (0.86H, dd, J = 5.4, 3.2 Hz, 6-H), 2.89
(0.14H, m, 4-H), 2.77 (0.86H, m, 4-H), 2.35–2.18 (2H, m, 7-Hd2);
2.90–2.80 (1H, m, 3-H), 1.06 [1.26H, s, C(CH3)3], 0.99 [7.74H,
s, C(CH3)3], 0.22 [7.74H, Si(CH3)3], 0.21 [1.26H, Si(CH3)3], 0.19
[1.26H, Si(CH3)3], 0.17 [7.74H, Si(CH3)3], 0.15 [7.74H, Si(CH3)3],
0.14 [1.26H, Si(CH3)3]; C (100 MHz) 138.77, 129.36, 100.14,
52.12, 47.69, 38.43, 31.24, 30.42, 4.68, 2.08, 1.53; m/z (EI) 400
(M+, 1%), 385 (M+ − CH3, 1%), 73 (100).
2,2-Diphenyl-1,1,1,3,3,3-hexamethyltrisilane 7.40 A mixture
of chlorotrimethylsilane (14.96 g, 137.2 mmol) and dichloro-
diphenylsilane (17.36 g, 68.62 mmol) was added to a stirred suspen-
sion of magnesium turnings in THF/HMPA (1:1, 100 ml), so as to
maintain a gentle reflux. The mixture was then heated to reflux for
a further 12 h. Saturated NH4Cl solution (100 ml) was then carefully
added. The organic layer was separated, and the aqueous layer ex-
tracted with ether (3 × 40 ml). The combined organic extracts were
dried over MgSO4, filtered and concentrated. Distillation gave the
title compound as a colourless oil (11.90 g, 53%). Bp 140 °C/1 mbar
(lit.40 147–148 °C/2 mbar). vmax (thin film) 3021, 2948, 2885, 1420,
1216, 1201, 1196, 914, 842 cm−1; H (300 MHz) 7.55–7.28 (10H,
m, Ar–H), 0.19 [18H, s, Si(CH3)3]; C (75 MHz) 135.93, 133.97,
128.12, 127.81, −0.50; m/z (EI) 328 (M+, 33%), 313 (M − CH3,
10%), 255 [M − Si(CH3)3, 100%].
2,2-Bis(trimethylsilyl)-3-[4′-methoxyphenyl]-3-trimethyl-
silyloxy-2-silabicyclo[2.2.1]hept-5-ene 5by. Reaction of 4-
methoxybenzoyltris(trimethylsilyl)silane 2b with cyclopentadiene
gave the title compound as a mixture of diastereoisomers (68%,
5:2 endo:exo). vmax (thin film) 3048, 2953, 2894, 1608, 1509,
1249, 1177, 1042, 1021, 838 cm−1; H (200 MHz) 7.21 (0.56H, d,
J = 7.6 Hz,Ar–H exo), 7.17 (1.44H, d, J = 7.6 Hz,Ar–H endo), 6.81
(0.56H, d, J = 7.6 Hz, Ar–H exo), 6.75 (1.44H, d, J = 7.6 Hz, Ar–H
endo) 6.40–6.30 (0.28H, dd, J = 5.4, 3.0 Hz, 5-H exo), 6.20–6.10
(0.72H, dd, J = 5.4, 3.0 Hz, 5-H endo), 5.95–5.85 (0.28H, dd,
J = 5.4, 3.0 Hz, 6-H exo), 5.85–5.75 (0.72H, dd, J = 5.4, 3.0 Hz,
6-H endo), 3.87 (0.84H, s, –OCH3 exo), 3.85 (2.16H, s, –OCH3
endo), 3.37 (0.28H, m, 4-H exo), 3.25 (0.72H, m, 4-H endo), 2.40
(0.28H, m, 7-HH exo), 2.35 (1.72H, m, 7-H2 endo and 7-HH exo),
1.98 (0.72H, m, 1-H endo), 1.90 (0.28H, m, 1-H exo), 0.26 [6.48H,
s, –OSi(CH3)3 endo], 0.16 [2.52H, s, OSi(CH3)3 exo], −0.14 [2.52H,
3,4-Diphenyl-3,4-bis(trimethylsilyloxy)-1,1,2,2-tetrakis-
(trimethylsilyl)-1,2-disilacyclobutane10a.11 Asolutionofbenzoyl-
tris(trimethylsilyl)silane (0.49 g, 1.38 mmol) in cyclohexane (50 ml)
was irradiated for approx. 2 h using a 1 kW mercury lamp. Con-
centration gave the crude product. Flash column chromatography
(eluting: petrol) gave the title compound as a white crystalline solid
(0.21 g, 43%); mp 148 °C (lit.11 149–150 °C). vmax (KBr disc) 3050,
2956, 2893, 1597, 1489, 1442, 1402, 1250 cm−1; H (200 MHz)
O r g . B i o m o l . C h e m . , 2 0 0 4 , 2 , 2 3 8 1 – 2 3 9 2
2 3 8 7