N. Tokitoh et al.
FULL PAPER
1H;3J 7 Hz; CHMe2), 6.40 (s, 2H; Tbt), 6.80 (s, 2H; Mes), 7.24 (s, 1H),
7.41 ppm (s, 1H); 13C NMR (125 MHz, C2D2Cl4, 1008C): d 2.6 (q; SiMe3),
3.4 (q; SiMe3), 3.5 (q; SiMe3), 17.3 (d; SiCHMe2), 20.7 (q; SiCHMe2), 22.20
(q; SiCHMe2), 22.25 (q; Mes p-Me), 24.9 (q; CHMe2), 25.1 (q; CHMe2),
25.6 (q; CHMe2), 26.1 (q; CHMe2), 26.9 (q; Mes o-Me), 29.4 (d; CHMe2),
29.6 (d; Tbt o-CH), 32.3 (d; Tbt p-CH), 35.8 (d; CHMe2), 126.7 (s), 127.2 (d;
Tip), 130.9 (s), 131.0 (d; Tip), 132.0 (d  2; Mes Tbt), 138.7 (s), 140.0 (s),
140.4 (s), 145.7 (s), 146.0 (s), 148.5 (s), 154.8 (s), 155.2 (s), 186.7 ppm (s); 29Si
NMR (99 MHz, C6D6): d 0.2, 2.0 ppm; high-resolution FAB-MS: m/z:
928.5825; calcd for C52H94NSi7:928.5771.
were assigned to the geometric isomers of 2-isopropenyl-1-mesityl-2-
methyl-1-{2,4,6-tris[bis(trimethylsilyl)methyl]phenyl}silacyclopropane (12).
After standing at room temperature for a further 18 h, the mixture was
heated at 508C for 7 h. However, no change was observed by NMR
spectroscopy. The mixture was heated at 608C for 4 h, at 808C for 2 h, and
1008C for 5 h, during which time the reaction was monitored by NMR
spectroscopy, and the peaks due to 12 disappeared. After further heating at
1008C for 6.5 h, the sealed tube was opened and the solvent was
evaporated. The residue was separated by PTLC (hexane) to afford 10
(34.3 mg, 0.0439 mmol, 60%) together with isocyanide 3e (17.3 mg,
0.0637 mmol, 79%).
Thermolysis of 5d:A solution of 5d in THF (1 mL), prepared from disilene
1 (54.7 mg, 0.0390 mmol) and isocyanide 3d (48.5 mg, 0.0839 mmol), was
heated at 808C for two days and then at 1008C for two days operating the
procedure similar to that mentioned above. The separation of the reaction
mixture with GPLC and DCC (SiO2/hexane) afforded 4,6-bis[bis(trime-
thylsilyl)methyl]-1-mesityl-2,2-bis(trimethylsilyl)benzo-1-silacyclobutene
(9)[28] (35.8 mg, 0.0512 mmol, 65%) together with isocyanide 3d (41.3 mg,
0.0714 mmol, 85%).
Reaction of 5e with isoprene:Isoprene (0.08 mL, 0.8 mmol) was added at
room temperature to a solution of the silylene isocyanide complex 5e in
THF (ca. 1.5 mL), prepared from disilene 1 (56.1 mg, 0.040 mmol) and
isocyanide 3e (23.9 mg, 0.088 mmol) in THF (1 mL). Stirring of the deep
blue solution for 10 min at ambient temperature resulted in the disappear-
ance of the color. After further stirring for 2.5 h, the mixture was separated
by GPLC (solvent:toluene) to afford 13 (51.7 mg, 0.0673 mmol, 84%)
together with isocyanide 3e (23.2 mg, 0.0855 mmol, 97%). 13:colorless
powder, m.p. 172 1758C (decomp); 1H NMR (500 MHz, C6D6, 758C): d
0.01 (s, 18H), 0.14 (s, 9H), 0.15 (s, 9H), 0.28 (s, 18H), 1.41 1.49 (m, 3H),
1.86 (s, 3H), 2.04 (s, 3H), 2.44 2.47 (m, 1H), 2.67 (s, 6H), 2.89 (brs, 2H),
4.32 (s, 1H), 4.43 (s, 1H), 6.57 (s, 2H), 6.70 ppm (s, 2H); 13C NMR
(125 MHz, C6D6, 758C): d 1.0 (q), 1.2 (q), 2.1 (q), 11.9 (t), 21.0 (q), 25.0
(q), 26.5 (q), 29.3 (d), 29.9 (d), 31.3 (d), 103.7 (t), 125.8 (s), 128.3 (d), 128.6
(s), 128.7 (d), 139.6 (s), 145.4 (s), 145.6 (s), 145.7 (s), 153.5 ppm (s); 29Si
NMR (99 MHz, C6D6, 758C): d À88.5, 2.6 ppm; elemental analysis calcd
(%) for C41H78Si7 ¥ H2O:C 62.68, H 10.26; found:C 62.59, H 10.07.
Thermolysis of 5e:A solution of 5e in THF (1 mL), prepared from disilene
1 (61.5 mg, 0.0440 mmol) and isocyanide 3e (25.6 mg, 0.0943 mmol), was
heated at 808C for two days and then at 1008C for 9 h operating the
procedure similar to that mentioned above. The separation of the reaction
mixture with DCC (SiO2/hexane) afforded 9 (48.1 mg, 0.0688 mmol, 78%)
together with isocyanide 3e (24.1 mg, 0.0888 mmol, 94%).
Reaction of silylene isocyanide complexes 5c e with 2,3-dimethyl-1,3-
butadiene
Reaction of 5c:A solution of the silylene isocyanide complex 5c in THF
(ca. 1.5 mL), prepared from disilene
1 (63.9 mg, 0.0457 mmol) and
Thermolysis of 13: A C6D6 solution of 13 (25.2 mg, 0.0328 mmol) was
heated at 1608C for 14 days in a sealed tube. The mixture was purified with
PTLC (hexane:CH2Cl2 20:1) to give 2,5-dihydro-1-mesityl-3-methyl-1-
isocyanide 3c (22.0 mg, 0.0959 mmol) in THF (1 mL), was placed in a dry
Pyrex 10f glass tube, and 2,3-dimethyl-1,3-butadiene (0.10 mL,
0.884 mmol) was added at room temperature. After five freeze-pump-
thaw cycles, the tube was evacuated and sealed. The bluish green solution
was allowed to stand at ambient temperature for five days, but no change
could be observed in the color of the solution. Heating at 508C for 97 h
resulted in the disappearance of the bluish green color and the sealed tube
was opened. After removal of the solvent under reduced pressure, the
residue was chromatographed (GPLC) and separated by PTLC
(hexane:CH2Cl2 20:1) to afford 2,5-dihydro-1-mesityl-3,4-dimethyl-1-
{2,4,6-tris[bis(trimethylsilyl)methyl]phenyl}silole
(14)
(22.1 mg,
0.0288 mmol, 88%). 14:colorless powder, m.p. 159 161 8C; 1H NMR
(500 MHz, CDCl3): d À0.09 (s, 9H), À0.08 (s, 9H), À0.02 (s, 9H), À0.01
(s, 9H), 0.04 (s, 18H), 1.28 (s, 1H), 1.78 (s, 3H), 1.78 1.84 (m, 1H;
CH2CH), 1.88 (d, 1H, 2J 19 Hz; CH2CMe), 2.02 (d, 1H, 2J 19 Hz;
CH2CMe), 2.06 (s, 1H), 2.09 2.15 (m, 1H; CH2CH), 2.16 (s, 1H), 2.21 (s,
3H), 2.37 (s, 6H), 5.56 (m, 1H), 6.24 (s, 1H), 6.37 (s, 1H), 6.74 ppm (s, 2H);
13C NMR (125 MHz, CDCl3): d 0.89 (q), 0.93 (q), 1.1 (q), 1.2 (q), 1.4 (q),
1.5 (q), 20.8 (q), 22.4 (q), 25.6 (q), 26.0 (t), 27.6 (d), 27.9 (d), 29.4 (t), 30.3 (d),
122.8 (d), 125.4 (d), 128.0 (d), 128.9 (s), 129.4 (d), 137.1 (s), 138.2 (s), 140.0
(s), 143.2 (s), 143.5 (s), 151.6 (s),151.8 ppm (s); 29Si NMR (99 MHz, CDCl3):
d 1.7, 2.2, 2.4, 2.6 ppm; elemental analysis calcd (%) for C41H78Si7: C
64.15, H 10.24; found:C 64.14, H 10.15.
{2,4,6-tris[bis(trimethylsilyl)methyl]phenyl}silole
(10)[28]
(35.0 mg,
0.0448 mmol, 49%) and 1-(mesityl{2,4,6-tris[bis(trimethylsilyl)methyl]phe-
nyl}hydroxysilyl)-2,3-dimethylbut-2-ene (11)[28] (10.9 mg, 0.0136 mmol,
15%) together with isocyanide 3c (12.8 mg, 0.0558 mmol, 58%).
Reaction of 5d:The silylene isocyanide complex 5d, prepared from
disilene
1
(62.5 mg, 0.0447 mmol) and isocyanide 3d (54.8 mg,
Reaction of silylene isocyanide complexes 5c e with methanol
0.0948 mmol), was allowed to react with 2,3-dimethyl-1,3-butadiene
(0.10 mL, 0.884 mmol) in THF (ca. 1.5 mL) at room temperature for
106 h operating a procedure similar to that described above. The reaction
mixture was separated by PTLC (hexane:CH2Cl2 10:1) to afford 10
(23.2 mg, 0.0297 mmol, 33%) and 11 (28.1 mg, 0.0351 mmol, 39%)
together with isocyanide 3d (50.2 mg, 0.0868 mmol, 92%).
Reaction of 5c at room temperature:Methanol (0.07 mL, 1.73 mmol) was
added at room temperature to a solution of the silylene isocyanide
complex 5c in THF (ca. 2.0 mL), prepared from disilene 1 (90.5 mg,
0.0647 mmol) and isocyanide 3c (32.3 mg, 0.141 mmol) in THF (1.5 mL).
Stirring for 5 min resulted in the disappearance of the bluish green color.
After stirring for 25 h, the solvent was evaporated. The residue was
separated by PTLC (hexane:CH2Cl2 10:1) to afford mesityl(methoxy)-
Reaction of 5e:The silylene isocyanide complex 5e, prepared from
disilene
1
(63.1 mg, 0.0451 mmol) and isocyanide 3e (25.8 mg,
{2,4,6-tris[bis(trimethylsilyl)methyl]phenyl}silane
0.0964 mmol, 70%) and methyl 1-mesityl-N-(2,4,6-triisopropylphenyl)-1-
({2,4,6-tris[bis(trimethylsilyl)methyl]phenyl}silanecarboximidate (16c)
(15)[28]
(66.1 mg,
0.0950 mmol), was allowed to react with 2,3-dimethyl-1,3-butadiene
(0.10 mL, 0.884 mmol) in THF (ca. 1.5 mL) at room temperature for 71 h
operating a procedure similar to that described above. The reaction
mixture was separated by PTLC (hexane:CH2Cl2 10:1) to afford 10
(23.7 mg, 0.0303 mmol, 34%) and 11 (34.1 mg, 0.0426 mmol, 47%)
together with quantitative recovery of isocyanide 3e.
(9.1 mg, 0.0947 mmol, 7%) together with isocyanide 3c (17.4 mg,
0.0759 mmol, 54%). 16c:white powder; m.p. 191 192 8C; 1H NMR
(500 MHz, CDCl3): d À0.069 (s, 9H), À0.065 (s, 9H), À0.06 (s, 9H), 0.00
(s, 9H), 0.04 (s, 18H), 0.67 (s, 3H), 0.87 (s, 3H), 1.03 (s, 3H), 1.20 (d, 3H,
3J 7 Hz), 1.21 (d, 3H, 3J 7 Hz), 1.29 (s  2, 1H 3H), 1.66 (s, 3H), 1.82
(brs, 1H), 1.99 (s, 1H), 2.11 (s, 1H), 2.17 (s, 3H), 2.31 (s, 3H), 2.79 (d, 1H,
3J 7 Hz), 3.17 (brs, 1H), 3.69 (s, 3H), 5.33 (s, 1H), 6.26 (s, 1H), 6.38 (s,
1H), 6.52 (s, 1H), 6.55 (s, 1H), 6.65 (s, 1H), 6.85 ppm (s, 1H); 13C NMR
(125 MHz, CDCl3): d 0.9 (q), 0.95 (q), 0.99 (q), 1.27 (q), 1.35 (q), 20.7 (q),
21.0 (q), 21.6 (q), 23.0 (q), 23.3 (q), 23.8 (q), 24.2 (q), 24.5 (q), 25.4 (q), 27.8
(d), 28.0 (d), 28.1 (d), 28.4 (d), 30.4 (d), 34.1 (d), 52.4 (q), 119.5 (d), 119.7
(d), 122.3 (s), 123.0 (d), 128.3 (d), 128.9 (d), 129.4 (d), 129.7 (s), 134.5 (s),
137.8 (s), 139.0 (s), 140.7 (s), 142.1 (s), 144.1 (s  2), 144.6 (s), 152.3 (s), 152.7
(s), 166.4 ppm (s); 29Si NMR (99 MHz, CDCl3): d À51.1, 1.7, 1.8, 2.26,
Observation of an intermediate in the reaction of 5e with 2,3-dimethyl-1,3-
butadiene:A solution of the silylene isocyanide complex 5e in C6D6 (ca.
1.0 mL), prepared from disilene 1 (50.8 mg, 0.0363 mmol) and isocyanide
3e (21.8 mg, 0.0803 mmol) in C6D6 (0.7 mL), was placed in a 5f NMR tube,
and 2,3-dimethyl-1,3-butadiene (0.10 mL, 0.884 mmol) was added at room
temperature. After three freeze-pump-thaw cycles, the tube was evacuated
and sealed. After standing at room temperature for 30 min, the 1H, 13C, and
29Si NMR spectra were observed at 258C over 2 h, during which time the
signals for 5e almost disappeared. The 29Si NMR spectrum showed three
peaks (d À76.3, À72.9, and À5.3 ppm with the peak height ratio of
approximately 2:6:3) besides the peaks for trimethylsilyl groups. The peak
at d À5.3 ppm was assigned to 11, and those at d À76.3, and À72.9 ppm
2.31, 2.4 ppm; IR (KBr): nÄ 2206 cmÀ1 (Si H stretching); high-resolution
À
FAB-MS: m/z:959.6489; calcd for C 53H97NOSi7:959.5955; elemental
3540
¹ 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2003, 9, 3530 3543