Beagley et al
739
Isolation of (R)-dichloro[1-(η5-3′-(1R, 2S, 5R)-5-methyl-
mixture was heated under reflux for 12 h, cooled to room
temp, and filtered to remove the lithium chloride formed.
Solvent was removed in vacuo to yield a brown residue
which was redissolved in diethyl ether, washed with water
(3 × 10 cm3), dried over Na2SO4,and the solvent removed in
vacuo to yield a yellow-brown oil. Excess 1-(chlorodimeth-
ylsilyl)-2,3,4,5-tetramethylcyclopentadiene was removed by
distillation (heating to 80°C, 0.01 mm Hg) to yield the iso-
mers of the desired menthyl product 2a as a brown residue.
Yield 3.55 g (67%). EI-MS m/z (%): 382 (M+, 10), 261
([M – TMCp]+, 31), 204 ([M – TMCpSiMe2]+, 100). 1H
NMR (250 MHz, CDCl3) δ:–0.35–0.10 (m, 6H, Si-CH3),
2-(2-propyl)cyclohexyl-cyclopentadienyl)-1′-(η5-2,3,4,5-
tetramethylcyclopentadienyl)dimethylsilane]titanium (4aR)
The above oil was dissolved in the minimium of boiling
hexane and crystallized at –30°C, to yield the title product as
red crystals. Yield 0.75g (19%), mp 162–164°C. [α]20 (c
0.032, DCM): –62.5° (589 nm), –103.1° (578 nm), and –256.3°
(549 nm). EI-MS m/z (%): 498 (M+, 10%), 463 ([M – Cl]+,
1
100). H NMR (250 MHz, CDCl3) δ: 0.66 (m, 3H, CH3),
0.76 (m, 3H, CH3), 0.79 (m, 3H, CH3), 0.82 (m, 3H, CH3),
0.83 (m, 3H, CH3), 0.88–1.76 (m, 9H, CH’s, CH2’s), 1.84 (s,
3H, Cp-CH3), 1.87 (s, 3H, Cp-CH3), 2.00 (s, 3H, Cp-CH3),
3
3
4
0.62 (d, JH,H = 6 Hz, 3H, CH3), 0.75 (d, JH,H = 6 Hz, 3H,
2.10 (s, 3H, Cp-CH3), 2.69–2.81 (m, 1H, CH), 5.37 (t, JH,H
3
= 3 Hz, 1H, Cp-H), 5.67 (t, 3JH,H = 4JH,H = 3 Hz, 1H, Cp-H),
CH3), 0.80 (d, JH,H = 6 Hz, 3H, CH3), 0.85–1.60 (m, 9H,
3
4
6.50 (t, JH,H JH,H = 3 Hz, 1H, Cp-H). 13C NMR (63 MHz,
CDCl3) δ: 155.2, 145.7, 139.1, 137.4, 128.7, 103.4, 96.8 (Cp
quarterary), 126.7, 122.6, 114.3 (C1, C3, C4), 48.6 (C12),
41.7, 41.2 (C6, C7), 35.2, 32.3 (C10, C8), 27.0 (C13), 24.8
(C11) 22.8, 21.8, 16.7, 16.3, 16.2, 13.8, 12.8 (TMCp CH3’s
and menthyl CH3’s), 0.36, –1.5 (SiMe2). Anal calcd. for
C26H40Cl2SiTi: C 62.5, H 8.1, Cl 14.2; found: C 62.4, H 8.1,
Cl 14.1.
CH2’s), 1.60–1.75 (m, 6H, Cp-CH3), 1.78 (s, 3H, Cp-CH3),
1.90 (s, 3H, Cp-CH3), 2.29 (m, 1H, menthyl CH), 2.61–3.21
(m, 2H, allylic), 5.8–6.60 (m, 3H, Cp-H). 13C NMR
(63 MHz, CDCl3) δ: 151.9, 150.4, 145.5, 136.1, 133.5 (Cp
tertiary), 143.0, 142.0, 133.9, 138.5, 131.1, 131.0, 130.4,
127.3, 126.8, 126.6 (Cp quaternary), 47.4, 46.6, 41.9, 33.0,
27.9, 27.7, 22.6, 21.6, 15.3, 14.7, 14.2, 11.3, 11.1 (CH3’s
and CH’s), 43.7, 35.4, 24.5, (CH2’s), 1.0, –4.0 (Si-CH3).
Isolation of (S)-dichloro[1-(η5-3′-(1R, 2S, 5R)-5-methyl-2-
(2-propyl)cyclohexyl-cyclopentadienyl)-1′-(η5-2,3,4,5-
tetramethylcyclopentadienyl)dimethylsilane]titanium (4aS)
A 1:1 diastereomeric mixture (2 g) of (R)- and (S)-
dichloro{1-[η5-3′-(menthylcyclopentadienyl)-1′-[η5-2,3,4,5-
tetramethylcyclopentadienyl)dimethylsilane]}titanium was
dissolved in toluene (200 cm3), cooled to –30°C, and irradi-
ated with UV light using a Hanovair medium pressure
125 W lamp. After 7 d the solvent was removed in vacuo
and the mixture filtered through a silanized silica column,
eluting with 4% diethyl ether in pet ether (40–60 oC), result-
Preparation of 1-(2,3,4,5-tetramethylcyclopentadienyl)-
1′-(3′-(1S, 2S, 5R)-5-methyl-2-(2-propylcyclohexyl-
cyclopentadienyl)dimethylsilane (2b)
An analogous procedure to that employed for the preparation
of 1-(2,3,4,5-tetramethylcyclopentadienyl)-1′-[3′-menthylcyclo-
pentadienyl]dimethylsilane but employing neomenthylcyclo-
pentadiene yielded the desired neomenthyl product 2b as a
yellow oil (70%) found to be 91% pure by GC. (EI) GC–MS
m/z (%): 382 (M+, 12), 261 ([M – TMCp]+, 78), 179 ([M –
1
nmCp]+, 100). H NMR (250 MHz, CDCl3) δ:–0.05–0.33
(m, 6H, Si-CH3), 0.90–1.11 (m, 9H, neomenthyl CH3), 1.07–
1.85 (m, 9H, CH2’s and CH’s), 1.85–2.20 (m, 12H, Cp-
CH3’s), 3.00–3.40 (m, 3H, allylic, neomenthyl CH), 6.15
(br s, 1H, olefinic), 6.36–6.48 (m, 1H, olefinic), 6.61–6.72
(m, 1H, olefinic). 13C NMR (63 MHz, CDCl3) δ: 156.5,
147.7, 147.3, 142.6, 136.1, 135.2, 133.2, 132.4, 129.0, 119.7
(Cp’s), 48.0, 47.9, 37.8, 37.7 (CH’s), 42.4, 35.8, 26.1
(neomenthyl CH2’s), 30.2, 26.5, 22.8, 21.4, 21.3, 14.7, 11.3
(CH3’s), 1.1, –2.6 (SiMe2).
1
ing in a viscous red oil (1.1 g) which was shown by H
NMR spectroscopy to contain a S:R ratio of 3:1. The red oil
was dissolved in boiling pentane and cooled to –30°C; the ti-
tle compound crystallized as red-brown microcrystals which
were collected by suction filtration (520 mg, 26%). FAB-
1
MS m/z (%): 498 (M+, 24), 463 ([M – Cl]+, 100). H NMR
(250 MHz, CDCl3) δ: 0.70 (s, 3H, CH3), 0.72 (m, 3H, CH3),
0.81 (m, 3H, CH3), 0.83 (m, 3H, CH3), 0.86 (m, 3H, CH3),
0.85–1.60 (m, 8H, CH’s, CH2’s), 1.69 (s, 3H, Cp-CH3), 1.83
(s, 3H, Cp-CH3), 2.05 (s, 3H, Cp-CH3), 2.13 (s, 3H, Cp-
CH3), 2.25–2.88 (m, 1H, CH), 2.65–2.78 (m, 1H, CH), 5.05
Synthesis of (R/S)-dichloro[1-(η5-3′-(1R, 2S, 5R)-5-methyl-
2-(2-propyl)cyclohexyl-cyclopentadienyl)-1′-(η5-2,3,4,5-
tetramethylcyclopentadienyl)dimethylsilane]titanium
4
4
3
4
(t, JH,H = JH,H = 3 Hz, 1H, Cp-H), 5.47 (t, JH,H = JH,H
=
3
4
3 Hz, 1H, Cp-H), 6.81 (t, JH,H = JH,H = 3 Hz, 1H, Cp-H).
13C NMR (63 MHz, CDCl3) δ: 148.3, 145.3, 141.6, 132.7,
127.8, 101.8, 96.5 (Cp quaternary), 134.9, 117.7, 115.0 (C1,
C3, C4), 50.1 (C12), 41.8, 40.3 (C6, C7), 35.6 (C10), 32.7
(C8), 27.3 (C13), 24.9 (C11), 22.8, 21.7, 16.3, 15.7 (TMCp
CH3’s and menthyl CH3’s), 0.0, 1.0 (SiMe2). Anal. calcd. for
C26H40Cl2SiTi: C 62.5, H 8.1, Cl 14.2; found: C 62.8, H 8.3,
Cl 14.3.
(4aR/S
)
1-(2,3,4,5-Tetramethylcyclopentadiene)-1′-[3′-menthylcyclo-
pentadiene]dimethylsilane (3.02 g, 7.9 mmol) was dissolved
in THF (45 cm3). A solution of n-butyllithium (2.5 M,
6.3 cm3, 15.8 mmol) in hexanes was added at 0°C and the
mixture stirred at room temp for 30 min. The solution was
cooled to –78°C and TiCl3·3THF (2.9 g, 7.9 mmol) was
added rapidly against a stream of nitrogen and the mixture
was allowed to warm to room temp before heating under re-
flux for 6 h. After cooling to room temp, chloroform
(45 cm3) and concentrated aqueous hydrochloric acid (1 M,
30 cm3) were added and the mixture stirred at room temp in
air for 30 min. The organic layer was separated, dried, and
the solvent removed in vacuo to yield a red viscous oil
Preparation of (R/S)-dichloro[1-(η5-2,3,4,5-tetramethyl-
cyclopentadienyl)-1′-(η5-3′-(1S, 2S, 5R)-5-methyl-2-(2-propyl)-
cyclohexylcyclopentadienyl)dimethylsilane]titanium (4bR/S
)
1-(2,3,4,5-Tetramethylcyclopentadienyl)-1′-[3′-neomenthyl-
cyclopentadienyl]dimethylsilane (3.07 g, 8 mmol) was dis-
solved in THF (45 cm3). A solution of n-butyllithium (2.5 M,
1
which was shown by H NMR to be a 3:1 mixture of R:S.
© 2001 NRC Canada