Reductive dehydroxy coupling of 2-(hydroxymethyl)indenes to prepare ethano-bridged bis(2-indenyl) ansa-titanocenes

Article abstract of DOI:10.1016/S0022-328X(99)00024-8

New examples of ansa-titanocenes derived from 1,2-bis(2-indenyl)ethane have been prepared. The titanium-mediated reductive coupling of 2-(hydroxymethyl)indenes provided a convenient method for substrate dimerization. Alkyl substitution of the indene ring at C(3) improved the regioselectivity of the reductive coupling to provide the ethylene bis(2-indenyl)ansa-ligands in 29-62% yield.

Full text of DOI:10.1016/S0022-328X(99)00024-8

Journal of Organometallic Chemistry 579 (1999) 338–347
Reductive dehydroxy coupling of 2-(hydroxymethyl)indenes to prepare
ethano-bridged bis(2-indenyl) ansa-titanocenes
Hasan Palandoken, Justin K. Wyatt, Shawn R. Hitchcock 1, Marilyn M. Olmstead,
Michael H. Nantz *
Department of Chemistry, Uni6ersity of California, Da6is, CA 95616, USA
Received 29 October 1998
Abstract
New examples of ansa-titanocenes derived from 1,2-bis(2-indenyl)ethane have been prepared. The titanium-mediated reductive
coupling of 2-(hydroxymethyl)indenes provided a convenient method for substrate dimerization. Alkyl substitution of the indene
ring at C(3) improved the regioselectivity of the reductive coupling to provide the ethylene bis(2-indenyl)ansa-ligands in 29–62%
yield. © 1999 Elsevier Science S.A. All rights reserved.
Keywords: ansa-Titanocenes; Chiral; Indenyl; Metallocene; Titanium; Reductive coupling
1. Introduction
its derivatives. The direct alkylation of an indenyl anion
with a 1,2-dihaloethane [5] (route a) and the metal-me-
diated coupling reaction of benzofulvene [6,7] (route b)
Chiral ansa-titanocenes have shown promise as ho-
mogeneous catalysts for various organic transforma-
tions including alkene epoxidation and hydrogenation
[1]. The field has primarily featured ansa-titanocenes
based on 1,2-bis(1-indenyl)ethane (1, Scheme 1, [2]). We
have examined the reactivity of ansa-titanocenes
derived from structurally isomeric 1,2-bis(2-in-
denyl)ethane (2) and observed that these systems also
are capable of catalytic reactivity [3]. However, the
synthesis of chiral bis(2-indenyl) ansa-titanocenes poses
a greater synthetic challenge due to the intrinsic inactiv-
ity of the indenyl C(2) position [4]. Examination of the
approaches used to synthesize ethano-bridged indenyl
ansa-ligands illustrates the difference in ease of prepa-
ration (Scheme 1). Two straightforward strategies, de-
picted by the key retrosynthetic considerations a and b,
have been used to prepare 1,2-bis(1-indenyl)ethane and
* Corresponding author. Tel.: +1-530-752-6357; fax: +1-530-752-
8995.
E-mail address: mhnantz@ucdavis.edu (M.H. Nantz)
1 Present address: Department of Chemistry, Illinois State Univer-
sity, Normal, IL 61761, USA.
Scheme 1. General approaches to ethano-bridged bis(indenyl) sys-
tems.
0022-328X/99/$ - see front matter © 1999 Elsevier Science S.A. All rights reserved.
PII: S0022-328X(99)00024-8

H. Palandoken et al. / Journal of Organometallic Chemistry 579 (1999) 338–347
339
Table 1
[9a]. Diradical coupling of the incipient allylic radicals
at either the terminal methylene carbon or indenyl
methine carbon accounts for the formation of 4a and
5a, respectively. Treatment of 3b under similar reaction
conditions gave identical results, affording a 1:1 mix-
ture of products 4b and 5b in 36% yield (Table 1).
Results of Ti-mediated coupling reactions (Eq. (1))
Alcohol
R1
R2
Yield %a (4+5)
Ratiob 4:5
3a
3b
3c
3d
3e
3f
H
CH3
H
H
H
H
H
36
36
35
33
44
25
82
1:1
1:1
6:1
8.3:1
Only 4e
Only 4f
3.2:1
i-Bu
i-Pr
Bn
SiMe3
Ph
c
H
H
3g
a Isolated.
b Determined by 1H-NMR.
c R2 on C(1), see structure, Scheme 2.
have provided convenient access to bis(1-indenyl) ansa-
ligands. These methods, however, cannot be employed
with ease to obtain the 1,2-bis(2-indenyl)ethane frame-
work due to the inactivity of the C(2) position.
To date, ethano-bridged 2-indenyl ansa-ligands have
been prepared by tetraalkylation of 1,4-bis(phenylsul-
fonyl)butane using o-bis(halomethyl)benzenes (route c)
[8]. Although expedient, the tetraalkylation approach
delivers 2 in optimized yields of only 12–15%. To
improve the availability of bis(2-indenyl) ansa-ligands,
we have examined a new synthesis based on retrosyn-
thetic consideration d. We report herein on the reduc-
tive dehydroxy coupling of 2-(hydroxymethyl)indenes
as a method for synthesis of ethano-bridged bis(2-in-
denyl) ligands.
(1)
Substitution at C(3) was examined to minimize for-
mation of the a-coupling products 5, a strategy that
alters only the order of alkylation previously reported
for synthesis of C(3)-substituted bis(2-indenyl) ansa-lig-
ands [3]. Silyl protection of the hydroxymethyl group of
3a was followed by treatment with n-BuLi and addition
of alkyl bromide to effect the alkylation (Scheme 2).
Subsequent silyl group removal by treatment with tetra-
butylammonium fluoride gave substituted indenes 3c–e
[11] in 30–74% overall yield.
Silylation of C(1) was accomplished by treatment of
3a with two equivalents of n-BuLi followed by quench-
ing with excess TMS-Cl. Aqueous work-up and silica
gel column chromatography was sufficient for O-silyl
group removal and gave indene 3f in 97% yield.
Introduction of a phenyl group onto C(3) was ac-
complished by regioselective opening of an indenyl
C(2)–C(3) epoxide at the benzylic position. This ap-
proach was initiated by treatment of 6 with mCPBA in-
2. Results and discussion
We became interested in 2-(hydroxymethyl)indene
(3a) as a potentially useful precursor of 2-indenyl ansa-
ligands due to the inherent symmetry of ethano-bridged
ansa-metallocenes. Disconnection of the bridging car-
bons suggests a dimerization strategy. The low-valent
titanium-mediated reductive coupling of allylic alcohols
is known to be an effective means of alkyl dimerization
[9]. Thus, we pursued the synthesis and reductive cou-
pling of 2-indenyllic alcohols.
2.1. Ligand syntheses
Initially, we examined the reductive coupling reac-
tions of 2-(hydroxymethyl)indene (3a) [10] and a
methyl-substituted derivative, 3b. Treatment of alcohol
3a with low-valent titanium [9a] in 1,2-dimethoxyethane
afforded a 1:1 mixture of the desired coupling product
4a and the regioisomeric a-coupling product 5a in 36%
combined yield (Eq. (1), Table 1). The isolation of 5a
was not unexpected since the formation of allylic radi-
cals has been postulated to occur on thermal fragmen-
tation of intermediate titanium (II) dialkoxide species
Scheme 2. Indene substitution, [i] tert-butyldimethylsilyl chloride,
Et3N, CH2Cl2, cat. DMAP; [ii] (a) n-BuLi, THF, −78°C, (b) R2Br,
55°C, 12 h; [iii] TBAF, THF; [iv] (a) n-BuLi (two equivalents), THF,
−78°C, (b) trimethylsilyl chloride; [v] mCPBA, CH2Cl2, pH 7 phos-
phate buffer, 0°C, 8 h; [vi] PhMgBr, CuI, THF, −65 to −20°C, 1 h;
[vii] SOCl2, pyridine, 0°C to r.t., 3 h; [viii] DMSO, H2O, 90°C, 3 h.

340
H. Palandoken et al. / Journal of Organometallic Chemistry 579 (1999) 338–347
Table 2
Substituent effect on complexation diastereoselectivity (Eq. (2))
Bisindene
R1
R2
Ratioa 8:9
4b
4c
4d
4e
4f
CH3
H
H
H
H
H
1:1
4:1
i-Bu
i-Pr
Bn
SiMe3
Ph
2:1
3.6:1b
c
–
4g
H
4.3:1
a Determined by 1H-NMR integration.
b Complexation ratio from Ref. [3].
c No metallocene formation, Ref. [16].
CH2Cl2. We observed that the epoxidation was effective
only when a pH 7 phosphate buffer was used to prevent
decomposition of the acid-sensitive benzylic epoxide
[12]. Subsequent exposure of the epoxide to PhMgBr in
the presence of catalytic CuI gave alcohol 7. Elimina-
tion of the 3° alcohol was effected by reaction with
thionyl chloride in pyridine. The crude elimination
product was then heated in aqueous DMSO [13] to
remove the silyl protection group. In this manner,
indenyl alcohol 3g was isolated in 31% yield from 3a.
With the C(3)-substituted 2-(hydroxymethyl)indenes
prepared, we examined their titanium-mediated reduc-
tive dehydroxy coupling using the conditions that were
optimal for the coupling of 3a. The reactions of the
C(3)-substituted substrates afforded 1,2-bis(2-in-
denyl)ethane derivatives 4 with greater regioselectivity
than the coupling of unsubstituted indenes (Table 1).
The formation of less amounts of the a-coupled prod-
ucts 5 is consistent with the expectation that C(3)-sub-
stitution might deter reaction at the more hindered
center. Substitution of C(3) with phenyl (e.g. 3g) greatly
improved the overall yield of the coupling reaction
presumably due to greater stabilization of the radical
intermediates. However, the regioselectivity of the cou-
pling reaction in this case was somewhat diminished
relative to the other C(3)-substituted examples.
Fig. 1. Molecular structure of compound 8c with 50% probability
ellipsoids depicted and the H atoms removed for clarity.
ratio [3,15]. The observation that a sterically more
demanding a-substituent slightly favors formation of
the racemic isomer is supported by the new examples.
Assignments of configuration were based on X-ray
crystallographic analyses of recrystallized products ob-
tained from 4b–d (Figs. 1–3).
(2)
The determination of diastereoselectivity in the com-
plexation of 4e was made by spectral comparison of the
crude hydrogenation mixture to a reference sample of
2.2. Ligand complexation
Preparation of the corresponding ansa-titanocene
complexes 8 and 9 from bis-indenes 4 was accomplished
using a literature procedure [3]. Treatment of the corre-
sponding dianions of 4 with TiCl3·(thf)3 [14] was fol-
lowed by oxidative work-up and immediate catalytic
hydrogenation of the crude reaction mixture. Mixtures
of racemic and meso bis(tetrahydroindenyl) ansa-ti-
tanocenes were obtained in varying ratios (Table 2).
Previous complexation studies suggested a relationship
between the size of the substituent proximal to the
ethylene bridge and the diastereomeric (racemic:meso)
Fig. 2. Molecular structure of compound 8d with 50% probability
ellipsoids depicted and the H atoms removed for clarity.

H. Palandoken et al. / Journal of Organometallic Chemistry 579 (1999) 338–347
341
based on the 1H-NMR spectrum observed for the crude
complexation mixture prior to hydrogenation. Collins
[15] has previously noted that the meso isomers of
a-substituted ethylene-bridged ansa-titanocenes exhibit
a compact 4H multiplet corresponding to the ethylene
bridge. The racemic isomers exhibit a distinctly separate
pair of 2H multiplets for the ethylene bridge [19]. The
major ansa-titanocene that is formed on complexation
of 4g exhibits a pair of 2H multiplets at l 3.12 and
2.44, thus suggesting the assignment of 8g as the major
isomer.
2.3. X-ray structures of ansa-titanocenes 8c-d and 9b
Crystal data for the three structures are given in
Table 3 and selected bond lengths and angles are given
in Tables 4–6. All structures were solved by direct
methods (SHELXS [20]) and refined by full-matrix least
Fig. 3. Molecular structure of compound 9b with 20% probability
ellipsoids depicted and the H atoms removed for clarity.
the racemic benzyl-substituted (2-tetrahydroindenyl)
ansa-titanocene [17].
squares based on F2
(SHELXL-97 [21]); empirical ab-
sorption corrections (XABS2 [22]) were performed. For
9b, there was disorder in the ethylene portion of the
ligand. Two positions were used to model this carbon
(the other is generated by a mirror plane). A chirality
test on 8c was performed and the flack parameter was
refined to the value 0.078 (11), indicating the correct
sense of chirality as depicted.
The largest diastereoselectivity on titanium complex-
ation was observed with phenyl-substituted bis-indene
4g, affording a 4.3:1 preference for the racemic isomer
8g (Table 2, [18]). Attempts to isolate 8g by recrystal-
lization from the hydrogenation reaction mixture were
unsuccessful. The stereochemical assignment for 8g is
Table 3
Crystal data for 8c, 8d, and 9b
8c
8d
9b
Empirical formula
Formula weight
Color and habit
Crystal system
C28H40Cl2Ti
495.40
Red needle
Orthorhombic
P212121
C26H36Cl2Ti
467.35
Red plate
Monoclinic
P21/n
C22H28Cl2Ti
411.24
Red parallelepiped
Orthorhombic
Pnma
Space group
Unit cell dimensions
˚
a (A)
8.6851(9)
10.875(2)
26.808(2)
8.377(2)
13.724(2)
19.891(4)
7.4166(9)
˚
b (A)
19.751(4)
13.839(3)
93.79(2)
2284.7(9)
130(2)
˚
c (A)
i (°)
3
˚
V (A )
2532.1(5)
130(2)
4
2024.6(5)
293(2)
4
Temperature (K)
Z
4
Crystal size (mm)
0.07×0.11×0.37
1.300
Cu–Ka (u=1.54178
4.885
0.12×0.50×0.60
1.359
Mo–Ka (u=0.71069)
0.619
0.16×0.20×0.24
1.349
Mo–Ka (u=0.71069)
0.689
Dcalc. (g cm−3
)
˚
Radiation (A)
v(Mo–Ka) (mm−1
)
Range of trans. factors
Diffractometer
0.59–0.76
Syntex P21
0.73–0.94
Siemens R3m/V
0.86–0.91
Siemens R3m/V
Index ranges
−25h510, −25k511, −45l529 −105h510, 05h525, 05h517
05h517, 05h525,05h59
U range (°)
3.30–57.08
3751
2916 [Rint=0.025]
2916
284
0.0874
1.80–27.50
5757
5250 [Rint=0.022]
5249
266
0.1009
2.05–27.49
2385
2385
2385
117
Reflections collected
Independent reflections
Number of data refined
Number of parameters refined
a
wR2 (all data)
0.2285
0.0705
R1b [I\2|(I)]
0.0386
0.0412
a wR2=[S[w(F2o−Fc2)2]/S[(wFo2)2]]1/2. w=1/[|2(F2o)+(aP)2+bP] where P=(Fo2+2F2c)/3.
b R1=SꢀꢀFoꢀ−ꢀFcꢀꢀ/SꢀFoꢀ.

342
H. Palandoken et al. / Journal of Organometallic Chemistry 579 (1999) 338–347
Table 4
Table 6
Selected bond lengths and angles for titanocene 8ca
Selected bond lengths and angles for titanocene 9ba
˚
˚
Bond lengths (A)
Bond lengths (A)
Ti(1)–Cl(1)
Ti(1)–Cl(2)
Ti(1)–C(1)
Ti(1)–C(2)
Ti(1)–C(3)
C(1)–C(2)
C(2)–C(3)
C(3)–C(4)
C(4)–C(5)
C(5)–C(6)
2.0303
2.3475
2.372
2.342
2.487
1.430
1.432
1.494
1.536
1.503
Ti(1)–C(12)
Ti(1)–C(20)
Ti(1)–C(19)
C(12)–C(20)
C(19)–C(20)
C(18)–C(19)
C(17)–C(18)
C(16)–C(17)
CentA–Ti
2.372
2.427
2.515
1.410
1.440
1.502
1.519
1.527
2.115
2.111
Ti(1)–Cl(1)
Ti(1)–Cl(2)
Ti(1)–C(1)
Ti(1)–C(5)
Ti(1)–C(4)
C(1)–C(5)
C(4)–C(5)
C(4)–C(10)
2.334
2.341
2.350
2.361
2.482
1.417
1.402
1.550
Ti(1)–C(1%)
Ti(1)–C(5%)
Ti(1)–C(4%)
C(9)–C(10)
C(8)–C(9)
C(1)–C(6A)
CentA–Ti
CentB–Ti
2.350
2.361
2.482
1.553
1.468
1.576
2.092
2.092
Bond angles (°)
Cl(1)–Ti(1)–Cl(2)
C(5)–C(1)–C(2)
C(3)–C(4)–C(5)
C(4)–C(5)–C(1)
CentB–Ti
94.96
105.1
107.0
109.3
C(8)–C(9)–C(10)
C(4)–C(10)–C(9)
C(1)–C(6A)–C(6B)
CentA–Ti–CentB
110.7
109.4
104.1
129.9
Bond angles (°)
Cl(1)–Ti(1)–Cl(2)
C(9)–C(1)–C(2)
C(1)–C(9)–C(8)
C(8)–C(3)–C(4)
96.70
107.1
108.4
123.9
C(6)–C(5)–C(4)
C(8)–C(9)–C(21)
C(1)–C(10)–C(11)
CentA-Ti-CentB
112.2
125.4
108.9
129.7
a CentA and CentB are the two centroids of the h5-coordinated
cyclopentadienyl rings.
a CentA and CentB are the two centroids of the h5-coordinated
cyclopentadienyl rings.
and work-up solvents were removed by rotary evapora-
tion unless otherwise indicated. All column chromatog-
raphy was performed using silica gel purchased from
EM Separations Technology (230–400 mesh). NMR
spectra were recorded on a General Electric QE-300
spectrometer. IR spectra were recorded as CHCl3 solu-
tions on a Mattson FTIR 3000 spectrometer. Melting
points are uncorrected. Mass spectral analyses were
performed by the University of Minnesota Mass Spec-
trometry Service Laboratory.
In summary, we have improved the access to deriva-
tives of 1,2-bis(2-indenyl)ethane. Our approach relies
on a titanium-mediated reductive dehydroxy coupling
of C(3)-substituted 2-(hydroxymethyl)indenes as the
key step. Application of this methodology has provided
new chiral, a-substituted ansa-titanocenes that may find
use in catalytic applications.
3.1. 2-(Hydroxymethyl)-5-methylindene (3b)
3. Experimental
To a stirred solution of methyl phenylsulfonylacetate
(12.5 g, 58.4 mmol) in DMF (90 ml) at 0°C, was added
in one portion LiH (1.40 g, 175.2 mmol). After stirring
for 2 h, 3,4-bis(chloromethyl)toluene (11.7 g, 61.9
mmol) was added and the reaction mixture was allowed
to warm to room temperature (r.t.). The reaction was
recooled to 0°C after 48 h, quenched by careful addi-
tion of saturated aqueous NH4Cl, and then diluted with
CH2Cl2 (200 ml) and H2O (150 ml). The layers were
separated and the aqueous phase was extracted with
CH2Cl2. The combined organic extract was washed
with water, saturated brine, and dried (Na2SO4). The
solvents were removed by rotary evaporation to afford
the crude product. Recrystallization of the residue from
methanol gave 15.5 g (80%) of 2-carbomethoxy-2-
phenylsulfonyl-5-methylindan as a white solid, m.p.
113–114°C; IR (CHCl3): 3029, 1735, 1320, 1258, 1146
Reactions were carried out under argon atmosphere
using standard Schlenk techniques. THF and Et2O were
distilled from Na-benzophenone ketyl immediately
prior to use. 1,2-Dimethoxyethane was distilled from
LiAlH4. DMF was distilled from MgSO4. All reaction
Table 5
Selected bond lengths and angles for titanocene 8da
˚
Bond lengths (A)
Ti(1)–Cl(1)
Ti(1)–Cl(2)
Ti(1)–C(1)
Ti(1)–C(2)
Ti(1)–C(3)
C(1)–C(2)
C(2)–C(3)
C(3)–C(4)
C(4)–C(5)
C(5)–C(6)
2.3307
2.3426
2.385
2.342
2.468
1.401
1.415
1.491
1.509
1.515
Ti(1)–C(12)
Ti(1)–C(20)
Ti(1)–C(19)
C(12)–C(20)
C(19)–C(20)
C(18)–C(19)
C(17)–C(18)
C(16)–C(17)
CentA–Ti
2.382
2.431
2.525
1.428
1.430
1.505
1.538
1.514
2.116
2.111
cm−1 1H-NMR (CDCl3): l 2.29 (s, 3H), 3.64 (d,
;
CentB–Ti
J=17.4 Hz, 2H), 3.67 (s, 3H), 3.80 (d, J=16.8 Hz,
2H), 7.02 (m, 3H), 7.54 (app. t, J=7.8 Hz, 2H), 7.65
(app. t, J=7.5 Hz, 1H), 7.85 (d, J=7.5 Hz, 2H);
13C-NMR (CDCl3): l 21.1, 38.0, 38.2, 53.4, 79.1, 123.8,
124.7, 128.1, 128.7, 129.7, 134.1, 135.3, 137.0, 138.5,
168.5. HRMS (EI) Calc. for C18H18O4S: 330.0926.
Found: 330.0927.
Bond angles (°)
Cl(1)–Ti(1)–Cl(2)
C(9)–C(1)–C(2)
C(1)–C(9)–C(8)
C(8)–C(3)–C(4)
92.48
108.3
107.0
123.6
C(6)–C(5)–C(4)
C(8)–C(9)–C(21)
C(1)–C(10)–C(11)
CentA–Ti–CentB
111.1
127.9
111.3
129.2
a CentA and CentB are the two centroids of the h5–coordinated
cyclopentadienyl rings.

H. Palandoken et al. / Journal of Organometallic Chemistry 579 (1999) 338–347
343
To a stirred solution of 2-carbomethoxy–2-phenyl-
sulfonyl-5-methylindan (10.6 g, 32.2 mmol) in THF
(110 ml) at −50°C was added a solution of KOt-Bu
(90 ml, 1.45 M in THF, 130.5 mmol). On complete
addition, the reaction mixture was stirred for 10 min
and then quenched by addition of saturated aqueous
NH4Cl (200 ml). The quenched reaction was diluted
with EtOAc and the layers were separated. The
aqueous layer was extracted with EtOAc. The com-
bined organic extract was washed with H2O, saturated
brine, and dried (Na2SO4). Removal of the solvents
afforded the crude product as a 2:1 mixture of methyl
120.6, 123.6, 124.1, 126.2, 126.6, 143.2, 144.9, 149.3;
HRMS (EI) Calc. for C16H24OSi: 260.1596. Found:
260.1597.
3.3. 2-(tert-Butyldimethylsilyloxymethyl)-1-phenyl-
indan-2-ol (7)
To
a
solution of 2-(tert-butyldimethylsilyloxy-
methyl)indene (107 mg, 0.411 mmol) in CH2Cl2 (6.9
ml), a phosphate buffer (6.9 ml, pH 7, 0.05 M in both
KH2PO4 and Na2HPO4) was added. To the biphasic
mixture at 0°C was added ‘acid free’ m-CPBA [23] (78
mg, 0.452 mmol) in one portion. After 8 h the reaction
mixture was poured into a 1:1 mixture of saturated
aqueous NaHCO3 (20 ml) and saturated aqueous
Na2S2O3 (20 ml) and extracted with CH2Cl2 three
times. The combined organic extract was dried over
Na2SO4, and the solvents were removed under reduced
pressure to afford the crude epoxide. 1H-NMR
(CDCl3): l 0.11 (s, 3H), 0.12 (s, 3H), 0.93 (s, 9H), 3.08
(d, J=17.7 Hz, 1H), 3.16 (d, J=17.9 Hz, 1H), 4.01 (d,
J=11.7 Hz, 1H), 4.11 (d, J=11.7 Hz, 1H), 4.17 (d,
J=0.74 Hz, 1H), 7.15–7.26 (m, 3H), 7.46 (d, J=7.2
Hz, 1H).
1
and tert-butyl esters. H-NMR (CDCl3): l 1.56 (s, 9H),
2.41 (s, 6H), 3.59 (br s, 2H), 3.64 (br s, 2H), 3.84 (s,
3H), 7.21–7.31 (m, 8H).
The crude mixture was dissolved in Et2O (160 ml)
and cooled to −78°C. To the solution diisobutylalu-
minum hydride was added dropwise (100 ml of a 1.0 M
solution in hexane, 100 mmol). The reaction was al-
lowed to warm to r.t. and stirred for 12 h. The reaction
was quenched by slowly pouring the reaction mixture
into an Erlenmeyer flask containing a vigorously stirred
solution of 3 M NaOH (200 ml). The layers were
separated and the aqueous phase was extracted with
additional portions of Et2O. The combined organic
extract was washed with 10% HCl, saturated brine and
dried (MgSO4). Removal of the solvents by rotary
evaporation afforded 5.03 g (97%) of 3b as an insepara-
ble mixture of isomers, m.p. 60–61°C; IR (CHCl3):
To a suspension of CuI in THF (3 ml) at −40°C,
PhMgBr (411 ml, 3.0 M solution in Et2O, 1.23 mmol)
was added. After stirring for 15 min the reaction was
cooled to −65°C and a solution of the crude epoxide
in THF (1 ml) was added dropwise via cannula. The
reaction was warmed to −20°C over 50 min in which
time the reaction was quenched with a saturated
aqueous solution of NH4Cl and diluted with Et2O. The
organic layer was washed with water, saturated brine,
and dried over Na2SO4. The solvents were removed and
the residue was purified by chromatography, eluting
with 2% ethyl acetate/hexane on SiO2, to afford 119 mg
(82%) of alcohol 7 as a colorless oil. IR (neat) 3563,
3331, 2912, 2859, 1031 cm−1 1H-NMR (CDCl3): l
;
2.38 (br s, 3H), 3.39 (br s, 2H), 4.57 (br s, 2H), 6.71 (br
s, 1H), 7.15–7.25 (m, 3H); 13C-NMR (CDCl3): l 21.3,
38.4, 38.7, 61.7, 120.4, 121.5, 123.31, 124.6, 125.3,
127.0, 127.4, 134.1, 135.9, 140.3, 141.9, 143.7, 144.8,
147.6, 148.9; HRMS (EI) Calc. for C11H12O: 160.0888.
Found: 160.0881.
3.2. 2-(tert-Butyldimethylsilyloxymethyl)indene (6)
3466, 3064, 3027, 1602, 1558, 1494, 1089, 1079 cm−1
;
1H-NMR (CDCl3): l 0.01 (s, 3H), 0.04 (s, 3H), 0.97 (s,
9H), 3.07 (d, J=16.2 Hz, 1H), 3.24, (s, 1H), 3.26 (d,
J=16.4 Hz, 1H), 3.32 (d, J=9.7 Hz, 1H), 3.40 (d,
J=9.7 Hz, 1H), 4.54 (s, 1H), 7.13–7.39 (m, 9H);
13C-NMR (CDCl3): l −5.7, −5.6, 18.1, 25.8, 42.8,
61.2, 66.9, 84.2, 124.7, 125.5, 126.6, 126.8, 127.0, 128.1,
129.0, 139.8, 140.9, 144.5; HRMS (EI) Calc. for
C22H30O2Si: 354.2015. Found: 354.2016.
To a solution of 2-(hydroxymethyl)indene (10.0 g,
68.4 mmol) in CH2Cl2 (250 ml) at r.t., Et3N (14.3 ml,
103 mmol), DMAP (1.0 g, 6.8 mmol) and tert-
butyldimethylsilyl chloride (11.3 g, 75.2 mmol) were
added sequentially. After stirring for 2 h, the reaction
mixture was cooled to 0°C and quenched by addition of
saturated aqueous NH4Cl. The layers were separated
and the aqueous phase was extracted with CH2Cl2. The
combined organic extract was washed with water, satu-
rated brine, and dried (Na2SO4). The solvents were
removed and the residue was passed through a short
column of silica, eluting with 3:1 hexane:ethyl acetate,
to afford 16.9 g (95%) of 6 as a yellow solid; m.p.
35–36°C; IR (CHCl3): 3059, 2955, 1471, 1097, 836
3.4. 2-(Hydroxymethyl)-3-(2-methylpropyl)indene (3c)
To a solution of silyl ether 6 (4.0 g, 15.4 mmol) in
THF (75 ml) at −78°C, n-BuLi (5.0 ml of a 2.5 M
solution in hexanes, 17.5 mmol) was added dropwise.
After stirring for 1 h, 1-bromo-2-methylpropane (2.5
ml, 23.1 mmol) and tetrabutylammonium iodide (1.14
g, 3.08 mmol) were added and the reaction mixture was
1
cm−1; H-NMR (CDCl3): l 0.14 (s, 6H), 0.98 (s, 9H),
3.37 (s, 2H), 4.61 (s, 2H), 6.71 (s, 1H), 7.15–7.43 (m,
4H); 13C-NMR (CDCl3): l −5.3, 18.4, 25.9, 38.7, 62.2,

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H. Palandoken et al. / Journal of Organometallic Chemistry 579 (1999) 338–347
warmed gradually to r.t. and followed by stirring at
55°C for 12 h. The solution was then cooled to 0°C and
quenched by addition of saturated aqueous NH4Cl. The
layers were separated and the aqueous phase was ex-
tracted with Et2O. The combined organic extract was
washed with water, saturated brine, and dried
(Na2SO4). The solvents were removed and the residue
was dissolved in THF (100 ml) and then treated at r.t.
with tert-butylammonium fluoride (46.2 ml of a 1 M
solution in THF, 46.2 mmol). After stirring for 30 min,
the reaction mixture was quenched by addition of satu-
rated aqueous NH4Cl. The layers were separated and
the aqueous phase was extracted with Et2O. The com-
bined organic extract was washed with water, saturated
brine, and dried (Na2SO4). The solvents were removed
and the crude product was purified by chromatography,
eluting with 5:1 hexane:ethyl acetate, to afford 1.49 g
(48%) of alcohol 3c as a yellow oil. IR (CHCl3): 3363,
3.7. 1-Trimethylsilyl-2-(hydroxymethyl)indene (3f)
To a solution of 2-(hydroxymethyl)indene (0.25 g,
1.71 mmol) in THF (5 ml) at 0°C, n-BuLi (1.40 ml of a
2.5 M solution in hexanes, 3.51 mmol) was added
dropwise. After stirring at 0°C for 0.5 h and at r.t. for
0.5 h, the reaction mixture was recooled to 0°C and
chlorotrimethylsilane (0.50 ml, 3.68 mmol) was added.
The reaction mixture was gradually warmed to r.t. and
stirred for 12 h. The solution was then cooled to 0°C
and quenched by addition of saturated aqueous
NaHCO3. The layers were separated and the aqueous
phase was extracted with EtOAc. The combined or-
ganic extract was washed with water, saturated brine,
and dried (MgSO4). The solvents were removed and the
crude product was purified by chromatography, eluting
with 5:1 hexane:ethyl acetate, to afford 0.36 g (97%) of
alcohol 3f as a yellow oil. IR (CHCl3): 3335, 2952,
1
1
3019, 2945, 1460 cm−1; H-NMR (CDCl3): l 0.93 (d,
1457, 838 cm−1; H-NMR (CDCl3): l −0.07 (s, 9H),
J=6 Hz, 6H), 1.90–1.97 (m, 1H), 2.42 (d, J=6 Hz,
2H), 3.46 (s, 2H), 4.51 (s, 2H), 7.14–7.32 (m, 3H), 7.41
(d, J=7.2 Hz, 1H); 13C-NMR (CDCl3): l 22.8, 28.0,
34.6, 38.9, 59.0, 119.6, 123.6, 124.6, 126.0, 139.2, 141.1,
143.0, 146.0; HRMS (EI) Calc. for C14H18O: 202.1358.
Found: 202.1347.
3.50 (s, 1H), 4.48 (dd, J=15.3, 1.0 Hz, 1 H), 4.58 (dd,
J=15.3, 1.0 Hz, 1 H), 6.74 (d, J=1.0 Hz, 1 H),
7.06–7.17 (m, 2 H), 7.30–7.33 (app. d, J=8.7 Hz, 2
H); 13C-NMR (CDCl3): l −2.1, 46.3, 62.2, 120.8,
123.1, 123.2, 125.1, 125.7, 144.0, 145.6, 151.0; HRMS
(EI) Calc. for C13H18OSi: 218.1127. Found: 218.1127.
3.5. 2-(Hydroxymethyl)-3-(1-methylethyl)indene (3d)
3.8. 2-(Hydroxymethyl)-3-phenylindene (3g)
The preparation of 2-(hydroxymethyl)-3-(1-methyl-
ethyl)indene (3d) was accomplished according to the
procedure described for the preparation 3c: 2.0 g of 6
(7.68 mmol), and 0.96 ml of 2-iodopropane (9.6 mmol)
were reacted to afford 3d as a yellow oil (0.38 g, 26%).
To a solution of 2-(tert-butyldimethylsilyloxymeth-
yl)-1-phenylindan-2-ol (1.0 g, 2.8 mmol) in pyridine (28
ml) at 0°C, SOCl2 (327 ml, 4.48 mmol) was added
dropwise via syringe. The reaction was stirred 2 h at
0°C and then 30 min at r.t. The reaction was quenched
by addition of saturated aqueous NH4Cl and then
diluted with Et2O. The Et2O layer was washed three
times with saturated aqueous CuSO4 and followed by
washing with water. The combined aqueous layers were
extracted with Et2O. The combined Et2O layers were
washed with saturated brine and dried over Na2SO4.
Removal of the solvents under reduced pressure af-
forded the crude silyloxy indene [1H-NMR (CDCl3): l
0.07 (s, 6H), 0.94 (s, 9H), 3.68 (s, 2H), 4.64 (s, 2H),
7.13–7.55 (m, 9H)], which was dissolved in a 5:1 mix-
ture of DMSO:water (16.8 ml) and heated to 90°C.
After 3 h the reaction was poured into water and
extracted with Et2O. The combined organic layers were
washed with water, saturated brine, and dried
(Na2SO4). The solvents were removed and the residue
was purified by chromatography, eluting with 20%
ethyl acetate/hexane on aluminum oxide (activated, ba-
sic, Brockmann 1), to afford 243 mg (39%) of alcohol
3g as a beige solid, m.p. 100–101°C; IR (powder): 3362,
3280, 2952, 1492, 1460, 1444 cm−1; 1H-NMR
(CDCl3): l 1.46 (t, J=5.72 Hz, 1H), 3.68 (s, 2H), 4.58
(d, J=6.35 Hz, 2H), 7.20–7.53 (m, 9H); 13C-NMR
(CDCl3): l 39.5, 59.5, 120.5, 123.8, 125.1, 126.3, 127.6,
;
IR (CHCl3): 3370, 2930, 1461 cm−1 1H-NMR
(CDCl3): l 1.22 (d, J=6 Hz, 6H), 3.01–3.10 (m, 1H),
3.26 (s, 2H), 4.38 (s, 2H), 7.03 (t, J=7.2 Hz, 1H), 7.14
(t, J=6.6 Hz, 1H), 7.27 (d, J=7.2 Hz, 1H), 7.38 (d,
J=7.5 Hz, 1H); 13C-NMR (CDCl3): l 21.3, 26.6, 39.2,
58.6, 120.9, 123.7, 124.2, 125.6, 138.9, 143.5, 144.4,
145.0; HRMS (EI) Calc. for C13H16O: 188.1201.
Found: 188.1197.
3.6. 3-Benzyl-2-(hydroxymethyl)indene (3e)
The preparation of 3-benzyl-2-(hydroxymethyl)in-
dene (3e) was accomplished according to the procedure
described for the preparation of 3c: 0.86 g of 6 (3.31
mmol), and 0.59 ml of benzylbromide (4.97 mmol) were
reacted to afford 3e as a yellow solid (0.58 g, 74%).
m.p. 87–88°C; IR (CHCl3): 3339, 3061, 2915, 1601,
1
1494 cm−1; H-NMR (CDCl3): l 3.57 (s, 2H), 3.98 (s,
2H), 4.63 (s, 2H), 7.17–7.44 (m, 8H), 7.45 (app. d,
J=6.9 Hz, 1H); 13C-NMR (CDCl3): l 31.1, 39.1, 58.7,
119.8, 123.5, 124.7, 126.0, 126.1, 128.2, 128.4, 137.8,
139.3, 141.9, 142.9, 145.5; HRMS (EI) Calc. for
C17H16O: 236.1201. Found: 236.1209.

H. Palandoken et al. / Journal of Organometallic Chemistry 579 (1999) 338–347
345
128.5, 129.1, 134.7, 141.3, 142.4, 143.0, 145.6; HRMS
(EI) Calc. for C16H14O: 222.1045. Found: 222.1045.
38.5, 40.9, 41.0, 41.1, 41.2, 48.5, 48.8, 48.9, 107.6,107.7,
107.9, 119.4, 119.5, 119.6, 120.4, 120.4, 120.5, 120.7,
122.7, 122.9, 123.0, 123.2, 123.3, 123.4, 123.5, 123.6,
123.7, 123.9, 124.0, 124.2, 124.3,, 124.5, 124.7, 124.9,
125.0, 125.2,125.3, 125.4; HRMS (EI) Calc. for C22H22:
286.1721. Found: 286.1730.
3.9. 1,2-Bis(2-indenyl)ethane (4a)
To a stirred solution of TiCl3 (1.6 g, 10.3 mmol) in
1,2-dimethoxyethane at 0°C, LiAlH4 (0.13 g, 3.42
mmol) was added in one portion. After stirring for 15
min, a solution of 3a (0.5 g, 3.42 mmol) in 1,2-
dimethoxyethane was cannulated into the resultant
black reaction mixture. After gradual warming to r.t.,
the reaction mixture was refluxed for 16 h. The solution
was then cooled to 0°C and quenched by addition of 1
M HCl. The layers were separated and the aqueous
phase was extracted with EtOAc. The combined or-
ganic extract was washed with water, saturated brine,
and dried (Na2SO4). The solvents were removed and
the crude product was purified by chromatography,
eluting with hexane to afford 0.079 g (18%) of 4a and
0.078 g (18%) of 5a. [Note: purification problems were
encountered when polar solvents such as CH2Cl2 were
used during chromatography. For best results, a solu-
tion of the crude product is added to a small amount of
silica and the suspension is evaporated to dryness. The
dry impregnated silica is then added to the top of a
silica gel chromatography column and eluted with
hexane].
Compound 5a: m.p. 55–56°C; IR (CHCl3): 3068,
1653, 1609, 1478 cm−1; 1H-NMR (CDCl3): l 2.84 (app.
d, J=6.6 Hz, 2H), 3.17 (br s, 2H), 3.57 (br s, 2H), 3.95
(m, 1H), 5.00 (d, J=1.8 Hz, 1H), 5.05 (d, J=1.8 Hz,
1H), 6.41 (s, 1H), 6.99–7.28 (m, 8H); 13C-NMR
(CDCl3): l 37.9, 38.6, 41.7, 49.1, 108.2, 120.1, 123.4,
123.7, 124.3, 124.4, 126.2, 126.4, 126.8, 128.7, 141.4,
143.3, 145.4, 145.6, 147.7, 152.3; HRMS (EI) Calc. for
C20H18: 258.1408. Found: 258.1402.
3.11. 1,2-Bis[(3-(2-methylpropyl)-2-indenyl)]ethane (4c)
The preparation of 4c was accomplished according to
the procedure described for the preparation of 4a: 1.20
g of 3c (5.93 mmol) was treated with TiCl3 to afford a
mixture of 4c and 5c.
Compound 4c: white solid (0.33 g, 30%); m.p. 70–
73°C; IR (CHCl3): 2951, 1364, 787 cm−1 1H-NMR
;
(CDCl3): l 0.95 (d, J=9 Hz, 12H), 1.95–2.02 (m, 2H),
2.41 (d, J=9 Hz, 4H), 2.69 (s, 4H), 3.37 (s, 4H),
7.10–7.16 (m, 6H), 7.40 (app. d, J=7.2 Hz, 2H);
13C-NMR (CDCl3): l 23.0, 23.1, 28.1, 29.2, 34.7, 40.1,
118.8, 123.2, 123.6, 126.0, 136.8, 142.5, 142.8, 146.8;
HRMS (EI) Calc. for C28H34: 370.2660. Found:
370.2660.
Compound 5c: yellow solid (0.058 g, 5%); m.p. 112–
1
113°C; IR (CHCl3): 3042, 1654, 1465, 882 cm−1; H-
NMR (CDCl3): l 0.49 (d, J=6.6 Hz, 3H), 0.77 (d,
J=6.6 Hz, 3H), 0.85 (d, J=6.6 Hz, 3H), 0.91 (d,
J=6.6 Hz, 3H), 1.42 (m, 1 H), 1.86 (m, 3H), 2.27 (d,
J=7.2 Hz, 2H), 2.47 (d, J=22.8 Hz, 1H), 2.70 (d,
J=22.8 Hz, 1H), 2.82 (d, J=14.4 Hz, 1H), 2.95 (d,
J=14.4 Hz, 1H), 3.46 (d, J=21.3 Hz, 1H), 3.60 (d,
J=21.3 Hz, 1H), 5.08 (m, 1H), 5.18 (m, 1H), 6.95–7.19
(m, 8H); 13C-NMR (CDCl3): l 22.8, 23.2, 24.4, 25.1,
25.3, 28.0, 34.9, 39.2, 41.7, 43.8, 52.2, 56.3, 107.8, 118.8,
122.8, 123.4, 124.2, 124.3, 125.5, 126.4, 126.9, 138.8,
140.4, 141.1, 143.3, 146.3, 148.2, 154.9; HRMS (EI)
Calc. for C28H34: 370.2660. Found: 370.2661.
3.10. 1,2-Bis[(5-methyl)-2-indenyl)]ethane (4b)
3.12. 1,2-Bis[(3-(1-methylethyl)-2-indenyl)]ethane (4d)
The preparation of 4b was accomplished according to
the procedure described for preparation of 4a: 1.0 g of
3b (6.24 mmol) was treated with TiCl3 to afford 4b as a
mixture with 5b.
The preparation of 4d was accomplished according to
the procedure described for the preparation of 4a: 0.16
g of 3d (0.82 mmol) was treated with TiCl3 to afford 4d
as a mixture with 5d.
Compound 4b: white solid (0.16 g, 18%); m.p. 130–
Compound 4d: white solid (0.041 g, 29%); m.p. 94–
1
1
131°C; IR (CHCl3): 2923, 2900, 1603, 878 cm−1; H-
95°C; IR (CHCl3): 2962, 1559, 1457, 766 cm−1; H-
NMR (CDCl3): l 2.48 (s, 6H), 2.96 (s, 4H), 3.39 (s,
4H), 6.61 (s, 2H), 6.96–7.34 (m, 6H); 13C-NMR
(CDCl3): l 21.4, 30.7, 40.7, 40.9, 104.9, 119.6, 120.8,
123.1, 124.4, 126.3, 126.5, 126.9; HRMS (EI) Calc. for
C22H22: 286.1721. Found: 286.1726.
NMR (CDCl3): l 1.31 (d, J=6.9 Hz, 12H), 2.68 (s,
4H), 3.13 (m, 2H), 3.30 (s, 4H), 7.10 (m, 2H), 7.22 (m,
2H), 7.38 (app. d, J=7.5 Hz, 2H), 7.45 (app. d, J=7.5
Hz, 2H); 13C-NMR (CDCl3): l 21.1, 26.8, 29.5, 40.7,
120.3, 123.4, 123.5, 125.7, 140.5, 142.7, 143.2, 145.1;
HRMS (EI) Calc. for C26H30: 342.2347. Found:
342.2345.
Compound 5b: yellow oil (0.17 g, 18%); IR (CHCl3):
1
3007, 2918, 1616, 805 cm−1; H-NMR (CDCl3): l 2.20
(br s, 3H), 2.25 (br s, 3H), 2.78 (br s, 2H), 3.08 (br s,
2H), 3.50 (br s, 2H), 3.86 (br s, 1H), 4.94 (br s, 1H),
5.01 (br s, 1H), 6.34 (br s, 1H), 6.84–7.19 (m, 6H);
13C-NMR (CDCl3): l 21.5, 37.6, 37.8, 38.0, 38.1, 38.3,
Compound 5d: yellow oil (0.006 g, 4%); IR (CHCl3):
1
3067, 2961, 1459, 885 cm−1; H-NMR (CDCl3): l 0.78
(d, J=6.6 Hz, 3H), 0.81 (d, J=6.6 Hz, 3H), 1.18 (d,
J=6.9 Hz, 3H), 1.24 (d, J=6.9 Hz, 3H), 1.92 (m, 1H),

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H. Palandoken et al. / Journal of Organometallic Chemistry 579 (1999) 338–347
2.38 (d, J=22.5 Hz, 1H), 2.51 (d, J=22.5 Hz, 1H),
3.00 (s, 2H), 3.12 (m, 1H), 3.45 (d, J=21.0 Hz, 1H),
3.57 (d, J=21.0 Hz, 1H), 5.02 (br s, 1H), 5.17 (br s,
1H), 6.87–7.36 (m, 8H); 13C-NMR (CDCl3): l 17.7,
18.0, 20.8, 21.0, 26.8, 37.6, 40.1, 41.0, 41.7, 58.9, 108.4,
120.5, 123.0, 123.1, 123.5, 124.0, 124.4, 125.1, 126.3,
126.8, 141.4, 143.8, 144.0, 144.3, 147.5, 153.8; HRMS
(EI) Calc. for C26H30: 342.2347. Found: 342.2347.
organic layer was dried (Na2SO4). The solvents were
removed and the crude product was dissolved in THF
(2 ml). PtO2 (0.001 g, 0.005 mmol) was added and the
reaction mixture was placed under H2 atmosphere.
After stirring for 48 h, the reaction mixture was filtered
through Celite and the removal of solvents gave 0.004 g
(36%) of a mixture of racemic (8b) and meso (9b)
ansa-titanocenes. The diastereomeric ratio was not
readily determined by spectroscopic techniques because
of the inherent similarities between the two stereoiso-
3.13. 1,2-Bis[(3-phenyl)-2-indenyl]ethane (4g)
1
mers. The crude product was characterized by its H-
1
To a stirred solution of TiCl3 (256 mg, 1.66 mmol) in
1,2-dimethoxyethane (12 ml) at 0°C, LiAlH4 (21 mg,
0.553 mmol) was added in one portion. After stirring
for 15 min, a solution of 2-(hydroxymethyl)indene (123
mg, 0.553 mmol) in 1,2-dimethoxyethane (2 ml) was
cannulated into the resultant black reaction mixture.
Upon gradual warming to r.t. the reaction mixture was
refluxed for 48 h. The solution was then cooled to 0°C
and quenched by addition of 1 M HCl. The layers were
separated and the aqueous phase was extracted with
EtOAc. The combined organic extract was washed with
water, saturated brine, and dried over Na2SO4. The
solvents were removed and the crude product was
recrystallized from hot hexanes to give 0.156g (46%) of
bis-indene 4g as a yellow solid. The mother liquor was
concentrated and the residue (0.122g, 36%) was deter-
NMR spectrum: H-NMR (CDCl3): l 1.05 (d, J=6.3
Hz, 6H), 1.60–1.74 (m, 4H), 2.46–2.62 (m, 4H), 2.83–
3.04 (m, 4H), 3.11 (s, 4H), 5.48 (s, 1H), 5.49 (s, 1H),
5.54 (s, 1H), 5.55 (s, 1H). Recrystallization from
CH2Cl2/hexane (1:2) gave meso ansa-titanocene 9b as a
red solid. IR (CHCl3): 2956, 2923, 1514, 1447, 1419,
1376 cm−1 1H-NMR (CDCl3): l 1.05 (CHCH3, d,
;
J=6.3 Hz, 6H), 1,60–1.74 (m, 6H), 2.46–2.62 (m, 4H),
2.83–3.04 (m, 4H), 3.11 (s, 4H), 5.48 (Cp–H, s, 1H),
5.49 (Cp–H, s, 1H), 5.54 (Cp–H, s, 1H), 5.55 (Cp–H,
s, 1H); 13C-NMR (CDCl3): l 22.2, 26.0, 29.6, 30.1,
31.0, 33.1, 111.1, 113.5, 137.4, 137.5, 137.8.
3.15. rac-Ethylene bis[p5-4,5,6,7-1-(2-methylpropyl)-
tetrahydro-2-indenyl] titanium dichloride (8c)
1
mined by H-NMR to contain a 4:5 mixture of 4g:5g.
The preparation of 8c was accomplished according to
the procedure for ethylene bis[tetrahydro-(5-methyl)-2-
indenyl] titanium dichloride: 0.22 g of 4c (0.60 mmol)
was treated with TiCl3·(thf)3 to afford a crude mixture
of 8c and 9c (0.26 g, 88%) with a 4:1 ratio as deter-
mined by 1H-NMR. Recrystallization from CH2Cl2/
hexane (1:2) gave pure racemic ansa-titanocene 8c as a
bright red solid, m.p. 271–272°C; IR (CHCl3): 2949,
Compound 4g: m.p. 169–171°C; IR (powder) 3018,
2951, 2901, 1612, 1603, 1491, 1459 cm−1 1H-NMR
;
(CDCl3): l 2.75 (s, 4H), 3.29 (s, 4H), 7.10–7.38 (m,
18H); 13C-NMR (CDCl3): l 29.3, 40.5, 119.6, 123.4,
124.2, 126.2, 127.0, 128.4, 129.1, 135.5, 140.0, 142.5,
143.7, 146.4; HRMS (EI) Calc. for C32H26: 410.2035.
Found: 410.2033.
Compound 5g: 1H-NMR (CDCl3): l 2.70 (d, J=23.0
Hz, 1H), 2.88 (d, J=23.2 Hz, 1H), 3.40 (d, J=14.3
Hz, 1H), 3.44 (d, J=20.3 Hz, 1H), 3.50 (d, J=14.0
Hz, 1H), 3.57 (d, J=20.3 Hz, 1H), 4.73 (app. t, J=2.3
Hz, 1H), 5.01 (app. t, J=2.0 Hz, 1H), 6.81–7.37 (m,
18H).
1558, 1506, 1456 cm−1 1H-NMR (CDCl3): l 0.86
;
(CH(CH3)2, m, 12H), 1.58–1.76 (m, 4H), 1.81–1.92 (m,
4H), 2.19 (m, 2H), 2.44 (m, 4H), 2.87 (d, J=8.4 Hz,
2H), 3.07 (m, 4H), 3.26 (d, J=9 Hz, 2H), 3.87 (t,
J=5.7 Hz, 4H), 5.14 (Cp–H, s, 2H); 13C-NMR
(CDCl3): l 21.9, 22.3, 22.4, 22.9, 24.1, 25.5, 28.0, 30.1,
36.7, 107.1, 131.3, 133.5, 134.9, 139.2; HRMS (FAB)
Calc. for C28H40TiCl2: 494.1986. Found: 494.2011.
3.14. rac- and meso-Ethylene bis[p5-4,5,6,7-1-tetra-
hydro(5-methyl)-2-indenyl] titanium dichloride (8b, 9b)
3.16. rac-Ethylene bis[p5-4,5,6,7-1-(1-methylethyl)-
tetrahydro-2-indenyl] titanium dichloride (8d)
To a degassed solution of 1,2-bis[(5-methyl)-2-in-
denyl]ethane (4b) (0.067 g, 0.23 mmol) in THF (3 ml) at
−70°C, n-BuLi (0.19 ml of a 2.5 M solution in hex-
anes, 0.47 mmol) was added dropwise. After stirring for
1 h, TiCl3·(thf)3 (0.088 g, 0.24 mmol) was added. The
resultant dark red reaction mixture was then allowed to
reach r.t. followed by refluxing for 4 h. After gradual
cooling to r.t. and to −40°C, HCl (6 M, 1.5 ml, 9.2
mmol) was added. Dry air was gently bubbled through
the reaction mixture while warming to r.t. for 1 h. The
reaction mixture was extracted with CH2Cl2 and the
The preparation of 8d was accomplished according to
the procedure for ethylene bis[tetrahydro-(5-methyl)-2-
indenyl] titanium dichloride: 0.022 g of 4d (0.06 mmol)
was treated with TiCl3·(thf)3 to afford a crude mixture
of 8d and 9d (0.021 g, 76%) with a 2:1 ratio as deter-
mined by 1H-NMR. Recrystallization from CH2Cl2/
hexane gave pure racemic ansa-titanocene 8d as a red
;
solid, IR (CHCl3): 2955, 1457, 817 cm−1 1H-NMR
(CDCl3): l 0.98 (CH(CH3)2, d, J=7.2 Hz, 6H), 1.09

H. Palandoken et al. / Journal of Organometallic Chemistry 579 (1999) 338–347
347
330. (b) N.M. Heron, J.A. Adams, A.H. Hoveyda, J. Am. Chem.
Soc. 119 (1997) 6205. (c) F.A. Hicks, S.L. Buchwald, J. Am.
Chem. Soc. 118 (1996) 11688. (d) B.A. Kuntz, R. Ramachan-
dran, N.J. Taylor, J. Guan, S. Collins, J. Organomet. Chem. 497
(1995) 133. (e) M.B. Carter, B. Schiott, A. Gutierrez, S.L.
Buchwald, J. Am. Chem. Soc. 116 (1994) 11667. (f) R.L. Halter-
man, T.M. Ramsey, Z.Z. Chen, J. Org. Chem. 59 (1994) 2642.
(g) C.A. Willoughby, S.L. Buchwald, J. Am. Chem. Soc. 116
(1994) 11703. (h) R.D. Broene, S.L. Buchwald, J. Am. Chem.
Soc. 115 (1993) 12569. (i) S.L. Colletti, R.L. Halterman, Tetra-
hedron Lett. 33 (1992) 1005.
(CH(CH3)2, d, J=6.9 Hz, 6H), 1.43–1.62 (m, 4H),
1.78–1.86 (m, 4H), 2.29–2.50 (m, 4H), 2.88 (d, J=9.6
Hz, 2H), 2.94–3.05 (m, 6H), 3.37 (d, J=9.6 Hz, 2H),
5.24 (Cp–H, s, 2H); 13C-NMR (CDCl3): l 21.8, 22.2,
24.4, 26.0, 28.1, 28.9, 38.7, 109.8, 126.3, 132.8, 134.7,
138.0; HRMS (FAB) Calc. for C26H36TiCl2: 466.1673.
Found: 466.1678.
3.17. rac-Ethylene bis(p5-4,5,6,7-1-benzyl-tetrahydro-2-
indenyl) titanium dichloride (8e)
[2] R.L. Halterman, Chem. Rev. 92 (1992) 965.
[3] S.R. Hitchcock, J.J. Situ, J.A. Covel, M.M. Olmstead, M.H.
Nantz, Organometallics 14 (1995) 3732.
The preparation of 8e was accomplished according to
the procedure for ethylene bis[tetrahydro-(5-methyl)-2-
indenyl] titanium dichloride: 0.25 g of 4e (1.07 mmol)
was treated with TiCl3 · (thf)3 to afford a crude mixture
of 8e and 9e (0.039 g, 74%) with a 3.6:1 ratio as
determined by 1H-NMR. Recrystallization from
CH2Cl2/hexane gave pure racemic ansa-titanocene 8e as
a red solid, m.p. 325°C (dec.); IR (CHCl3): 3088, 2937,
[4] (a) R.L. Halterman, T.L. Ramsey, Organometallics 12 (1993)
2879. (b) W.W. Ellis, T.K. Hollis, W. Odenkirk, J. Whelan; R.
Ostrander, A.L. Rheingold, B. Bosnich, Organometallics 12
(1993) 4391.
[5] (a) F.R.W.P. Wild, L. Zsolnai, G. Huttner, H.H. Brintzinger, J.
Organomet. Chem. 232 (1982) 233. (b) R.B. Grossman, R.A.
Doyle, S.L. Buchwald, Organometallics 11 (1991) 1501.
[6] W. Spaleck, M. Antberg, V. Dolle, R. Klein, J. Rohrmann, A.
Winter, New J. Chem. 14 (1990) 499.
[7] For related fulvene-coupling approaches to ansa-metallocenes,
see: (a) P. Burger, K. Hortmann, J. Deibold, H.H. Brintzinger, J.
Organomet. Chem. 417 (1991) 9. (b) S. Collins, Y. Hong, N.J.
Taylor, Organometallics 9 (1990) 2695. (c) S. Gutmann, P.
Burger, H.U. Hund, J. Hofmann, H.H. Britzinger, J.
Organomet. Chem. 369 (1989) 343. (d) H. Schwemlein, H.H.
Britzinger, J. Organomet. Chem. 254 (1983) 69.
1
1600, 1507, 1492 cm−1; H-NMR (CDCl3): l 1.56 (m,
4H), 1.68–1.80 (m, 2H), 1.84–1.94 (m, 2H), 2.45 (m,
2H), 2.78 (m, 2H), 3.05–3.20 (m, 6H), 3.35 (m, 2H), 3.49
(PhCH2Cp, d J=16 Hz, 2H), 3.63 (PhCH2Cp, d, J=16
Hz, 2H), 5.33 (Cp–H, s, 2H), 7.01 (d, J=7.4 Hz, 4H),
7.16–7.29 (m, 6H); 13C-NMR (CDCl3): l 21.8, 22.1,
23.9, 25.5, 27.9, 33.0, 107.4, 126.2, 128.0, 128.5, 129.1,
134.1, 135.7, 139.6, 139.8; HRMS (FAB) Calc. for
C34H36TiCl2 [M+ −Cl]: 527.1985. Found: 527.1950.
[8] M.H. Nantz, S.R. Hitchcock, S.C. Sutton, M.D. Smith,
Organometallics 12 (1993) 5012.
[9] (a) J.E. McMurry, M.J. Silvestri, Org. Chem. 40 (1975) 2687. (b)
K.B. Sharpless, R.P. Hanzlik, E.E. van Tamelen, J. Am. Chem.
Soc. 90 (1968) 209. (c) Y.-H. Lai, Org. Prep. Proc. Int. 12 (1980)
363. (d) M. Sato, K. Oshima, Chem. Lett. (1982) 157.
[10] H. Palandoken, W.T. McMillen, M.H. Nantz, Org. Prep. Proc.
Int. 28 (1996) 702.
4. Supplementary material
[11] Compounds 3c–e are obtained as inseparable mixtures of in-
denyl double bond isomers at positions C(1)–(3). Treatment
with triethylamine at reflux gives the depicted isomers.
[12] A.G. Myers, N.J. Tom, M.E. Fraley, S.B. Cohen, D.J. Madar, J.
Am. Chem. Soc. 119 (1997) 6072.
[13] G. Maiti, S.C. Roy, Tetrahedron Lett. 38 (1997) 495.
[14] L.E. Manzer, Inorg. Synth. 21 (1982) 135.
[15] S.C. Collins, Y. Hong, R. Ramachandran, N.J. Taylor,
Organometallics 10 (1991) 2349.
[16] M.M. Olmstead, S.R. Hitchcock, M.H. Nantz, Acta Crystallogr.
C52 (1996) 1523.
[17] Hydrogenation of the previously reported (Ref. [3]) racemic,
benzyl-substituted, 2-(indenyl) ansa-titanocene afforded the ref-
erence sample of rac-8e.
Further details of the crystal structure investigations
are available on request from the Cambridge Crystallo-
graphic Data Centre, where the CCDC numbers are as
follows: 8c CCDC 104502; 8d CCDC 104503; 9b CCDC
104504. Copies of this information may be obtained free
of charge from The Director, CCDC, 12 Union Road,
Cambridge, CB2 1EZ, UK (Fax: +44-1223-336-033;
e-mail: deposit@ccdc.cam.ac.uk or www: http://
www.ccdc.cam.ac.uk).
[18] To our knowledge there are no other examples of a-phenyl
ansa-titanocenes.
Acknowledgements
[19] In the 1H-NMR spectrum of a rac:meso mixture, the meso 4H
multiplet for an a-substituted ethano-bridged ansa-titanocene is
typically observed between the chemical shifts of the two racemic
2H multiplets.
The authors thank Bernd Steinmetz for assistance with
the preparation of ansa-titanocenes 8b and 9b. Support-
ing information available: tables of X-ray crystallo-
graphic data for compounds 8c–d and 9b (27 pages).
[20] G.M. Sheldrick, SHELXS. Program for the solution of crystal
structures, Acta Crystallogr. A46 (1990) 467.
[21] G.M. Sheldrick, SHELXL-97. Program for the refinement of
crystal structures, University of Go¨ttingen, Germany, 1997.
[22] S.R. Parkin, B. Moezzi, H. Hope, J. Appl. Cryst. 28 (1995) 53.
[23] O. Bortolini, S. Campestrini, F. Di Furia, G. Modena, J. Org.
Chem. 52 (1987) 5093.
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