Highly enantiomerically enriched planar chiral cyclopentadienyl(indenyl) ruthenium complexes

Article abstract of DOI:10.1021/om400845t

The functionalization of highly enantiomerically enriched planar chiral cyclopentadienyl(4-bromoindenyl)ruthenium complexes is detailed. Lithium/bromine exchange followed by an electrophilic quench using N,N-dimethylformamide (DMF), trimethylsilyl chloride, benzaldehyde, acetone, or 1,2-diiodoethane afforded the corresponding enantiomerically enriched planar chiral complexes. Suzuki-Miyaura cross-coupling led to cyclopentadienyl(indenyl)ruthenium complexes bearing aryl and alkenyl groups in high yields. Similarly, in situ generation of the boronate intermediate using 9-MeO-9-BBN and a metalated species in the Suzuki-Miyaura reaction gave heteroaryl, alkynyl, and alkyl cyclopentadienyl(indenyl)ruthenium complexes with retention of configuration and enantiomeric excess.

Full text of DOI:10.1021/om400845t

Article
pubs.acs.org/Organometallics
Highly Enantiomerically Enriched Planar Chiral
Cyclopentadienyl(indenyl)ruthenium Complexes
Simon Wagschal, Audrey Mercier, and E. Peter Kundig*
̈
Department of Organic Chemistry, University of Geneva, Quai Ernest Ansermet 30, 1211 Geneva 4, Switzerland
S
* Supporting Information
ABSTRACT: The functionalization of highly enantiomerically
enriched planar chiral cyclopentadienyl(4-bromoindenyl)ruthenium
complexes is detailed. Lithium/bromine exchange followed by an
electrophilic quench using N,N-dimethylformamide (DMF), trime-
thylsilyl chloride, benzaldehyde, acetone, or 1,2-diiodoethane
afforded the corresponding enantiomerically enriched planar chiral
complexes. Suzuki−Miyaura cross-coupling led to cyclopentadienyl-
(indenyl)ruthenium complexes bearing aryl and alkenyl groups in
high yields. Similarly, in situ generation of the boronate intermediate
using 9-MeO-9-BBN and a metalated species in the Suzuki−Miyaura
reaction gave heteroaryl, alkynyl, and alkyl cyclopentadienyl(indenyl)
ruthenium complexes with retention of configuration and enantio-
meric excess.
to thermal or oxidative cleavage of the arene−metal bond in
INTRODUCTION
■
comparison to their chromium analogues.
Planar chirality arising from the π coordination of a metal
fragment on an enantiotopic face of an unsymmetrically
substituted arene has found numerous applications in organic
synthesis and catalysis.1 The use of the planar chiral phosphine
xyliphos in the key iridium-catalyzed hydrogenation step of the
synthesis of metolachlor2 and the kinetic resolution of
secondary alcohols using Fu’s planar chiral analogue of
DMAP3 are premier examples. The predominant routes of
access to highly enantiomerically enriched planar chiral
compounds rely on racemate resolution4 or diastereoselective5
or enantioselective6 methods. In all of these methods, the use of
a stoichiometric amount of a chiral auxiliary is required. Several
research groups have focused on asymmetric catalysis to
overcome this drawback.7 A particularly attractive method was
developed in our group for the desymmetrization of [Cr-
(CO)3(η6-5,8-dibromonaphthalene)] by means of a palladium/
chiral phosphoramidite-catalyzed hydrogenolysis to access
[Cr(CO)3(η6-5-bromonaphthalene)] in good yield and high
enantiomeric purity.8
Replacement of the hydride source by various boronic acids
led to the corresponding enantiomerically enriched naphthale-
nechromium complexes with an additional bromine atom for
further functionalization9 (Scheme 1, left). More recently,
palladium-catalyzed hydrogenolysis was also applied to the
isoelectronic cationic10 [Ru(η6-5,8-dibromonaphthalene)(η5-
C5R5)][PF6] (R = H, Me) and neutral [Ru(η5-4,7-
dibromoindene)(η5-C5R5)] (R = H, Me), affording the
corresponding planar chiral complexes in high yield and
enantiomeric excess (Scheme 1, middle and right).11 These
planar chiral scaffolds may find applications in synthesis and
catalysis and material science because of their higher resistance
With this efficient asymmetric synthesis of enantioenriched
planar chiral metal−arene complexes in hand, the next step was
to develop suitable procedures to construct valuable scaffolds of
potential use in asymmetric catalysis or in the chemistry of new
materials. Indeed, one can take advantage of the remaining
bromide in the desymmetrized planar chiral complexes for
further functionalization by metalation/electrophilic quench
sequences or transition-metal-catalyzed coupling reactions.
Functionalization of sensitive planar chiral naphthalene
tricarbonylchromium complexes using these strategies has
been previously reported,12 and monodentate phosphine
ligands derived from the neutral [Ru(η5-Cp)(η5-indene)]
complexes were recently investigated.13
Herein, we report our efforts toward the functionalization of
[Ru(η5-4-bromoindene)(η5-Cp)]complexes using lithiation/
electrophile trapping reactions as well as palladium- and
copper-catalyzed reactions. All experiments were first carried
out and optimized with rac-1. Reactions were then repeated
with enantioenriched (Sp)-114 with consistent yields and
without erosion of enantiomeric excess.
RESULTS AND DISCUSSION
■
Metalation/Electrophilic Quench Procedure. Lithium/
bromine exchange followed by an electrophilic quench was
previously investigated for the synthesis of monodentate
phosphines derived from compound (Sp)-113 with retention
Received: August 22, 2013
© XXXX American Chemical Society
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Scheme 1. Desymmetrization Strategy To Access Enantiomerically Enriched Planar Chiral Complexes
of stereochemistry and enantimeric purity and later applied to
desired products in high yields (Table 1, entries 2 and 3). In the
latter case, the planar chiral complex (Sp)-2e was obtained as a
2.5:1 mixture of diastereomers. The tertiary alcohol (Sp)-2f and
iodo derivative (Sp)-2g were also obtained with this procedure,
albeit in moderate yields (Table 1, entries 4 and 5). In all cases,
the air-stable planar chiral complexes (Sp)-2c−g were obtained
with conservation of stereochemistry and enantiomeric excess.
The poor result obtained for (Sp)-2g prompted us to
investigate an alternative strategy for the synthesis of this
iodinated planar chiral complex (Scheme 3). A copper-
catalyzed aromatic Finkelstein reaction procedure reported by
Buchwald et al.16 was successfully applied to substrate (Sp)-1
that exhibits remarkable stability even under these relatively
harsh conditions.
the synthesis of carboxylic acid (Sp)-2b (Scheme 2).15
Scheme 2. Initial Results of Lithiation/Electrophile
Trapping Sequence
Palladium-Catalyzed Reactions. Suzuki−Miyaura cross-
coupling conditions were previously developed for sensitive
Cr(CO)3 complexes12 and cationic Ru(η5-Cp) complexes.13
Initial studies with phenylboronic acid revealed that the
conditions previously developed for the chromium complexes
(Pd(dba)2, t-Bu3P) were efficient at 100 °C, leading to complex
(Sp)-3a in 92% yield. For practical reason, Organ’s one-
component catalyst17 was subsequently chosen for probing the
scope of this cross-coupling reaction. This set of conditions
delivered high yields for phenyl-, 2-toluyl-, naphthyl-, and
styrylboronic acids (Table 2, entries 1−3 and 5). The hindered
substrate (Sp)-3d was obtained in moderate yield only (Table 2,
entry 4). Here again, the transformations proceeded without
erosion of the enantiomeric excess.
However, when different electrophiles such as DMF,
benzaldehyde, and trimethylsilyl chloride were tested under
these conditions, the results were disappointing and difficult to
reproduce. Hence, a more robust protocol was sought and we
turned our attention toward a noncoordinating solvent such as
toluene in the presence of a diamine and an organolithium
reagent. After optimization with DMF as the electrophile, it was
found that complete conversion could be achieved along with a
91% product yield using 3 equiv of t-BuLi in toluene in the
presence of a stoichiometric amount of TMEDA at −78 °C
(Table 1, entry 1). This procedure proved to be also efficient
for trimethylsilyl chloride and benzaldehyde, affording the
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Table 1. Lithiation/Electrophile Trapping
Table 2. Suzuki−Miyaura Cross-Coupling
a
(Sp)-1 (95% ee) afforded (Sp)-3a (95% ee).
a
b
(Sp)-1 (90% ee) afforded (Sp)-2c (90% ee). Isolated as a 2.5:1 ratio
of diastereomers.
(Table 3, entry 1). Analogously, alkynes (Sp)-4b−d bearing
silane, alkene, or ketals were isolated with the same efficiency
(Table 3, entries 2−4). The versatility of this method permits
coupling with simple methyllithium (Table 3, entry 5) as well
as a wide range of lithiated species generated via heterocycle
deprotonation (Table 3, entry 6) or lithium/bromine exchange
(Table 3, entry 7). Finally, this procedure was compatible with
sodium propynide (Table 3, entry 8). The silylethynylindenyl
complex (Sp)-4b was readily desilylated to give the
cyclopentadienyl(4-ethynylindenyl)ruthenium complex ((Sp)-
4i).
Scheme 3. Copper-Catalyzed Halogen Exchange
As already observed in the [Cr(CO)3] complexes,12 all
enantioenriched cyclopentadienyl(indenyl)ruthenium com-
plexes products feature large optical rotation values. In
particular, the carboxaldehyde complex (Sp)-2c had an [α]20
D
value of 3610° (c 0.1, CHCl3).
When the complex (Sp)-1 was subjected to Sonogashira
reaction conditions, the formation of a complex mixture was
observed along with a difficult separation between (Sp)-4a and
phenylacetylene dimer resulting from the Glaser oxidative
coupling. We then turned our attention to the “9-MeO-9-BBN
variant” of the Suzuki−Miyaura cross-coupling,18 which had
proved very useful for sensitive chromium complexes.12 This
modification allows broader substrate scope and particularly
CONCLUSION
■
The highly enantioenriched ruthenium complex (Sp)-1 was
recently synthesized via asymmetric palladium-catalyzed hydro-
genolysis of the corresponding meso-dibromo complex. In this
report, we demonstrate that this substrate constitutes a valuable
building block to rapidly access a wide range of planar chiral
complexes with retained enantiomeric excess through metal-
ation/electrophile-trapping sequences and palladium-catalyzed
cross-coupling reactions. These cyclopentadienyl(indenyl)-
ruthenium complexes are more robust toward temperature,
2
2
3
Sp −Sp and Sp −Sp C−C bond formation. The previously
optimized conditions afforded a clean formation of alkyne (Sp)-
4a in a 90% yield with retention of the enantiomeric excess
C
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relative to SiMe4 (residual CHCl3, δH 7.26 ppm; CDCl3, δC 77.05
ppm; residual CHDCl2, δH 5.32 ppm; CD2Cl2, δC 53.9 ppm; residual
C6HD5, δH 7.15 ppm; C6D6, δC 128.0 ppm). Coupling constants J are
quoted in Hz. Infrared spectra were recorded on a Perkin−Elmer 1650
FT-IR spectrometer using diamond ATR Golden Gate sampling.
Electron impact (EI) HRMS mass spectra were obtained using a
Finnigan MAT 95 instrument operating at 70 eV. Electrospray
ionization (ESI) HRMS analyses were measured on a VG Analytical
7070E instrument. Optical rotations were measured at 20 °C on a
PerkinElmer 241 polarimeter using a quartz cell (l = 10 cm) with a Na
high-pressure lamp (λ 589 nm). Melting points were measured in
Table 3. “9-MeO-9-BBN Variant” of the Suzuki−Miyaura
Cross-Coupling
open capillary tubes on a Buchi 540 apparatus and are uncorrected.
̈
Representative Procedure for the Lithiation/Electrophile
Trapping Procedure. A solution of t-BuLi (166 μL, C = 1.6 M in
pentane, 0.6 mmol, 3.0 equiv) was added to a 0.05 M solution of
distilled tetramethylethylenediamine (30 μL,0.2 mmol, 1.0 equiv) in
toluene at −78 °C. After 15 min, a 0.1 M solution of (Sp)-1 (72 mg,
0.2 mmol, 1.0 equiv, 90% ee) in toluene was added and the resulting
yellow mixture was stirred for 2 h at −78 °C. After addition of DMF
(21 μL, 0.6 mmol, 3.0 equiv), the reaction mixture was stirred for 15
min more before being warmed to room temperature and quenched
with aqueous HCl (1 M). The aqueous layer was separated and
extracted with ether. The combined organic phases were dried with
sodium sulfate and filtered, and the volatile materials were removed
under reduced pressure. The residue was purified by flash column
chromatography on silica gel.
[Ru(η5-Cp)(η5-4-(carboxaldehyde)indene)] ((Sp)-2c). Purification
by flash column chromatography (95/5 pentane/diethyl ether) on
silica gel afforded (Sp)-2c as a yellow oil (56 mg, 91%, 90% ee). Rf =
1
0.3 (95/5 pentane/diethyl ether). H NMR (CDCl3, 400 MHz): δ
9.98 (s, 1H), 7.82 (d, J = 8.6 Hz, 1H), 7.41 (d, J = 6.6 Hz, 1H), 6.93
(dd, J = 8.6, 6.6 Hz, 1H), 6.23−6.12 (m, 1H), 5.26 (dd, J = 2.5 Hz, J =
0.9 Hz, 1H), 4.76 (t, J = 2.5 Hz, 1H), 4.21 (s, 5H). 13C NMR (CDCl3,
100.6 MHz): δ 192.0, 136.9, 135.3, 134.7, 120.8, 91.0, 86.8, 75.0, 70.4,
67.2, 66.3. IR (thin film) 3097, 2924, 2803, 2720, 1668, 1600, 1521,
1453, 1391, 1334, 1309, 1099, 1061, 996, 808 cm−1. [α]20 = +3610°
D
(c 0.1, CHCl3). HPLC (Daicel Chiralpak AD-H, hexane/isopropyl
alcohol 99/1, 0.5 mL min−1, λ 254 nm): tR1 = 19.6 min, tR2 = 22.2 min.
HRMS (ESI): calcd for C15H13ORu [M + H]+ 311.0004, found
311.0005.
[Ru(η5-Cp)(η5-4-(trimethylsilyl)indene)] ((Sp)-2d). This compound
was prepared according to the general procedure from (Sp)-1 (32 mg,
0.09 mmol), TMEDA (13 μL, 0.09 mmol), t-BuLi (1.6 M, 167 μL,
0.27 mmol), and trimethylsilyl chloride (23 μL, 0.18 mmol).
Purification by flash chromatography (pentane/diethyl ether, 90/10)
gave (Sp)-2d as a yellow solid (26 mg, 83%). Rf = 0.3 (pentane). Mp:
79−80 °C. 1H NMR (CDCl3, 400 MHz): δ 7.40 (d, J = 8.7 Hz, 1H),
6.97 (dd, J = 6.3, 1.0 Hz, 1H), 6.77 (dd, J = 8.7, 6.3 Hz, 1H), 5.25 (d, J
= 2.5 Hz, 1H), 5.21 (dd, J = 2.5, 1.0 Hz, 1H), 4.62 (t, J = 2.5 Hz, 1H),
4.18 (s, 5H), 0.38 (s, 9H). 13C NMR (CDCl3, 100.6 MHz): δ 138.2,
129.8, 128.2, 122.3, 95.1, 91.1, 72.8, 70.3, 67.1, 65.6. IR (thin film):
2956, 2924, 1405, 1330, 1145, 1099, 1043, 1028, 998, 919, 832, 801
(Sp)-1 (93% ee) afforded (Sp)-4b (93% ee).
base, and air than their chromium analogues and thus represent
a very attractive scaffold for the development of new chiral
ligands or the chemistry of new materials.
cm−1. [α]20 = +659° (c 0.1, CHCl3). HRMS (EI): calcd for
D
C17H20RuSi [M]+ 354.0372, found 354.0372.
EXPERIMENTAL SECTION
■
[Ru(η5-Cp)(η5-4-(phenylmethanol)indene)] ((Sp)-2e). This com-
pound was prepared according to the general procedure from (Sp)-1
(72 mg, 0.2 mmol), TMEDA (30 μL, 0.2 mmol), t-BuLi (1.6 M, 177
μL, 0.6 mmol), and benzaldehyde (15 μL, 0.3 mmol). Purification by
flash chromatography (pentane/diethyl ether, 95/5) gave (Sp)-2e as a
yellow oil (64 mg, 83%). (Sp)-2e was isolated as a 2.5/1 mixture of
unseparable diastereomers. Rf = 0.3 (major) and 0.25 (minor) (90/10
pentane/diethyl ether). Data for the major diastereomer are as follows.
1H NMR (CDCl3, 400 MHz): δ 7.51 (d, J = 6.9 Hz, 2H), 7.42−7.29
(m, 4H), 6.76 (dd, J = 8.6, 6.6 Hz, 1H), 6.66 (d, J = 6.6 Hz, 1H), 6.06
(d, J = 2.7 Hz, 1H), 5.35 (d, J = 2.5 Hz, 1H), 5.25 (dd, J = 2.5, 1.0 Hz,
1H), 4.61 (t, J = 2.5 Hz, 1H), 4.13 (s, 5H), 2.84 (d, J = 2.7 Hz, 1H).
13C NMR (CDCl3, 100.6 MHz): δ 142.1, 140.7, 128.4, 127.7, 127.0,
126.7, 122.8, 120.2, 92.4, 89.4, 73.1, 70.3, 66.8, 64.8. Data for the
General Remarks. All reactions and manipulations were carried
out under an inert atmosphere of nitrogen using an inert gas/vacuum
double-manifold line and standard Schlenk techniques unless
otherwise stated. Solvents were dried by passing through activated
Al2O3 using a Solvtek purification system or by following standard
procedures.19 When required, the solvents were degassed by three
successive freeze−thaw−pump cycles. Commercially available chem-
icals were used as received unless otherwise stated. [Pd2(dba)3]20 and
[Ru(η5-Cp)(η5-4-bromoindene)] ((Sp)-1) were synthesized according
to literature procedures.11
Flash column chromatography was performed using silica gel 60
(32−63 mesh) or neutral alumina (50−200 μm). Analytical thin-layer
chromatography (TLC) was performed on precoated aluminum plates
1
(silica gel 60 F254). H and 13C NMR spectra were recorded on 500,
1
400, and 300 MHz Bruker Avance spectrometers in the solvent
minor diastereomer are as follows. H NMR (CDCl3, 400 MHz): δ
1
indicated. H and 13C NMR chemical shifts (δ) are quoted in ppm
7.53 (d, J = 7.4 Hz, 2H), 7.41−7.27 (m, 4H), 7.07 (d, J = 6.6 Hz, 1H),
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6.85 (dd, J = 8.6, 6.6 Hz, 1H), 5.92 (d, J = 3.9 Hz, 1H), 5.22 (dd, J =
2.5, 1.0 Hz, 1H), 5.13 (d, J = 2.5 Hz, 1H), 4.54 (t, J = 2.5 Hz, 1H),
4.02 (s, 5H), 2.80 (d, J = 3.9 Hz, 1H). 13C NMR (CDCl3, 100.6
MHz): δ 143.3, 140.4, 128.4, 127.7, 126.7, 126.7, 122.9, 119.8, 92.5,
89.1, 73.1, 70.1, 66.3, 64.7. IR (thin film): 3342, 2922, 2851, 1718,
1648, 1603, 1492, 1452, 1334, 1187, 1098, 1063, 1026, 997, 953 cm−1.
[α]20 = +512° (c 0.1, CHCl3). HRMS (EI): calcd for C21H18O104Ru
[M]+D390.0405, found 390.0406.
10.5 min. HRMS (EI): calcd for C20H16Ru [M]+ 358.0293, found
358.0290.
[Ru(η5-Cp)(η5-4-(2-toluyl)indene)] ((Sp)-3b). This compound was
prepared according to the general procedure from (Sp)-1 (36 mg, 0.1
mmol), o-tolylboronic acid (20 mg, 0.15 mmol), Cs2CO3 (98 mg, 0.3
mmol), and PEPPSI-IPr catalyst (4 mg, 0.005 mmol). Purification by
flash chromatography (pentane) gave (Sp)-3b as a yellow oil (35 mg,
1
94%). Rf = 0.1 (pentane). H NMR (CDCl3, 400 MHz): δ 7.50−7.40
[Ru(η5-Cp)(η5-4-(2-propan-2-ol)indene)] ((Sp)-2f). This compound
was prepared according to the general procedure from (Sp)-1 (32 mg,
0.09 mmol), TMEDA (13 μL, 0.09 mmol), t-BuLi (1.6 M, 167 μL,
0.27 mmol), and acetone (23 μL, 0.18 mmol). Purification by flash
chromatography (pentane/diethyl ether, 90/10) gave (Sp)-2f as a
(m, 1H), 7.38 (d, J = 8.6 Hz, 1H), 7.35−7.24 (m, 3H), 6.86 (dd, J =
8.6, 6.6 Hz, 1H), 6.68 (d, J = 6.6 Hz, 1H), 5.30 (dd, J = 2.5, 1.0 Hz,
1H), 4.92−4.84 (br s, 1H), 4.59 (t, J = 2.5 Hz, 1H), 4.23 (s, 5H),
2.31−2.21 (br s, 3H). 13C NMR (CDCl3, 100.6 MHz): δ 141.1, 136.2,
130.4, 129.8, 127.4, 125.7, 125.5, 122.8, 122.7, 92.3, 72.9, 70.1, 66.1,
66.0, 20.2. IR (thin film): 3054, 2922, 1600, 1475, 1334, 1262, 1098,
1034, 996, 804, 754, 730 cm−1. [α]20D = +443° (c 0.1, CHCl3). HPLC
(Daicel Chiralcel OD-H, hexane/isopropyl alcohol 99/1, 0.5 mL
min−1, λ 254 nm): tR1, 10.3 min, tR2 = 12.2 min. HRMS (EI): calcd for
C21H18Ru [M]+ 372.0446, found 372.0447.
1
yellow oil (26 mg, 55%). Rf = 0.3 (pentane). H NMR (CD2Cl2, 400
MHz): δ 7.30 (d, J = 8.6 Hz, 1H), 6.86 (dd, J = 6.8, 0.9 Hz, 1H), 6.79
(dd, J = 8.5, 6.8 Hz, 1H), 5.49 (dd, J = 2.5, 1.0 Hz, 1H), 5.27 (dd, J =
2.5, 1.0 Hz, 1H), 4.67 (t, J = 2.5 Hz, 1H), 4.21 (s, 5H), 2.62 (s, 1H),
1.72 (d, J = 3.1 Hz, 6H). 13C NMR (CD2Cl2, 100.6 MHz): δ 145.9,
126.1, 123.1, 117.9, 93.3, 89.2, 73.8, 73.4, 70.6, 67.6, 66.3, 60.7, 30.6,
30.6. IR (thin film): 3402, 2970, 2929, 1460, 1363, 1260, 1099, 807
[Ru(η5-Cp)(η5-4-(1-naphthyl)indene)] ((Sp)-3c). This compound
was prepared according to the general procedure from (Sp)-1 (72
mg, 0.2 mmol), 2-naphthylboronic acid (52 mg, 0.3 mmol), Cs2CO3
(196 mg, 0.6 mmol), and PEPPSI-IPr catalyst (8 mg, 0.01 mmol).
Purification by flash chromatography (pentane) gave (Sp)-3c as a
yellow solid (76 mg, 93%). (Sp)-3c was isolated as a mixture of two
rotamers in a 1.4/1 ratio at 20 °C. Rf = 0.1 (pentane). Mp: 133−134
cm−1. [α]20 = +430° (c 0.1, CHCl3). HRMS (EI): calcd for
D
C17H18ORu [M]+ 340.0398, found 340.0396.
[Ru(η5-Cp)(η5-4-iodoindene)] ((Sp)-2g): Copper-Catalyzed Ar-
omatic Finkelstein Reaction Procedure. A Schlenk tube was
charged with (Sp)-1 (100 mg, 0.28 mmol), CuI (3 mg, 0.014 mmol,
5.0 mol %), and NaI (100 mg, 0.56 mmol, 2.0 equiv), briefly evacuated
and back-filled with nitrogen. Racemic trans-N,N′-dimethyl-1,2-
cyclohexanediamine (5 μL, 0.03 mmol, 10 mol %) and dioxane (1
mL) were added under nitrogen. The Schlenk tube was sealed with a
Teflon valve, and the reaction mixture was stirred at 110 °C for 24 h.
The resulting suspension was warmed to reach room temperature,
diluted with 30% aqueous ammonia (2 mL), poured into water (8
mL), and extracted with dichloromethane (3 × 5 mL). The combined
organic phases were dried with sodium sulfate, filtered, and
concentrated. The residue was purified by flash chromatography on
silica gel (pentane) to provide (Sp)-2g as a yellow solid (100 mg,
1
°C. H NMR (CDCl3, 400 MHz): δ 8.02 (d, J = 8.3 Hz, 1H), 7.97−
7.86 (m, 4.8H), 7.80 (d, J = 8.5 Hz, 1.4H), 7.74 (d, J = 7.0 Hz, 1H),
7.62−7.44 (m, 9.6H), 7.41−7.34 (m, 1.4H), 6.98−6.91 (m, 2.4H),
6.89 (d, J = 6.3 Hz, 2.4H), 5.36−5.32 (m, 2.4H), 4.95 (d, J = 2.5 Hz,
1H), 4.80 (d, J = 2.5 Hz, 1.4H), 4.60 (t, J = 2.5 Hz, 1H), 4.56 (t, J =
2.5 Hz, 1.4H), 4.26 (s, 7H), 4.19 (s, 5H). 13C NMR (CDCl3, 100.6
MHz): δ 138.7, 138.4, 134.1, 133.9, 132.2, 132.0, 128.3, 128.3, 127.9,
127.5, 127.2, 126.6, 126.6, 126.3, 126.2, 126.0, 125.9, 125.8, 125.7,
125.5, 125.3, 124.0, 123.9, 123.0, 122.4, 94.7, 93.3, 92.6, 92.4, 73.0,
72.8, 70.2, 70.1, 66.4, 66.2, 66.0, 65.9. IR (thin film): 3045, 2925, 1590,
1505, 1335, 1262, 1099, 1023, 997, 801, 777 cm−1. [α]20 = +465° (c
D
1
89%). Rf = 0.3 (pentane). Mp: 59−60 °C. H NMR (CDCl3, 400
0.1, CHCl3). HPLC (Daicel Chiralcel OD-H, hexane/isopropyl
alcohol 99/1, 0.5 mL min−1, λ 254 nm): tR1 = 10.3 min, tR2 = 12.2
min. HRMS (EI): calcd for C24H18Ru [M]+ 408.0447, found 408.0447.
[Ru(η5-Cp)(η5-4-(2-biphenyl)indene)] ((Sp)-3d). This compound
was prepared according to the general procedure from (Sp)-1 (36
mg, 0.1 mmol), 2-biphenylboronic acid (20 mg, 0.15 mmol), Cs2CO3
(98 mg, 0.3 mmol), and PEPPSI-IPr catalyst (4 mg, 0.005 mmol).
Purification by flash chromatography (pentane) gave (Sp)-3d as a
MHz): δ 7.39 (d, J = 8.6 Hz, 1H), 7.23 (d, J = 6.8 Hz, 1H), 6.47 (dd, J
= 8.6, 6.8 Hz, 1H), 5.42 (dd, J = 2.5, 1.0 Hz, 1H), 5.25 (d, J = 2.5 Hz,
1H), 4.63 (t, J = 2.5 Hz, 1H), 4.27 (s, 5H). 13C NMR (CDCl3, 100.6
MHz): δ 132.0, 127.0, 123.2, 96.3, 95.7, 92.7, 72.9, 70.4, 70.0, 67.5. IR
(thin film): 3087, 2923, 2852, 1771, 1494, 1464, 1434, 1404, 1376,
1327, 1298, 1121, 1098, 1030, 997, 886, 845, 809 cm−1. [α]20
=
D
+874° (c 0.1, CHCl3). HPLC (Daicel Chiralcel OD-H, hexane/
1
isopropyl alcohol 99/1, 0.5 mL min−1, λ 254 nm): tR1 = 12.6 min, tR2
=
yellow solid (28 mg, 65%). Rf = 0.1 (pentane). Mp: 110−111 °C. H
13.5 min. HRMS (EI): calcd for C14H11IRu [M]+ 407.8951, found
407.8944.
NMR (CDCl3, 400 MHz): δ 7.83−7.74 (br s), 7.53−7.44 (m, 3H),
7.26 (d, J = 8.6 Hz, 1H), 7.26−7.08 (m, 5H), 6.66 (dd, J = 8.6, 6.6 Hz,
1H), 6.48 (d, J = 6.6 Hz, 1H), 5.23−5.18 (br s, 1H), 5.00−4.88 (br s,
1H), 4.55−4.47 (br s, 1H), 4.23 (s, 5H). 13C NMR (CDCl3, 100.6
MHz): δ 141.7, 141.0, 139.1, 130.8, 130.5, 129.4, 127.9, 127.8, 127.5,
126.6, 125.5, 124.6,122.8, 92.2, 72.8, 70.1, 66.2, 65.9. IR (thin film):
Representative Procedure for the Suzuki−Miyaura Cross-
Coupling Procedure. (Sp)-1 (36 mg, 0.1 mmol, 1.0 equiv, 95% ee),
phenylboronic acid (18 mg, 0.15 mmol, 1.5 equiv), cesium carbonate
(98 mg, 0.3 mmol, 3.0 equiv), and PEPPSI-IPr catalyst (4 mg, 0.005
mmol, 5 mol %) were placed in a Schlenk and evacuated three times
before adding dioxane (0.5 mL). The resulting mixture was then
stirred and refluxed for 3 h. The crude mixture was then passed
through a short pad of silica, flushed with diethyl ether, and
concentrated. The residue was purified by flash column chromatog-
raphy on silica gel.
3054, 2929, 1471, 1335, 1099, 1035, 997, 909, 756, 730 cm−1. [α]20
=
D
+1052° (c 0.1, CHCl3). HPLC (Daicel Chiralcel OD-H, hexane/
isopropyl alcohol 99/1, 0.5 mL min−1, λ 254 nm): tR1 = 11.4 min, tR2
=
12.6 min. HRMS (EI): calcd for C26H20Ru [M]+ 434.0603, found
434.0603.
[Ru(η5-Cp)(η5-4-(2-styryl)indene)] ((Sp)-3e). This compound was
prepared according to the general procedure from (Sp)-1 (72 mg, 0.2
mmol), trans-2-phenylvinylboronic acid (45 mg, 0.3 mmol), Cs2CO3
(196 mg, 0.6 mmol), and PEPPSI-IPr catalyst (8 mg, 0.01 mmol).
Purification by flash chromatography (pentane) gave (Sp)-3e as a
[Ru(η5-Cp)(η5-4-phenylindene)] ((Sp)-3a). Purification by flash
chromatography on silica gel (pentane) afforded (Sp)-3a as a yellow
oil (56 mg, 91%, 95% ee). The enantiomeric purity of the product was
confirmed by HPLC analysis on a chiral stationary phase. Rf = 0.1
(pentane). 1H NMR (CDCl3, 400 MHz): δ 7.82−7.78 (m, 2H), 7.49−
7.43 (m, 2H), 7.41−7.35 (m, 2H), 6.91−6.86 (m, 2H), 5.32−5.29 (m,
2H), 4.66 (t, J = 2.5 Hz, 1H), 4.27 (s, 5H). 13C NMR (CDCl3, 100.6
MHz): δ 141.1, 139.7, 128.6, 128.2, 127.5, 126.0, 123.4, 122.1, 92.8,
90.5, 73.4, 70.3, 66.6, 66.2. IR (thin film): 3055, 2924, 1599, 1475,
1
yellow solid (76 mg, 93%). Rf = 0.1 (pentane). Mp: 98−99 °C. H
NMR (CDCl3, 400 MHz): δ 7.60−7.55 (d, J = 7.3 Hz, 2H), 7.43−7.37
(m, 2H), 7.35−7.25 (m, 4H), 7.01 (d, J = 6.8 Hz, 1H), 6.83 (dd, J =
8.6, 6.8 Hz, 1H), 5.52 (d, J = 2.5 Hz, 1H), 5.28 (dd, J = 2.5, 1.0 Hz,
1H), 4.68 (t, J = 2.5 Hz, 1H), 4.24 (s, 5H). 13C NMR (CDCl3, 100.6
MHz): δ 141.7, 141.0, 139.1, 130.8, 130.5, 129.4, 127.9, 127.8, 127.5,
126.6, 125.5, 124.6, 122.8, 92.2, 72.8, 70.1, 66.2, 65.9. IR (thin film):
3045, 2925, 1590, 1505, 1335, 1262, 1099, 1023, 997, 801, 777 cm−1.
1450, 1407, 1332, 1262, 1098, 1036, 996, 807, 729, 699 cm−1. [α]20
=
D
+1038° (c 0.1, CHCl3). HPLC (Daicel Chiralpak AD-H, hexane/
isopropyl alcohol 99/1, 0.5 mL min−1, λ 254 nm): tR1 = 9.6 min, tR2
=
E
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[α]20 = +932° (c 0.025, CHCl3). HRMS (EI): calcd for C22H18Ru
(Sp)-1 (72 mg, 0.2 mmol), n-BuLi (250 μL, 0.4 mmol), 1-
propiolaldehyde diethyl acetal (57 μL, 0.4 mmol), 9-MeO-9-BBN (C
= 1.0 M, 0.4 mL, 0.4 mmol), Pd(dba)2 (3 mg, 0.005 mmol), [HP-t-
Bu3][BF4] (2 mg, 0.006 mmol), and KF (0.3 mg, 0.006 mmol).
Purification by flash chromatography (pentane/diethyl ether, 96/4)
gave (Sp)-4d as a yellow oil (55 mg, 61%). Rf = 0.3 (pentane/diethyl
ether, 96/4). 1H NMR (CDCl3, 400 MHz): δ 7.43 (d, J = 8.6 Hz, 1H),
7.02 (d, J = 6.8 Hz, 1H), 6.78 (dd, J = 8.6, 6.8 Hz, 1H), 5.58 (s, 1H),
5.42 (d, J = 2.5 Hz, 1H), 5.23 (dd, J = 2.5, 1.0 Hz, 1H), 4.63 (t, J = 2.5
Hz, 1H), 4.23 (s, 5H), 3.90 (qdd, J = 9.6, 7.0, 1.3 Hz, 2H), 3.72 (qdd, J
= 9.4, 7.0, 1.3 Hz, 2H), 1.32 (t, J = 7.0 Hz, 3H), 1.32 (t, J = 7.0 Hz,
3H). 13C NMR (CDCl3, 100.6 MHz): δ 128.8, 128.0, 122.0, 119.4,
92.7, 92.2, 91.4, 87.9, 83.8, 73.1, 70.2, 66.6, 65.7, 61.1, 61.0, 15.4. IR
(thin film): 3096, 2974, 2929, 2880, 2222, 1353, 1330, 1233, 1099,
1048, 998,803, 773, 720 cm−1. [α]20D = +2256° (c 0.1, CHCl3). HPLC
(Daicel Chiralpak AD-H, hexane/isopropyl alcohol 99/1, 0.5 mL
min−1, λ 254 nm): tR1 = 13.7 min, tR2 = 17.6 min. HRMS (EI): calcd
for C21H22O2Ru [M]+ 408.0662, found 408.0658.
[M]+D384.0444, found 384.0447.
Representative Procedure for the “9-MeO-9-BBN Variant” of
the Suzuki−Miyaura Cross-Coupling Procedure. A 0.4 M
solution of phenylacetylene (44 μL, 0.4 mmol, 2.0 equiv) in diethyl
ether was treated with n-BuLi (250 μL, C = 1.6 M in hexanes, 0.4
mmol, 2.0 equiv) at −78 °C for 30 min. 9-MeO-9-BBN (0.4 mL, C =
1.0 M in hexanes, 0.4 mmol, 2.0 equiv) was added dropwise at −78 °C,
and the resulting solution was stirred at −78 °C for 2 h. In a separate
Schlenk tube, (Sp)-1 (72 mg, 0.2 mmol, 1.0 equiv, 93% ee) was added
to a solution of Pd(dba)2 (3 mg, 0.005 mmol, 2.5 mol %), [HP-t-
Bu3][BF4] (2 mg, 0.006 mmol, 3 mol %), and KF (0.3 mg, 0.006
mmol, 3 mol %) in toluene (0.1 M). The boronate solution was then
added by cannula to the latter solution, and the resulting mixture was
stirred for 14 h at room temperature. The crude mixture was then
passed through a short pad of silica, flushed with diethyl ether, and
concentrated. The residue was purified by flash column chromatog-
raphy on silica gel.
[Ru(η5-Cp)(η5-4-(2-phenylethynyl)indene)] ((Sp)-4a). Purification
by flash chromatography on silica gel (pentane) afforded (Sp)-4a as
[Ru(η5-Cp)(η5-4-methylindene)] ((Sp)-4e). To a 0.4 M solution of
methyllithium (C = 1.6 M in diethyl ether, 250 μL, 0.4 mmol) in
diethyl ether was added dropwise at −78 °C 9-MeO-9-BBN (C = 1.0
M in hexanes, 0.4 mL, 0.4 mmol), and the resulting solution was
stirred at −78 °C for 2 h. In a separate Schlenk tube, (Sp)-1 (72 mg,
0.2 mmol) was added to a solution of Pd(dba)2 (3 mg, 0.005 mmol),
[HP-t-Bu3][BF4] (2 mg, 0.006 mmol), and KF (0.3 mg, 0.006 mmol)
in toluene (0.1 M). The boronate solution was then added by cannula
to the latter solution, and the resulting mixture was stirred overnight at
room temperature. The crude mixture was then passed through a short
pad of silica and flushed with diethyl ether. Flash chromatography on
silica gel (pentane) afforded (Sp)-4e as a yellow oil (42 mg, 71%). Rf =
1
a yellow oil (68 mg, 90%, 93% ee). Rf = 0.2 (pentane). H NMR
(CDCl3, 400 MHz): δ 7.60 (dd, J = 7.9, 1.6 Hz, 2H), 7.43 (d, J = 8.7
Hz, 1H), 7.41−7.31 (m, 3H), 7.06 (d, J = 6.7 Hz, 1H), 6.78 (dd, J =
8.7, 6.7 Hz, 1H), 5.51 (d, J = 2.5 Hz, 1H), 5.26 (dd, J = 2.5, 1.0 Hz,
1H), 4.66 (t, J = 2.5 Hz, 1H), 4.26 (s, 5H). 13C NMR (CDCl3, 100.6
MHz): δ 131.8, 128.5, 128.3, 128.2, 127.1, 123.8, 122.3, 120.8, 93.2,
92.9, 91.6, 88.0, 73.0, 70.3, 66.6, 65.8. IR (thin film): 3079, 3054, 2957,
2920, 2851, 2202, 1597, 1489, 1334, 1098, 1024, 998, 753, 719, 688
cm−1. [α]20 = +1736° (c 0.1, CHCl3). HPLC (Daicel Chiralpak AD-
D
H, hexane/isopropyl alcohol 99/1, 0.5 mL min−1, λ 254 nm): tR1
=
11.9 min, tR2 = 13.0 min. HRMS (EI): calcd for C22H16Ru [M]+
382.0295, found 382.0300.
1
0.1 (pentane). H NMR (CDCl3, 400 MHz): δ 7.22 (d, J = 8.6 Hz,
1H), 6.72 (dd, J = 8.6, 6.4 Hz, 1H), 6.57 (dt, J = 6.4, 1.0 Hz, 1H), 5.24
(dd, J = 2.5, 1.0 Hz, 1H), 5.26 (d, J = 2.5 Hz, 1H), 4.58 (t, J = 2.5 Hz,
1H), 4.19 (s, 5H), 2.38 (s, 3H). 13C NMR (CDCl3, 100.6 MHz): δ
136.3, 123.7, 123.3, 120.9, 93.0, 92.8, 72.3, 69.8, 66.3, 64.1, 18.9. IR
(thin film): 3084, 2962, 2850, 2233, 1611, 1538, 1458, 1406, 1376,
[Ru(η5-Cp)(η5-4-(2-trimethylsilylethynyl)indene)] ((Sp)-4b). This
compound was prepared according to the general procedure from
(Sp)-1 (72 mg, 0.2 mmol), n-BuLi (250 μL, 0.4 mmol),
trimethylsilylacetylene (57 μL, 0.4 mmol), 9-MeO-9-BBN (1.0 M,
0.4 mL, 0.4 mmol), Pd(dba)2 (3 mg, 0.005 mmol), [HP-t-Bu3][BF4]
(2 mg, 0.006 mmol), and KF (0.3 mg, 0.006 mmol). Purification by
flash chromatography (pentane) gave (Sp)-4b as a yellow oil (66 mg,
87%). Rf = 0.2 (pentane). 1H NMR (CDCl3, 400 MHz): δ 7.40 (d, J =
8.7 Hz, 1H), 6.99 (d, J = 6.7 Hz, 1H), 6.72 (dd, J = 8.7, 6.7 Hz, 1H),
5.42 (d, J = 2.5 Hz, 1H), 5.23 (dd, J = 2.5, 1.0 Hz, 1H), 4.63 (t, J = 2.5
Hz, 1H), 4.24 (s, 5H), 0.30 (s, 9H). 13C NMR (CDCl3, 100.6 MHz):
δ 128.5, 127.5, 122.2, 120.8, 103.5, 98.3, 93.0, 91.5, 73.1, 70.3, 66.7,
65.9. IR (thin film): 3096, 2958, 2920, 2143, 1594, 1478, 1336, 1098,
1340, 1259, 1098, 1025, 996, 758, 723 cm−1. [α]20 = +417° (c 0.1,
D
CHCl3). HPLC (Daicel Chiralcel OD-H, hexane/isopropyl alcohol
99/1, 0.5 mL min−1, λ 254 nm): tR1 = 13.7 min, tR2 = 15.9 min. HRMS
(EI): calcd for C15H14Ru [M]+ 296.0137, found 296.0134.
[Ru(η5-Cp)(η5-4-(2-furyl)indene)] ((Sp)-4f). A 0.4 M solution of
furan (38 μL, 0.4 mmol) in diethyl ether was treated with t-BuLi (C =
1.6 M in pentane, 230 μL, 0.4 mmol) at −78 °C for 90 min. 9-MeO-9-
BBN (C = 1.0 M in hexanes, 0.4 mL, 0.4 mmol) was added dropwise
at −78 °C, and the resulting solution was stirred at −78 °C for 2 h. In
a separate Schlenk tube, (Sp)-1 (72 mg, 0.2 mmol) was added to a
solution of Pd(dba)2 (3 mg, 0.005 mmol), [HP-t-Bu3][BF4] (2 mg,
0.006 mmol), and KF (0.3 mg, 0.006 mmol) in toluene (0.1 M). The
boronate solution was then added by cannula to the latter solution,
and the resulting mixture was stirred overnight at room temperature.
The crude mixture was then passed through a short pad of silica and
flushed with diethyl ether. Flash chromatography on silica gel
(pentane) afforded (Sp)-4f as a yellow oil (53 mg, 76%). Rf = 0.1
1023, 986, 839, 801, 720, 699 cm−1. [α]20 = +1711° (c 0.1, CHCl3).
D
HPLC (Daicel Chiralpak AD-H, hexane/isopropyl alcohol 99/1, 0.5
mL min−1, λ 254 nm): tR1 = 19.6 min, tR2 = 22.2 min. HRMS (EI):
calcd for C19H20RuSi [M]+ 378.0376, found 378.0372.
[Ru(η5-Cp)(η5-4-(2-cyclohexen-1-ylethynyl)indene)] ((Sp)-4c). This
compound was prepared according to the general procedure from
(Sp)-1 (72 mg, 0.2 mmol), n-BuLi (250 μL, 0.4 mmol), 1-
ethynylcyclohexene (47 μL, 0.4 mmol), 9-MeO-9-BBN (C = 1.0 M,
0.4 mL, 0.4 mmol), Pd(dba)2 (3 mg, 0.005 mmol), [HP-t-Bu3][BF4]
(2 mg, 0.006 mmol), and KF (0.3 mg, 0.006 mmol). Purification by
flash chromatography (pentane) gave (Sp)-4c as a yellow solid (55 mg,
1
(pentane). H NMR (CDCl3, 400 MHz): δ 7.53 (d, J = 1.6 Hz, 1H),
7.36 (d, J = 8.5 Hz, 1H), 7.23 (d, J = 7.0 Hz, 1H), 6.86 (dd, J = 8.5, 7.0
Hz, 1H), 6.79 (d, J = 3.1 Hz, 1H), 6.55 (dd, J = 3.1, 1.6 Hz, 1H), 5.62
(d, J = 2.5 Hz, 1H), 5.28 (dd, J = 2.5, 1.0 Hz, 1H), 4.68 (t, J = 2.5 Hz,
1H), 4.21 (s, 5H). 13C NMR (CDCl3, 100.6 MHz): δ 153.5, 141.9,
128.6, 126.4, 122.7, 119.0, 111.7, 107.0, 92.9, 87.9, 73.3, 70.2, 66.4,
66.1. IR (thin film): 3096, 2925, 1527, 1494, 1472, 1407, 1261, 1214,
1099, 1016, 936, 884, 770, 722 cm−1. [α]20D = +1370° (c 0.1, CHCl3).
HPLC (Daicel Chiralpak AD-H, hexane/isopropyl alcohol 99/1, 0.5
mL min−1, λ 254 nm): tR1 = 12.0 min, tR2 = 12.3 min. HRMS (EI):
calcd for C18H14RuO [M]+ 348.0090, found 348.0083.
1
71%). Rf = 0.1 (pentane). Mp: 96−97 °C. H NMR (CDCl3, 400
MHz): δ 7.36 (d, J = 8.6 Hz, 1H), 6.94 (d, J = 6.8 Hz, 1H), 6.73 (dd, J
= 8.6, 6.6 Hz, 1H), 6.29−6.25 (m, 1H), 5.41 (d, J = 2.5 Hz, 1H), 5.22
(dd, J = 2.5, 1.0 Hz, 1H), 4.62 (t, J = 2.5 Hz, 1H), 4.24 (s, 5H), 2.34−
2.28 (m, 2H), 2.22−2.16 (m, 2H), 1.76−1.69 (m, 2H), 1.69−1.62 (m,
2H). 13C NMR (CDCl3, 100.6 MHz): δ 135.1, 127.4, 126.4, 122.4,
121.4, 121.2, 95.3, 93.0, 91.6, 85.3, 72.8, 70.2, 66.5, 65.8. IR (thin
film): 3092, 2931, 2858, 2184, 1657, 1521, 1434, 1337, 1238, 1099,
1034, 998,805, 721 cm−1. [α]20 = + 1231 (c 0.1, CHCl3). HPLC
[Ru(η5-Cp)(η5-4-(2-thiophenyl)indene)] ((Sp)-4g). A 0.4 M solution
of 2-bromothiophene (38 μL, 0.4 mmol) in diethyl ether was treated
with n-BuLi (C = 1.6 M in hexanes, 250 μL, 0.4 mmol) at 0 °C for 90
min. 9-MeO-9-BBN (C = 1.0 M in hexanes, 0.4 mL, 0.4 mmol) was
added dropwise at −78 °C, and the resulting solution was stirred at
−78 °C for 2 h. In a separate Schlenk tube, (Sp)-1 (72 mg, 0.2 mmol)
D
(Daicel Chiralpak AD-H, hexane/isopropyl alcohol 99/1, 0.5 mL
min−1, λ 254 nm): tR1 = 10.4 min, tR2 = 10.7 min. HRMS (EI): calcd
for C22H20Ru [M]+ 386.0607, found 386.0603.
[Ru(η5-Cp)(η5-4-(3,3-diethoxypropyn-1-yl)indene)] ((Sp)-4d). This
compound was prepared according to the general procedure from
F
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was added to a solution of Pd(dba)2 (3 mg, 0.005 mmol), [HP-t-
Bu3][BF4] (2 mg, 0.006 mmol), and KF (0.3 mg, 0.006 mmol) in
toluene (0.1 M). The boronate solution was then added by cannula to
the latter solution, and the resulting mixture was stirred overnight at
room temperature. The crude mixture was then passed through a short
pad of silica and flushed with diethyl ether. Flash chromatography on
silica gel (pentane) afforded (Sp)-4g as a yellow solid (42 mg, 58%). Rf
= 0.2 (pentane). Mp: 73−74 °C. 1H NMR (CDCl3, 400 MHz): δ 7.49
(dd, J = 3.6, 1.2 Hz, 1H), 7.39 (d, J = 8.6 Hz, 1H), 7.34 (dd, J = 5.1,
1.2 Hz, 1H), 7.15 (dd, J = 5.1, 3.6 Hz, 1H), 7.01 (d, J = 6.8 Hz, 1H), 6.
84 (dd, J = 8.6, 6.8 Hz, 1H), 5.57 (d, J = 2.5 Hz, 1H), 5.30 (dd, J = 2.5,
1.0 Hz, 1H), 4.67 (t, J = 2.5 Hz, 1H), 4.27 (s, 5H). 13C NMR (CDCl3,
100.6 MHz): δ 143.1, 132.8, 127.5, 126.3, 124.7, 124.6, 123.0, 121.8,
93.0, 89.5, 73.4, 70.3, 66.8, 66.3. IR (thin film): 3097, 2921, 2851,
2880, 1599, 1427, 1406, 1330, 1098, 1027, 997,805, 770, 722, 694
AUTHOR INFORMATION
Corresponding Author
*E-mail for E.P.K.: peter.kundig@unige.ch.
Notes
■
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
We thank the Swiss National Science Foundation and the
University of Geneva for financial support. We gratefully
acknowledge a postdoctoral grant to S.W. by the Ecole
Polytechnique, Paris.
REFERENCES
■
cm−1. [α]20 = +1065° (c 0.1, CHCl3). HPLC (Daicel Chiralpak AD-
(1) Transition Metal Arene π-Complexes in Organic Synthesis and
D
H, hexane/isopropyl alcohol 99/1, 0.5 mL min−1, λ 254 nm): tR1
=
Catalysis; Kundig, E. P., Ed.; Springer-Verlag: Berlin, 2004; Topics in
̈
12.6 min, tR2 = 13.2 min. HRMS (EI): calcd for C18H14RuS [M]+
363.9857, found 363.9854.
Organometallic Chemistry 7.
(2) (a) Blaser, H. U.; Brieden, W.; Pugin, B.; Spindler, F.; Studer, M.;
Togni, A. Top. Catal. 2002, 19, 3−16. (b) Blaser, H. U. Adv. Synth.
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(3) (a) Fu, G. C. Acc. Chem. Res. 2000, 33, 412−420. For a recent
application on dynamic kinetic resolution, see: (b) Lee, S. Y.; Murphy-
Knight, J. M.; Ukai, A.; Fu, G. C. J. Am. Chem. Soc. 2012, 134, 15149−
15153.
[Ru(η5-Cp)(η5-4-(propyn-1-yl)indene)] ((Sp)-4h). A 0.4 M solution
of sodium propynide (26 mg, 0.4 mmol) in diethyl ether was treated
with 9-MeO-9-BBN (C = 1.0 M in hexanes, 0.4 mL, 0.4 mmol)
dropwise at −78 °C, and the resulting solution was stirred at −78 °C
for 2 h. In a separate Schlenk tube, (Sp)-1 (36 mg, 0.1 mmol), was
added to a solution of Pd(dba)2 (1.5 mg, 0.0025 mmol), [HP-t-
Bu3][BF4] (1 mg, 0.003 mmol), and KF (0.15 mg, 0.003 mmol) in
toluene (0.1 M). The boronate solution was then added by cannula to
the latter solution, and the resulting mixture was stirred overnight at
room temperature. The crude mixture was then passed through a short
pad of silica and flushed with diethyl ether. Flash chromatography on
silica gel (pentane) afforded (Sp)-4h as a yellow solid (27 mg, 85%). A
75% yield was obtained with 2.0 equiv of propynylsodium and 9-MeO-
9-BBN. Rf = 0.1 (pentane). Mp: 136−137 °C. 1H NMR (CDCl3, 400
MHz): δ 7.35 (d, J = 8.7 Hz, 1H), 6.90 (d, J = 6.7 Hz, 1H), 6.71 (dd, J
= 8.7, 6.7 Hz, 1H), 5.40 (d, J = 2.5 Hz, 1H), 5.22 (dd, J = 2.5, 1.0 Hz,
1H), 4.61 (t, J = 2.5 Hz, 1H), 4.24 (s, 5H), 2.16 (s, 3H). 13C NMR
(CDCl3, 100.6 MHz): δ 127.1, 127.0, 122.4, 121.7, 93.3, 91.6, 89.5,
78.0, 72.8, 70.2, 66.4, 65.8, 5.0. IR (thin film): 2921, 2852, 1726, 1460,
(4) (a) Garrett, C. E.; Fu, G. C. J. Am. Chem. Soc. 1998, 120, 7479−
7483. (b) Ratni, H.; Kundig, E. P. Org. Lett. 1999, 1, 1997−1999.
̈
(c) Wurz, R. P.; Lee, E. C.; Ruble, J. C.; Fu, G. C. Adv. Synth. Catal.
2007, 349, 2345−2352. (d) Thimmaiah, M.; Luck, R. L.; Fang, S. Y. J.
Organomet. Chem. 2007, 692, 1956−1962. (e) Ratni, H.; Kundig, E. P.
̈
Org. Lett. 1999, 1, 1997−1999. (f) Correction: Ratni, H.; Kundig, E.
̈
P. Org. Lett. 2000, 2, 1983−1984.
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1409, 1336, 1260, 1098, 1075, 1017, 801, 767 cm−1. [α]20 = +1543°
D
(c 0.1, CHCl3). HPLC (Daicel Chiralpak AD-H, hexane/isopropyl
alcohol 99/1, 0.5 mL min−1, λ 254 nm): tR1 = 8.8 min, tR2 = 9.0 min.
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[Ru(η5-Cp)(η5-4-ethynylindene)] ((Sp)-4i). To a 0.05 M solution of
(Sp)-4b (180 mg, 0.48 mmol) in methanol (10 mL) was added K2CO3
(20 mg, 0.14 mmol, 30 mol %), and the resulting mixture was stirred
at room temperature overnight. Dichloromethane and water were
added to the reaction mixture. The separated aqueous phase was
extracted twice with dichloromethane. The combined organic layers
were washed with water and brine and dried over sodium sulfate.
Removal of the volatile materials afforded pure (Sp)-4i (144 mg, 99%)
1
as a yellow oil. Rf = 0.2 (pentane). H NMR (CDCl3, 400 MHz): δ
7.45 (d, J = 8.7 Hz, 1H), 7.05 (d, J = 6.6 Hz, 1H), 6.74 (dd, J = 8.7, 6.6
Hz, 1H), 5.44 (d, J = 2.5 Hz, 1H), 5.24 (dd, J = 2.5, 1.0 Hz, 1H), 4.64
(t, J = 2.5 Hz, 1H), 4.25 (s, 5H), 3.34 (s, 1H). 13C NMR (CDCl3,
100.6 MHz): δ 128.8, 128.2, 122.0, 119.6, 92.8, 91.4, 82.2, 80.6, 73.1,
70.2, 66.6, 65.7. IR (thin film): 3284, 3092, 2961, 2962, 2922, 2852,
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D
= +1205° (c 0.1, CHCl3). HRMS (EI): calcd for C16H12Ru [M]+
305.9979, found 305.9978.
Chem. 2002, 67, 1929−1935. (h) Fretzen, A.; Kundig, E. P. Helv.
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ASSOCIATED CONTENT
Chim. Acta 1997, 80, 2023−2026. (i) Fretzen, A.; Ripa, A.; Liu, R. G.;
■
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̈
S
* Supporting Information
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Synthesis 2009, 1761−1785. Addendum: (b) Ogasawara, M.;
Watanabe, S. Synthesis 2009, 3177. (c) Uemura, M.; Nishimura, H.;
Hayashi, T. Tetrahedron Lett. 1993, 34, 107−110. (d) Uemura, M.;
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Figures giving NMR spectra for all new compounds and HPLC
traces for three representative examples (2c, 3a, 4a). This
material is available free of charge via the Internet at http://
pubs.acs.org.
G
dx.doi.org/10.1021/om400845t | Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
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