Catalytic Access to Indole-Fused Benzosiloles by 2-Fold Electrophilic C-H Silylation with Dihydrosilanes

Article abstract of DOI:10.1021/acs.organomet.6b00801

A protocol for the catalytic synthesis of indole-fused benzosiloles starting from 2-aryl-substituted indoles and dihydrosilanes is reported. Compared to known procedures, this method does not require prefunctionalized starting materials and, hence, allows for a rapid access to those siloles. The net reaction is a 2-fold electrophilic C-H silylation catalyzed by cationic Ru-S complexes. Both reaction steps were separately investigated, and these results eventually led to the development of a two-step procedure. By preparing new Ru-S complexes with different weakly coordinating anions (WCAs), it is also shown that the latter can have a dramatic influence on the outcome of these reactions. Furthermore, the substrate scope of the new method is discussed.

Full text of DOI:10.1021/acs.organomet.6b00801

Article
pubs.acs.org/Organometallics
Catalytic Access to Indole-Fused Benzosiloles by 2‑Fold Electrophilic
C−H Silylation with Dihydrosilanes
Lukas Omann and Martin Oestreich*
Institut fur Chemie, Technische Universitat Berlin, Strasse des 17. Juni 115, 10623 Berlin, Germany
̈
̈
S
* Supporting Information
ABSTRACT: A protocol for the catalytic synthesis of indole-
fused benzosiloles starting from 2-aryl-substituted indoles and
dihydrosilanes is reported. Compared to known procedures, this
method does not require prefunctionalized starting materials and,
hence, allows for a rapid access to those siloles. The net reaction is
a 2-fold electrophilic C−H silylation catalyzed by cationic Ru−S
complexes. Both reaction steps were separately investigated, and
these results eventually led to the development of a two-step
procedure. By preparing new Ru−S complexes with different
weakly coordinating anions (WCAs), it is also shown that the
latter can have a dramatic influence on the outcome of these reactions. Furthermore, the substrate scope of the new method is
discussed.
Scheme 1. Previously Reported Methods for the
Construction of Indole-Fused Benzosiloles
INTRODUCTION
■
Organic π-conjugated molecules with incorporated silicon
atoms feature interesting optoelectronic properties.1 Among
this family of compounds siloles have emerged as promising
molecules for the development of new materials.2 Conse-
quently, numerous catalytic reactions for their preparation,3 in
particular for benzo-4 and dibenzosiloles,5 have been reported
over the last years. On the contrary, methods for the
construction of indole-fused benzosiloles 1 are by far less
developed despite their fascinating blue-fluorescence proper-
ties.6 In fact, only two procedures have been described in the
literature:7,8 Shimizu, Hiyama, and co-worker introduced a
delicate route to 1 by a palladium-catalyzed C−H/C−OTf
coupling (Scheme 1, 2 → 1aa);9 this reaction involves an
unusual 1,2-silyl migration.10 More recently, He and co-workers
disclosed an elegant approach to these molecules by a rhodium-
catalyzed domino cyclization/Si−C bond activation reaction (3
→ 1bb).11 Although both of these methods are highly efficient,
we asked ourselves whether it was possible to construct these
molecules from more easily accessible, i.e., not prefunctional-
ized, starting materials by the strategy outlined below (Scheme
2).
dihydrosilanes 6 would initially react to the C3-silylated indole
7 followed by ring closure at higher temperatures to eventually
afford 1 with an overall release of two molecules of dihydrogen.
The utility of this approach lies in the ready availability of 5
through directing-group-free catalytic C−H arylation meth-
ods.20 It is important to mention that the idea can be traced
back to the work of Curless and Ingleson, who employed
B(C6F5)3 as a catalyst in this transformation.17c The electron-
deficient borane was indeed capable of forming 7, but no ring
closure to 1 was observed. Instead, the catalyst was converted
We had reported before that cationic Ru−S complexes12
[4]+[X]− (X = BArF ) are capable of splitting the Si−H bond of
4
hydrosilanes R3SiH into a sulfur-stabilized silicon cation and a
ruthenium hydride.13 This was applied to the catalytic
intermolecular SEAr of electron-rich indoles.14,15 More recently,
we extended this methodology to the intramolecular SEAr of
benzenes, thereby providing access to dibenzosiloles.16,17 We
then anticipated that this catalytic system could also be
applicable to the activation of dihydrosilanes R2SiH2 and,
hence, envisioned the development of a 2-fold Friedel−Crafts-
type C−H silylation18,19 where 2-aryl-substituted indoles 5 and
Received: October 18, 2016
© XXXX American Chemical Society
A
DOI: 10.1021/acs.organomet.6b00801
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an electron-rich phosphine ligand (entries 1 and 2). The
reaction turned out to be sensitive toward the amount of
dihydrosilane, providing higher conversions with an excess of
3.0 equiv (entry 2 versus entry 3). Lowering the catalyst loading
from 5 mol % to 2 mol % did not diminish the yield (entry 4),
and high conversions were even obtained at a catalyst loading
of 1 mol %. For screening the reaction conditions of the next
reaction step, we conducted a gram-scale synthesis, which
afforded 7ac in 92% isolated yield. It is noteworthy that, under
these reaction conditions, we have never observed any
formation of traces of indoline.
Scheme 2. New Approach to Indole-Fused Benzosiloles by 2-
Fold Electrophilic C−H Silylation
a
Optimization of the Intramolecular C−H Bond
Silylation. We next focused on the intramolecular SEAr, i.e.,
the ring closure of 7ac to 1ac. Our previously reported
procedure for the synthesis of dibenzosiloles required micro-
wave heating at 140 °C.16 Hence, we tested catalysts
[4a]+[BArF ]− and [4b]+[BArF ]− under similar reaction
4
4
conditions (Table 2, entries 1 and 2). With a catalyst loading
a
ArF = 3,5-bis(trifluoromethyl)phenyl.
Table 2. Optimization of the Intramolecular Electrophilic
C−H Silylation
into the catalytically inactive ion pair [indoline−H]+[H−
B(C6F5)3]−, hence inhibiting the reaction at 70% conversion.21
In addition to the susceptibility of indoles to be reduced to
indolines, the difficulty of such a transformation lies also in the
fact that the silylated indole 7 is prone to protodesilylation in
the presence of Brønsted acids.
RESULTS AND DISCUSSION
■
Optimization of the Intermolecular C−H Bond
Silylation. We decided to begin with investigating both
reaction steps separately and chose 1-methyl-2-phenylindole
(5a) and MePhSiH2 (6c) as model substrates for our
optimization study (Table 1). Our previously reported
Table 1. Optimization of the Intermolecular Electrophilic
C−H Silylation
c
T
conv
b
ratio
a
entry
(°C)
solvent
ClC6H5
ClC6H5
catalyst
(%)
1ac:5a:8ac
1
2
3
4
5
140
140
160
180
180
180
180
180
[4a]+[BArF ]−
[4b]+[BArF ]−
1,2-Cl2C6H4 [4a]+[BArF ]−
37
27
0:29:8
4
5:13:9
4
82
14:50:18
25:33:31
61:10:22
13:41:45
56:11:31
54:18:19
4
1,2-Cl2C6H4 [4a]+[BArF ]−
89
4
mesitylene
mesitylene
mesitylene
mesitylene
[4a]+[BArF ]−
93
4
d
6
e
[4a]+[BArF ]−
>99
99
4
7
[4a]+[BArF ]−
4
a
b
entry
equiv of 6c
catalyst
conv (%)
8
[4b]+[BArF ]−
91
4
1
2
3
4
3.0
3.0
1.1
3.0
3.0
[4b]+[BArF ]− (5 mol %)
23
97
40
97
a
4
All reactions were performed in an open vessel (to release H2) on a
0.05 mmol scale at a concentration of 0.5 M. Determined by GLC
analysis with reference to 7ac. Determined by GLC analysis; ratio
based on integration of baseline-separated peaks. With a higher
[4a]+[BArF ]− (5 mol %)
b
4
[4a]+[BArF ]− (5 mol %)
c
4
[4a]+[BArF ]− (2 mol %)
d
4
c
d
e
5
[4a]+[BArF ]− (1 mol %)
95 (92)
catalyst loading (5 mol %). With 2,6-dichloropyridine (0.1 equiv) as
4
a
an additive.
All reactions were performed in an open vessel (to release H2) with
0.05 mmol of 5a in ClC6H5 (1 M). Reaction times 15−18 h.
b
c
Determined by GLC analysis with reference to 5a. Reaction was
of 2 mol %, desired 1ac was only formed in traces (entry 2).
Instead, the major compound found was in both cases indole 5a
as a result of protodesilylation of 7ac.23 In addition, another
byproduct was detected and identified as fluorosilane 8ac,
performed on a 1.0 g scale (4.8 mmol of 5a); reaction time 44 h.
d
Isolated yield after flash chromatography and subsequent distillation
in parentheses.
proving that the BArF − counteranion is slowly decomposing
4
procedure for the C3 silylation of indoles with hydrosilanes
R3SiH is performed without solvent.14a However, the reaction
of solid 5a and volatile 6c does not allow for a solvent-free
protocol. Hence, we performed all reactions in ClC6H5 as
solvent at a concentration of 1 M.22
under these conditions. Consequently, a gradual increase in
temperature to 160 °C (entry 3) and 180 °C (entry 4) with
[4a]+[BArF ]− as catalyst and higher boiling 1,2-Cl2C6H4 as
4
solvent led to an increased formation of 8ac, but, at the same
time, desired 1ac was now formed in substantial amounts. A
significant improvement was obtained when apolar mesitylene
was used as solvent, affording silole 1ac as the major
Catalyst [4a]+[BArF ]−, with an electron-poor phosphine
4
ligand, performed significantly better than [4b]+[BArF ]−, with
4
B
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Table 3. Reactivity Screening of Complexes with Different Counteranions
a
d
e
entry
catalyst for step 1
catalyst for step 2 or additive 9
conv (%)
ratio 1ac:7ac:8ac
b
1
[4a]+[BArF ]−

90




64
77

76
62:6:22
4
b
fg
,
2
[4a]+[B(C6F5)4]−

b
f
3
[4a]+[CHB11Me5Br6]−
[4b]+[B(C6F5)4]−

b
gh
,
4

b
h
5
[4b]+[CHB11Me5Br6]−
[4a]+[CHB11Me5Br6]−
[4a]+[CHB11Me5Br6]−
[4a]+[CHB11Me5Br6]−

b
6
[4b]+[CHB11Me5Br6]−
21:43:0
73:4:0

b
7
9
bi
,
8
9
9
c
[4a]+[BArF ]−
[4b]+[CHB11Me5Br6]−
75:1:0
4
a
All reactions were perfomed in an open vessel (to release H2) with 0.20 mmol of 5a and 0.60 mmol (3.0 equiv) of 6c according to GP3 (without
removal of the catalyst used in step 1) or GP4 (with removal of the catalyst used in step 1; see the Experimental Section for detailed procedures).
b
c
d
According to GP3. According to GP4. Determined by GLC analysis with reference to 5a. Reversion of step 1, that is, protodesilylation of 7ac to
e
5a, under the conditions of step 2 accounts for seemingly incomplete conversion. Determined by GLC analysis; ratio based on integration of
baseline-separated peaks. High conversion was achieved in step 1, but complete decomposition of 7ac to 5a was observed in step 2. Under
microwave heating, additional impurities due to substituent scrambling at the silicon atom were observed by GC-MS analysis. Only moderate
conversion was achieved in step 1. Ruthenium hydride 9 was added in step 1, resulting in complete inhibition of the reaction.
f
g
h
i
component (entry 5). Increasing the catalyst loading to 5 mol
% was detrimental to the reaction (entry 6). Besides the
expected increased formation of 8ac due to higher amounts of
from substituent scrambling at the silicon atom.29 We next
investigated the reactivity of the corresponding catalysts with an
electron-rich phosphine ligand [4b]+[B(C6F5)4]− and
[4b]+[CHB11Me5Br6]−. In accordance with our initial screening
results, these showed only moderate conversions in the
silylation of the indole core (entries 4 and 5; cf. Table 1,
entry 1). Since our findings suggest that the second reaction
step is less sensitive to the type of phosphine ligand in [4]+[X]−
(cf. Table 2, entry 5 versus entry 8), we added
[4b]+[CHB11Me5Br6]− as a catalyst after step 1 had been
catalyzed by [4a]+[CHB11Me5Br6]− (entry 6). Indeed, desired
1ac was now formed in moderate amounts. The comparatively
low yield of 1ac might be due to competitive reactivity of both
catalysts. We next added proton-accepting ruthenium hydride
930 as an additive (entry 7), now affording 1ac as the major
product in high yields. Importantly, 9 entirely shuts down the
reaction if already used as an additive in step 1 (entry 8),
presumably due to formation of a dimer that would not be
reactive at room temperature.31 We also developed a two-step
the BArF − counteranion, the relative ratio between the 1ac and
4
protodesilylated 5a also decreased. This finding can be
explained by a higher concentration of Brønsted-acidic
intermediates at higher catalyst loadings, demonstrating once
more the lability of intermediate 7ac. Addition of Lewis bases
such as 2,6-dichloropyridine had no beneficial effect on the
reaction outcome (entry 7).24 Changing the catalyst to
[4b]+[BArF ]− also gave 1ac predominantly in satisfactory
4
amounts (entry 8). Given our library of Ru−S complexes with
different ligands, we also applied catalysts with iPr3P25 and
Ph3P26 as well as an NHC as ligands.27 Those afforded 1ac in
lower yields though (not shown). It is also important to
mention that conventional oil-bath heating led to complete
decomposition of 7ac to 5a (not shown).
Reactivity Screening of Complexes with Different
Counteranions. Having identified catalyst [4a]+[BArF ]− as
4
procedure, in which catalyst [4a]+[BArF ]− is removed after the
active in both reaction steps, we next developed a two-step
procedure without the need of isolating 7ac (Table 3). Indeed,
a catalyst loading of 2 mol % was sufficient to perform both
bond formations, affording 1ac in good yields (entry 1). It must
be mentioned here that the excess of dihydrosilane used in the
first step must be removed before heating the reaction in a
microwave, as otherwise no product formation is observed (see
the Experimental Section for a detailed procedure). To avoid
the formation of fluorosilane 8ac and to improve the yield of
silole 1ac, we prepared Ru−S complexes with chemically more
robust counteranions and investigated their reactivity in the
two-step procedure. We succeeded in preparing [4a]+[B-
4
first step by silica gel filtration and [4b]+[CHB11Me5Br6]− is
added to perform the ring-closing reaction (entry 9). This setup
seemed to be the most efficient, as it provided indole-fused
benzosilole 1ac in good yield without the formation of
fluorosilane 8ac. This procedure was then used to assess the
substrate scope.
Investigation of the Substrate Scope. Model substrate
5a afforded product 1ac in 63% isolated yield (Figure 1).
Running the reaction with a single catalyst ([4a]+[BArF ]−; cf.
4
Table 3, entry 1) allowed for isolating 1ac in still 50% yield,
despite the formation of fluorosilane 8ac as an additional
byproduct. Next, we probed different protective groups on the
nitrogen atom. The slightly larger ethyl group in 5c already led
to a decreased reactivity in the intermolecular C−H silylation
step. However, with slightly higher catalyst loading (5 mol %),
desired 1cc was isolated in good yield. Consequently, substrates
28
(C6F5)4]− and [4a]+[CHB11Me5Br6]− and subjected these
catalysts to our protocol (entries 2 and 3). As expected, both
afforded intermediate 7ac under the optimized reaction
conditions, but no ring closure to 1ac was observed with
[4a]+[B(C6F5)4]−, also giving additional byproducts resulting
C
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Figure 1. Substrate scope of the 2-fold C−H silylation for the
synthesis of indole-fused benzosiloles with different protective groups
at the nitrogen atom (top) as well as with different dihydrosilanes
(bottom). All reactions were performed with 0.20 mmol of 5
according to GP4 (Table 3, entry 9). Yields of isolated products after
Figure 2. Substrate scope of the 2-fold C−H silylation for the
synthesis of indole-fused benzosiloles with different substituents at C5
of the indole. All reactions were performed with 0.20 mmol of 5
according to GP4 (Table 3, entry 9). Yields of isolated product after
a
purification by flash chromatography. According to GP3 (Table 3,
b
entry 1). With 5 mol % of [4a]+[BArF ]− and 0.10 mL of ClC6H5 (2
4
c
M). Step 1 performed at 60 °C and with 0.10 mL of ClC6H5 (2 M).
purification by flash chromatography. aWith 5 mol % of [4a]+[BArF ]−
4
b
and 0.10 mL of ClC6H5 (2 M). With 0.20 mmol (1.0 equiv) of 6c.
with larger protective groups such as benzyl (5d), phenyl (not
shown), and triethylsilyl (not shown) did not react. For the
latter two, electronic effects are likely to contribute to their lack
of reactivity. Conversely, the newly developed protocol is
applicable to different types of dihydrosilanes 6: With less
reactive nBu2SiH2 (6d), a slightly higher temperature (60 °C)
was necessary for the first bond formation; 1ad was eventually
isolated in 53% yield. With Ph2SiH2 (6e), intermediate 7ae was
readily formed under the optimized reaction setup. The Si−H
bond activation in 7ae is however hampered due to steric
congestion, accounting for the lower yield of 1ae (35%).32
Having identified the optimal protective group and the most
reactive dihydrosilane, we further explored the scope for
different precursors functionalized in the 5-position of the
indole core (Figure 2). 5e and 5f decorated with either a
methyl or a silyl group reacted smoothly, affording 1ec and 1 fc
in 64% and 60% yield, respectively. A bromine substituent as in
5g was not tolerated, thwarting the silylation of the indole core
cObtained as a mixture containing 7% of 5i.
even at a higher catalyst loading (5 mol % of [4a]+[BArF ]−).
4
Accordingly, 5h substituted with a fluorine atom required a
higher catalyst loading to achieve high conversion to
intermediate 7hc. After microwave heating, 1hc was isolated
in 60% yield. Substrates 5i and 5j, with an electron-donating
amino group, showed significantly higher reactivity in the
silylation of the indole core. In fact, no excess of dihydrosilane
6c was required for these compounds. If 3.0 equiv of
dihydrosilane 6c was used, conversion of 5i to intermediate
7ic was even accompanied by the formation of an unknown
byproduct. After microwave heating, 7ic had not converted into
1ic though. Strikingly, blocking the activated para-position of
the aniline moiety by a methyl group (as in 5j) allowed for
isolating desired 1jc. This result is impressive, given the fact
that the Lewis-basic amino group is likely to provoke undesired
reaction pathways in the presence of the silicon electrophile at
these high temperatures.
Figure 3. Additional substrate scope of the 2-fold C−H silylation for
the synthesis of indole-fused benzosiloles. All reactions were
performed with 0.20 mmol of 5 according to GP4 (Table 3, entry
9). Yields of isolated products after purification by flash chromatog-
raphy. aWith 5 mol % of [4a]+[BArF ]− and 0.10 mL of ClC6H5 (2 M).
4
c
bObtained as a mixture containing 4% 5k. Obtained as a mixture
containing 9% 5o.
obtained with higher catalyst loading (5 mol %), and silole 1lc
was successfully prepared. The position of a chlorine
substituent had a dramatic influence on the reaction outcome:
5m, with a chlorine atom at C6, was not sufficiently reactive to
undergo the intermolecular SEAr step. In contrast, 5n, with a
chlorinated phenyl core, underwent step 1 when using a higher
5k decorated with a silicon-protected hydroxy group
smoothly converted into corresponding 7kc. However, no
ring closure to 1kc was observed (Figure 3). An ethyl group at
C7 of the indole core in 5l led to a slight decrease in reactivity
in the intermolecular step. Yet again, intermediate 7lc was
catalyst loading (5 mol % of [4a]+[BArF ]−); microwave
4
D
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ppm for 13C NMR; CDHCl2: δ 5.32 ppm for 1H NMR and CD2Cl2: δ
heating afforded 1nc in an overall 38% yield. We next replaced
the phenyl ring by larger naphthyl moieties. Substrate 5o could
form two different ring systems. Although intermediate 7oc was
formed in high yields, no ring closure was observed for this
compound. We hypothesize that the rotation around the C−C
bond between the indole and the sterically demanding naphth-
1-yl moiety is hampered in this molecule, thereby even
preventing the formation of a six-membered ring. Hence, we
synthesized 5p with a napth-2-yl group. Indeed, this substrate
underwent both bond formations to yield 1pc in 41% yield as a
single regioisomer.
1
53.84 ppm for 13C NMR; CD3CD2HCO: δ 2.05 ppm for H NMR
and (CD3)2CO: δ 29.84 ppm for 13C NMR). Data are reported as
follows: chemical shift, multiplicity (s = singlet, d = doublet, t =
triplett, q = quartet, quin = quintet, m = multiplet, mc
=
centrosymmetric multiplet, br = broad signal), coupling constants
(Hz), and integration. Pseudotriplets of unsymmetrical molecules were
assigned as doublets of doublets. Gas−liquid chromatography (GLC)
was performed on an Agilent Technologies 7820A gas chromatograph
equipped with an FS-SE-54 capillary column (30 m × 0.32 mm, 0.25
μm film thickness) by CS-Chromatographie Service using the
following program: N2 carrier gas, injection temperature: 240 °C,
detector temperature: 300 °C, flow rate: 1.74 mL/min; temperature
program: start temperature: 40 °C, heating rate 10 °C/min, end
temperature: 280 °C for 10 to 30 min. Infrared (IR) spectra were
recorded on an Agilent Technologies Cary 630 FT-IR spectrometer
equipped with an ATR unit or a Jasco FT/IR-4100 spectrometer, and
the signals are reported in wavenumbers (cm−1). Melting points (mp)
were determined with a Stuart Scientific SMP20 or a Wagner & Munz
Leica Galen III melting-point apparatus and are not corrected. High-
resolution mass spectra (HRMS) and elemental analyses were
CONCLUSION
■
In summary, we elaborated a Ru−S-catalyzed double sila-
Friedel−Crafts protocol that facilitates the synthesis of indole-
fused benzosiloles 1 from readily available 2-aryl-substituted
indoles 5 and dihydrosilanes 6. As previously reported,17c this
transformation is challenging due to the lability of the
intermediate C3-silylated indole 7 being prone to proto-
desilylation. Although the substrate scope of the new method
comes with limitations, it notably extends the variety of
synthetically accessible silole motifs.
obtained from the Analytical Facility at the Institut fur Chemie,
̈
Technische Universitat Berlin.
̈
General Procedure for the Preparation of N-Protected
Indoles (GP1). Similar to a reported procedure,14a oil-free sodium
hydride (12.0−30.1 mmol, 1.20 equiv) is placed in a Schlenk flask in a
glovebox and suspended outside the glovebox in two-thirds of dry
DMF (0.17 M). At 0 °C, a solution of the corresponding indole
(10.0−25.5 mmol, 1.00 equiv) in the remaining third of dry DMF is
added dropwise, resulting in vigorous gas evolution. After stirring for
1−2 h at 0 °C, the electrophile (13−32 mol, 1.2−1.3 equiv) is added.
The mixture is kept in the ice bath for 1−2 h and then allowed to
reach room temperature over 15−24 h. Saturated aqueous ammonium
chloride, distilled water, and methyl tert-butyl ether are added. The
aqueous phase is extracted with methyl tert-butyl ether, and the
combined organic phases are dried over MgSO4. After evaporation of
the solvents under reduced pressure, the residue is usually purified by
silica gel filtration or flash-column chromatography using the indicated
solvent mixture as eluent. Alternatively, the crude is purified by
recrystallization.
EXPERIMENTAL SECTION
■
General Remarks. All reactions were performed in flame-dried
glassware using an MBraun glovebox or conventional Schlenk
techniques under a static pressure of argon (glovebox) or nitrogen
unless otherwise stated. Microwave reactions were carried out in a
Discover-SP microwave by CEM using 35 mL microwave flasks with
silicone caps (ActiVent) by CEM. Reactions under microwave heating
were performed in “open vessel mode” allowing for perforation of the
cap with a cannula (0.9 mm thickness) to liberate the formed
dihydrogen gas. Heating of microwave reactions was performed in
“dynamic mode” at 300 W, and mixtures were stirred with “high
mixing”. Liquids and solutions were transferred with syringes. Solvents
for chromatography were distilled prior to use. Solvents (CH2Cl2,
Et2O, 1,2-F2C6H4, THF, and toluene) were dried and purified
following standard procedures. Dry DMF was purchased from Acros
and degassed by bubbling nitrogen through the solvent. Dry CH2Cl2
for the catalyst syntheses was obtained from an MBraun solvent
system, degassed with three freeze−pump−thaw cycles, and stored in a
glovebox over thermally activated 4 Å molecular sieves. ClC6H5 for
sila-Friedel−Crafts reactions was dried over CaH2, distilled, degassed
with three freeze−pump−thaw cycles, and stored in a glovebox over
thermally activated 4 Å molecular sieves. Mesitylene for sila-Friedel−
Crafts reactions was dried over sodium/benzophenone, distilled,
degassed with three freeze−pump−thaw cycles, and stored in a
glovebox over thermally activated 4 Å molecular sieves. n-Butyllithium
solutions were titrated using Suffert’s reagent.33 Ruthenium chloride
complexes [(Et3P)Ru(SDmp)(Cl)]12 and [((4-FC6H4)3P)Ru-
(SDmp)(Cl)]26 as well as cationic ruthenium complexes
General Procedure for the Preparation of 2-Aryl-Substituted
Indoles (GP2). Similar to a reported procedure,35 a Schlenk tube is
charged with the corresponding N-protected indole (3.23−22.1 mmol,
1.00 equiv), the iodobenzene derivative (6.5−44 mmol, 1.2−2.0
equiv), palladium(II) acetate (0.33−2.2 mmol, 5.2−10 mol %),
silver(I) oxide (2.4−17 mmol, 0.75−0.77 equiv), and o-nitrobenzoic
acid (4.9−34 mmol, 1.5 equiv). After suspending in dry DMF (0.5 M),
the mixture is stirred at room temperature for 17−71 h. Polar
byproducts are removed by a silica gel filtration eluting with CH2Cl2.
After removal of CH2Cl2 under reduced pressure, saturated aqueous
sodium bicarbonate is added, and the aqueous phase is extracted with
CH2Cl2. The combined organic phases are washed with distilled water
and dried over MgSO4, and all solvents are removed under reduced
pressure. The residue is prepurified by flash-column chromatography
on silica gel using the indicated solvent mixture as eluent. Afterward,
the residue is usually purified further by recrystallization.
General Procedure for the Preparation of Indole-Fused
Benzosiloles without Removal of the Catalyst Used in Step 1
(GP3). In a glovebox, the corresponding 2-aryl-substituted indole 5
(0.20 mmol, 1.00 equiv), preformed ruthenium complex [4]+[X]− (4.0
μmol, 2.0 mol %), and the corresponding dihydrosilane 6 (0.60 mmol,
3.00 equiv) are weighed into a GLC vial. Dry and degassed ClC6H5
(0.20 mL, 1.0 M) is added, the vial is closed, and a cannula is put
through the septum to liberate the formed dihydrogen gas. After
stirring overnight (15−18 h) at room temperature, the GLC vial is
transferred into a Schlenk flask, and outside the glovebox all volatiles
are removed under reduced pressure (40 °C/10−6 mbar). The reaction
mixture is brought back to a glovebox, and the residue is transferred
with dry and degassed mesitylene (0.40 mL, 0.5 M) into a 35 mL
microwave vessel. When indicated, either [4b]+[CHB11Me5Br]− (4.0
12
26
[4a]+[BArF ]− and [4b]+[BArF ]− were prepared according to
4
4
reported procedures. Cs[CHB11H11] was purchased from KatChem,
used as received, and further converted into Cs[CHB11Me5Br6].34 To
reach pressures of 10−6 mbar, a turbomolecular pump by Edwards or a
diffusion pump by Vacuubrand was used. Analytical thin-layer
chromatography (TLC) was performed on silica gel 60 F254 glass
plates or on basic aluminum oxide 60 F254 glass plates by Merck.
Flash-column chromatography was performed on silica gel 60 (40−63
μm, 230−400 mesh, ASTM) by Grace using the indicated solvents.
For purification of siloles 1, silica gel 60 (15−40 μm) by Merck was
1
used. H, 11B, 13C, 19F, 29Si, and 31P NMR spectra were recorded in
C6D6, CDCl3, CD2Cl2, or (CD3)2CO on a Bruker AV500 or an AV700
instrument. Chemical shifts are reported as parts per million (ppm)
and are referenced to the residual solvent resonance as the internal
standard (C6D5H: δ 7.16 ppm for 1H NMR and C6D6: δ 128.06 ppm
1
for 13C NMR; CHCl3: δ 7.26 ppm for H NMR and CDCl3: δ 77.16
E
DOI: 10.1021/acs.organomet.6b00801
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
μmol, 2.0 mol %) or ruthenium hydride 9 (4.0 μmol, 2.0 mol %) is
added. The vessel is capped, and the reaction mixture is heated in the
microwave (300 W) outside the glovebox for 60 min at 180 °C. After
ramping the temperature, the cap is perforated with a cannula. The
mixture is finally diluted with cyclohexane/Et3N/CH2Cl2 (v:v:v =
93:5:2) and filtered over a small silica gel/Celite column (3 cm of silica
covered with 1 cm of Celite) using the same mixture as eluent.36 After
removal of all volatiles under reduced pressure, the crude is further
purified by flash-column chromatography on silica gel (15−40 μm)37
using the indicated solvent mixture as eluent.
green reaction mixture was stirred at room temperature for 16 h. The
solvent was removed under reduced pressure, and the residue was
redissolved in C6H6 (4 mL). The precipitate was filtered off under an
inert atmosphere. Removal of the solvent under reduced pressure
afforded catalyst [4b]+[CHB11Me5Br6]− as a green powder (95 mg,
93%). 1H NMR (500 MHz, CD2Cl2): δ 0.19 (s, 15H), 1.01 (dt,
3J(H,P) = 17.3 Hz, 3J(HH) = 7.4 Hz, 9H), 1.88−1.91 (m, 12H), 1.96
(s, 6H), 2.06 (br s, 1H), 2.32 (s, 3H), 2.46 (s, 3H), 4.99 (s, 2H), 6.93
(s, 2H), 7.35 (d, 3J(HH) = 6.8 Hz, 1H), 7.71−7.74 (m, 2H). 11B NMR
(161 MHz, CD2Cl2): −12.7 (s), −10.2 (s), −3.5 (s). 13C{1H} NMR
1
General Procedure for the Preparation of Indole-Fused
Benzosiloles with Removal of the Catalyst Used in Step 1
(GP4). In a glovebox, the corresponding 2-aryl-substituted indole 5
(0.20 mmol, 1.00 equiv), preformed ruthenium complex
(176 MHz, CD2Cl2): δ −1.8 (br m), 8.6, 18.0 (d, J(C,P) = 28 Hz),
18.7, 20.5, 20.7, 21.3, 54.9, 72.9, 104.4, 106.5, 109.5, 128.5, 128.8,
130.0, 132.6, 133.3, 135.9, 136.4, 137.9, 142.8, 163.0. 31P{1H} NMR
(203 MHz, CD2Cl2): δ 23.5. HRMS (ESI): calculated for C30H40PSRu
[M − CHB11Me5Br6]+ 565.1632; found 565.1631. Elemental analysis
results are outside the tolerance range.
[4a]+[BArF ]− (4.0−10 μmol, 2.0−5.0 mol %), and the corresponding
4
dihydrosilane 6 (0.20−0.60 mmol, 1.00−3.00 equiv) are weighed into
a GLC vial. Dry and degassed ClC6H5 (0.10−0.20 mL, 1.0−2.0 M) is
added, the vial is closed, and a cannula is put through the septum to
liberate the formed dihydrogen gas. After stirring for 16 h to 18 d at
room temperature or 60 °C, the reaction is stopped by diluting with
cyclohexane/Et3N/CH2Cl2 (v:v:v = 93:5:2) and filtration over a small
silica gel/Celite column (3 cm silica covered with 1 cm Celite) using
the same mixture as eluent.36 After removal of all volatiles under
reduced pressure, the crude intermediate is dried (60 °C/10−3 mbar).
[((4-FC6H4)3P)Ru(SDmp)]+[B(C6F5)4]− ([4a]+[B(C6F5)4]−). In a
glovebox, ruthenium chloride [((4-FC6H4)3P)Ru(SDmp)(Cl)]26 (50
−
mg, 63 μmol, 1.0 equiv) and Na+[B(C6F5)4 ] (70 mg, 0.99 μmol, 1.6
equiv) were suspended in dry and degassed CH2Cl2 (5.0 mL). The
green reaction mixture was stirred at 40 °C for 16 h. The precipitate
was filtered off under an inert atmosphere. Removal of the solvent
under reduced pressure afforded catalyst [4a]+[B(C6F5)4]− as a green
1
powder (92 mg, 98%). H NMR (500 MHz, CD2Cl2): 1.60 (s, 3H),
In
a glovebox, either preformed ruthenium complex
1.85 (s, 6H), 1.94 (s, 6H), 2.30 (s, 3H), 4.71 (s, 2H), 6.85 (s, 2H),
[4b]+[CHB11Me5Br]−] (4.0 μmol, 2.0 mol %) or ruthenium chloride
complex [(Et3P)Ru(SDmp)(Cl)] (4.0 μmol, 2.0 mol %) together with
Na[CHB11Me5Br6] (4.8 μmol, 2.4 mol %) [in situ formation of the
active catalyst [4b]+[CHB11Me5Br]−] are weighed into a GLC vial.
This mixture and the crude intermediate are both transferred with dry
and degassed mesitylene (0.40 mL, 0.5 M) into a 35 mL microwave
vessel. The vessel is capped, and the reaction mixture is heated in the
microwave (300 W) outside the glovebox for 60 min at 180 °C. After
ramping the temperature, the cap is perforated with a cannula. The
mixture is finally diluted with cyclohexane/Et3N/CH2Cl2 (v:v:v =
93:5:2) and filtered over a small silica gel/Celite column (3 cm silica
covered with 1 cm Celite) using the same mixture as eluent.36 After
removal of all volatiles under reduced pressure, the crude is purified
further by flash-column chromatography on silica gel (15−40 μm)37
7.13−7.17 (m, 6H), 7.29−7.34 (m, 6H), 7.44 (br d, 3J(HH) = 7.7 Hz,
3
3
1H), 7.70 (br d, J(HH) = 7.6 Hz, 1H), 7.80 (dd, J(HH) = 7.7 Hz,
3J(HH) = 7.6 Hz, 1H). 11B NMR (161 MHz, CD2Cl2): −16.7 (s).
13C{1H} NMR (176 MHz, CD2Cl2): δ 18.2, 18.7, 20.5, 21.1, 74.6,
2
2
107.3, 107.4, 116.1 (br d, J(C,P) = 20 Hz), 117.0 (dd, J(C,F) = 22
Hz, 3J(C,P) = 12 Hz), 124.3 (mc), 126.0 (dd, 1J(C,P) = 50 Hz, 4J(C,F)
= 3 Hz), 128.3, 128.4, 131.0, 132.6, 135.5, 135.7, 136.4 (dd, 2J(C,P) =
15 Hz, 3J(C,F) = 9 Hz), 136.7 (br d, 1J(C,F) = 246 Hz), 138.4, 138.7
(br d, 1J(C,F) = 243 Hz), 142.9, 148.6 (br d, 1J(C,F) = 242 Hz), 163.6,
164.5, 166.0. 19F NMR (471 MHz, CD2Cl2): δ −167.5 (t, 3J(F,F) = 18
3
Hz), −163.6 (t, J(F,F) = 20 Hz), −133.2 (s), −106.8 (mc). 31P{1H}
NMR (203 MHz, CD2Cl2): δ 30.0. HRMS (ESI): calculated for
C42H37F3PRuS [M − B(C6F5)4]+ 763.1349; found 763.1354.
Elemental analysis results are outside the tolerance range.
using the indicated solvent mixture as eluent.
[(Et3P)Ru(SDmp)]+[B(C6F5)4]− ([4b]+[B(C6F5)4]−). In a glovebox,
ruthenium chloride [(Et3P)Ru(SDmp)(Cl)]12 (28 mg, 47 μmol, 1.0
−
[ ( ( 4 - F C 6 H 4 ) ]
3 P ) R u ( S D m p ) ] + [ C H B 1 1 M e 5 B r 6
([4a]+[CHB11Me5Br6]−). In a glovebox, ruthenium chloride [((4-
FC6H4)3P)Ru(SDmp)(Cl)]26 (10 mg, 13 μmol, 1.0 equiv) and
Na[CHB11Me5Br6]34 (27 mg, 38 μmol, 3.0 equiv) were suspended in
dry and degassed 1,2-F2C6H4 (1 mL). The green reaction mixture was
stirred at 80 °C for 17 h. The solvent was removed under reduced
pressure, and the residue was redissolved in C6H6 (ca. 2 mL). The
precipitate was filtered off under an inert atmosphere. Removal of the
solvent under reduced pressure afforded catalyst
−
equiv) and Na+[B(C6F5)4 ] (39 mg, 56 μmol, 1.2 equiv) were
suspended in dry and degassed CH2Cl2 (1.5 mL). The green reaction
mixture was stirred at room temperature for 15 h. The precipitate was
filtered off under an inert atmosphere. Removal of the solvent under
reduced pressure afforded catalyst [4b]+[B(C6F5)4]− as a green
1
powder (50 mg, 86%). H NMR (500 MHz, CD2Cl2): δ 0.99 (dt,
3J(H,P) = 17.2 Hz, 3J(HH) = 7.6 Hz, 9H), 1.85−1.91 (m, 12H), 1.95
[4a]+[CHB11Me5Br6]− as a green powder (17 mg, 94%). H NMR
1
(s, 6H), 2.31 (s, 3H), 2.39 (s, 3H), 4.86 (s, 2H), 6.93 (s, 2H), 7.37
3
4
3
(dd, J(H,H) = 7.6 Hz, J(H,H) = 1.3 Hz, 1H), 7.69 (dd, J(H,H) =
7.6 Hz, 4J(H,H) = 1.3 Hz, 1H), 7.75 (dd, 3J(H,H) = 7.6 Hz, 3J(H,H) =
7.6 Hz, 1H). 11B NMR (161 MHz, CD2Cl2): −16.7 (s). 13C{1H}
(500 MHz, CD2Cl2): δ 0.22 (s, 15H), 1.65 (s, 3H), 1.86 (s, 6H), 1.98
(s, 6H), 2.15 (s, 1H), 2.30 (s, 3H), 4.82 (s, 2H), 6.86 (s, 2H), 7.16−
7.20 (m, 6H), 7.30−7.35 (m, 6H), 7.43 (dd, 3J(HH) = 7.5 Hz, 4J(HH)
1
3
4
NMR (176 MHz, CD2Cl2): δ 8.5, 18.0 (d, J(C,P) = 28 Hz), 18.5,
20.3, 20.5, 21.2, 71.6, 104.7, 106.5, 109.5 (d, J(C,P) = 9 Hz), 124.3
= 1.3 Hz, 1H), 7.76 (dd, J(HH) = 7.6 Hz, J(HH) = 1.0 Hz, 1H),
2
3
7.82 (dd, J(HH) = 7.7 Hz, J = 7.5 Hz, 1H). The signal at 7.35 ppm
was attributed to the remaining C6H6. 11B NMR (161 MHz, CD2Cl2):
−12.4 (s), −10.4 (s), − 3.7 (s).13C{1H} NMR (176 MHz, CD2Cl2): δ
−1.7 (br m), 18.7, 19.0, 20.6, 21.1, 55.5, 75.1, 107.1, 107.6, 116.1 (d,
(mc), 128.5, 128.7, 130.2, 132.8, 133.1, 135.9, 136.3, 136.7 (br d,
1J(C,F) = 243 Hz), 138.1, 138.7 (br d, 1J(C,F) = 246 Hz), 142.9, 148.6
1
(br d, J(C,F) = 239 Hz), 163.2. 19F NMR (471 MHz, CD2Cl2): δ
−167.5 (t, 3J(F,F) = 17 Hz), −163.5 (t, 3J(F,F) = 20 Hz), −133.2 (s).
31P{1H} NMR (203 MHz, CD2Cl2): δ 23.3. HRMS (ESI): calculated
for C30H40PRuS [M − B(C6F5)4]+ 565.1632; found 565.1635.
Elemental analysis results are outside the tolerance range.
2J(C,P) = 22 Hz), 117.1 (dd, J(C,F) = 22 Hz, J(C,P) = 12 Hz),
2
3
1
4
126.2 (dd, J(C,P) = 49 Hz, J(C,F) = 3 Hz), 128.3, 129.0, 132.4,
2
3
133.1, 135.6, 135.7, 136.5 (dd, J(C,P) = 14 Hz, J(C,F) = 9 Hz),
138.2, 142.7, 163.3, 164.4, 165.9. 19F NMR (471 MHz, CD2Cl2): δ
−106.9 (mc). 31P{1H} NMR (203 MHz, CD2Cl2): δ 30.2. HRMS
(ESI): calculated for C42H37F3PSRu [M − CHB11Me5Br6]+ 763.1349;
found 763.1361. Elemental analysis results are outside the tolerance
range.
1-Methyl-3-(methyl(phenyl)silyl)-2-phenyl-1H-indole (7ac).
In a glovebox, 1-methyl-2-phenyl-1H-indole (5a, 1.00 g, 4.84 mmol,
1.00 equiv), ruthenium complex [4a]+[BArF ]− (78 mg, 48 μmol, 1.0
4
mol %), and methylphenylsilane (6c, 2.00 mL, 1.78 g, 14.6 mmol, 3.01
equiv) were weighed into a flask. Dry and degassed ClC6H5 (4.8 mL,
1.0 M) was added, and the reaction mixture was stirred at room
temperature for 44 h. The flask was not sealed to enable liberation of
the formed dihydrogen gas. The reaction was stopped by diluting with
[(Et3P)Ru(SDmp)]+[CHB11Me5Br6]− ([4b]+[CHB11Me5Br6]−). In a
glovebox, ruthenium chloride [(Et3P)Ru(SDmp)(Cl)]12 (49 mg, 82
μmol, 1.0 equiv) and Na[CHB11Me5Br6]34 (70 mg, 99 μmol, 1.2
equiv) were suspended in dry and degassed CH2Cl2 (8 mL). The
F
DOI: 10.1021/acs.organomet.6b00801
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
3
cyclohexane/Et3N/CH2Cl2 (v:v:v = 93:5:2) and filtration over silica
gel using the same mixture as eluent.36 The solvents were removed
under reduced pressure. Remaining dihydrosilane and starting material
were removed by Kugelrohr distillation (135 °C, 10−3 mbar) to give
the product (1.45 g, 92%) as a brownish oil, which solidified upon
cooling to −35 °C. Mp = 56 °C (CH2Cl2). Rf = 0.59 (cyclohexane/
7.9 Hz, J(H,H) = 7.5 Hz, 1H), 7.20−7.26 (m, 2H), 7.31−7.34 (m,
2H), 7.36−7.39 (m, 1H), 7.41−7.44 (m, 2H), 7.58 (dd, 3J(H,H) = 7.8
4
3
Hz, J(H,H) = 0.8 Hz, 1H), 7.63−7.65 (m, 3H), 7.73 (d, J(H,H) =
7.9 Hz, 1H). 13C{1H} NMR (126 MHz, CD2Cl2): δ −4.5, 15.8, 40.0,
110.0, 110.1, 120.8, 120.9, 122.0, 122.2, 127.2, 128.4, 130.1, 130.4,
130.7, 133.9, 134.7, 135.9, 141.9, 142.1, 144.0, 152.9. 29Si DEPT NMR
(99 MHz, CD2Cl2): δ −14.7. HRMS (APCI): calculated for
C23H22NSi [M + H]+ 340.1516; found 340.1519. Anal. Calcd for
C23H21NSi: C, 81.37; H, 6.23; N, 4.13. Found: C, 80.91; H, 6.60; N,
4.12.
̃
Et3N = 95:5; basic aluminum oxide). IR (ATR): ν = 3065, 2120, 2088,
1605, 1523, 1462, 1427, 1372, 1337, 1302, 1251, 1236, 1220, 1156,
1107, 1073, 1050, 1023, 987, 920, 878, 841, 824, 797, 739, 720, 698,
603 cm−1. 1H NMR (500 MHz, CD2Cl2): δ 0.39 (d, 3J(H,H) = 4.1 Hz,
3H), 3.60 (s, 3H), 4.88 (q, 3J(H,H) = 4.1 Hz, 1H), 7.09 (ddd, 3J(H,H)
10,10-Dibutyl-5-methyl-5,10-dihydrobenzo[4,5]silolo[3,2-b]-
indole (1ad). I. Preparation of nBu2SiH2 (6d): To a solution of di-n-
butyldichlorosilane (9.0 mL, 8.9 g, 42 mmol, 1.00 equiv) in dry
CH2Cl2 (90 mL) at 0 °C was added a DIBAL-H solution (ca. 1.0 M in
CH2Cl2, 90 mL, 90 mmol, 2.1 equiv) with a syringe pump (3 mL/
min). The reaction mixture was allowed to reach room temperature
and stirred for 17 h. Freshly ground Na2SO4·10H2O was carefully
added until no further gas evolution was observed. The mixture was
filtrated, and the filtrate was subsequently washed with aqueous HCl
(2 M), aqueous NaOH (2 M), and brine. The organic phase was dried
over MgSO4, and the solvent was removed under reduced pressure.
Distillation (65 °C/10 mbar) afforded the product (2.18 g, 36%) as a
3
4
= 7.5 Hz, J(H,H) = 7.4 Hz, J(H,H) = 1.0 Hz, 1H), 7.23−7.45 (m,
10H), 7.49−7.51 (m, 2H), 7.59 (d, J(H,H) = 7.9 Hz, 1H). 13C{1H}
3
NMR (126 MHz, CD2Cl2): δ −4.4, 31.2, 102.9, 110.0, 120.3, 121.6,
122.1, 128.1, 128.4, 128.9, 129.4, 131.3, 133.4, 133.6, 134.9, 137.7,
139.0, 149.3. 29Si DEPT NMR (99 MHz, CD2Cl2): δ −29.6. HRMS
(EI): calculated for C22H21NSi [M]+ 327.1443; found 327.1448. Anal.
Calcd for C22H21NSi: C, 80.68; H, 6.46; N, 4.28. Found: C, 80.20; H,
6.86; N, 4.77.
5,10-Dimethyl-10-phenyl-5,10-dihydrobenzo[4,5]silolo[3,2-
b]indole (1ac). This was prepared from 1-methyl-2-phenyl-1H-indole
(5a, 41 mg, 0.20 mmol, 1.0 equiv), ruthenium complex [4a]+[BArF ]−
4
̃
colorless liquid. IR (ATR): ν = 2956, 2922, 2857, 2121, 1618, 1464,
(6.5 mg, 4.0 μmol, 2.0 mol %), and methylphenylsilane (6c, 73 mg,
0.60 mmol, 3.0 equiv) according to GP3. The reaction time for step 1
was 16 h. Purification by flash-column chromatography on silica gel
(15−40 μm)37 using cyclohexane/Et3N/methyl tert-butyl ether (v:v:v
= 94:5:1)36 as eluent afforded the product (33 mg, 50%) as a brownish
oil. This was also prepared from 1-methyl-2-phenyl-1H-indole (5a, 41
1408, 1296, 1182, 1082, 1026, 941, 897, 828, 714, 632 cm−1. 1H NMR
3
(500 MHz, C6D6): δ 0.59−0.63 (m, 4H), 0.87 (t, J(H,H) = 7.2 Hz,
6H), 1.26−1.38 (m, 8H), 3.93 (quin, 3J(H,H) = 3.7 Hz, 2H). 13C{1H}
NMR (126 MHz, C6D6): δ 9.21, 14.0, 26.3, 28.1. 29Si DEPT NMR (99
MHz, C6D6): δ −28.6 ppm. Elemental analysis was not performed for
this compound. II. Preparation of 1ad: This was prepared from 1-
methyl-2-phenyl-1H-indole (5a, 41 mg, 0.20 mmol, 1.0 equiv),
mg, 0.20 mmol, 1.0 equiv), ruthenium complex [4a]+[BArF ]− (6.5
4
mg, 4.0 μmol, 2.0 mol %), methylphenylsilane (6c, 73 mg, 0.60 mmol,
3.0 equiv), ruthenium chloride complex [(Et3P)Ru(SDmp)(Cl)] (2.4
mg, 4.0 μmol, 2.0 mol %), and Na[CHB11Me5Br6] (3.4 mg, 4.8 μmol,
2.4 mol %) according to GP4. Step 1 was performed at room
temperature for 16 h with ClC6H5 (0.20 mL, 1.0 M) as a solvent.
Purification by flash-column chromatography on silica gel (15−40
μm)37 using cyclohexane/Et3N/methyl tert-butyl ether (v:v:v =
94:5:1)36 as eluent afforded the product (41 mg, 63%) as a brownish
oil. Rf = 0.45 (cyclohexane/Et3N = 95:5; basic aluminum oxide). IR
ruthenium complex [4a]+[BArF ]− (6.5 mg, 4.0 μmol, 2.0 mol %),
4
di-n-butylsilane (6d, 87 mg, 0.60 mmol, 3.0 equiv) ruthenium chloride
complex [(Et3P)Ru(SDmp)(Cl)] (2.4 mg, 4.0 μmol, 2.0 mol %), and
Na[CHB11Me5Br6] (3.4 mg, 4.8 μmol, 2.4 mol %) according to GP4.
Step 1 was performed at 60 °C for 3 d with ClC6H5 (0.10 mL, 2.0 M)
as a solvent. Purification by flash-column chromatography on silica gel
(15−40 μm)37 using cyclohexane/Et3N/methyl tert-butyl ether (v:v:v
= 95:4:1)36 as eluent afforded the product (37 mg, 53%) as a yellowish
oil. This compound was found to be sensitive to air/moisture and was
therefore stored in a glovebox. NMR spectra were recorded with dry
CD2Cl2 in a sealed tube. Rf = 0.61 (cyclohexane/Et3N/methyl tert-
̃
(ATR): ν = 3047, 2926, 1610, 1584, 1470, 1429, 1417, 1396, 1340,
1329, 1285, 1247, 1204, 1157, 1131, 1111, 1067, 1014, 998, 979, 929,
1
916, 821, 792, 773, 756, 744 cm−1. H NMR (500 MHz, CD2Cl2): δ
3
3
̃
butyl ether = 95:4:1; basic aluminum oxide). IR (ATR): ν = 2953,
0.78 (s, 3H), 4.14 (s, 3H), 7.12 (br dd, J(H,H) = 7.8 Hz, J(H,H) =
7.1 Hz, 1H), 7.22−7.27 (m, 2H), 7.31−7.35 (m, 2H), 7.36−7.44 (m,
3H), 7.58 (br d, 3J(H,H) = 7.8 Hz, 1H), 7.63−7.66 (m, 3H), 7.85 (d,
3J(H,H) = 7.8 Hz, 1H). 13C{1H} NMR (126 MHz, CD2Cl2): δ −4.9,
2919, 2869, 2854, 1586, 1464, 1418, 1401, 1376, 1326, 1284, 1265,
1203, 1177, 1129, 1112, 1069, 1021, 1013, 977, 919, 885, 821, 770,
738 cm−1. 1H NMR (500 MHz, CD2Cl2): δ 0.83 (t, 3J(H,H) = 7.2 Hz,
6H), 0.92−1.06 (m, 4H), 1.28−1.45 (m, 8H), 4.11 (s, 3H), 7.11 (ddd,
32.6, 109.7, 110.2, 120.9, 121.0, 121.9, 122.2, 127.2, 128.4, 130.1,
130.2, 130.5, 133.9, 134.7, 135.9, 142.1, 143.0, 143.9, 153.9. 29Si DEPT
NMR (99 MHz, CD2Cl2): δ −14.4 ppm. HRMS (APCI): calculated
for C22H20NSi [M + H]+ 326.1360; found 326.1363. Elemental
analysis results were outside the tolerance range.
3
4
3J(H,H) = 7.6 Hz, J(H,H) = 7.3 Hz, J(H,H) = 1.0 Hz, 1H), 7.19−
7.24 (m, 2H), 7.36−7.41 (m, 2H), 7.57−7.60 (m, 2H), 7.82 (d,
3J(H,H) = 7.8 Hz, 1H). 13C{1H} NMR (126 MHz, CD2Cl2): δ 12.7,
13.9, 26.9, 27.0, 32.5, 110.0, 110.5, 120.5, 120.7, 121.9, 122.2, 126.7,
1
129.8, 130.9, 133.9, 142.3, 142.9, 144.2, 153.5 ppm. H,29Si-HMQC
5-Ethyl-10-methyl-10-phenyl-5,10-dihydrobenzo[4,5]silolo-
[3,2-b]indole (1cc). This was prepared from 1-ethyl-2-phenyl-1H-
indole (5c, 44 mg, 0.20 mmol, 1.0 equiv), ruthenium complex
NMR (99 MHz, J = 7 Hz, CD2Cl2): δ −4.5. No signal was detected in
1
the 29Si DEPT NMR spectrum. Another signal in the H,29Si HMQC
[4a]+[BArF ]− (6.5 mg, 4.0 μmol, 2.0 mol %), methylphenylsilane (6c,
NMR spectrum at −21.6 ppm was attributed to a grease impurity.
HRMS (APCI): calculated for C23H30NSi [M + H]+ 348.2142; found
348.2140. Elemental analysis results were outside the tolerance range.
8-Methyl-10,10-diphenyl-5,10-dihydrobenzo[4,5]silolo[3,2-
b]indole (1ae). This was prepared from 1-methyl-2-phenyl-1H-indole
4
73 mg, 0.60 mmol, 3.0 equiv), ruthenium chloride complex
[(Et3P)Ru(SDmp)(Cl)] (2.4 mg, 4.0 μmol, 2.0 mol %), and
Na[CHB11Me5Br6] (3.4 mg, 4.8 μmol, 2.4 mol %) according to
GP4. Step 1 was performed at room temperature with ClC6H5 (0.10
mL, 2.0 M) as a solvent. After stirring for 16 h, additional ruthenium
(5a, 41 mg, 0.20 mmol, 1.0 equiv), ruthenium complex [4a]+[BArF ]−
4
complex [4a]+[BArF ]− (9.8 mg, 6.0 μmol, 3.0 mol %) was added. Step
(6.5 mg, 4.0 μmol, 2.0 mol %), diphenylsilane (6e, 111 mg, 0.602
mmol, 3.01 equiv), ruthenium chloride complex [(Et3P)Ru(SDmp)-
(Cl)] (2.4 mg, 4.0 μmol, 2.0 mol %), and Na[CHB11Me5Br6] (3.4 mg,
4.8 μmol, 2.4 mol %) according to GP4. Step 1 was performed at
room temperature for 16 h with ClC6H5 (0.20 mL, 1.0 M) as a solvent.
Purification by flash-column chromatography on silica gel (15−40
μm)37 using cyclohexane/Et3N/methyl tert-butyl ether (v:v:v =
95:4:1)36 as eluent afforded the product (27 mg, 35%) as a pale
yellow solid. Mp = 208 °C (CH2Cl2). Rf = 0.38 (cyclohexane/Et3N =
4
1 was stopped after a total of 39 h. Purification by flash-column
chromatography on silica gel (15−40 μm)37 using cyclohexane/Et3N/
methyl tert-butyl ether (v:v:v = 94:5:1)36 as eluent afforded the
product (38 mg, 56%) as a brownish solid. Mp = 130 °C (CH2Cl2). Rf
= 0.50 (cyclohexane/Et3N/methyl tert-butyl ether = 94:5:1; basic
̃
aluminum oxide). IR (ATR): ν = 3053, 2980, 2932, 1583, 1479, 1456,
1418, 1405, 1379, 1342, 1326, 1285, 1262, 1248, 1188, 1156, 1132,
1124, 1109, 1085, 1067, 1021, 999, 988, 929, 863, 836, 798, 786, 764
cm−1. 1H NMR (500 MHz, CD2Cl2): δ 0.76 (s, 3H), 1.56 (t, 3J(H,H)
= 7.2 Hz, 3H), 4.59 (q, 3J(H,H) = 7.2 Hz, 2H), 7.11 (br dd, 3J(H,H) =
̃
95:5; basic aluminum oxide). IR (ATR): ν = 3050, 3009, 2924, 1585,
1470, 1427, 1415, 1391, 1355, 1340, 1324, 1285, 1265, 1187, 1161,
G
DOI: 10.1021/acs.organomet.6b00801
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
1129, 1111, 1064, 1028, 1014, 997, 977, 924, 858, 819, 772, 749 cm−1.
1H NMR (500 MHz, CD2Cl2): δ 4.15 (s, 3H), 7.15 (dd, 3J(H,H) = 7.5
Hz, 3J(H,H) = 7.4 Hz, 1H), 7.25 (br dd, 3J(H,H) = 7.8 Hz, 3J(H,H) =
phenylsilane (6c, 73 mg, 0.60 mmol, 3.0 equiv), ruthenium chloride
complex [(Et3P)Ru(SDmp)(Cl)] (2.4 mg, 4.0 μmol, 2.0 mol %), and
Na[CHB11Me5Br6] (3.4 mg, 4.8 μmol, 2.4 mol %) according to GP4.
Step 1 was performed at room temperature with ClC6H5 (0.10 mL, 2.0
M) as a solvent. After stirring for 24 h, additional ruthenium complex
3
3
7.6 Hz, 1H), 7.29 (dd, J(H,H) = 7.3 Hz, J(H,H) = 7.3 Hz, 1H),
3
7.35−7.38 (m, 4H), 7.40−7.47 (m, 4H), 7.66 (d, J(H,H) = 7.9 Hz,
[4a]+[BArF ]− (9.8 mg, 6.0 μmol, 3.0 mol %) was added. Step 1 was
3
1H), 7.73−7.75 (m, 4H), 7.79 (d, J(H,H) = 7.1 Hz, 1H), 7.89 (d,
4
3J(H,H) = 7.8 Hz, 1H). 13C{1H} NMR (126 MHz, CD2Cl2): δ 32.6,
stopped after a total of 18 d. Purification by flash-column
chromatography on silica gel (15−40 μm)37 using cyclohexane/
Et3N/methyl tert-butyl ether (v:v:v = 95:4:1)36 as eluent afforded the
product (41 mg, 60%) as a pale violet solid. Mp = 138 °C (CH2Cl2).
Rf = 0.40 (cyclohexane/Et3N/methyl tert-butyl ether = 95:4:1; basic
108.4, 110.3, 121.2, 121.3, 122.0, 122.4, 127.5, 128.5, 130.4, 130.6,
133.9, 134.6, 135.7, 142.2, 142.4, 143.2, 154.3. The signal for one
quaternary carbon atom was not detected. 29Si DEPT NMR (99 MHz,
CD2Cl2): δ −19.0. HRMS (APCI): calculated for C27H22NSi [M +
H]+ 388.1516; found 388.1516. Elemental analysis results were outside
the tolerance range.
̃
aluminum oxide). IR (ATR): ν = 3058, 2917, 2849, 1618, 1585, 1483,
1430, 1403, 1585, 1483, 1430, 1403, 1342, 1302, 1265, 1240, 1161,
1129, 1111, 1066, 1017, 989, 938, 881, 851, 818, 781, 764, 736 cm−1.
1H NMR (500 MHz, CD2Cl2): δ 0.76 (s, 3H), 4.12 (s, 3H), 6.97 (ddd,
5,8,10-Trimethyl-10-phenyl-5,10-dihydrobenzo[4,5]silolo-
[3,2-b]indole (1ec). This was prepared from 1,5-dimethyl-2-phenyl-
1H-indole (5e, 41 mg, 0.20 mmol, 1.0 equiv), ruthenium complex
3
4
3J(H,H/F) = 9.2 Hz, J(H,H/F) = 9.1 Hz, J(H,H) = 2.4 Hz, 1H),
[4a]+[BArF ]− (6.5 mg, 4.0 μmol, 2.0 mol %), methylphenylsilane (6c,
7.22 (dd, 3J(H,F) = 9.4 Hz, 4J(H,H) = 2.4 Hz, 1H), 7.27 (dd, 3J(H,H)
4
3
73 mg, 0.60 mmol, 3.0 equiv), ruthenium chloride complex
[(Et3P)Ru(SDmp)(Cl)] (2.4 mg, 4.0 μmol, 2.0 mol %), and
Na[CHB11Me5Br6] (3.4 mg, 4.8 μmol, 2.4 mol %) according to
GP4. Step 1 was performed at room temperature for 17 h with ClC6H5
(0.20 mL, 1.0 M) as a solvent. Purification by flash-column
chromatography on silica gel (15−40 μm)37 using cyclohexane/
Et3N/methyl tert-butyl ether (v:v:v = 95:4:1)36 as eluent afforded the
product (44 mg, 65%) as a white solid. Crystals suitable for X-ray
diffraction were obtained by recrystallization of 1ec from cyclohexane/
n-pentane at 8 °C. Mp = 158 °C (CH2Cl2). Rf = 0.50 (cyclohexane/
Et3N/methyl tert-butyl ether = 95:4:1; basic aluminum oxide). IR
= 7.4 Hz, J(H,H) = 7.2 Hz, 1H), 7.30−7.40 (m, 4H), 7.43 (ddd,
3J(H,H) = 7.7 Hz, J(H,H) = 7.6 Hz, J(H,H) = 1.2 Hz, 1H), 7.62−
3
4
7.65 (m, 3H), 7.84 (d, J(H,H) = 7.8 Hz, 1H). 13C{1H} NMR (126
3
2
MHz, CD2Cl2): δ −4.6, 32.8, 106.5 (d, J(C,F) = 23 Hz), 109.5 (d,
4J(C,F) = 5 Hz), 110.1 (d, J(C,F) = 27 Hz), 110.8 (d, J(C,F) = 10
2
3
3
Hz), 121.1, 127.5, 128.5, 130.2, 130.2, 130.8 (d, J(C,F) = 10 Hz),
134.0, 134.7, 135.5, 139.6, 141.7, 143.9, 155.4, 159.0 (d, 1J(C,F) = 234
Hz). 19F NMR (471 MHz, CD2Cl2): δ −125.0 (m). 29Si DEPT NMR
(99 MHz, CD2Cl2): δ −14.4. HRMS (APCI): calculated for
C22H19FNSi [M + H]+ 344.1265; found 344.1268. Elemental analysis
results were outside the tolerance range.
̃
(ATR): ν = 3054, 3007, 2908, 1618, 1588, 1565, 1471, 1428, 1418,
8-(N-Methyl-p-tolylamino)-5,10-dimethyl-10-phenyl-5,10-
dihydrobenzo[4,5]silolo[3,2-b]indole (1jc). This was prepared
from 5-(N,4-dimethyl-p-tolylamino)-1-methyl-2-phenyl-1H-indole (5j,
1398, 1334, 1306, 1284, 1242, 1176, 1150, 1129, 1114, 1072, 1021,
1
997, 867, 802, 786, 765 cm−1. H NMR (500 MHz, CD2Cl2): δ 0.76
3
72 mg, 0.22 mmol, 1.1 equiv), ruthenium complex [4a]+[BArF ]− (6.5
(s, 3H), 2.42 (s, 3H), 4.10 (s, 3H), 7.06 (dd, J(H,H) = 8.4 Hz,
4
4J(H,H) = 1.4 Hz, 1H), 7.23 (br dd, 3J(H,H) = 7.3 Hz, 3J(H,H) = 7.3
mg, 4.0 μmol, 2.0 mol %), methylphenylsilane (6c, 24 mg, 0.20 mmol,
1.0 equiv), ruthenium chloride complex [(Et3P)Ru(SDmp)(Cl)] (2.4
mg, 4.0 μmol, 2.0 mol %), and Na[CHB11Me5Br6] (3.4 mg, 4.8 μmol,
2.4 mol %) according to GP4. Step 1 was performed at room
temperature for 16 h with ClC6H5 (0.20 mL, 1.0 M) as a solvent.
Purification by flash-column chromatography on silica gel (15−40
μm)37 using cyclohexane/Et3N/methyl tert-butyl ether (v:v:v =
95:4:1)36 as eluent afforded the product (33 mg, 37%) as a yellow
solid. Mp = 103 °C (CH2Cl2). Rf = 0.35 (cyclohexane/Et3N/methyl
3
Hz, 1H), 7.28 (d, J(H,H) = 8.4 Hz, 1H), 7.31−7.34 (m, 2H), 7.36−
3
7.42 (m, 3H), 7.61−7.65 (m, 3H), 7.82 (d, J(H,H) = 7.8 Hz, 1H).
13C{1H} NMR (126 MHz, CD2Cl2): δ −4.5, 21.5, 32.6, 109.1, 109.8,
120.8, 121.7, 123.8, 127.1, 128.4, 130.1, 130.2, 130.2, 130.7, 133.9,
134.7, 136.0, 141.4, 142.2, 143.9, 153.9. 29Si DEPT NMR (99 MHz,
CD2Cl2): δ −14.6. HRMS (APCI): calculated for C23H22NSi [M +
H]+ 340.1516; found 340.1519. Anal. Calcd for C23H21NSi: C, 81.37;
H, 6.23; N, 4.13. Found: C, 81.25; H, 6.37; N, 3.68.
̃
tert-butyl ether = 95:4:1; basic aluminum oxide). IR (ATR): ν = 3003,
5,10-Dimethyl-8-(dimethyl(phenyl)silyl)-10-phenyl-5,10-
dihydrobenzo[4,5]silolo-[3,2-b]indole (1fc). This was prepared
from 5-(dimethyl(phenyl)silyl)-1-methyl-2-phenyl-1H-indole (5f, 68
2922, 2850, 2804, 1607, 1511, 1486, 1471, 1429, 1399, 1312, 1293,
1
1268, 1245, 1111, 1061, 1021, 987, 901, 845, 789, 759, 744 cm−1. H
mg, 0.20 mmol, 1.0 equiv), ruthenium complex [4a]+[BArF ]− (6.5
NMR (500 MHz, CD2Cl2): δ 0.76 (s, 3H), 2.26 (s, 3H), 3.30 (s, 3H),
4.12 (s, 3H), 6.73−6.75 (m, 2H), 6.99−7.03 (m, 3H), 7.25 (dd,
4
mg, 4.0 μmol, 2.0 mol %), methylphenylsilane (6c, 73 mg, 0.60 mmol,
3.0 equiv), ruthenium chloride complex [(Et3P)Ru(SDmp)(Cl)] (2.4
mg, 4.0 μmol, 2.0 mol %), and Na[CHB11Me5Br6] (3.4 mg, 4.8 μmol,
2.4 mol %) according to GP4. Step 1 was performed at room
temperature for 18 h with ClC6H5 (0.20 mL, 1.0 M) as a solvent.
Purification by flash-column chromatography on silica gel (15−40
μm)37 using cyclohexane/Et3N/methyl tert-butyl ether (v:v:v =
95:4:1)36 as eluent afforded the product (55 mg, 60%) as a brownish
oil. Rf = 0.45 (cyclohexane/Et3N = 95:5; basic aluminum oxide). IR
3
3J(H,H) = 7.3 Hz, J(H,H) = 7.2 Hz, 1H), 7.31−7.39 (m, 5H), 7.42
3
3
4
(ddd, J(H,H) = 7.7 Hz, J(H,H) = 7.6 Hz, J(H,H) = 1.2 Hz, 1H),
7.63 (m, 3H), 7.84 (d, J(H,H) = 7.8 Hz, 1H). 13C{1H} NMR (126
3
MHz, CD2Cl2): δ −4.4, 20.5, 32.7, 41.3, 109.5, 110.8, 116.5, 117.3,
120.5, 120.9, 127.2, 127.8, 128.4, 129.7, 130.1, 130.2, 131.3, 133.9,
134.7, 135.8, 140.1, 142.0, 143.7, 143.9, 148.7, 154.4. 29Si DEPT NMR
(99 MHz, CD2Cl2): δ −14.5. HRMS (APCI): calculated for
C30H29N2Si [M + H]+ 445.2095; found 445.2090. Anal. Calcd for
C30H28N2Si: C, 81.04; H, 6.35; N, 6.30. Found: C, 80.88; H, 6.96; N,
6.46.
̃
(ATR): ν = 3047, 2953, 1586, 1472, 1428, 1418, 1397, 1329, 1291,
1
1245, 1189, 1156, 1110, 1090, 1019, 987, 813, 770, 765 cm−1. H
NMR (500 MHz, CD2Cl2): δ 0.61 (s, 6H), 0.79 (s, 3H), 4.13 (s, 3H),
7.26 (br dd, 3J(H,H) = 7.5 Hz, 3J(H,H) = 7.1 Hz, 1H), 7.32−7.44 (m,
9H), 7.57−7.58 (m, 2H), 7.65−7.67 (m, 3H), 7.81 (br s, 1H), 7.85 (d,
3J(H,H) = 7.8 Hz, 1H). 13C{1H} NMR (126 MHz, CD2Cl2): δ −4.4,
6-Ethyl-5,10-dimethyl-10-phenyl-5,10-dihydrobenzo[4,5]-
silolo[3,2-b]indole (1lc). This was prepared from 7-ethyl-1-methyl-
2-phenyl-1H-indole (5l, 47 mg, 0.20 mmol, 1.0 equiv), ruthenium
complex [4a]+[BArF ]− (6.5 mg, 4.0 μmol, 2.0 mol %), methyl-
4
phenylsilane (6c, 73 mg, 0.60 mmol, 3.0 equiv), ruthenium chloride
complex [(Et3P)Ru(SDmp)(Cl)] (2.4 mg, 4.0 μmol, 2.0 mol %), and
Na[CHB11Me5Br6] (3.4 mg, 4.8 μmol, 2.4 mol %) according to GP4.
Step 1 was performed at room temperature with ClC6H5 (0.10 mL, 2.0
M) as a solvent. After stirring for 15 h, additional ruthenium complex
−1.9, −1.8, 32.6, 109.8, 109.9, 121.0, 127.3, 127.9, 128.1, 128.4, 128.4,
128.8, 129.2, 130.1, 130.2, 130.6, 133.9, 134.6, 134.7, 135.9, 139.9,
142.0, 143.7, 143.9, 154.1. 29Si DEPT NMR (99 MHz, CD2Cl2): δ
−14.2, −7.9. HRMS (APCI): calculated for C30H30NSi2 [M + H]+
460.1911; found 460.1913. Anal. Calcd for C30H29NSi2: C, 78.38; H,
6.36; N, 3.05. Found: C, 78.32; H, 6.79; N, 2.79.
[4a]+[BArF ]− (9.8 mg, 6.0 μmol, 3.0 mol %) was added. Step 1 was
4
stopped after a total of 5 d. Purification by flash-column
chromatography on silica gel (15−40 μm)37 using cyclohexane/Et3N
(v:v = 97:3)36 as eluent afforded the product (33 mg, 47%) as a
yellowish oil. Rf = 0.35 (cyclohexane/Et3N = 97:3; basic aluminum
8-Fluoro-5,10-dimethyl-10-phenyl-5,10-dihydrobenzo[4,5]-
silolo[3,2-b]indole (1hc). Prepared from 5-fluoro-1-methyl-2-
phenyl-1H-indole (5h, 45 mg, 0.20 mmol, 1.0 equiv), ruthenium
complex [4a]+[BArF ]− (6.5 mg, 4.0 μmol, 2.0 mol %), methyl-
4
H
DOI: 10.1021/acs.organomet.6b00801
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
oxide). IR (ATR): ν
̃
= 3050, 2955, 2929, 1587, 1464, 1428, 1406,
Anal. Calcd for C26H21NSi: C, 83.16; H, 5.64; N, 3.73. Found: C,
82.94; H, 5.68; N, 3.54.
1
1324, 1251, 1111, 1064, 1013, 821, 777, 739 cm−1. H NMR (500
3
MHz, CD2Cl2): δ 0.76 (s, 3H), 1.41 (t, J(H,H) = 7.5 Hz, 3H), 3.17
(q, 3J(H,H) = 7.5 Hz, 2H), 4.35 (s, 3H), 6.99−7.04 (m, 2H), 7.24 (dd,
3J(H,H) = 7.3 Hz, 3J(H,H) = 7.2 Hz, 1H), 7.31−7.43 (m, 5H), 7.64−
ASSOCIATED CONTENT
* Supporting Information
■
S
7.65 (m, 3H), 7.83 (d, J(H,H) = 7.9 Hz, 1H). 13C{1H} NMR (126
3
The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/acs.organo-
met.6b00801.
MHz, CD2Cl2): δ −4.6, 16.8, 26.6, 35.7, 110.8, 120.2, 121.2, 121.3,
124.2, 127.0, 128.4, 129.0, 130.1, 130.1, 131.7, 133.9, 134.7, 135.9,
141.5, 142.3, 144.0, 155.0. 29Si DEPT NMR (99 MHz, CD2Cl2): δ −
14.4. HRMS (APCI): calculated for C24H24NSi [M + H]+ 354.1673;
found 354.1674. Elemental analysis results were outside the tolerance
range.
Synthetic procedures of weakly coordinating anions and
substrates, including analytical data, NMR spectra of all
compounds synthesized in this paper, and crystal
structures of 1ec as well as 1pc. (PDF)
2-Chloro-5,10-dimethyl-10-phenyl-5,10-dihydrobenzo[4,5]-
silolo[3,2-b]indole (1nc). This was prepared from 2-(4-chlorophen-
yl)-1-methyl-2-phenyl-1H-indole (5n, 48 mg, 0.20 mmol, 1.0 equiv),
Crystallographic data (CIF)
ruthenium complex [4a]+[BArF ]− (6.5 mg, 4.0 μmol, 2.0 mol %),
4
methylphenylsilane (6c, 73 mg, 0.60 mmol, 3.0 equiv), ruthenium
chloride complex [(Et3P)Ru(SDmp)(Cl)] (2.4 mg, 4.0 μmol, 2.0 mol
%), and Na[CHB11Me5Br6] (3.4 mg, 4.8 μmol, 2.4 mol %) according
to GP4. Step 1 was performed at room temperature with ClC6H5
(0.10 mL, 2.0 M) as a solvent. After stirring for 24 h, additional
AUTHOR INFORMATION
Corresponding Author
*E-mail: martin.oestreich@tu-berlin.de.
ORCID
Lukas Omann: 0000-0002-8689-250X
Martin Oestreich: 0000-0002-1487-9218
Notes
■
ruthenium complex [4a]+[BArF ]− (9.8 mg, 6.0 μmol, 3.0 mol %) was
4
added. Step 1 was stopped after a total of 3 d. Purification by flash-
column chromatography on silica gel (15−40 μm)37 using cyclo-
hexane/Et3N/methyl tert-butyl ether (v:v:v = 95:4:1)36 as eluent
afforded the product (27 mg, 38%) as a brownish solid. Mp = 186 °C
(CH2Cl2). Rf = 0.44 (cyclohexane/Et3N/methyl tert-butyl ether =
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
̃
95:4:1; basic aluminum oxide). IR (ATR): ν = 3064, 3022, 2926, 1583,
■
1558, 1459, 1428, 1400, 1381, 1330, 1249, 1204, 1147, 1109, 1097,
L.O. thanks the Fonds der Chemischen Industrie for a
predoctoral fellowship (2015−2017), and M.O. is indebted to
the Einstein Foundation (Berlin) for an endowed professorship.
We thank Simon Karleskind (Ecole Polytechnique, Palaiseau/
France) for skillful experimental assistance during an internship,
1014, 978, 915, 889, 817, 782, 726 cm−1. 1H NMR (500 MHz,
3
CD2Cl2): δ 0.78 (s, 3H), 4.10 (s, 3H), 7.12 (dd, J(H,H) = 7.5 Hz,
3
3
3J(H,H) = 7.4 Hz, 1H), 7.24 (ddd, J(H,H) = 7.6 Hz, J(H,H) = 7.6
4
Hz, J(H,H) = 0.9 Hz, 1H), 7.32−7.41 (m, 5H), 7.56−7.57 (m, 2H),
7.62−7.64 (m, 2H), 7.75 (d, J(H,H) = 8.2 Hz, 1H). 13C{1H} NMR
3
Susanne Bahr for the synthesis of the ruthenium hydride, and
̈
(126 MHz, CD2Cl2): δ −4.7, 32.5, 109.9, 110.3, 121.1, 121.8, 122.0,
122.5, 128.5, 129.9, 130.4, 130.4, 133.1, 133.8, 134.7, 135.0, 140.4,
143.0, 146.9, 152.9. 29Si DEPT NMR (99 MHz, CD2Cl2): δ −13.8.
HRMS (APCI): calculated for C22H19ClNSi [M + H]+ 360.0970;
found 360.0977. Anal. Calcd for C22H18ClNSi: C, 73.42; H, 5.04; N,
3.89. Found: C, 73.07; H, 5.31; N, 4.05.
Dr. Elisabeth Irran for the X-ray analyses (both TU Berlin).
REFERENCES
■
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5,12-Dimethyl-12-phenyl-5,12-dihydronaphtho[2′,3′:4,5]-
silolo[3,2-b]indole (1pc). This was prepared from 1-methyl-2-
(naphthalene-2-yl)-1H-indole (5p, 51 mg, 0.20 mmol, 1.0 equiv),
ruthenium complex [4a]+[BArF ]− (6.5 mg, 4.0 μmol, 2.0 mol %),
4
methylphenylsilane (6c, 73 mg, 0.60 mmol, 3.0 equiv), ruthenium
chloride complex [(Et3P)Ru(SDmp)(Cl)] (2.4 mg, 4.0 μmol, 2.0 mol
%), and Na[CHB11Me5Br6] (3.4 mg, 4.8 μmol, 2.4 mol %) according
to GP4. Step 1 was performed at room temperature for 16 h with
ClC6H5 (0.20 mL, 1.0 M) as a solvent. Purification by flash-column
chromatography on silica gel (15−40 μm)37 using cyclohexane/Et3N/
methyl tert-butyl ether (v:v:v = 95:4:1)36 as eluent afforded the
product (31 mg, 41%) as a pale yellow solid. Crystals suitable for X-ray
diffraction were obtained by recrystallization of 1pc from cyclohexane/
n-pentane at 8 °C. Mp = 219 °C (CH2Cl2). Rf = 0.31 (cyclohexane/
Et3N/methyl tert-butyl ether = 95:4:1; basic aluminum oxide). IR
̃
(ATR): ν = 3019, 2945, 2893, 1620, 1595, 1476, 1464, 1428, 1392,
1376, 1335, 1268, 1246, 1199, 1186, 1157, 1127, 1113, 1055, 1015,
1
975, 945, 894, 872, 795, 735 cm−1. H NMR (500 MHz, CD2Cl2): δ
0.84 (s, 3H), 4.25 (s, 3H), 7.14 (ddd, 3J(H,H) = 7.5 Hz, 3J(H,H) = 7.4
4
3
3
Hz, J(H,H) = 1.0 Hz, 1H), 7.27 (ddd, J(H,H) = 7.7 Hz, J(H,H) =
4
7.6 Hz, J(H,H) = 1.1 Hz, 1H), 7.32−7.38 (m, 3H), 7.43−7.47 (m,
3
3
4
2H), 7.51 (ddd, J(H,H) = 7.4 Hz, J(H,H) = 7.4 Hz, J(H,H) = 1.1
Hz, 1H), 7.61 (br d, 3J(H,H) = 7.7 Hz, 1H), 7.68−7.70 (m, 2H), 7.79
(br d, 3J(H,H) = 8.0 Hz, 1H), 7.88 (d, 3J(H,H) = 8.0 Hz, 1H), 8.07 (s,
1H), 8.20 (s, 1H). 13C{1H} NMR (126 MHz, CD2Cl2): δ − 4.0, 32.7,
110.2, 112.3, 119.0, 120.9, 122.2, 122.8, 126.4, 127.4, 128.3, 128.4,
128.7, 130.1, 130.5, 133.1, 134.4, 134.8, 135.0, 136.2, 138.4, 141.9,
143.5, 153.7. 29Si DEPT NMR (99 MHz, CD2Cl2): δ −14.8. HRMS
(ESI): calculated for C26H22NSi [M + H]+ 376.1516; found 376.1517.
I
DOI: 10.1021/acs.organomet.6b00801
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
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̈
Preparation and characterization of ruthenium hydrides will be
reported elsewhere.
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(36) To avoid decomposition, the silica gel must be deactivated with
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(37) Silica gel with a larger particle size (40−63 μm) did not provide
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̈
J
DOI: 10.1021/acs.organomet.6b00801
Organometallics XXXX, XXX, XXX−XXX