A General Rhodium Catalyst for the Deuteration of Boranes and Hydrides of the Group 14 Elements

Article abstract of DOI:10.1021/acs.joc.0c01967

Pinacolborane, catecholborane, triethylsilane, triphenylsilane, dimethylphenylsilane, 1,1,1,3,5,5,5-heptamethyltrisiloxane, triethylgermane, triphenylgermane, and triphenylstannane deuterated at the heteroatom position have been catalytically prepared in

Full text of DOI:10.1021/acs.joc.0c01967

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Note
A General Rhodium Catalyst for the Deuteration of Boranes and
Hydrides of the Group 14 Elements
́ ́
Miguel A. Esteruelas,* Antonio Martínez, Montserrat Olivan, and Andrea Velez
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sı Supporting Information
ABSTRACT: Pinacolborane, catecholborane, triethylsilane, triphenylsilane,
dimethylphenylsilane, 1,1,1,3,5,5,5-heptamethyltrisiloxane, triethylgermane,
triphenylgermane, and triphenylstannane deuterated at the heteroatom position
have been catalytically prepared in 50−70% isolated yield, through H/D
exchange between the D molecule and the respective boranes and hydrides of
2
the group 14 elements, in the presence of the rhodium(I)-monohydride catalyst
3
i
i
precursor RhH{κ -P,O,P-[xant(P Pr ) ]} (xant(P Pr ) = 9,9-dimethyl-4,5-bis-
2
2
2 2
(
diisopropylphosphino)xanthene).
dditions of B−H and E−H bonds of boranes (R BH) and
Scheme 1. Reactions with Deuterium
2
A
hydrides of the group 14 elements (R EH; E = Si, Ge, Sn)
3
to unsaturated organic molecules, the so-called reactions of
1
2
3
hydroboration, hydrosilylation, hydrogermylation, and
4
hydrostannation, are powerful tools in the modern organic
synthesis, which allow access to a great number of handy
synthetic intermediates. The use of isotopically labeled
reagents for these reactions is of paramount importance from
two different points of view: they provide relevant mechanistic
5
information, which is necessary for a rational improvement of
the reactions, and generate products bearing heavy isotopes
6
with a slower metabolism, facilitating lower pharmaceutical
doses. Unfortunately, deuterated-boranes, -silanes, -germanes,
and -stannanes are very expensive and the required one is not
always commercially available. As a consequence, they are
prepared by graduate students and postdoctoral researchers in
the majority of the academic laboratories of organic chemistry,
including organometallics.
1
3
silanes (b) include ruthenium-polyhydrides, half-sandwich
14
15
rhodium(III) derivatives, iridium(III)-NHC compounds,
and platinum(0)-phosphine species. To our knowledge,
catalysts for the reactions with germanes (c) and stannanes
16
(
d) have not been reported to date. This specificity forces us to
prepare or to buy a particular catalyst for the preparation of
each class of deuterated reagent that is desired. In this note, we
report and recommend the use of the square-planar complex
Preparation of such reagents by multistep procedures may
be even more expensive than the commercial products, given
the loss of yield in each step and the time required. So,
catalytic one-pot synthesis promoted by transition metals is an
3
i
i
RhH{κ -P,O,P-[xant(P Pr ) ]} (xant(P Pr ) = 9,9-dimethyl-
2
2
2 2
7
8
4,5-bis(diisopropylphosphino)xanthene) as catalyst precusor,
which is efficient for the four reactions of Scheme 1, working
under very mild conditions and with low catalyst loading.
This complex is a notable example of stable late-transition-
metal unsaturated monohydride. It catalyzes the direct
borylation of arenes, the decianative borylation of nitriles,
attractive alternative. Benzene-d , D O, and D are usual
6
2
2
sources of deuterium. The use of the former requires that the
catalyst activates C−D bonds, whereas the utility of the second
one needs of stable metal species toward the hydrolysis. So,
17
only D has general applicability. Thus, reactions shown in
18
19
2
Scheme 1 are the most clean and straightforward method to
prepare these classes of deuterated compounds. Catalysts are
20
the dehydrogenation of ammonia borane, the dehydropoly-
9
also specific for each type of reagent. Some complexes of iron,
1
0
11
12
Received: September 11, 2020
cobalt, rhodium, and iridium stabilized by P,N,P- and
N,N,N-pincer and chelate-diphosphines and NHC ligands
have shown to be efficient for the exchange in boranes (a).
Deuterated pinacolborane (pinBD) has been also synthesized
in high yield, by deuterogenolysis of B pin , in the presence of
2
2
9
,10b
iron and cobalt precursors.
Catalysts for the deuteration of
©
XXXX American Chemical Society
https://dx.doi.org/10.1021/acs.joc.0c01967
A
J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
pubs.acs.org/joc
Note
2
1
merization of amine boranes, and the hydroboration of
Table 1. H/D Isotopic Exchange of Boranes, Silanes,
2
2
3
diphenylacetylene. Furthermore, it participates in the
catalytic cycle of dehydrogenative borylation−hydroborylation
of bis(alkyl)alkynes. So far, a handicap for its use was the
preparation procedure, which afforded a moderate yield. In
order to solve this issue and to give it a more general use, we
have significantly improved its preparation. Now, it is simple
Germanes, and Stannanes Catalyzed by RhH{κ -P,O,P-
i
a
[xant(P Pr ) ]}
2 2
23
(
see Experimental Section) with reduced reaction time,
resulting in a high yield (90%) in spite of involving two
3
steps. It starts from the chloride derivative RhCl{κ -P,O,P-
i
[
xant(P Pr ) ]}, which is almost quantitatively transformed
2
2
3
into the dihydride-rhodium(III) complex RhH Cl{κ -P,O,P-
2
i
[
xant(P Pr ) ]} by oxidative addition of H in pentane. The
2
2
2
t
dechlorination of the latter with KO Bu also in pentane yields
the monohydride (Scheme 2).
3
i
Scheme 2. Preparation of RhH{κ -P,O,P-[xant(P Pr ) ]}
2
2
a
The catalysis was carried out at room temperature, under
Reactions were carried out in diethyl ether (5 mL) in a 160 mL
screw cap Schlenk flask under 1.14 bar of D . The deuteration of
1
.14 bar of D , in diethyl ether as solvent, with concentrations
2
2
−
3
of substrate and catalyst of 0.36 M and 3.6 × 10 M,
respectively. Under these conditions, the boranes pinacolbor-
ane and catecholborane; the silanes triethylsilane, triphenylsi-
lane, dimethylphenylsilane and 1,1,1,3,5,5,5-heptamethyl-
trisiloxane; and the germanes triethylgermane and triphenyl-
germane were transformed in the respective species
monodeuterated at the element with conversions higher than
HSnPh was performed in the presence of hydroquinone (5 mol %)
and in the absence of light. To ensure full deuteration two D loadings
are used. Deuterium incorporation based on integration of H NMR
spectra.
3
2
1
the four compounds of the same manner, to give the related
trans-dihydrides RhH (BR ){κ -P,O,P-[xant(P Pr ) ]} (BR =
3
i
2
2
2 2
2
3
i
9
5%, in all cases, after 6 h (Table 1). The stannane
Bpin, Bcat) and RhH (SiR ){κ -P,O,P-[xant(P Pr ) ]} (SiR =
2 3 2 2 3
24
i
triphenylstannane was also converted into the monodeuterated
counterpart. However, in this case, the reaction had to be
performed in the absence of light and in the presence of 5 mol
SiEt , SiPh ). The ether-diphosphine xant(P Pr ) is flexible,
3 3 2 2
and the ether function displays hemilabile character. As results,
transitory and stable species bearing the ligand coordinated in
3
26
3
27
2
28
2
29
%
of hydroquinone, to prevent the formation of the radical
fashions κ -mer, κ -fac, κ -cis, and κ -trans are known.
This coordinating versatility allows it a fast interconversion
between the different coordination modes. Thus, it adapts to
the requirements of the participating intermediates of the
catalytic cycles, enabling the necessary geometrical trans-
formations on the metal coordination sphere to allowing
reactions initially forbidden. As proof of this ability, complexes
Ph Sn·. The latter dimerizes to afford Ph Sn−SnPh , which is a
3
3
3
usual impurity of the reagent. The deuterated compounds were
isolated in 50−70% yield after purification and were
characterized by NMR spectroscopy. The purification of the
deuterated triphenylsilane, triphenylgermane, and triphenyl-
stannane was performed by column chromatography on silica
gel, whereas the remaining compounds were distillated in a
Kugelrohr glass oven.
3
i
3
RhH (BR ){κ -P,O,P-[xant(P Pr ) ]} and RhH (SiR ){κ -
P,O,P-[xant(P Pr ) ]} undergo reductive elimination of H ,
2
2
2
2
2
3
i
2
2
2
The deuteration can be rationalized according to Scheme 3.
to give the respective square-planar boryl- and silyl-derivatives
3
3
i
3
Under a D atmosphere, complex RhH{κ -P,O,P-[xant-
Rh(BR ){κ -P,O,P-[xant(P Pr ) ]} and Rh(SiR ){κ -P,O,P-
2
2 2 2 3
i
i
(
P Pr ) ]} undergoes H/D exchange to afford the deuteride
counterpart RhD{κ -P,O,P-[xant(P Pr ) ]}, which is the true
[xant(P Pr ) ]} in spite of the trans disposition of the hydride
2
2
2 2
3
i
24
ligands and the concerted nature of the elimination. Under
2
2
catalyst of the reactions. This species oxidatively adds the B−H
or E−H bond of the substrates, along the O−Rh−H axis with
the electropositive element on the oxygen atom of the
diphosphine, to afford the respective rhodium(III) derivatives
the catalytic conditions, the square-planar boryl complexes and
3
i
the Rh(ER ){κ -P,O,P-[xant(P Pr ) ]} counterparts can be
3
2 2
similarly formed by reductive elimination of HD from
3
i
3
RhHD(BR ){κ -P,O,P-[xant(P Pr ) ]} and RhHD(ER ){κ -
2
2 2
3
3
i
3
i
RhHD(BR ){κ -P,O,P-[xant(P Pr ) ]} and RhHD(ER ){κ -
P,O,P-[xant(P Pr ) ]}. In this way, the subsequent oxidative
2
2 2
3
2 2
i
P,O,P-[xant(P Pr ) ]}. This is strongly supported by the
reactions of RhH{κ -P,O,P-[xant(P Pr ) ]} with pinacolborane
addition of D to the metal center of these square-planar
2
2
2
3
i
species, now along the O−Rh−B or O−RhE axis, could give
2
2
3
(
pinBH), catecholborane (catBH), triethylsilane (Et SiH), and
the cis-dideuteride intermediates RhD (BR ){κ -P,O,P-[xant-
3
2
2
24
i
3
i
triphenylsilane (Ph SiH). As is well-known, there is a marked
(P Pr ) ]} and RhD (ER ){κ -P,O,P-[xant(P Pr ) ]}, which
3
2 2 2 3 2 2
diagonal relationship between the elements of rows 2 and 3,
which is particularly pronounced for boron and silicon and
evident in the chemistry of the platinum group metals. In
accordance with it, the square-planar monohydride reacts with
should yield the wished R BD and R ED products through
2 3
the respective reductive eliminations, regenerating the catalyst.
The behavior of the catalyst during the deuteration of
25
3
1
1
Et SiH was followed by P{ H} NMR spectroscopy (Figure
3
B
https://dx.doi.org/10.1021/acs.joc.0c01967
J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
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Note
Scheme 3. Deuteration Mechanism
S30). In accordance with Scheme 3, the hydride-deuteride-
temperature for 12 h, and during this time the gradual darkening of
the color was observed. The resulting suspension was extracted with
pentane (5 × 30 mL) and filtered through a porous frit to remove the
potassium salts, obtaining a very dark solution that was dried to
vacum to afford a very dark solid. Yield: 850 mg (91%). NMR data
3
i
rhodium(III) complex RhHD(SiEt ){κ -P,O,P-[xant(P Pr ) ]}
3
2 2
(
δ31P, 61.8; δ , −5.87; δ , −5.9) is the key species of the
1H
2H
catalysis. It is rapidly formed and the unique detected species
while Et SiH is present in the solution. Once the deuteration is
3
17
agree with those reported previously.
completed, the deuteride-rhodium(I) catalyst is quantitatively
regenerated. These observations confirm the cycle proposed on
the basis of the previously mentioned stoichiometric reactions
and points out the reductive elimination of H−D from
General Procedure for the Deuteration Experiments. In an
argon-filled glovebox a screw cap Schlenk flask (volume ∼160 mL)
3
i
was charged with RhH{κ -P,O,P-[xant(P Pr ) ]} (10 mg, 0.018
2
2
mmol), the corresponding substrate (1.83 mmol), and diethyl ether
3
i
RhHD(SiEt ){κ -P,O,P-[xant(P Pr ) ]} as the rate-determin-
(5 mL). The resulting solution was freeze−pump−thaw degassed and
3
2 2
ing step of the catalysis.
filled with D (0.14 bar over the atmospheric pressure) while
2
3
In conclusion, the rhodium(I)-monohydride RhH{κ -P,O,P-
immersed in liquid N . The solution was thawed and stirred for 3 h at
2
i
[
xant(P Pr ) ]} is an efficient catalyst precursor to perform the
room temperature. Then, the flask atmosphere was removed and it
2
2
was charged again with 1.14 bar of D . After an additional 3 h, the
H/D exchange between the D molecule and the heteroatom−
2
2
deuterium atmosphere was replaced by argon and two different
purification methods were used: flash chromatography over silica gel
using diethyl ether as eluent (DSiPh , DGePh , and DSnPh ) or by
H bond of boranes and hydrides of the group 14 elements. The
deuterated products are obtained in high yields, and >95%
deuterium incorporation was achieved at the desired position.
The preparation of this precursor is simple, with reduced
reaction time, and results in very high yields.
3
3
3
evaporation to dryness and vacuum distillation (DBpin, DBcat,
DSiEt , DSiMe Ph, DSiMe(OSiMe ) , and DGeEt ). The deuteration
3
2
3
2
3
of HSnPh was performed following the general procedure but in the
3
presence of hydroquinone (0.09 mmol) and in the absence of light.
EXPERIMENTAL SECTION
Pinacolborane-d
1
. Colorless liquid. Yield: 153 mg (65%). NMR
■
1
Spectra (Figures S1−S3): H NMR (300.13 MHz, C D ): δ 1.00 (s,
6
6
General Information. All reactions were carried out with
exclusion of air using Schlenk-tube techniques or in a drybox.
Pentane and diethyl ether were obtained oxygen- and water-free from
2
1
2H). H NMR (46.07 MHz, C H ): δ 4.25 (broad s, ν = 67 Hz).
6 6 1/2
1
1
1
B NMR (96.29 MHz, C D ): δ 28.3 (broad t, J = 20.4 Hz).
B‑D
NMR data agree with those reported previously.
Catecholborane-d . Colorless liquid. Yield: 104 mg (47%). NMR
Spectra (Figures S4−S6): H NMR (300.13 MHz, C D ): δ 6.97 (dd,
6
6
30
1
2
11
1
13
1
an MBraun solvent purification apparatus. H, H, B{ H}, C{ H},
and 2 Si{ H} NMR spectra were recorded on Bruker 300 ARX,
9
1
1
1
6
6
Bruker Avance 300 MHz, Bruker Avance 400 MHz, or Bruker Avance
J
= 5.7 Hz, J
= 3.3 Hz, 2H), 6.75 (dd, J
= 6.0 Hz, J
=
5
00 MHz instruments at 25 °C. Chemical shifts (expressed in ppm)
H−H
H−H
H−H
H−H
2
1
2
13
3.6 Hz, 2H). H NMR (46.07 MHz, C H ): δ 4.38 (broad s, ν = 60
are referenced to residual solvent peaks ( H, H, C), BF ·OEt
6 6 1/2
3
2
1
1
11
29
Hz). B NMR (96.29 MHz, C D ): δ 28.6 (broad s). NMR data
6 6
31
(
B), or SiMe ( Si). High-resolution electrospray (HRMS) and
4
agree with those reported previously.
Triethylsilane-d . Colorless liquid. Yield: 155 mg (72%). NMR
MALDI-TOF mass spectra were acquired using a MicroTOF-Q
hybrid quadrupole time-of-flight spectrometer and a Bruker Autoflex
III, MALDITOF/TOF equipped with a DCTB matrix, respectively.
1
1
Spectra (Figures S7−S9): H NMR (300.13 MHz, C D ): δ 0.97 (t, J
6
6
2
3
i
= 7.8 Hz, 9H), 0.53 (q, J = 7.8 Hz, 6H). H NMR (61.42 MHz,
RhH Cl{κ -P,O,P-[xant(P Pr ) ]} was prepared as reported previ-
ously.
2
2 2
17
29
1
1
C H ): δ 3.9 (s). Si{ H} NMR (59.63 MHz, C D ): δ −0.1 (t, J
6
6
6
6
Si‑D
7d
3
=
27.4 Hz). NMR data agree with those reported previously.
Triphenylsilane-d . White solid. Yield: 373 mg (78%). NMR
Spectra (Figures S10−S12): H NMR (300.13 MHz, C D ): δ 7.70
Improved Method of Synthesis of RhH{κ -P,O,P-[xant-
i
3
i
(
P Pr ) ]}. A suspension of RhH Cl{κ -P,O,P-[xant(P Pr ) ]} (1000
1
2
2
2
2 2
t
1
mg, 1.71 mmol) in pentane (30 mL) was treated with K BuO (250
mg, 2.23 mmol). The resulting mixture was stirred at room
6
6
2
(m, 6H), 7.30 (m, 9H). H NMR (61.42 MHz, C H ): δ 5.7 (s).
6
6
C
https://dx.doi.org/10.1021/acs.joc.0c01967
J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
pubs.acs.org/joc
Note
2
9
1
1
Si{ H} NMR (59.63 MHz, C H ): δ −18.7 (t, J = 30.0 Hz).
Si‑D
Authors
6
6
1
3b
NMR data agree with those reported previously.
Antonio Martínez − Departamento de Química Inorgánica −
Instituto de Síntesis Química y Catálisis Homogénea
Dimethylphenylsilane-d . Colorless liquid. Yield: 171 mg
1
1
(
68%). NMR Spectra (Figures S13−S15): H NMR (300.13 MHz,
(
(
ISQCH) − Centro de Innovación en Química Avanzada
ORFEO−CINQA), Universidad de Zaragoza − CSIC,
2
C D ): δ 7.44 (m, 2H), 7.17 (m, 3H), 0.18 (s, 6H). H NMR (61.42
6
6
2
9
1
MHz, C H ): δ 4.6 (s). Si{ H} NMR (59.63 MHz, C D ): δ −17.8
6
6
6
6
1
50009 Zaragoza, Spain; orcid.org/0000-0002-7292-
8591
́
Montserrat Olivan − Departamento de Química Inorgánica −
Instituto de Síntesis Química y Catálisis Homogénea
(ISQCH) − Centro de Innovación en Química Avanzada
(ORFEO−CINQA), Universidad de Zaragoza − CSIC,
50009 Zaragoza, Spain;
0917
Andrea Velez − Departamento de Química Inorgánica −
́
Instituto de Síntesis Química y Catálisis Homogénea
(
t, JSi‑D 7= 28.9 Hz). NMR data agree with those reported
d
previously.
,1,1,3,5,5,5-Heptamethyltrisiloxane-d . Colorless liquid.
1
1
1
Yield: 286 mg (70%). NMR Spectra (Figures S16−S18): H NMR
(
2
300.13 MHz, C D ): δ 0.15 (s, 21H). H NMR (61.42 MHz, C H ):
6 6 6 6
29
1
δ 5.0 (s). Si{ H} NMR (59.63 MHz, C D ): δ 3.6 (s), −42.0 (t,
6
6
1
7d
JSi‑D = 36.0 Hz). NMR data agree with those reported previously.
orcid.org/0000-0003-0381-
3
2
Triethylgermane-d1. Colorless liquid. Yield: 170 mg (58%).
1
NMR Spectra (Figures S19−S21): H NMR (300.13 MHz, C D ): δ
1
C H ): δ 3.9 (s). C{ H} NMR (75.47 MHz, C D ): δ 9.4, 8.4.
HRMS (Figure S22, electrospray, m/z): calcd for C H Ge [M − D] ,
1
6
6
2
.11 (t, J = 7.5 Hz), 0.87 (q, J = 7.8 Hz, 6H). H NMR (61.42 MHz,
13
1
6
6
6
6
+
(ISQCH) − Centro de Innovación en Química Avanzada
6
15
(
5
ORFEO−CINQA), Universidad de Zaragoza − CSIC,
0009 Zaragoza, Spain; orcid.org/0000-0003-1974-
61.0381; found, 161.0367.
32
Triphenylgermane-d1. White solid. Yield: 403 mg (72%).
1
NMR Spectra (Figures S23−S25): H (300.13 MHz, C D ): δ 7.50
5507
6
6
2
(
m, 6H), 7.14 (m, 9H). H NMR (61.42 MHz, C H ): δ 5.9 (s).
C{ H} NMR (75.47 MHz, C D ): δ 151.2, 135.6, 129.5, 128.8.
6 6
Complete contact information is available at:
https://pubs.acs.org/10.1021/acs.joc.0c01967
13
1
6
6
+
MALDI-TOF (m/z): calcd for C H Ge [M − D] , 305.038; found,
3
1
8
15
04.968.
Triphenylstannane-d1. Oily white solid. Yield: 521 mg (81%).
3
2
Notes
1
NMR Spectra (Figures S26−S28): H (300.13 MHz, C D ): δ 7.60
(
tin satellites, J1
(
The authors declare no competing financial interest.
6
6
2
m, 6H), 7.10 (m, 9H). H NMR (61.42 MHz, C D ): δ 6.9 (s with
6 6
1
1
13
1
= 319 Hz, J
= 303 Hz). C{ H} NMR
ACKNOWLEDGMENTS
19Sn‑D
117Sn‑D
■
75.47 MHz, C D ): δ 137.7, 137.3, 129.4, 129.0. HRMS (Figure S29,
6 6
+
Financial support from the MINECO of Spain (Projects
CTQ2017-82935-P and RED2018-102387-T (AEI/FEDER,
electrospray, m/z): calcd for C H Sn [M − D] , 351.0193; found,
1
8
15
3
51.0175.
NMR Spectroscopic Study of the Catalytic Deuteration of
Triethylsilane. In the glovebox, two J Young NMR tubes were
UE)), Gobierno de Aragon (Group E06_20R, project
́
LMP148_18, and predoctoral contract to A.M.), FEDER,
and the European Social Fund is acknowledged.
3
i
charged with a solution of RhH{κ -P,O,P-[xant(P Pr ) ]} (10 mg,
2
2
0
.02 mmol) and triethylsilane (30 μL, 0.2 mmol) in diethyl ether
0.40 mL) or diethyl ether-d10 (0.40 mL), respectively. The argon
atmosphere was replaced by a deuterium atmosphere (1.14 bar), and
(
REFERENCES
■
31
1
1
2
(
1) See for example: (a) Chong, C. C.; Kinjo, R. Catalytic
P{ H}, H, and H NMR spectra were recorded periodically.
Hydroboration of Carbonyl Derivatives, Imines, and Carbon Dioxide.
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L.; Bose, S. K. Recent advances in the catalytic hydroboration of
carbonyl compounds. Catal. Sci. Technol. 2019, 9, 3307−3336.
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1
filled glovebox a screw cap Schlenk flask (volume ∼160 mL) was
charged with RhH{κ -P,O,P-[xant(P Pr ) ]} (54.6 mg, 0.1 mmol),
HSiPh3 (2.604 g, 10 mmol), and diethyl ether (27.5 mL). The
resulting solution was freeze−pump−thaw degassed and filled with D
(
The solution was thawed and stirred for 1 h at room temperature.
Afterward, the flask atmosphere was removed and it was charged again
with 1.14 bar of D . This procedure was repeated each hour, up to
four times. Then the deuterium atmosphere was replaced by argon,
and triphenylsilane-d was purified by flash chromatography over silica
gel using diethyl ether as eluent. Isolated yield: 2.28 g (87%).
3
i
2
2
2
0.14 bar over the atmospheric pressure) while immersed in liquid N .
2
(
2) See for example: (a) Hydrosilylation: A Comprehensive Review on
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2
1
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ASSOCIATED CONTENT
■
2
*
sı Supporting Information
The π-(Hydroxyalkenyl)germane Complexes Rh(acac){η -(E)-
Et GeCHCHC(OH)R }(PCy ) (R = Me, Ph) as Intermediates
The Supporting Information is available free of charge at
https://pubs.acs.org/doi/10.1021/acs.joc.0c01967.
3
2
3
in the Hydrogermylation of Alkynols Catalyzed by Rh(acac)-
(
cyclooctene)(PCy ). Organometallics 1999, 18, 2267−2270. (b) Mat-
3
NMR spectra, selected HRMS (PDF)
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Catalyzed trans-Hydrogermylation of Alkynes: Formation of 2,5-
Disubstituted Germoles through Double trans-Hydrogermylation of
AUTHOR INFORMATION
1
,3-Diynes. Org. Lett. 2010, 12, 1056−1058. (c) Itazaki, M.; Kamitani,
■
M.; Nakazawa, H. Trans-selective hydrogermylation of alkynes
promoted by methyliron and bis(germyl)hydridoiron complexes as
a catalyst precursor. Chem. Commun. 2011, 47, 7854−7856.
Corresponding Author
Miguel A. Esteruelas − Departamento de Química Inorgánica
−
(
(
5
7
Instituto de Síntesis Química y Catálisis Homogénea
ISQCH) − Centro de Innovación en Química Avanzada
ORFEO−CINQA), Universidad de Zaragoza − CSIC,
(d) Meißner, G.; Kretschmar, K.; Braun, T.; Kemnitz, E. Consecutive
Transformations of Tetrafluoropropenes: Hydrogermylation and
Catalytic C-F Activation Steps at a Lewis Acidic Aluminum Fluoride.
Angew. Chem., Int. Ed. 2017, 56, 16338−16341. (e) Liang, H.; Ji, Y.-
X.; Wang, R.-H.; Zhang, Z.-H.; Zhang, B. Visible-Light-Initiated
0009 Zaragoza, Spain; orcid.org/0000-0002-4829-
590; Email: maester@unizar.es
D
https://dx.doi.org/10.1021/acs.joc.0c01967
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The Journal of Organic Chemistry
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F
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