Hydroboration of Terminal Alkenes and trans-1,2-Diboration of Terminal Alkynes Catalyzed by a Manganese(I) Alkyl Complex

Article abstract of DOI:10.1002/anie.202110736

A Mn^I-catalyzed hydroboration of terminal alkenes and a 1,2-diboration of terminal alkynes with pinacolborane (HBPin) is described. For alkenes, anti-Markovnikov hydroboration takes place; for alkynes the reaction proceeds with excellent trans-1,2-selectivity. The most active pre-catalyst is bench-stable alkyl bisphosphine Mn^I complex fac-[Mn(dippe)(CO)₃(CH₂CH₂CH₃)]. The catalytic process is initiated by migratory insertion of a CO ligand into the Mn–alkyl bond to yield an acyl intermediate, which undergoes B?H bond cleavage of HBPin (for alkenes) and rapid C?H bond cleavage (for alkynes), forming the active Mn^I boryl and acetylide catalysts [Mn(dippe)(CO)₂(BPin)] and [Mn(dippe)(CO)₂(C≡CR)], respectively. A broad variety of aromatic and aliphatic alkenes and alkynes was efficiently and selectively borylated. Mechanistic insights are provided based on experimental data and DFT calculations revealing that an acceptorless reaction is operating involving dihydrogen release.

Full text of DOI:10.1002/anie.202110736

A Journal of the Gesellschaft Deutscher Chemiker
Angewandte
Chemie
International Edition
www.angewandte.org
Accepted Article
Title: Hydroboration of Terminal Alkenes and trans-1,2-Diboration of
Terminal Alkynes Catalyzed by a Mn(I) Alkyl Complex
Authors: Stefan Weber, Daniel Zobernig, Berthold Stöger, Luis F
Veiros, and Karl Kirchner
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To be cited as: Angew. Chem. Int. Ed. 10.1002/anie.202110736
Link to VoR: https://doi.org/10.1002/anie.202110736

10.1002/anie.202110736
Angewandte Chemie International Edition
COMMUNICATION
Hydroboration of Terminal Alkenes and trans-1,2-Diboration of
Terminal Alkynes Catalyzed by a Mn(I) Alkyl Complex
Stefan Weber,+ Daniel Zobernig,+ Berthold Stöger, Luis F. Veiros, and Karl Kirchner*
carbonyls,[12] nitriles,[13] and CO2 were reported. Interestingly,
[14]
Abstract: A Mn(I)-catalyzed hydroboration of terminal alkenes and a
the hydroboration of alkenes[15] and alkynes[16] is as yet restricted
1,2-diboration of terminal alkynes with pinacolborane (HBPin) is
to manganese complexes in the oxidation state +II containing
potentially non-innocent ligands such as terpyridine or benzylic
imines. An overview of manganese-based hydroboration
catalysts for alkenes and alkynes is depicted in Scheme 1.
described. In the case of alkenes anti-Markovnikov hydroboration
takes place, while in the case of alkynes the reaction proceeds with
excellent trans-1,2-selectivity. The most active pre-catalyst is the
bench-stable
alkyl
bisphosphine
Mn(I)
complex
fac-
Our group recently reported additive-free hydrogenation of
[Mn(dippe)(CO)3(CH2CH2CH3)]. The catalytic process is initiated by
migratory insertion of a CO ligand into the Mn-alkyl bond to yield an
acyl intermediate which undergoes B-H bond cleavage of HBPin (in
the case of alkenes) and rapid C-H bond cleavage (in the case of
alkynes) forming the active Mn(I) boryl and acetylide catalysts
[Mn(dippe)(CO)2(BPin)] and [Mn(dippe)(CO)2(C≡CR)], respectively. A
broad variety of aromatic and aliphatic alkenes and alkynes was
efficiently and selectively borylated. Mechanistic insights are provided
based on experimental data and DFT calculations revealing that an
acceptorless reaction is operating involving dihydrogen release.
nitriles,[17] alkenes,[18] ketones,[19] CO2,
the dimerization and
[20]
cross coupling of terminal alkynes,[21] and dehydrogenative
silylation of alkenes[22] catalyzed by bench stable Mn(I) alkyl
carbonyl complexes. In contrast to the vast majority of reported
Mn(I) complexes,[23] these newly introduced systems operate via
an inner-sphere mechanism.
O
n
BPi
HB
R
R
O
OTf
n
N
N
N
N
The use of organoboron reagents especially in the field of cross-
coupling chemistry increased within the last decades.[1]
Hydroboration reactions display a powerful tool for the synthesis
of organoboron compounds.[2] In the last years, the use of
dialkoxyboranes such as pinacolborane (HBPin) was
implemented in organic synthesis due to the stability of HBPin as
reagent and convenient handling of the hydroborated product.[3]
However, due to the superior stability of dialkoxyboranes in
comparison to “BH3”-species, low reactivity towards
hydroboration of alkenes is attributed.[4] Within this context the
transition-metal catalyzed hydroboration of C-C multiple bonds
displays a versatile route towards organoboron species.[5]
Catalysts with noble metal such as Rh[6] and Ir[7] are already well
established in the field of C-C multiple bond hydroboration. In the
last years, non-precious metal catalysts based on Cu,[8] Ni,[9]
Co[10] and Fe[11] were successfully introduced in this area. As
manganese is concerned, several examples for Mn(I)-catalyzed
hydroborations of polarized C-X multiple bonds such as
M
n
M
n
M
N
N
N
N
N
N
DIPP
DIPP
r
B
O
T
f
CH2TMS
r
TMSH2C
B
omas
mo
ar on
e
u
R
er
an
Th
2018
K
t
d
it 2021
&
Zh g 2016
,
,
,
t
t
mo
l
%
a
u
mo
mo
a
l N
%
u
mo
no a
°
ve
2
6
l
N
O B
5
l
15
O B
%
%
1
l
dditi
%
°
°
60
C
60
C
25
C
'
R
O
R
F
G
HB
FG
'
R
n
BPi
O
R
N
n
N
M
N
DIPP
DIPP
Cl
Cl
ue
pi g 2020
n
R
,
mo
mo
a
N BEt H
%
[
C
2
l
%
4
l
°
]
3
-
,
=
so ro
en
DIPP 2 6 dii
p
ylph yl
25
w r
s
o
Thi
k
O
O
.
mo
n
BPi
0 25
l
%
HB
HB
R2
R
R
,
°
C
THF 80
P
CO
CO
n
M
P
n
Bpi
CO
R2
O
.
mo
0 5 l%
THF 70
R
=
i
r
,
°
R
R
P
C
O
[a]
Dr. Stefan Weber, Daniel Zobernig, Prof. Dr. Karl Kirchner
Institute of Applied Synthetic Chemistry
Vienna University of Technology
n
BPi
Scheme 1. Overview of manganese-based hydroboration
Getreidemarkt 9/163-AC, A-1060 Wien, Austria.
E-mail: karl.kirchner@tuwien.ac.at
catalysts.
[b]
[c]
[+]
Dr. Berthold Stöger
X-Ray Center
Vienna University of Technology
Getreidemarkt 9, A-1060 Wien, Austria.
Prof. Dr. Luis F. Veiros
We hereby took advantage of the fact that alkyl ligands undergo
migratory insertion reactions. This leads to the formation of a
complex, containing a strongly basic acyl ligand. If the entering
substrate contains a weakly polarized E-H bond (E = H, C≡CR,
SiR3, BR2), the acyl ligand is capable of initiating E-H bond
cleavage thereby forming the catalytically Mn-E species and a
weakly bonded aldehyde ligand which can be easily substituted
by incoming substrates (Scheme 2).
Centro de Química Estrutural and Departamento de Engenharia
Química, Instituto Superior Técnico, Universidade de Lisboa
Av Rovisco Pais, 1049-001 Lisboa (Portugal)
These authors contributed equally.
Supporting information for this article is given via a link at the end of
the document.
This article is protected by copyright. All rights reserved.

10.1002/anie.202110736
Angewandte Chemie International Edition
COMMUNICATION
be detected for 2 and 3. This proved the crucial role of the alkyl
group for the catalytic performance. Complex 1 shows high
reactivity in THF or toluene, but no productivity in MeOH due to
rapid methanolysis of HBPin leading to massive hydrogen gas
evolution. It should be noted that the selectivity for all optimization
reactions was at least 96 % to the anti-Markovnikov (4a). The
catalyst loading could be decreased to only 0.25 mol%. Lowering
the catalyst amount to 0.1 mol% still gave 76 % conversion.
Scheme 2. Formation of the active species via migratory insertion
and deprotonation of the entering ligand
Table 2. Substrate scope for the manganese-catalyzed
hydroboration of terminal alkenes[a]
Here,
we
describe
the
(dippe
activity
=
of
fac-
[Mn(dippe)(CO)3(CH2CH2CH3)]
1,2-bis(di-iso-
.
n
BPi
mo
l
%
)
O
O
1
0 25
(
n
BPi
HB
R
R
R
propylphosphino) (1), fac-[Mn(dippe)(CO)3(Br)] (2) and fac-
[Mn(dippe)(CO)3(H)] (3) as pre-catalysts for the selective anti-
Markovnikov hydroboration of terminal alkenes and the selective
trans-1,2-diboration of terminal alkynes. A plausible reaction
mechanism based on detailed experimental and theoretical
studies is presented.
Initial catalyst evaluation for the hydroboration of terminal
alkenes was carried out with complexes 1, 2 and 3 and 4-
chlorostyrene as model substrate and HBPin.
,
°
,
C
24 h
THF 80
4
5
n
BPi
n
BPi
n
BPi
n
BPi
n
BPi
r
B
Cl
F
Cl
a
c
e
4
91 83
( )
4
4b
99 73
(
4
4d
>
99 82
(
>
>
>
99 90
(
99 84
(
)
)
)
)
F
n
BPi
F
F
n
n
r
n
n
BPi
BPi
B
BPi
n
BPi
F
O
F
4
j
4h
86 71
(
4f
94 89
(
4g
4i
80 58
(
85 69
(
>
)
99 80
(
)
)
)
)
n
n
BPi
BPi
n
BPi
n
BPi
O
BPi
N
O
Table 1. Optimization reaction for the manganese catalyzed
4k
89 65
(
n
4
b
]
m
4
98 75
(
o
4l[
4
hydroboration of 4-chlorostyrene with HBPin.[a]
)
85 56
(
)
92 75
(
)
)
95 77
(
)
n
BPi
.
ca mo
n
BPi
t
l
%
)
O
(
H
n
BPi
n
Bpi
n
BPi
n
BPi
O
b
n
BPi
N
HB
,
°
,
so ven
Cl
l
t
70
18 h
O
C
Cl
Cl
Cl
4t
a
4
a
5
b
s
[ ]
4
r[
4
]
4q
4p
86 79
88 69
86 58
(
)
(
)
81 75
(
(
)
50 46
( )
)
R2
P
R2
P
R2
P
r
B
H
n
BPi
CO
CO
CO
CO
CO
n
BPi
n
BPi
Si
n
BPi
n
n
n
M
M
M
CO
r
P
P
P
v
CO
CO
CO
u
4
79 48
(
x
n
4
R2
R2
R2
w
4
4
. .
n r
. .
d
. .
n
d
( )
85 82
(
)
)
14
(
)
=
i
=
i
=
i
R P
r
P
r
P
R
R
1
2
3
[a] Conditions: alkene (1.13 mmol, 1 equiv), HBPin (1.15 mmol,
1.02 equiv), 1 (0.25 mol%), 0.5 mL THF, 80 °C, 24 h, Ar,
conversion, and isomer ratio (≥98:2 of 4:5) determined by GC-MS,
isolated yield given in parenthesis. [b] 1 (1mol%) was used.
Entry
Catalyst
(mol%)
Solvent
Conversion[b] Ratio
(%)
>99
2
4a:5a[b]
1
1 (2)
THF
97:3
n.d.
Having established the optimized reaction conditions, the scope
and limitation of catalyst 1 was examined (Table 2). A broad
variety of aryl substrates was investigated, tolerating a range of
functional groups including halides, ethers, amines, and esters.
Notably, the isomer ratio for all substrates was ≥98:2 towards the
anti-Markovnikov product. High conversions for substrates
containing an electron withdrawing-group were achieved (4a-4c
and 4e-4g). The investigation of aromatic systems bearing
electron-donating groups in the para-position (4h-4j) resulted in a
minor drop in reactivity. A good yield was also achieved for 2,4,6-
trimethylstyrene (4l) a sterically demanding substrate, if the
catalyst loading was increased to 1 mol%. Investigation of the
scope for aliphatic alkenes revealed high reactivity for a large
number of alkyl substrates (4n-4v). Negligible conversion of α-
methylstyrene (4w) and no conversion of cyclohexene (4x) was
found.
2
2 (2)
THF
3
3(2)
THF
6
n.d.
4
1 (1)
THF
>99
>99
n.r.
88
97
76
7
97:3
96:4
n.d.
5
1 (1)
Toluene
MeOH
THF
6
1 (1)
7
1 (0.5)
1 (0.25)
1 (0.1)
none
98:2
98:2
99:1
99:1
8c
9c
10c
THF
THF
THF
[a] Conditions: 4-chlorostyrene (1.13 mmol, 1 equiv), HBPin (1.15
mmol, 1.02 equiv), catalyst (0.1-2 mol%), 0.5 mL solvent, 70 °C,
18 h, Ar. [b] determined by GC-MS analysis. [c] 80 °C, 24 h.
In order to get some mechanistic insights several experiments
were carried out employing 4-chlorostyrene as substrate. The
homogeneity of the system was proven upon addition of one drop
of Hg which did not lead to a loss of productivity. On the other
hand, addition of 1 equiv of PMe3 resulted in only 8 % conversion
Selected optimization reactions are depicted in Table 1 (for
details see SI). The screening of complexes 1, 2 and 3 revealed
excellent performance for 1, whereas only traces of product could
This article is protected by copyright. All rights reserved.

10.1002/anie.202110736
Angewandte Chemie International Edition
COMMUNICATION
which is in line with an uncatalyzed reaction (7 % conversion,
Table 1, entry 10). This indicates that the reaction proceeds via
an inner-sphere reaction since PMe3 blocks the vacant
coordination site of the actual catalyst. Interestingly, 1 reacts with
pinacolborane to yield [Mn(dippe)(CO)2(κ2-HBPin)] (6) in 68 %
isolated yield. The structure of 6 was elucidated by X-ray
crystallography (Scheme 4). This complex could be detected by
in situ NMR analysis upon reaction progress. Importantly, the
same reactivity and selectivity for the hydroboration of 4-
chlorostyrene was achieved by employing complex 6 as catalyst.
We also studied the hydroboration of terminal alkynes. Apart
from E-, Z- and geminal hydroborated products (8-10), significant
amounts of the unsaturated trans-1,2-diborated isomer (7) was
observed (Table 3), which is an important building block in organic
chemistry.[24h] This transformation is so far not known for any
transition metal-catalyst, since 1,2-diboration of (terminal) alkynes
typically afford syn-1,2-diborated compounds employing boron
dimers such as B2Pin2.[24] It should be mentioned that no formation
of alkyne-dimerization was observed under the given reaction
conditions.
Upon optimization reactions (see SI), a selectivity of up to 55 %
of the desired trans-1,2-diborated product was achieved with only
0.5 mol% of catalyst 1. The formation of the trans-1,2-diborated
product seems to be attributed to a massive formation of
hydrogen gas and is thus described as an acceptorless process
(vide infra). Investigation of the substrate scope revealed a broad
applicability of the investigated transformation for aromatic (7a-7i)
and aliphatic systems (7j-7m) (Table 3). The presence of the C-H
bond of the terminal alkyne is crucial for this transformation, since
in case of diphenylacetylene (7n) only low conversion and no
formation of the desired trans-1,2-diborated product was
observed.
Table 3. Substrate scope for the manganese-catalyzed trans-1,2
diboration of terminal alkynes[a]
n
Bpi
n
Bpi
10
.
mo
0 5
O
O
1
l
%
)
(
n
BPi
HB
R
R
R
R
R
,
°
,
THF 70
C
24 h
n
n
BPi
BPi
9
7
8
n
BPi
n
BPi
n
BPi
n
BPi
n
BPi
n
BPi
n
BPi
n
BPi
n
BPi
n
BPi
F
Cl
a
c
7
7b
7
7d
99 34
( )
e
7
98 32
(
b
]
b
]
97 36
(
9
7
41 [
95 44 [
)
)
(
)
( )
n
BPi
n
BPi
n
BPi
n
BPi
n
BPi
n
BPi
n
BPi
n
BPi
O
C
l
O
7g
80 37
7f
98 34
(
7h
7i
b
]
b
]
9
4
46 [
99 33 [
(
)
)
(
)
(
)
n
BPi
n
BPi
n
BPi
n
BPi
n
BPi
Cl
n
Ph
Ph
.
n
BPi
BPi
n
BPi
n
BPi
7
j
(
m
7
95 13
(
n
7
.
7k
93 29
7l
99 31
81 35
n
13
(
)
d
)
(
)
)
(
)
[a] Conditions: alkyne (1.13 mmol, 1 equiv), HBPin (1.7 mmol, 1.5
equiv), 1 (0.5 mol%), 0.5 mL THF, 70 °C, 24 h, Ar, conversion
determined by GC-MS, isolated yield given in parenthesis. [b] yield
determined by GC-MS using n-dodecane as standard.
n
BPi
n
Bpi
O
O
n
BPi
HB
Ph
Ph
Ph
Ph
Ph
n
n
BPi
BPi
a
9
a
10
a
7
a
8
.
.
con
v
mo
0 5
O
O
1
l
%
(
)
97
%
Ph
HB
HB
a
7
a
a
a
a: a: a:
: :
48 35 7 6
a
8
9
H2
10
7
8 9
10
,
°
,
THF 70
C
24 h
:
e ec e
d
t
h
t
d
d by GC
ace
ea
s
p
(
)
no ca a
s
t
O
O
t
ly
Ph
.
a
8
conv
11
%
,
°
,
s n
gl
e somer orme
i
f d
)
THF 70
C
24 h
i
(
.
mo
l
%
)
O
1
0 5
(
a or a or
a
8
9
10
no reac on
ti
HB
HB
,
°
,
C
24 h
O
O
THF 70
.
mo
l
%
1
0 5
(
)
n
BPi
no reac on
ti
Ph
,
°
,
C
24 h
O
THF 70
11
A variety of experiments were carried out in order to establish a
plausible reaction mechanism (Scheme 3). Head space analysis
showed that hydrogen gas is released during the reaction. This
proves that the reaction operates via an acceptorless pathway. In
absence of catalyst exclusively the unsaturated mono-borated E-
isomer (8a) is formed in low yield. Neither mono-borylated
compounds 8a, 9a, 10a nor the mono-borylated alkyne species
(11), which was detected in traces (<3 %) upon substrate scope
investigations for some aromatic substrates, showed any
reactivity under the given reaction conditions. The reaction seems
to proceed via a concerted mechanism rather than a stepwise
hydroboration/dehydrogenative borylation process. A deuterium
labeling experiment employing phenylacetylene-d1 revealed that
only traces of deuterium are incorporated in the trans-1,2-
diborated product. Interestingly, complex 6 exhibited a similar
catalytic reactivity to 1 and may be considered as resting state
which can be activated under these reaction conditions (Scheme
3).
.
n
BPi
.
mo
O
O
1
0 5
l
v
%
con
(
)
94
%
Ph
D
HB
HB
H/D
a
a
9
a
10
a: a: a:
a
10
8
7
8
:
9
: :
Ph
,
°
,
C
24 h
THF 70
56 27 9 8
n
BPi
ncor ora e
t
d
<
5
D i
p
%
.
.
mo
0 5 l%
O
O
6
co
nv
(
)
95
%
Ph
a
7
a
a
9
a
10
a: a: a: a
10
8
7
8 9
: :
,
°
,
C
24 h
THF 70
:
46 42 6 6
Scheme 3. Mechanistic experiments for the manganese-
catalyzed trans-1,2-diboration of terminal alkynes.
energy profiles are provided in the SI (Figures S1-S4). A simplified
catalytic cycle is depicted in Scheme 4.
Catalyst initiation, reported previously,[21] starts from 1 to give
the 16e acetylide catalyst [Mn(dippe)(CO)2(C≡CPh)] (A) together
with liberated butanal. It has to be noted that the direct activation
of the B-H bond of HBin to form the reactive 16e boryl
intermediate [Mn(dippe)(CO)2(BPin)] was also considered but this
process is less favorable by 8 kcal/mol in comparison to C-H bond
activation of the terminal alkyne (see SI, Figure S4). This process
however seems to take place in the case of alkene hydroboration.
Addition of HBPin to A results in the formation of intermediate
B where B-C and Mn-H bonds are formed with the B-H bond
remaining still intact. This is a facile process with a barrier of only
4 kcal/mol (TSAB). From B, the BPin moiety undergoes a 1,2-boryl
shift to form vinyl intermediate D. This the rate determining step
overcoming a barrier of 20 kcal/mol and is accompanied by B-H
bond cleavage and formation of a new C-H bond. Addition of a
The mechanism of the trans-1,2-diboration of terminal alkynes
catalyzed by 1 was investigated in detail by DFT calculations
using phenylacetylene as model substrate.[25] The resulting free
This article is protected by copyright. All rights reserved.

10.1002/anie.202110736
Angewandte Chemie International Edition
COMMUNICATION
second molecule of HBPin results in the formation of F where the
second C-B bond is formed (the overall barrier for these steps is
11 kcal/mol) (see SI Figure S1). Facile B-H bond cleavage in F
Acknowledgements
Financial support by the Austrian Science Fund (FWF) is
gratefully acknowledged (Project No. P 33016-N). Centro de
Química Estrutural acknowledges the financial support of
Fundação para a Ciência e Tecnologia (UIDB/00100/2020).
Ph
n
Ph
BPi
n
BPi
R2
P
R2
P
H
n
M
H
n
M
CO
P
CO
CO
B
P
R2
CO
D
R2
n
HBPi
n
HBPi
Conflict of Interest
The authors declare no conflict of interest.
Ph
n
Ph
H
n
Pi
B
H
R2
P
R2
R2
P
H
P
CO
CO
n
BPi
n
M
n
M
M
Keywords: manganese alkyl complex ⋅ hydroboration ⋅ 1,2-
diboration ⋅ alkenes ⋅ alkynes
Ph
CO
CO
P
P
P
CO
1
CO
A
R2
R2
CO
R2
O
F
=
i
r
P
H
R
H
n
H
H
Pi
B
[1]
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R2
H
P
R2
n
BPi
P
n
M
H
Ph
CO
n
M
P
Ph
H
CO
G
R2
CO
P
CO
J
R2
H
n
B
n
i
Pi
B
H
n
Pi
B
P
H
B
n
i
- P
R2
P
H
n
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Ph
BPi
H
n
M
CO
P
6
CO
6
R2
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Scheme 4. Simplified catalytic cycle for the trans-1,2-diboration
of phenyl acetylene with HBPin. Inset: X-ray structure of complex
6
results in the formation of the intermediate G containing a hydride
ligand and the product coordinated in η2-fashion. After product
release, the hydride intermediate J is formed which reacts with
phenyl acetylene to reform pre-catalyst A. This transformation
requires two steps involving C-H bond activation of the alkyne with
concomitant formation of a dihydrogen intermediate which readily
releases dihydrogen (for details see SI, Figures S2 and S3). J
may also react with HBPin to give isolable 6 as a dormant species,
which can be activated upon dissociation of HBPin.
In conclusion, the bench-stable alkyl bisphosphine Mn(I)
complex fac-[Mn(dippe)(CO)3(CH2CH2CH3)] turned out to be an
efficient catalyst for an additive-free hydroboration of terminal
alkenes and the trans-1,2-diboration of terminal alkynes with
HBPin. The diboration reaction is accompanied by dihydrogen
release. In the case of alkenes anti-Markovnikov hydroboration
takes place, while in the case of alkynes the reaction proceeds
with excellent trans-1,2-selectivity. The catalytic process is
initiated by migratory insertion of a CO ligand into the Mn-alkyl
bond to yield an acyl intermediate which undergoes B-H bond
cleavage of HBPin (in the case of alkenes) and rapid C-H bond
cleavage (in the case of alkynes) forming the active 16e- Mn(I)
boryl and acetylide catalysts [Mn(dippe)(CO)2(BPin)] and
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E. Pittenauer, B. Stöger, K. Kirchner, Organometallics 2021, 40, 278-
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[9]
[Mn(dippe)(CO)2(C≡CR)], respectively.
A broad variety of
[10]
aromatic and aliphatic alkenes and alkynes was efficiently and
selectively borylated. Mechanistic insights are provided based on
experimental data. In the case of the diboration reaction, a
detailed mechanism is provided based on DFT calculations
revealing that an acceptorless reaction pathway is operating
involving dihydrogen release.
[11]
For selected examples for Fe-catalyzed hydroboration reactions see:
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a) R. G. Parr, W. Yang, Density Functional Theory of Atoms and
Molecules; Oxford University Press: New York, 1989 b) Calculations
performed at the M06/(6-311++G**)//PBE0/(SDD,6-31G**) level using
the GAUSSIAN 09 package. Single-point energy calculations included
solvent effects (THF) using the PCM/SMD model. A full account of the
computational details and a complete list of references are provided
as SI.
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A
Mn(I)-catalyzed hydroboration of
Stefan Weber, Daniel Zobernig, Berthold
Stöger, Luis F. Veiros, Karl Kirchner*
terminal alkenes and the 1,2-diboration
of terminal alkynes with pinacolborane
is described. In the case of alkenes
anti-Markovnikov hydroboration takes
place, while in the case of alkynes the
reaction proceeds with trans-1,2-
selectivity.
Hydroboration of Terminal Alkenes
and trans-1,2-Diboration of Terminal
Alkynes Catalyzed by a Mn(I) Alkyl
Complex
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