Copper-catalyzed borylstannylation of alkynes with tin fluorides

Article abstract of DOI:10.1021/acs.organomet.7b00058

Tin fluorides were found to be suitable electrophiles for the copper-catalyzed borylstannylation of terminal alkynes with bis(pinacolato)diboron to afford cis-vic-boryl- (stannyl)alkenes straightforwardly. A fluorine atom proved to play a pivotal role in generating a key catalytic intermediate, a borylcopper species, both in the induction period and in the σ-bond metathesis step.

Full text of DOI:10.1021/acs.organomet.7b00058

Article
pubs.acs.org/Organometallics
Copper-Catalyzed Borylstannylation of Alkynes with Tin Fluorides
Hiroto Yoshida,* Miki Kimura, Itaru Osaka, and Ken Takaki
Department of Applied Chemistry, Graduate School of Engineering, Hiroshima University, Higashi-Hiroshima 739-8527, Japan
S
* Supporting Information
ABSTRACT: Tin fluorides were found to be suitable electro-
philes for the copper-catalyzed borylstannylation of terminal
alkynes with bis(pinacolato)diboron to afford cis-vic-boryl-
(stannyl)alkenes straightforwardly. A fluorine atom proved to
play a pivotal role in generating a key catalytic intermediate, a
borylcopper species, both in the induction period and in the σ-bond metathesis step.
Scheme 2. Cu-Catalyzed Formation of Alkynylstannanes
INTRODUCTION
■
Borylstannylation1 of unsaturated carbon−carbon bonds, which
leads to synchronous carbon−boron and carbon−tin bond
formation at vicinal positions, is of high synthetic value, because
multifunctionalized organometallic compounds thus generated
have bench-stable/easy-to-handle properties and can serve as
convenient and potent intermediates for constructing complex
molecular skeletons by site-selective carbon−carbon (e.g.,
Suzuki−Miyaura and Migita−Kosugi−Stille coupling)2 and/or
carbon−heteroatom3 bond-forming processes at their C−B4
and C−Sn5 moieties. In particular, much attention has thus far
been focused on the reaction of alkynes, which provides regio-
and stereodefined vic-boryl(stannyl)alkenes, owing to the
potential utility for accessing diverse multisubstituted alkenes
of biological and pharmacological significance.6 Within this
context, we have already developed the copper-catalyzed three-
component borylstannylation of alkynes1f using bis-
(pinacolato)diboron ((pin)B−B(pin)) and tin alkoxides,
where a copper alkoxide acts as a key catalytic species.7,8
Although a variety of vic-boryl(stannyl)alkenes are efficiently
accessible by this reaction, terminal alkynes, especially aliphatic
ones, turned out to give the respective products only in
moderate yield (Scheme 1), which is ascribed to the formation
of alkynylstannanes and a distannane9 as byproducts.
envisaged that the use of another tin electrophile with a less
basic leaving group (X), which inevitably diminishes the
basicity of a Cu−X intermediate, should retard the
alkynylcopper formation to result in the successful boryl-
stannylation of terminal alkynes. We report herein that a tin
fluoride serves as an effective tin electrophile for this purpose
(Scheme 2, eq 2) and that the reaction becomes more practical
due to the extremely bench stable property of a tin fluoride as
opposed to a moisture-sensitive tin alkoxide.
The former should come from a reaction of an intermediary
generated alkynylcopper species with a tin alkoxide (Scheme 2,
red arrow), which has been demonstrated by an independent
reaction (Scheme 2, eq 1).10 The catalytic involvement of a
copper alkoxide of relatively high basicity should rationalize the
facile generation of an alkynylcopper species,11 and thus we
Scheme 1. Cu-Catalyzed Borylstannylation with Tin
Alkoxides
RESULTS AND DISCUSSION
■
At the outset, we conducted the reaction of diphenylacetylene
(1a) with (pin)B−B(pin) (2) using tributyltin fluoride (3a) as
a tin electrophile in THF in the presence of PCy3−CuCl
catalyst to observe the stereoselective formation of a syn-
borylstannylated product (4aa) in 50% yield (entry 1, Table 1).
Received: January 24, 2017
© XXXX American Chemical Society
A
DOI: 10.1021/acs.organomet.7b00058
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Article
a
a
Table 1. Optimization of Reaction Conditions
Table 2. Substrate Scope
yield
b
b
entry
Cu cat.
solvent
yield (%)
entry
R
R′
3
time (h)
(%)
4:4′
>99:1
97:3
1
2
3
4
5
6
7
PCy3/CuCl
[(PPh3)CuCl]4
PtBu3/CuCl
PnBu3/CuCl
IMesCuCl
THF
50
45
38
0
1
2
3
Ph
Me (1b)
Me (1c)
H (1d)
H (1d)
H (1d)
H (1e)
H (1f)
H (1g)
H (1h)
H (1i)
H (1d)
H (1e)
H (1h)
H (1i)
H (1j)
H (1k)
H (1l)
H (1m)
3a
3a
3a
3a
3a
3a
3a
3a
3a
3a
3b
3b
3b
3b
3b
3b
3b
3b
32
48
24
13
24
27
37
37
37
37
5
74
44
78
68
27
62
43
48
61
68
70
68
70
64
59
58
30
56
c
THF
nPent
nHex
nHex
nHex
Ph
THF
93:7
c
THF
4
cd
,
80:20
68:32
>99:1
>99:1
>99:1
84:16
88:12
88:12
>99:1
71:29
72:28
79:21
71:29
>99:1
44:56
THF
trace
trace
61
74
41
0
5
6
7
8
9
IPrCuCl
THF
PCy3/CuCl
PCy3/CuCl
PCy3/CuCl
PCy3/CuCl
toluene
toluene
DMF
toluene
4-BrC6H4
3-MeC6H4
NC(CH2)3
Phth(CH2)4
nHex
d
8
9
de
,
10
10
11
12
13
14
15
16
17
18
a
Reaction conditions unless specified otherwise: ligand/Cu = 1, 1a
(0.39 mmol), 2 (0.39 mmol), 3a (0.30 mmol), solvent (1 mL), 60 °C,
24 h. Isolated yield. 1 mol %. 100 °C. nBu3SnCl was used instead
of nBu3SnF.
Ph
32
34
31
16
48
48
22
b
c
d
e
NC(CH2)3
Phth(CH2)4
Cl(CH2)3
TBSO(CH2)2
TMS
The use of PPh3 or PtBu3 as a ligand also gave a comparable
yield of 4aa (entries 2 and 3), whereas the reaction with PnBu3
or an N-heterocyclic carbene (IMes or IPr) was found to be
unsuccessful (entries 4−6). The reaction turned out to proceed
best in toluene (entries 7 and 8; 61% at 60 °C, 74% at 100 °C),
and a polar solvent such as DMF was unfit (entry 9). It should
be noted that 4aa did not form at all with tributyltin chloride
(entry 10), demonstrating the crucial role of a fluorine atom in
the catalytic process (vide infra).
BnOCH2
a
Reaction conditions unless specified otherwise: 1 (0.39 mmol), 2
b
(0.39 mmol), 3 (0.30 mmol), toluene (1 mL), 100 °C. Isolated yield.
c
d
CuCl (4 mol %) was used instead of [(PCy3)CuCl]2. nBu3SnOMe
was used instead of nBu3SnF.
absence of 1a, as described in Scheme 3. In each case, no
halogen exchange reaction took place at all, showing that such a
process is not operative in the induction period.
In addition to internal alkynes such as 1-phenyl-1-propyne
(1b) and 2-octyne (1c), which provided regioselectively the
respective products (4ba and 4ca) bearing a B(pin) moiety
geminal to a methyl group (entries 1 and 2, Table 2), an
aliphatic terminal alkyne, 1-octyne (1d), proved to be facilely
convertible into 4da in 78% yield with the preferential
installation of B(pin) into a terminal carbon (93:7, entry 3).
With tributyltin fluoride, cuprous chloride alone similarly
promoted the reaction, albeit at the cost of its yield and
regioselectivity (68%, 80:20), while the reaction with tributyltin
methoxide again resulted in low yield (27%, 68:32) (entries 4
and 5). Perfect regioselectivity was observed with arylacetylenes
(1e−g) (entries 6−8), and functionalized aliphatic alkynes
(1h,i) were efficiently converted to the products (4ha,ia)
(entries 9 and 10). Furthermore, trioctyltin fluoride (3b)12,13
could participate in the reaction, where 1d,e were transformed
with efficacy similar to that with 3a (entries 11 and 12). In
addition to 1h,i, aliphatic terminal alkynes having a C−Cl bond
(1j) or silyl ether (1k) also afforded the borylstannylation
products (4hb−kb) with these functional groups intact,
although the regioselectivities dropped to some extent in
comparison to that with 1d (entries 13−16).14 The reaction
was applicable to trimethylsilylacetylene (1l) to give solely 4lb
(entry 17), and almost equal amounts of regioisomers (4mb
and 4′mb) were produced with a propargyl ether (1m) (entry
18).
Scheme 3. Reaction of (PPh3)3CuCl with a Tin Fluoride
On the other hand, the reaction of 5a with 2 and 3a was
found to readily produce (pin)B−F (6a)18 and its hydrolyzed
product (pin)B−O−B(pin) (6b) (Scheme 4, eq 1),19 which
indicates that 5a may be converted into the borylcopper species
(PPh3)3Cu−B(pin), although we could not confirm the
formation by 11B NMR probably owing to its instability
under the reaction conditions.20 In addition to these results, the
fact that nothing happened by simply mixing 5a and 2 (Scheme
4, eq 2) leads to the conclusion that tin fluoride-assisted
generation of a borylcopper species (7a, Scheme 5, step A)21
may trigger the borylstannylation. Then the resulting
borylcopper accepts insertion of an alkyne to form an
alkenylcopper species (7b, step B), which is captured by a tin
fluoride to afford the product and a cuprous fluoride complex
(7c, step C). Regeneration of 7a by σ-bond metathesis between
2 and 7c (step D) has been examined by the stoichiometric
reaction of 2 with (PPh3)3CuF (5b) (Scheme 4, eq 3).
Assuming that facile conversion of a Cu−Cl complex into a
Cu−F complex, which should undergo σ-bond metathesis with
2 in some borylations,15,16 may occur in the borylstannylation,
(PPh3)3CuCl (5a)17 was treated with 3a in the presence or
B
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Scheme 4. 11B NMR Experiments
Although no signal of a borylcopper species was again
observable in 11B NMR, 6b and (pin)B−OH (6c)19 arising
from hydrolysis22 of 6a were found to form with rapid
consumption of 2, demonstrating the facility of step D
experimentally. In addition, the validity of step C was
confirmed by the ready capture of the catalytically generated
alkenylcopper species 8 (from (E)-borylstyrene 9a)23,24 with
3a, which provided (E)-stannylstyrene 9b (Scheme 6). A
catalytic cycle similar to that of the borylstannylation may also
be operative in this boron−tin exchange.
C
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Article
available reagents were used without purification. Toluene and THF
were distilled from sodium/benzophenone ketyl. DMF was distilled
from CaH2.
Scheme 5. Plausible Catalytic Cycle
Materials. Trioctyltin fluoride (3b),12 2-fluoro-4,4,5,5-tetramethyl-
1,3,2-dioxaborolane (6a),19a 2,2′-oxybis(4,4,5,5-tetramethyl-1,3,2-diox-
aborolane) (6b),19b 4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-ol
25
(6c),19c and [(PCy3)CuCl]2 were prepared according to reported
procedures.
Cu-Catalyzed Borylstannylation of Alkynes: General Proce-
dure. A Schlenk tube equipped with a magnetic stirring bar was
charged with [(PCy3)CuCl]2 (6.0 μmol). To the residue were added
an alkyne (0.39 mmol), bis(pinacolato)diboron (0.39 mmol), a tin
fluoride (0.30 mmol), and toluene (1.0 mL), and the resulting mixture
was stirred at 100 °C for the period as specified in Table 2. The
mixture was diluted with ethyl acetate and filtered through a Celite
plug. The organic solution was washed with brine, dried over MgSO4,
and evaporated. The residual tin fluoride was removed by column
chromatography (10% w/w anhydrous K2CO3−silica gel; ethyl acetate
as eluent), and the product was isolated by silica gel column
chromatography (hexane/ethyl acetate as eluent) or gel permeation
chromatography (toluene as eluent). In 13C NMR spectra, boron-
bound carbons were not detected because of quadrupolar relaxation.
Characterization of Borylstannylation Products. (E)-Tributyl-
(1-phenyl-2-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)prop-1-
en-1-yl)stannane (4ba).1f 1H NMR (CDCl3): δ 0.70−0.78 (m, 6H),
0.83 (t, J = 7.3 Hz, 9H), 1.16−1.25 (m, 6H), 1.30 (s, 12H), 1.32−1.39
(m, 6H), 1.64 (s, JH−Sn = 9.9 Hz, 3H), 6.75−6.79 (m, 2H), 7.07 (t, J =
7.3 Hz, 1H), 7.26 (t, J = 7.7 Hz, 2H). 13C NMR (CDCl3): δ 12.48
(JC−Sn = 334.6 Hz), 13.70, 18.85 (JC−Sn = 51.4 Hz), 24.82, 27.54 (JC−Sn
Scheme 6. Capture of an Alkenylcopper Species with a Tin
Fluoride
= 59.8 Hz), 29.14 (JC−Sn = 19.7 Hz), 83.52, 124.33, 125.68 (JC−Sn
=
15.1 Hz), 127.88, 147.84 (JC−Sn = 35.5 Hz), 166.95. 119Sn NMR
(CDCl3): δ −57.08.
Mixture of (E)-Tributyl(2-(4,4,5,5-tetramethyl-1,3,2-dioxaboro-
lan-2-yl)oct-2-en-3-yl)stannane (4ca) and (E)-Tributyl(3-(4,4,5,5-
tetramethyl-1,3,2-dioxaborolan-2-yl)oct-2-en-2-yl)stannane
(4′ca).1f 1H NMR (CDCl3): δ 0.79−0.94 (m, 18H), 1.17−1.36 (m,
24H), 1.39−1.53 (m, 6H), 1.80 (s, JH−Sn = 10.7 Hz, 3H), 2.33 (t, J =
7.7 Hz, JH−Sn = 59.6 Hz, 2H). 13C NMR (CDCl3): δ 12.07 (JC−Sn
=
327.9 Hz), 13.77, 14.11, 15.96 (JC−Sn = 62.0 Hz), 22.67, 24.76, 27.70
(JC−Sn = 60.3 Hz), 28.45, 29.40 (JC−Sn = 18.6 Hz), 32.10, 35.78 (JC−Sn
= 47.6 Hz), 83.23, 166.77. 119Sn NMR (CDCl3): δ −55.40.
Mixture of (Z)-Tributyl(1-(4,4,5,5-tetramethyl-1,3,2-dioxaboro-
lan-2-yl)oct-1-en-2-yl)stannane (4da) and (E)-Tributyl(2-(4,4,5,5-
tetramethyl-1,3,2-dioxaborolan-2-yl)oct-1-en-1-yl)stannane
(4′da).1f 1H NMR (CDCl3): δ 0.82−1.01 (m, major/minor, 18H),
1.21−1.35 (m, major/minor, 24H), 1.36−1.57 (m, major/minor, 8H),
2.22 (t, J = 7.4 Hz, minor, 2H), 2.31 (t, J = 6.6 Hz, major, 2H), 6.09 (s,
JH−Sn = 152.9 Hz, major, 1H), 6.69 (s, JH−Sn = 81.9 Hz, minor, 1H).
13C NMR (CDCl3): δ 11.44 (JC−Sn = 329.5 Hz), 13.73, 14.08, 22.62,
CONCLUDING REMARKS
■
In conclusion, we have disclosed that tin fluorides act as
effective electrophiles for capturing catalytically generated
alkenylcopper species, enabling the facile borylstannylation of
alkynes. The mechanistic studies revealed that a fluorine atom
played a pivotal role both in the induction period and in the σ-
bond metathesis step. Further studies on copper-catalyzed
three-component couplings using fluorine-containing electro-
philes as well as on the synthetic application of tin fluorides to
catalytic stannylations are in progress.
22.67, 24.74, 27.46, 27.59 (JC−Sn = 59.1 Hz), 28.80, 29.00, 29.26, 29.33,
29.40, 29.76, 31.82, 40.53, 45.42 (JC−Sn = 45.6 Hz), 82.99, 83.25,
149.58, 177.63. 119Sn NMR (CDCl3): δ −55.89 (major), −68.34
(minor).
(Z)-Tributyl(1-phenyl-2-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-
2-yl)vinyl)stannane (4ea).1f 1H NMR (CDCl3): δ 0.84 (t, J = 7.2 Hz,
9H), 0.89−0.95 (m, 6H), 1.20−1.27 (m, 6H), 1.31 (s, 12H), 1.37−
1.47 (m, 6H), 6.27 (s, JH−Sn = 137.2 Hz, 1H), 6.98−7.02 (m, 2H), 7.15
(t, J = 7.3 Hz, 1H), 7.26 (t, J = 7.4 Hz, 2H). 13C NMR (CDCl3): δ
12.31 (JC−Sn = 335.7 Hz), 13.70, 24.80, 27.44 (JC−Sn = 59.3 Hz), 29.09
(JC−Sn = 19.1 Hz), 83.34, 125.79, 125.85 (JC−Sn = 13.7 Hz), 127.79,
150.11, 175.77. 119Sn NMR (CDCl3): δ −51.68.
(Z)-(1-(4-Bromophenyl)-2-(4,4,5,5-tetramethyl-1,3,2-dioxaboro-
lan-2-yl)vinyl)tributylstannane (4fa). 1H NMR (CDCl3): δ 0.85 (t, J
= 7.2 Hz, 9H), 0.89−1.00 (m, 6H), 1.18−1.27 (m, 6H), 1.30 (s, 12H),
1.33−1.49 (m, 6H), 6.24 (s, JH−Sn = 132.5 Hz, 1H), 6.84−6.91 (m,
2H), 7.36−7.41 (m, 2H). 13C NMR (CDCl3): δ 12.30 (JC−Sn = 335.6
Hz), 13.70, 24.80, 27.42 (JC−Sn = 51.5 Hz), 29.08 (JC−Sn = 20.1 Hz),
83.46, 127.48, 127.53, 127.58, 130.86, 149.11, 174.38. 119Sn NMR
(CDCl3): δ −50.98. HRMS: calcd for C22H35O2BrBSn, [M − C4H9]+,
541.0930; found, m/z 541.0925. Anal. Calcd for C26H44O2BBrSn: C,
52.22; H, 7.42. Found: C, 52.51; H, 7.41.
EXPERIMENTAL SECTION
■
General Remarks. All manipulations of oxygen- and moisture-
sensitive materials were conducted with standard Schlenk techniques
under a purified argon atmosphere. Nuclear magnetic resonance
spectra were taken on a Varian System 500 (1H, 500 MHz; 13C, 125
MHz; 11B, 160 MHz; 119Sn, 186 MHz) spectrometer using residual
chloroform (1H, δ 7.26) or CDCl3 (13C, δ 77.0) as an internal standard
and boron trifluoride diethyl etherate (11B, δ 0.00) or tetramethyltin
1
(
119Sn, δ 0.00) as an external standard. H NMR data are reported as
follows: chemical shift, multiplicity (s = singlet, d = doublet, t = triplet,
q = quartet, m = multiplet), coupling constants (Hz), integration.
High-resolution mass spectra were obtained with a Thermo Fisher
Scientific LTQ Orbitrap XL spectrometer. Preparative recycling gel
permeation chromatography was performed with a GL Science PU
614 instrument equipped with Shodex GPC H-2001L and -2002L
columns (toluene as eluent). Column chromatography was carried out
using Merck Kieselgel 60. Unless otherwise noted, commercially
D
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(Z)-Tributyl(2-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1-(m-
yl-1,3,2-dioxaborolan-2-yl)-6-(trioctylstannyl)hex-5-enenitrile
1
1
tolyl)vinyl)stannane (4ga). H NMR (CDCl3): δ 0.84 (t, J = 7.2 Hz,
(4′hb). H NMR (CDCl3): δ 0.84−0.98 (m, major/minor, 15H), δ
9H), 0.88−1.00 (m, 6H), 1.19−1.27 (m, 6H), 1.30 (s, 12H), 1.33−
1.53 (m, 6H), 2.32 (s, 3H), 6.27 (s, JH−Sn = 138.3 Hz, 1H), 6.78−6.84
(m, 2H), 6.97 (d, J = 7.6 Hz, 1H), 7.15 (t, J = 7.6 Hz, 1H). 13C NMR
(CDCl3): δ 12.34 (JC−Sn = 331.3 Hz), 13.71, 21.44, 24.80, 27.46 (JC−Sn
= 60.2 Hz), 29.11 (JC−Sn = 19.9 Hz), 83.32, 122.97, 126.54, 126.67,
127.69, 137.22, 150.01, 175.89. 119Sn NMR (CDCl3): δ −52.19.
HRMS: calcd for C27H47O2BNaSn, [M + Na]+, 557.2583; found, m/z
557.2582. Anal. Calcd for C27H47O2BSn: C, 60.82; H, 8.89. Found: C,
60.59; H, 8.96.
1.19−1.34 (m, major/minor, 42H), 1.41−1.54 (m, major/minor, 6H),
1.66−1.75 (m, major, 2H), 1.76−1.84 (m, minor, 2H), 2.26 (t, J = 7.5
Hz, minor, 2H), 2.28 (t, J = 7.2 Hz, major, 2H), 2.35 (t, J = 7.0 Hz,
minor, 2H), 2.45 (t, J = 7.1 Hz, JH−Sn = 41.6 Hz, major, 2H), 6.12 (s,
JH−Sn = 144.2 Hz, major, 1H), 6.79 (s, JH−Sn = 75.7 Hz, minor, 1H).
13C NMR (CDCl3): δ 11.81 (JC−Sn = 330.3 Hz, major), 11.85 (minor),
14.11, 16.32, 22.67, 24.58, 24.74, 26.95, 27.02 (JC−Sn = 19.2 Hz), 29.23,
29.27, 29.32, 31.92, 34.48, 34.60 (JC−Sn = 56.1 Hz), 39.50, 43.46, 83.27
(major), 83.58 (minor), 119.55, 153.42, 174.23. 119Sn NMR (CDCl3):
Mixture of (Z)-6-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-5-
(tributylstannyl)hex-5-enenitrile (4ha) and (E)-5-(4,4,5,5-tetrameth-
yl-1,3,2-dioxaborolan-2-yl)-6-(tributylstannyl)hex-5-enenitrile
(4′ha). 1H NMR (CDCl3): δ 0.85−1.00 (m, major/minor, 15H),
1.21−1.35 (m, major/minor, 18H), 1.42−1.51 (m, major/minor, 6H),
1.68−1.75 (m, major, 2H), 1.76−1.83 (m, minor, 2H), 2.27 (t, J = 7.4
Hz, minor, 2H), 2.29 (t, J = 7.4 Hz, major, 2H), 2.35 (t, J = 7.3 Hz,
minor, 2H), 2.45 (t, J = 7.1 Hz, major, 2H), 6.16 (s, JH−Sn = 144.7 Hz,
major, 1H), 6.79 (s, JH−Sn = 74.4 Hz, minor, 1H). 13C NMR (CDCl3):
δ 11.43 (JC−Sn = 328.9 Hz, major), 11.48 (minor), 13.71, 13.75, 16.31,
24.56, 24.73, 27.39, 27.46, 27.52 (JC−Sn = 58.7 Hz), 29.26, 30.61, 39.50,
43.45 (JC−Sn = 46.4 Hz), 83.28 (major), 83.58 (minor), 119.57, 120.05,
153.29, 174.10. 119Sn NMR (CDCl3): δ −53.74 (major), −67.09
(minor). HRMS: calcd for C24H46O2NBNaSn, [M + Na]+, 534.2536;
found, m/z 534.2538. Elemental analysis results were outside the
tolerance range.
δ
−54.11 (major), −67.38 (minor). HRMS: calcd for
C36H70O2NBNaSn, [M + Na]+, 702.4420; found, m/z 702.4419.
Elemental analysis results were outside the tolerance range.
Mixture of (Z)-2-(6-(4,4,5,5-Tetramethyl-1,3,2-dioxaborolan-2-
yl)-5-(trioctylstannyl)hex-5-en-1-yl)isoindoline-1,3-dione (4ib) and
(E)-2-(4-(4,4,5,5-Tetramethyl-1,3,2-dioxaborolan-2-yl)-5-
(trioctylstannyl)pent-4-en-1-yl)isoindoline-1,3-dione (4′ib). 1H
NMR (CDCl3): δ 0.83−0.95 (m, major/minor, 15H), 1.17−1.31
(m, major/minor, 40H), 1.35−1.53 (m, major/minor, 10H), 1.63−
1.70 (m, major/minor, 2H), 2.25 (t, J = 7.5 Hz, minor, 2H), 2.34 (t, J
= 7.5 Hz, JH−Sn = 42.0 Hz, major, 2H), 3.67 (t, J = 7.2 Hz, major/
minor, 2H), 6.01 (s, JH−Sn = 150.7 Hz, major, 1H), 6.72 (s, JH−Sn
=
78.4 Hz, minor, 1H), 7.68−7.72 (m, major/minor, 2H), 7.81−7.85
(m, major/minor, 2H). 13C NMR (CDCl3): δ 11.73 (JC−Sn = 329.6
Hz, major), 14.09 (JC−Sn = 219.7 Hz major), 14.19, 22.59, 22.65, 24.62,
24.68 (JC−Sn = 222.2 Hz), 24.74 (JC−Sn = 22.2 Hz), 24.81, 26.39, 26.91,
26.98, 27.05, 28.22, 29.21, 29.31, 31.91, 34.36, 34.58 (JC−Sn = 56.0 Hz),
34.81, 37.85, 38.33, 44.53, 44.60, 44.65, 83.00 (major), 83.28 (minor),
122.96, 123.14, 132.13, 132.19, 133.66, 133.67, 133.75, 168.23, 176.59.
119Sn NMR (CDCl3): δ −55.79 (major), −63.54 (minor). HRMS:
Mixture of (Z)-2-(6-(4,4,5,5-Tetramethyl-1,3,2-dioxaborolan-2-
yl)-5-(tributylstannyl)hex-5-en-1-yl)isoindoline-1,3-dione (4ia) and
(E)-2-(5-(4,4,5,5-Tetramethyl-1,3,2-dioxaborolan-2-yl)-6-
(tributylstannyl)hex-5-en-1-yl)isoindoline-1,3-dione (4′ia). 1H NMR
(CDCl3): δ 0.81−0.96 (m, major/minor, 15H), 1.20−1.30 (m, major/
minor, 18H), 1.34−1.50 (m, major/minor, 8H), 1.61−1.71 (m, major/
calcd for C44H76O4NBNaSn, [M + Na]+, 836.4787; found, m/z
836.4788. Elemental analysis results were outside the tolerance range.
Mixture of (Z)-(5-Chloro-1-(4,4,5,5-tetramethyl-1,3,2-dioxaboro-
lan-2-yl)pent-1-en-2-yl)trioctylstannane (4jb) and (E)-(5-Chloro-2-
(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)pent-1-en-1-yl)-
minor, 2H), 2.25 (t, J = 7.2 Hz, minor, 2H), 2.34 (t, J = 7.6 Hz, JH−Sn
=
44.8 Hz, major, 2H), 3.67 (t, J = 7.2 Hz, major/minor, 2H), 6.08 (s,
JH−Sn = 149.8 Hz, major, 1H), 6.71 (s, JH−Sn = 80.1 Hz, minor, 1H),
7.67−7.73 (m, major/minor, 2H), 7.80−7.85 (m, major/minor, 2H).
13C NMR (CDCl3): δ 11.38 (JC−Sn = 329.1 Hz, major), 11.45 (minor),
13.72, 24.74, 26.45, 27.42, 27.52 (JC−Sn = 59.5 Hz), 28.25, 29.24 (JC−Sn
= 19.0 Hz), 37.91 (JC−Sn = 33.8 Hz), 44.68 (JC−Sn = 47.2 Hz), 83.05,
83.32, 123.04, 123.10, 132.14, 133.75, 168.32, 176.52. 119Sn NMR
(CDCl3): δ −55.43 (major), −68.18 (minor). HRMS: calcd for
C32H52O4NBNaSn, [M + Na]+, 668.2904; found, m/z 668.2911. Anal.
Calcd for C32H52O4BNSn: C, 59.66; H, 8.14. Found: C, 59.80; H,
8.25.
1
trioctylstannane (4′jb). H NMR (CDCl3): δ 0.84−1.01 (m, major/
minor, 15H), 1.18−1.35 (m, major/minor, 42H), 1.41−1.57 (m,
major/minor, 6H), 1.78−1.86 (m, major, 2H), 1.86−1.94 (m, minor,
2H), 2.35 (t, J = 7.4 Hz, minor, 2H), 2.46 (t, J = 7.5 Hz, JH−Sn = 41.6
Hz, major, 2H), 3.50 (t, J = 6.7 Hz, 2H), 6.14 (s, JH−Sn = 146.6 Hz,
major, 1H), 6.78 (s, JH−Sn = 76.9 Hz, minor, 1H). 13C NMR (CDCl3):
δ 11.43 (JC−Sn = 329.3 Hz), 13.73, 24.70 (JC−Sn = 21.7 Hz), 24.79
(JC−Sn = 22.5 Hz), 27.47, 27.55 (JC−Sn = 59.5 Hz), 27.63, 29.17, 29.28,
29.39, 31.71, 31.89, 32.07, 41.94 (JC−Sn = 46.1 Hz), 44.36 (JC−Sn
=
Mixture of (Z)-Trioctyl(1-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-
2-yl)oct-1-en-2-yl)stannane (4db) and (E)-Trioctyl(2-(4,4,5,5-tetra-
methyl-1,3,2-dioxaborolan-2-yl)oct-1-en-1-yl)stannane (4′db). 1H
NMR (CDCl3): δ 0.82−0.94 (m, major/minor, 18H), 1.18−1.34 (m,
major/minor, 50H), 1.45−1.55 (m, major/minor, 6H), 2.22 (t, J = 7.1
Hz, minor, 2H), 2.31 (t, J = 7.1 Hz, JH−Sn = 44.9 Hz, major, 2H), 6.09
(s, JH−Sn = 151.6 Hz, major, 1H), 6.70 (s, JH−Sn = 81.8 Hz, minor, 1H).
13C NMR (CDCl3): δ 11.83 (JC−Sn = 328.3 Hz), 14.12, 22.65, 22.71,
24.75, 26.99, 27.08, 27.17, 28.88, 29.07, 29.31, 29.37, 29.45, 29.78,
31.86, 31.98, 34.53, 34.67 (JC−Sn = 55.3 Hz), 40.50, 45.44, 82.99
(major), 83.25 (minor), 149.73, 177.79. 119Sn NMR (CDCl3): δ
−56.12 (major), −68.57 (minor). HRMS: calcd for C30H60O2BSn, [M
− C8H17]+, 583.3703; found, m/z 583.3702. Anal. Calcd for
C38H77O2BSn: C, 65.62; H, 11.16. Found: C, 65.41; H, 11.38.
(Z)-Trioctyl(1-phenyl-2-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-
2-yl)vinyl)stannane (4eb). 1H NMR (CDCl3): δ 0.85−0.94 (m, 15H),
1.18−1.32 (m, 42H), 1.39−1.47 (m, 6H), 6.26 (s, JH−Sn = 136.2 Hz,
1H), 7.00 (d, J = 8.3 Hz, 2H), 7.15 (t, J = 7.4 Hz, 1H), 7.26 (t, J = 6.7
Hz, 2H). 13C NMR (CDCl3): δ 12.72 (JC−Sn = 334.4 Hz), 14.13,
22.69, 24.81, 26.87 (JC−Sn = 19.7 Hz), 29.26, 29.33, 31.94, 34.54 (JC−Sn
= 55.6 Hz), 83.33, 125.80, 125.88, 127.78, 150.10, 175.93. 119Sn NMR
(CDCl3): δ −52.06. HRMS: calcd for C30H52O2BSn, [M − C8H17]+,
575.3077; found, m/z 575.3078. Elemental analysis results were
outside the tolerance range.
154.0 Hz), 44.67, 83.18 (major), 83.48 (minor), 175.16 (JC−Sn = 357.5
Hz, major). 119Sn NMR (CDCl3): δ −54.66 (major), −67.38 (minor).
HRMS: calcd for C27H53O2BClSn, [M − C8H17]+, 575.2849; found,
m/z 575.2839. Anal. Calcd for C35H70O2BClSn: C, 61.11; H, 10.26.
Found: C, 60.92, H, 10.51.
Mixture of (Z)-tert-Butyldimethyl((4-(4,4,5,5-tetramethyl-1,3,2-
dioxaborolan-2-yl)-3-(trioctylstannyl)but-3-en-1-yl)oxy)silane (4kb)
and (E)-tert-Butyldimethyl((3-(4,4,5,5-tetramethyl-1,3,2-dioxaboro-
lan-2-yl)-4-(trioctylstannyl)but-3-en-1-yl)oxy)silane (4′kb). 1H NMR
(CDCl3): δ 0.04 (s, major/minor, 6H), 0.84−1.96 (m, major/minor,
24H), 1.20−1.31 (m, major/minor, 42H), 1.45−1.53 (m, major/
minor, 6H), 2.46 (t, J = 7.0 Hz, minor, 2H), 2.56 (t, J = 7.6 Hz, JH−Sn
44.0 Hz, major, 2H), 3.56 (t, J = 7.3 Hz, major, 2H), 3.62 (t, J = 7.3
Hz, minor, 2H), 6.16 (s, JH−Sn = 148.9 Hz, major, 1H), 6.81 (s, JH−Sn
=
=
14.6 Hz, minor, 1H). 13C NMR (CDCl3): δ −5.20 (major), −5.15
(minor), 11.80 (JC−Sn = 332.0 Hz), 14.13, 18.38, 22.70, 24.73, 24.79,
26.01, 26.05, 26.96, 27.03 (JC−Sn = 19.3 Hz), 29.28, 29.36, 31.96, 34.53,
34.64 (JC−Sn = 56.0 Hz), 44.24, 47.91 (JC−Sn = 42.6 Hz), 63.00, 63.60,
83.11 (major), 83.36 (minor), 153.91, 172.75. 119Sn NMR (CDCl3): δ
−54.61 (major), −69.55 (minor). HRMS: calcd for
C40H83O3BNaSiSn, [M + Na]+, 793.5124; found, m/z 793.5128.
Anal. Calcd for C40H83O3BSiSn: C, 62.42; H, 10.87. Found: C, 62.18;
H, 11.09.
(Z)-Trimethyl(2-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1-
(trioctylstannyl)vinyl)silane (4lb). 1H NMR (CDCl3): δ 0.06 (s, 9H),
0.86−0.97 (m, 15H), 1.22−1.31 (m, 42H), 1.41−1.52 (m, 6H), 7.11
Mixture of (Z)-6-(4,4,5,5-Tetramethyl-1,3,2-dioxaborolan-2-yl)-5-
(trioctylstannyl)hex-5-enenitrile (4hb) and (E)-5-(4,4,5,5-Tetrameth-
E
DOI: 10.1021/acs.organomet.7b00058
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Organometallics
Article
(s, JH−Sn = 201.0 Hz, 1H). 13C NMR (CDCl3): δ −0.79, 12.65 (JC−Sn
=
formation using organostannanes, see: (b) Lam, P. Y. S.; Vincent, G.;
Bonne, V.; Clark, C. G. Tetrahedron Lett. 2002, 43, 3091−3094.
(c) Furuya, T.; Strom, A. E.; Ritter, T. J. Am. Chem. Soc. 2009, 131,
1662−1663.
320.5 Hz), 14.13, 22.70, 24.80, 27.12 (JC−Sn = 18.7 Hz), 29.29, 29.36,
31.97, 34.69 (JC−Sn = 58.1 Hz), 83.41, 182.23. 119Sn NMR (CDCl3): δ
−56.62. HRMS: calcd for C27H56O2BSiSn, [M − C8H17]+, 571.3165;
found, m/z 571.3158. Anal. Calcd for C35H73O2BSiSn: C, 61.50; H,
10.76. Found: C, 61.23; H, 11.08.
(4) For a review on organic synthesis with organoboranes, see:
Boronic Acids; Hall, D. G., Ed.: Wiley-VCH: Weinheim, Germany,
2011.
Mixture of (Z)-(3-(Benzyloxy)-1-(4,4,5,5-tetramethyl-1,3,2-dioxa-
borolan-2-yl)prop-1-en-2-yl)trioctylstannane (4mb) and (E)-(3-
(Benzyloxy)-2-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)prop-1-
en-1-yl)trioctylstannane (4′mb). 1H NMR (CDCl3): δ 0.83−0.99
(m, major/minor, 15H), 1.19−1.36 (m, major/minor, 42H), 1.43−
1.57 (m, major/minor, 6H), 4.16−4.19 (m, major, 2H), 4.20−4.23 (m,
(5) For a review on organic synthesis with organostannanes, see:
Orita, A.; Otera, J. Tin in Organic Synthesis. In Main Group Metals in
Organic Synthesis; Yamamoto, H., Oshima, K., Eds.; Wiley-VCH:
Weinheim, Germany, 2004; pp 621−720.
(6) (a) Howell, A.; Robertson, J. F. R.; Quaresma Albano, J.;
Aschermannova, A.; Mauriac, L.; Kleeberg, U. R.; Vergote, I.; Erikstein,
B.; Webster, A.; Morris, C. J. Clin. Oncol. 2002, 20, 3396−3403.
(b) Jordan, V. C. J. Med. Chem. 2003, 46, 1081−1111. (c) Kusama, M.;
Miyauchi, K.; Aoyama, H.; Sano, M.; Kimura, M.; Mitsuyama, S.;
Komaki, K.; Doihara, H. Breast Cancer Res. Treat. 2004, 88, 1−8.
(7) For reviews on copper-catalyzed borylations, see: (a) Yun, J.
Asian J. Org. Chem. 2013, 2, 1016−1025. (b) Fujihara, T.; Semba, K.;
Terao, J.; Tsuji, Y. Catal. Sci. Technol. 2014, 4, 1699−1709. (c) Semba,
K.; Fujihara, T.; Terao, J.; Tsuji, Y. Tetrahedron 2015, 71, 2183−2197.
(d) Yoshida, H. ACS Catal. 2016, 6, 1799−1811.
minor, 2H), 4.49 (s, minor, 2H), 4.52 (s, major, 2H), 6.49 (s, JH−Sn
=
140.9 Hz, minor, 1H) 7.18 (s, JH−Sn = 77.3 Hz, major, 1H), 7.23−7.39
(m, major/minor, 5H). 13C NMR (CDCl3): δ 11.61 (JC−Sn = 334.4
Hz, minor), 11.79 (JC−Sn = 340.9 Hz, major), 14.12, 22.68, 24.74,
24.76, 26.98 (JC−Sn = 19.5 Hz), 29.27, 29.29, 29.34, 31.95, 34.54 (JC−Sn
= 53.8 Hz, major), 34.59 (JC−Sn = 56.7 Hz, minor) 71.80, 72.04, 75.12,
79.42, 83.20, 83.46, 127.22, 127.27, 127.45, 127.55, 128.16, 138.54,
138.94, 151.56, 171.21. 119Sn NMR (CDCl3): δ −57.60 (minor),
−64.92 (major). HRMS: calcd for C40H73O3BNaSn, [M + Na]+,
755.4572; found, m/z 755.4576. Elemental analysis results were
outside the tolerance range.
(8) For our reports on copper-catalyzed metalation reactions for
synthesizing main-group organometallics containing boron, tin, or
silicon, see: (a) Yoshida, H.; Kawashima, S.; Takemoto, Y.; Okada, K.;
Ohshita, J.; Takaki, K. Angew. Chem., Int. Ed. 2012, 51, 235−238.
(b) Yoshida, H.; Kageyuki, I.; Takaki, K. Org. Lett. 2013, 15, 952−955.
(c) Yoshida, H.; Shinke, A.; Takaki, K. Chem. Commun. 2013, 49,
11671−11673. (d) Kageyuki, I.; Yoshida, H.; Takaki, K. Synthesis
2014, 46, 1924−1932. (e) Yoshida, H.; Takemoto, Y.; Takaki, K.
Chem. Commun. 2014, 50, 8299−8302. (f) Yoshida, H.; Takemoto, Y.;
Takaki, K. Asian J. Org. Chem. 2014, 3, 1204−1209. (g) Yoshida, H.;
Hayashi, Y.; Ito, Y.; Takaki, K. Chem. Commun. 2015, 51, 9440−9442.
(h) Yoshida, H.; Shinke, A.; Kawano, Y.; Takaki, K. Chem. Commun.
2015, 51, 10616−10619. (i) Yoshida, H. Chem. Rec. 2016, 16, 419−
434.
ASSOCIATED CONTENT
* Supporting Information
The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/acs.organo-
met.7b00058.
■
S
Ligand effect on the borylstannylation of 1h, 19F NMR
experiments, and 1H and 13C NMR spectra of the
products (PDF)
AUTHOR INFORMATION
Corresponding Author
*E-mail for H.Y.: yhiroto@hiroshima-u.ac.jp.
■
(9) For details on the distannane formation, see ref 1f.
ORCID
(10) In the Zn-catalyzed synthesis of alkynylstannanes from terminal
alkynes and a tin alkoxide, cuprous bromide was reported to also show
moderate catalytic activity. See: Kiyokawa, K.; Tachikake, N.; Yasuda,
M.; Baba, A. Angew. Chem., Int. Ed. 2011, 50, 10393−10396.
(11) For generation of alkynylcopper species from copper alkoxides
and terminal alkynes, see: (a) Osakada, K.; Takizawa, T.; Yamamoto,
T. Organometallics 1995, 14, 3531−3538. (b) Whittaker, A. M.; Lalic,
G. Org. Lett. 2013, 15, 1112−1115. (c) Cox, N.; Dang, H.; Whittaker,
A. M.; Lalic, G. Tetrahedron 2014, 70, 4219−4231. (d) Jin, L.;
Romero, E. A.; Melaimi, M.; Bertrand, G. J. Am. Chem. Soc. 2015, 137,
15696−15698.
Hiroto Yoshida: 0000-0001-6890-4397
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
This paper is dedicated to Prof. Tamejiro Hiyama on the
occasion of his 70th birthday. This work was financially
supported by JSPS KAKENHI Grant Number JP16H01031 in
Precisely Designed Catalysts with Customized Scaffolding.
(12) Dandge, D. K.; Taylor, C.; Heller, J. P. J. Polym. Sci., Part A:
Polym. Chem. 1989, 27, 1053−1063.
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■
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F
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Organometallics
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4da and 4′da: 86% (4da:4′da = 74:26) with 5a, 76% (4da:4′da =
74:26) with 5b.
(18) The formation of 6a was also confirmed by 19F NMR. See the
Supporting Information for details.
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(22) Commercial 5b has been found to partially exist as an ethanol
complex and a hydrate, which results in the complete conversion of 6a
1
into 6b and 6c. For the H NMR spectrum of 5b, see the Supporting
Information.
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G
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