1,1-Organoboration of Trimethyl-1-propynyltin Using Diorganoboryl-Substituted Ferrocenes

Article abstract of DOI:10.1515/znb-1996-0615

The reactions of various diorganoborylferrocenes, Fc-BR₂ [1, R = Me (a), Et (b), ⁱPr (c), ^tBu (d), Ph (f), R₂B = 9-borabicyclo[3.3.1]nonyl (e)] and 1,1′-bis(9-borabicyclo[3.3.1]nonyl)-ferrocene (2) with trimethyl-1-propynyltin (3) were studied, and the products of the 1,1-organoboration were characterized as the alkenyltin compounds 4-6 by ¹H, ¹¹B, ¹³C and ¹¹⁹Sn NMR. In the cases of 1a-1d and 1f, there is competition between the transfer of a ferrocenyl group and the other organyl groups R from boron to carbon, whereas in the case of the 9-borabicyclo[3.3.1]nonane derivatives 1e and 2, the enlargement of the bicyclic system takes place selectively (compounds 4e and 6). The molecular structure of the product 6, obtained from the reaction between the 1,1′-diborylated ferrocene 2 and two equivalents of 3, was determined by single crystal X-ray analysis (space group P2₁/c; monoclinic; Z = 4, a = 958.3(2), b = 1610.4(3), c = 2405.3(5) pm and β= 90.33(3)°).

Full text of DOI:10.1515/znb-1996-0615

1,1-Organoboration of Trimethyl-l-propynyltin Using
Diorganoboryl-Substituted Ferrocenes
Bernd Wrackmeyer*, Udo Dörfler, Wolfgang Milius, Max Herberhold*
Laboratorium für Anorganische Chemie, Universität Bayreuth, D-95440 Bayreuth
Z. Naturforsch. 51b, 851-858 (1996); received October 26. 1995
Ferrocenes, Trimethyl-l-propynyltin, 1,1-Organoboration, Alkenyltin Compounds, X-Ray
The reactions of various diorganoborylferrocenes, F c-B R 2 [1, R = Me (a), Et (b), 'Pr (c),
'Bu (d), Ph (f), R2B = 9-borabicyclo[3.3.1]nonyl (e)] and 1,1 '-bis(9-borabicyclo[3.3.1]nonyl)-
ferrocene (2) with trimethyl-l-propynyltin (3) were studied, and the products of the 1,1-
organoboration were characterized as the alkenyltin compounds 4-6 by ‘H, UB, 13C and
119Sn NMR. In the cases of la -Id and If, there is competition between the transfer of a
ferrocenyl group and the other organyl groups R from boron to carbon, whereas in the case
of the 9-borabicyclo[3.3.1]nonane derivatives le and 2, the enlargement of the bicyclic system
takes place selectively (compounds 4e and 6). The molecular structure of the product 6,
obtained from the reaction between the l,l'-diborylated ferrocene 2 and two equivalents of
3, was determined by single crystal X-ray analysis (space group P2x!c\ monoclinic; Z = 4, a =
958.3(2), b = 1610.4(3), c = 2405.3(5) pm and ß = 90.33(3)°).
Introduction
interested in diorganoboryl-substituted ferrocenes
[6,7] which are fairly stable towards redistribution
in solution. H ere we report on the synthesis of the
ferrocene derivatives la - f and 2 [see eq. (1) —(3)],
and on their behaviour in 1,1-organoboration re-
actions, using trim ethyl-l-propynyltin (3) as a re-
presentative alkynyltin compound.
The stereoselective 1,1-organoboration of alky-
nyltin compounds opens a convenient route to a
variety of organometallic-substituted alkenes [1].
The presence of a stannyl and a diorganoboryl
group in cis positions at the C=C bond (e.g. in A,
prepared from the reaction between a triorgano-
borane R 3B and M e^S n-C ^C R 1) offers consider-
able synthetic potential for further trans-
formations [2-4].
Results and Discussion
Synthesis
Diorganoboryl-substituted ferrocenes, R2B -F c,
can be prepared by the reaction of dibromoboryl-
ferrocene [6] and R4Sn (R = Me) [6] or R4Pb (R =
Me, Et) as shown in eq. (1) for la,b. For more
bulky groups R, e.g. in lc -f, the reaction of lithio-
ferrocene with alkoxy-diorganoboranes [7] is pre-
ferred [eq. (2)]. Starting from l,l'-dilithioferro-
cene, the same type of reaction affords 1,1'-
bis[9-(9-borabicyclo[3.3.1]nonyl)]ferrocene (2) as
shown in eq. (3).
R2B/ ^ NSnMe3
A
If 1,1-organoboration reactions are carried out
with triorganoboranes of the type R ' - B R 2 instead
of R3B, mixtures of alkenes may be formed [5],
depending on the relative rate of transfer of either
R' or R from boron to carbon. So far little is
known about the factors which influence the pro-
duct distribution of 1,1-organoboration reactions
if there are boron-carbon bonds with different re-
activity. In order to avoid equilibration between
R ' - B R 2 and R -B R '2, R3B and R^B, we became
Fc-BBr2
+ 2 PbR4 ------> Fc-BR2 + 2 R3PbBr (1)
R = Me, Et
|1q |1b
R IMeIEt
Abbreviations: Fc = 1-ferrocenyl, (775-C5H5)Fe(/75-C5H4-);
fc = l,l'-ferrocenediyl, Fe(?/5-C5H4-)2.
F c _ Li
+
MeOBR, ____» Fc-BR,
+
LiOMe (2)
11f
R,R = ‘Pr, tßu, C8H14, Ph
1d |1e
1c
Requests for reprints to Prof. Dr. B. Wrackmeyer or
Prof. Dr. M. Herberhold.
u
R.Rl'Prltau
D
0932-0776/96/0600-0851 $06.00 © 1996 Verlag der Zeitschrift für Naturforschung. All rights reserved.
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B. W rackmeyer et al. • 1,1-Organoboration of Trimethyl-l-propynyltin
852
migrate more readily than an alkyl group because
of the greater polarity of the B -C (F c) bond. How-
ever, the electrophilic attack of the stannyl group
in B, accompanied by the transfer of a bulky group
R, is expected to lead to sterically less strained
c ^ L i
+2 M e O -B -^
------------------------
2 LiOMe
Fe
^ > - L i
►
-=V,
) V ’ B'
Fe
-
alkenes than the transfer of the ferrocenyl group.
(3)
If the groups R are less bulky (R = Me, Et), both
steric effects and polarity are in favour of the pre-
ferred migration of the ferrocenyl group, in accord
with the experimental results. In the case of R =
Ph, the polarities of all B -C bonds are similar, but
the transfer of the more bulky ferrocenyl group is
preferred. Again, this can be explained con-
sidering the different steric strain in the final pro-
ducts 4f and 5f.
The reactions of the compounds 1 and 2 with
trim ethyl-l-propynyltin (3) were carried out on a
small scale in NMR tubes in order to monitor the
progress of the 1,1-organoboration reactions by
NMR spectroscopy. All reactions proceeded
smoothly between -7 8 °C and room tem perature;
interm ediates could not be detected.
In the case of the noncyclic boranes, mixtures
consisting of the organometallic-substituted al-
kenes 4 and 5 were obtained. The compounds 4
result from the transfer of an organyl group R
from boron to carbon, whereas the migration of
the ferrocenyl group Fc leads to the compounds
5 [eq. (4)]. The product distribution is shown in
eq. (4).
%
-
R - B-= - Me
B
Fc*
+SnMe3
The reactions between 3 and the 9-borabicyclo-
[3.3.1]nonane derivatives le and 2 gave selectively
the products 4e and 6, respectively, in which the
bicyclic ring systems are enlarged by an olefinic
carbon atom [eq. (5)]. This behaviour is typical of
1,1-organoboration reactions of 1-alkynyltin com-
pounds with 9-organyl-9-borabicyclo[3.3.1]no-
nanes [9,10], and it has been shown that the com-
Me3Sn- = -M e
Fc-B R 2
1f
1b 1c 1d
10
•Pr
l Bu
Ph
R
Me Et
^
r B
(4)
Fe
Fc
Me
Fc(R)B
4a
SnMe3
4f
R2B
SnMe3
4b 4c 4d
5b 5c 5d 5f
5a
+ 2 Me3S n -= -M e
3
R
X
Et 'Pr
Ph
'Pr
Ph
Me
lBu
R
Me Et
tßu
%
30 60
50 35
30 50 65 70 40
70
(5)
A statistical product distribution would corre-
spond to 2/3 of type 4 and 1/3 of type 5, as ob-
served approximately for R = 'Pr and 'Bu. In all
other cases, including R = Ph, the migration of the
ferrocenyl group Fc is preferred. The 1,1-organo-
boration reactions proceed via cleavage of the
S n - C = bond to give an alkynylborate-like inter-
mediate B [8], in which the Me3Sn group is for-
mally coordinated to the C = C bond of the alkynyl
group. In principle, the ferrocenyl group should
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853
B. Wrackmeyer et al. • 1,1-Organoboration of Trimethyl-l-propynyltin
Table I. Chemical shifts ö n B and d13C of the diorganoboryl-ferrocenes (la -f, 2).
R.R
<313C(3,4)
(d‘H(3,4))
<313C(Cp)
(<3'H(Cp))
d n B
<3I3C(l)[bl
ö I3C(2,5)
(<3'H(2,5))
d13C(R)
(ö!H(R))
la
75.9
74.6
71.7
74.2
71.4
73.0
69.0
(3.83)
68.5
(3.89)
68.3
(3.69)
69.2
(3.98)
68.1
(4.01)
69.7
10.0 [br]
(0.92)
16.0 [br] 9.9
(1.30) (1.11)
21.4 [br] 20.2
(1.87) (1.19)
30.5 [br] 29.4
Me
Et
70.4
75.3
75.0
80.6
76.3
69.4
75.6
(4.29)
75.5
(4.32)
75.7
(4.35)
76.4
(4.26)
75.1
(4.33)
78.9
75.2
(4.36)
75.0
(4.38)
74.5
(4.36)
71.5
(4.34)
74.8
(4.42)
76.6
lb
lc
'Pr
Id
leW
lf
'Bu
CsH 14
Ph
(1.26)
29.0 [br] 34.8 24.3
(2.10-1.40)
144.1 (i) [br]
(4.49)
(4.49)
(3.91)
138.9 (o) 127.6 (m) 131.1 (p)
(7.2 - 7.8)
29.5 [br] 34.7 24.2
(2.10-1.40)
2tcl
-
77.5
71.2
75.6
(4.44)
74.5
(4.48)
C8H 14
-
All data for solutions in C6D6 (5-15% ) at 25 °C if not stated otherwise, [br] = broad; lbl the 13C(1) NMR signals
are readily observed at low temperature ("quadrupolar decoupling” of n B): solutions in [Dx]toluene measured at -
60 °C; ^ data from ref. [7],
Table II. 13C- and 119Sn NMR data!3! of the alkenes 4a-4d, 4f and 5a-5d, 5f and 3+Et3Btf], 3+Ph3B for comparison.
4f
3+Et3B 3+Ph3B
4b
5b
5d
5f
4a
5a
4c
5c
4d
-47.9
133.5
[508.0] [540.0]
-42.3
d119Sn
-52.9
139.9
-48.3
139.3
-53.3
140.3
-49.5
137.6
-54.1
137.5
-50.4
136.7
-54.0 -50.7
137.3 135.8
-45.3
148.1
-40.8
142.4
147.7
[513.0]
r)13C (Sn-C =)
[542.0] [508.1] [542.4] [518.8] [547.2] [528.7] [549.0] [541.9] [505.6]
159.0
[66.5]
163.0
[br]
158.9
[70.8]
156.1
[br]
158.8
[79.5]
162.2
[br]
158.8
[br]
166.5
[63.7] [br]
-7.3 -8 .2
155.8
169.3
[62.0]
155.2
[br]
161.6
[br]
SnMe3
-6.8
-7.4
-7.2
-8.2
-5.9
-6.8
-7.6
-8 .4
-8.6
-8.5
[323.6] [322.9] [321.4] [320.9] [317.6] [321.0] [315.0] [315.0] [326.0] [328.5] [320.0]
[328.5]
21.0
22.7
[60.0]
20.6
22.7
[61.0]
21.9
[66.5] [60.0]
31.9 (68.2)
(68.0) [92.5]
(67.8)
[28.3] (66.8)
24.1
[62.0]
24.8
n.o.
22.5
[67.3]
22.8
19.7
[66.0]
22.7
[61.0]
=C -M e
23.5
[69.9]
[68.7]
[60.5]
(69.1)
141.9lcl
[84.8]
-
= C -R (Fc)tbl 17.5
24.9
(67.9)
37.9
(72.6) 142.3
(70.7) [84.8] (69.8) [83.0]
(69.1)
(67.8)
(69.7)
23.1
[81.5] (68.1) [90.1]
-
(69.9) [84.8]
(68.9) 19.4
(69.1) [12.9] (67.9)
-
(68.1)
14.3
31.6
[< 3]
-
(69.8)
(69.7) [10.5]
13.6
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
83.0
[103.8]
83.5
[107.3]
84.5
[113.4]
85.0
[99.0]
84.3
=C -C (1)
[110.6]
-
-
-
-
69.2
16.7
69.2
-
-
69.4
-
69.7
69.9
-
Cp
21.4
8.5
B -R
8.8
9.5
17.0
10.7
22.2
31.9
28.2
30.4
27.8
142.2tdl 143.8^1
142.0^1
-
-
-
-
-
-
-
-
76.7
78.5
80.7
78.5
76.6
B -F ctb-el
-
-
-
-
-
-
-
-
-
-
-
-
-
76.7
74.4
74.4
76.5
74.7
73.1
77.4
73.9
72.7
78.5
75.7
75.7
(C (2)-C (5))
75.3
74.6
73.5
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
69.0
69.0
68.8
69.3
69.9
Cp
In [D8]toluene measured at 25 °C, [br] = broad, "■/('19Sn13C) in Hz are given in [ ]. 'H and UB NMR data are
listed in the experimental part. tb' No assignment of C(2) to C(5) of the cyclopendienyl rings. C-ipso; no assign-
ment of C-ortho, meta, para: 4f 140.7, 136.6, 128.2; 3+BPh3 140.3, 139.7, 126.2. C-ipso: no assignment of C-
ortho, meta, para: 4f 129.1, 128.0, 125.8; 5f 130.0, 128.5, 126.2; 3+BPh, 129.2, 128.6. Ie] The signals of the C (l) of
the ferrocenyl rings (4a, 4b, 4c, 4d, 4f) are broad and not dedected;
B. Wrackmeyer, Polyhedron 5, 1709 (1986).
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B. Wrackmeyer et al. • 1,1-Organoboration of Trimethyl-l-propynyltin
854
Table III. 'H, UB, 13C and ll9Sn NMR data'al of the ferrocene derivatives 4e and 6.
Compound 6
Compound 4e
d lH
d 13C
d'H
3.35
<313C
=C -C H
35.9 [71.4]
3.35
36.1 [74.8]
30.2
24.2
30.4
32.9
-6.3
167.4
146.5
21.6
76.2
73.3
69.1
C H - C H 2
30.4
24.1
30.2
32.2
-6.5 [324.8]
167.3
1.1-2.3
1.1-2.3
- C H 2-
b - C H 2
SnMe*
B -C =
Sn-C =
=C -M e
C(2,5)
C(3,4)
Cp
-0.17 [50.4]
[323.9]
-0.08 [49.4]
[548.9]
[68.9]
146.6 [546.8]
[69.4]
21.3
11A
73.6
-
1.90 [53.8]
4.38
4.26
1.98 [53.8]
4.33
4.51
3.96
82.4
-43.2
83.0
-43.6
d u B
c)119Sn
In [D8]toluene, at 25 °C; coupling constants "7(119SnI3C) and "y(ll9Sn'H) (Hz) are given in square brackets.
This is supported by the changes in the magnitude
of l3/ ( 119Sn13C (l)Fc) I in the series 5a-d, which are
parallel to those of 117(119Sn13Cc=) I- All d 119Sn
values lie in a narrow range between d -4 0 and
-55, in agreement with literature data for similar
compounds [14].
The 13C NMR spectrum of complex 6 at -7 0 °C
(Fig. 1) shows two sets of NM R signals, suggesting
the presence of diastereom ers 6 and 6 ' as a result
of hindered rotation about the B -C (l) bond. For
a m ore detailed discussion of dynamic processes
in ferrocenylboranes see ref. [7]. According to the
results of a single crystal X-ray analysis of 6 (vide
infra), only one diastereom er is present in the
solid state; a sample taken from the bulk of the
solid material of 6 gave a powder pattern which
agrees with that calculated from the single crystal
diffraction data. The situation is comparable to
that found previously for triferrocenylborane [15].
pounds with enlarged ring systems are the result
of a kinetically controlled reaction [9],
N M R spectroscopic data
The 'H , n B and 13C NM R data of the diorgano-
borylferrocenes la - f and 2 are listed in Table I.
The 13C and 119Sn NMR data of the alkenes 4 and
5 are given in Table II, together with 13C and 119Sn
NM R data for the 1,1-organoboration products
obtained from 3 with E t3B [11] and Ph3B; the lat-
ter 1,1-organoboration product has not been re-
ported previously. Table III contains the 'H , n B,
13C and 119Sn NM R data for the ferrocene deriva-
tives 4e and 6.
All NM R data support the proposed structures.
It can be readily shown by 'H /!H NOE difference
experiments [12] that the boryl and the stannyl
groups occupy ds-positions at the C=C double
bond in 4, 5 and 6, as well as in 3+Et3B and in
3+Ph3B. The ratio of the isomers 4 and 5 follows
from the 'H NMR spectra, in agreement with the
13C and 119Sn NMR spectra. The one-bond coup-
ling constants I'/ ( '19Sn13C Me) I cover only a small
range between 315 and 328.5 Hz. The range is
somewhat larger for the values IlJ (l19Sn13Cc=)I:
X-ray analysis o f the 1,1' -diboryl-substituted
ferrocene 6
The experimental data pertinent to the X-ray
analysis of compound 6 are given in Table IV [16].
The molecular structure of 6 is depicted in Fig. 2.
and selected bond distances and angles are given
in the caption of Fig. 2. The substituted cyclopen-
tadienyl rings are shifted by 9.2° from the ecliptic
conformation. Their planes are not exactly parallel
but form an angle of 5.5°, the opening pointing
towards the substituents in l,l'-positions. Bonding
505.6
to
549.0
Hz.
The
magnitude
of
117(119Sn13Cc =) I increases with decreasing group
electronegativity of the boryl group: A smaller de-
gree of polarization of the S n-C = bond causes less
negative contributions to the coupling interaction
as described by the Fermi contact mechanism [13],
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B. Wrackmeyer et al. ■1,1-Organoboration of Trimethyl-l-propynyltin
855
C(2,5)
C(3,4)
\\
Sn-C=
B-C=
SnMea
C(1)
n_rr 1>11•1!'r
I 1' 11I1111I
167
165
146
144
II
M/v'
Fig. 1. 67.9 MHz ^C f'H ) NMR
Spectrum of 6 (in CD2C12 at
-70 °C). With the exception of
the 13C (B -C =) resonance sig-
nals, all NMR signals are
doubled. At low temperature in
solution, both diastereomers 6
and 6' are present in an ap-
proximate 1:1 ratio.
'i ■11' r ‘ ' ■r M111■11r " 1r 111r ■
i|
80
77
74
71
||
'vH*
q
-
h
S 13c
i
---1----1---1----1----1----r-
”7-------
1
-------
j
------
1-------1-------
i-------1-------
(------
1-------
1-------
1
-------
r
|
20
10
30
-10
Table IV. Experimental data related to the X-ray analysis of compound 6.
Formula (mol. mass)
Colour; crystal size
Crystal system; space group; Z
Unit cell dimensions [pm]
V [A3]; £)(calcd.)
C3sH6()B2FeSn (831.7)
Dark red; 0.34x0.30x0.30 mm3
Monoclinic; P2]/c; 4
a = 958.3(2), b = 1610.4(3), c = 2405.3(5); ß = 90.33(3)c
3771.7(13); 1.488 g/cm3
Absorption coefficient
Diffractometer; temperature
Radiation [pm]
1.746 mm-1
Siemens P4; 173 K
MoKa, A = 71.073, graphite-monochromator
4.0 to 50.0°; cu
20-range; scan type
Reflections collected
Independent/observed reflections
Refined parameters
8199
6517/6517
389
Direct methods (SHELXTL PLUS)
0.0342/0.0239 (w-1 = a2(F))
0.77/-0.45
Solution
R-/wR-\alue (weight, scheme)
Max./min. residual electron
density [eA-3]
of other 1,1-organoboration products of alkynyltin
compounds [1], the stannyl and the boryl group
F e -B interactions must be negligible, since the
B (l)-C (l) and B (2)-C (6) bonds are bent by only
1.2° towards the iron atom, in contrast to the situa- occupy ds-positions at the C=C bond. The steric
tion found for l,l'-bis(dibrom oboryl)ferrocene strain in these substituted alkenes is indicated by
[17]. The surroundings of the boron atoms are trig- the non-planar arrangem ent of the four substitu-
onal planar within the experimental error. The
bond lengths B ( l)-C (l) [156.6(5) pm] and B (2 )-
C(6) [155.5(5) pm] are similar to those in triferro-
cenylborane [15]. As proposed for the structure
ents at the C=C bonds with torsion angles B -C =
C -S n of 13.6° and 14.1°.
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B. Wrackmeyer et al. • 1.1-Organoboration of Trimethyl-l-propynyltin
DiethyIboryl-ferrocene (lb)
856
By the same procedure, the reaction of 0.33 ml
PbEt4 (3 M) in toluene and 1.8 g (0.5 mmol) of
dibromoboryl-ferrocene afforded lb as
brown oil (0.09 g, 71%).
a red-
Diisopropylboryl-ferrocene (1c)
Diisopropyl-methoxyborane (0.54 g, 4.2 mmol)
was added dropwise at -7 8 °C to a suspension of
0.8 g (4.2 mmol) lithioferrocene in 20 ml of hex-
ane/thf (1:1). A fter warming to room tem perature,
the solvents were removed. The residue was taken
up in hexane and unsoluble material was filtered
off. Removal of the solvent gave lc as a red oil
(0.7 g, 60%).
C(22)
Di-tert-butyIboryl-ferrocene (Id)
Fig. 2. Molecular structure of the l.l'-diborylferrocene
derivative 6. Selected bonddistances [pm] and bond ang-
les [°]: B (l)-C (l) 156.6(5); B(2)-C(6) 155.5(5); B (l)-
C(19) 154.8(5); Sn(l)-C (21) 217.2(3); C(19)-C(21)
135.5(4); C (l)-B (l)-C (1 4 ) 120.0(4); C (l)-B (l)-C (1 9 )
120.4(4); B (l)-C (19)-C (21)-S n(l) 13.6.
By use of the same procedure as for lc, the reac-
tion of lithioferrocene (0.8 g, 4.2 mmol) in 20 ml
of hexane/thf (1:1) and 0.65 g (4.2 mmol) di-tert-
butyl(m ethoxy)borane afforded Id (0.7 g. 55%) as
a red oil.
Diphenylboryl-ferrocene (If)
Experimental
The analogous reaction of lithioferrocene (0.8 g.
4.2 mmol) in 20 ml of hexane and 0.8 g (4.20
mmol) diphenylmethoxyborane afforded If (0.9 g,
62%) as a red oil.
All compounds were prepared and handled in
an inert atmosphere (A r) by using carefully dried
glassware and solvents. Tetramethyl- and tetraeth-
yllead were commercial products. Dibromoboryl-
ferrocene [6], di-fm -butyl(m ethoxy)borane [18],
9-methoxy-9-borabicyclo[3.3.1]nonane [19], tri-
m ethyl-l-propynyltin [20], lithioferrocene [21] and
lj'-dilithioferroeene [22] were prepared accord-
ing to literature procedures.
NM R spectra were measured by using JE O L
FX 90Q, Bruker AC 300 ( ‘H, 1]B, 13C, 119Sn
NM R) and JEO L EX 270 ('H , 13C NM R) spec-
trometers. Chemical shifts are given with respect
9-Borabicyclo[3.3.1] -9-nonyl-ferrocene (le)
9-Methoxy-9-borabicyclo[3.3.1]nonane (0.3 g.
2.1 mmol) was added in one portion to a suspen-
sion of lithioferrocene (0.3 g, 2.1 mmol) in 20 ml
of hexane/thf (3:1) at -7 8 °C. The solution was
stirred for 10 min at room tem perature before the
solvent was removed in vacuo. The residue was
then dissolved in 20 ml of hexane, and unsoluble
material was filtered off. Evaporation of the
solvent left le as a yellow oil (0.5 g, 77 %).
to Me4Si (0>H(C6D sH)
= 7.15; d 13C(C6D 6) =
128.0) and external E t70 - B F 3 (dn B=0; E (n B) =
32.083972 MHz); SnM e4 (ö119Sn=0; ~(U9Sn) =
37290665 MHz).
1,1'-Bis(9-borabicyclo[3.3.1] -9-nonyl)-ferrocene
(2)
Using the same procedure as for le, the reaction
of l,l'-dilithioferrocene (0.7 g, 3.55 mmol) in 20
ml of hexane/thf (3:1) with 1.1 g (7.1 mmol) 9-
methoxy-9-borabicyclo[3.3.1]nonane afforded 2 as
a yellow oil (1.2 g, 79%).
DimethyIboryl-ferrocene (la)
A solution of 0.33 ml PbM e4 (3 M) in toluene
was added dropwise at -6 0 °C to a solution of 1.8 g
(0.5 mmol) dibromoboryl-ferrocene in 15 ml of
toluene. After stirring for 2 h at room tem per-
ature, the solvent was removed in vacuo. Then the
residue was dissolved in 50 ml of hexane and
PbM e3Br was filtered off. la was isolated as a
brown oil (0.08 g, 68%).
Reaction between trimethyl-l-propynyltin (3) and
the dialkyIboryl-ferrocenes la -If
General procedure: At -7 8 °C 1 mmol of the
dialkylboryl-ferrocene la -If was added to 0.2 g
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B. Wrackmeyer et al. • lJ-Organoboration of Trimethyl-l-propynyltin
857
(1 mmol) of 3 dissolved in 0.3 ml of [D8]toluene.
The reaction mixture was left for 2 d at room tem -
perature. Then the 1,1-organoboration products
were characterized by NM R (see Table II for 13C
and 119Sn NM R data).
(E)-l-diisopropylboryl-l-ferrocenyl-2-
trimethylstannyl-1 -propene (5c):
'H NM R (in [D8]toluene, 25 °C):
6 1H[7(119Sn,1H)] = 4.36-3.76 (m, ferrocenyl); 2.31
[53.4] (s,3H,=CMe); 1.32 (sept,2H,BCH); 1.12
(d,12H,BCCH); 0.04 [51.3] (s, 9H,SnM e3), d u B:
81.0.
(E)-3-Ferrocenyl(methyl)boryl-2-trimethylstannyl-
2-butene (4a):
(E)-3-tert-Butyl(ferrocenyl) bory1-4,4-dimethy1-2-
trimethylstannyl-2-pentene (4d):
*H NM R (in [D8] toluene, 25 °C):
ö1H[/,y(119Sn,1H)]
= 4.40-3.80 (m, ferrocenyl);
*H NM R (in [D8]toluene, 25 °C):
(31H[7(119Sn,1H)] = 4.50-3.84 (m, ferrocenyl); 2.12
[57.8] (s,3H,=CMe); 1.38 (s,9H,=CCMe3); 1.16
(s,9H,BCMe3); -0.17 [51.0] (s,9H,SnMe3); d n B:
80.0.
1.92 [53.8] (s,3H,=CMe); 1.64 [12.2] (s,3H,=CMe);
0.85 (s.3H,BMe); -0.02 [52.1] (s,9H, SnMe3);
d u B: 80.5.
(E)-l-Dimethylboryl-1 -ferrocenyl-2-
trimethylstannyl-1 -propene (5a):
(E)-l-Di-tert-butylboryl-1 -ferrocenyl-2-
trimethylstannyl-1 -propene (5d) :
'H NM R (in [D8]toluene, 25 °C):
'H NM R (in [D8]toluene, 25 °C):
<3lH[7(119Sn,1H)] = 4.50-3.84 (m, ferrocenyl); 2.50
[54.9] (s,3H,=CMe); 1.03 (s,18H,BCMe3); 0.19
[51.2] (s,9H,SnMe3); d u B: 80.0.
<31H [/(119Sn,1H ) = 4.40-3.80 (m, ferrocenyl); 1.97
[54.6] (s,3H =CM e); 1.06 (s,6H,BMe); 0.12 [51.8]
(s,9H,SnMe3); d u B: 80.5.
(E)-l-Ferrocenyl(phenyl) boryl-l -phenyl-2-
trimethylstannyl-2-propene (4f):
(E) -3-Ethyl(ferrocenyl)boryl-2-trimethylstannyl-2-
pentene (4b):
*H NM R (in [D8]toluene, 25 °C):
^ ^ [ / ( “ ^ n ^ H )] = 4.80-3.91 (m, ferrocenyl); 2.12
[51.3] (s,3H =CM e); -0.002 [53.0] (s,9H,SnMe3),
8.2-8.0, 7.6-7.2 (m, phenyl); <3n B: 81.3.
‘H NM R (in [D8]toluene, 25 °C):
^ ‘H ^ C ^ S n /H )] = 4.36-3.80 (m, ferrocenyl); 2.00
[53.8] (s,3H,=CMe); 2.45 (q,2H,=CCH2); 1.12
(t,3H,=CCCH3);
(t,3H,BCCH3); -0.08 [52.1] (s,9H,SnMe3); d u B:
81.5.
1.45
(q,2H,
BCH2),
1.10
(E)-l-Diphenylboryl-1 -ferrocenyl-2-
trimethylstannyl-1 -propene (5f):
'H NM R (in [D8]toluene, 25 °C):
(51H[7(119Sn,1H)] = 4.80-3.91 (m, ferrocenyl); 2.02
[50.8] (s,3H,=CMe); -0.43 [53.4] (s,9H,SnMe3),
8.2-8.0, 1 .6 -1 .2 (m, phenyl); d u B: 81.3.
(E)-1-Diethylboryl-1 -ferrocenyl-2-
trimethylstannyl-1 -propene (5b):
NM R (in [D8]toluene, 25 °C):
(51H [/(119Sn,1H)] = 4.36-3.80 (m, ferrocenyl); 2.08
[54.6] (s,3H,=CMe); 1.45 (q,4H,BCH2); 1.17
(t,6H ,BCCH 3); 0.11 [52.1] (s,9H, SnMe3); d u B:
81.5.
Reaction o f trimethyl-l-propynyltin (3) with 1,1'-
bis(9-borabicyclo[3.3.1]-9-nonyI)ferrocene (2)
The reaction between 3 and 2 was carried out in
an analogous m anner, but only 0.5 mmol of 2 were
used. Compound 6 was isolated as red crystals
(0.6 g, 72%; m.p. 164-165 °C). Crystals for X-ray
analysis were grown from toluene solutions.
(E) -3-Ferrocenyl(isopropyl)boryl-4-methyl-2-
trimethylstannyl-2-pentene (4c):
Acknowledgements
'H NM R (in [D8]toluene, 25 °C):
We are grateful to the Deutsche Forschungs-
(31H [/(119Sn,1H)] = 4.36-3.76 (m, ferrocenyl); 2.78 gemeinschaft and the Fonds der Chemischen In-
[54.7](s,3H,=CCH3); 1.95 [54.7] (s,3H,=CMe); 2.78 dustrie for support of this work. We thank Prof.
Dr. R. Köster for providing the compounds of
'Pr2BOMe, Ph2BOM e and Ph3B.
(sept,lH ,=C C H ); 1.22 (d,6H ,=CCCH3); 1.63
(sept,lH , BCH); 1.14 (d,6H ,BCCH3); d u B: 81.0.
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