gem-Silylborylation approach for tri- and tetrametalmethanes: The first synthesis of boryl(germyl)(silyl)(stannyl)methanes

Article abstract of DOI:10.1016/S0022-328X(03)00561-8

gem-Silylborylation of halomethyllithiums with silylboranes allows us to prepare boryl(silyl)methanes substituted by such heteroatoms as Cl, Br, I, O, S, Si, Ge, and Sn in high yields. With B, Si, and Sn- or B, Ge, and Si-substituted methanes, the first s

Full text of DOI:10.1016/S0022-328X(03)00561-8

Journal of Organometallic Chemistry 686 (2003) 286Á293
/
www.elsevier.com/locate/jorganchem
gem-Silylborylation approach for tri- and tetrametalmethanes: the
first synthesis of boryl(germyl)(silyl)(stannyl)methanes
Masaki Shimizu *, Takuya Kurahashi, Hirotaka Kitagawa, Katsuhiro Shimono,
Tamejiro Hiyama
Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan
Received 23 April 2003; received in revised form 9 June 2003; accepted 16 June 2003
Abstract
gem-Silylborylation of halomethyllithiums with silylboranes allows us to prepare boryl(silyl)methanes substituted by such
heteroatoms as Cl, Br, I, O, S, Si, Ge, and Sn in high yields. With B, Si, and Sn- or B, Ge, and Si-substituted methanes, the first
synthesis of B, Ge, Si, and Sn-substituted methanes was achieved via deprotonation of the trimetalated methane followed by
germylation with Me3GeCl or stannylation with Bu3SnCl, respectively.
# 2003 Elsevier Science B.V. All rights reserved.
Keywords: Boron; Carbenoid; Halomethane; gem-Silylborylation; Silicon; Silylborane; Tetrametalmethane
1. Introduction
hyde addition. Using (dialkoxyboryl)methylzinc iodide
[3], Pd catalyzed-cross coupling reaction with an alkenyl
halide and subsequent aldehyde allylation was achieved
in one pot [4]. Moreover, functionalized allylic silanes
were prepared from tris[(trimethylsilyl)methyl]borane,
which can be regarded as both silicon and boron
substituted methane, via treatment of the borane with
1-alkynyllithium followed by the addition of an alde-
hyde [2v].
We recently reported that alkylidene-type lithium
carbenoids reacted with silylboranes to generate the
corresponding borates in which a silyl group migrated in
1,2-fashion to afford 1-boryl-1-silyl-1-alkenes in good
yields (Scheme 1) [5]. This novel gem-silylborylation is
applicable to sp3 carbenoids generated from allylic
chlorides, giving rise to 1-boryl-1-silyl-2-alkenes stereo-
specifically in good yields [6]. Both silylborylated
compounds are valuable reagents in organic synthesis.
We envisioned that heteroatom-substituted boryl(si-
lyl)methanes, potentially versatile C1 organometallic
Di-, tri-, and tetrametalated methanes especially
containing silicon and/or boron are versatile C1 reagents
in organic synthesis, because the polymetalated reagents
can efficiently perform multiple chemical transforma-
tions in one vessel via a single operation or stepwise
manipulations and thus can serve as valuable precursors
of functionalized organometallic reagents [1,2]. For
example, fluorotris(trimethylsilyl)methane reacted with
aldehydes in the presence of fluoride ion to give 1,3-
disubstituted 2-fluoroallyllic alcohols 2o, 2p. The reac-
tion involves five events in single operation: generation
of naked methyl anion, aldehyde addition, Peterson
elimination, generation of naked sp2 anion, and alde-
* Corresponding author. Tel.: ꢀ
5555.
E-mail address: shimizu@npc05.kuic.kyoto-u.ac.jp (M. Shimizu).
/
81-75-753-5535; fax: ꢀ81-75-753-
/
0022-328X/03/$ - see front matter # 2003 Elsevier Science B.V. All rights reserved.
doi:10.1016/S0022-328X(03)00561-8

M. Shimizu et al. / Journal of Organometallic Chemistry 686 (2003) 286Á
/
293
287
Table 1
Silylborylation of halomethanes 2
a
Yield (%)
Entry
1
2
E
X
3
1
1a 2a
1a 2b
1a 2c
1a 2d
1a 2e
1a 2f
1a 2g
1a 2h
1a 2i
1b 2i
MeO
MEO b
SEO c
MeS
Cl
Cl
Cl
Cl
Cl
3aa
3ab
3ac
3ad
3ae
17
37
41
45
20
47
69
88
76
59
26
51
67
62
2
3
4
5
Cl
Br
6
Br 3af
7
I
I
3ag
3ah
3ai
3bi
3ci
3aj
3aj
3al
Scheme 1. gem-Silylborylation of lithium carbenoids with silylbo-
ranes.
8
Me3Si
Me3Ge
Me3Ge
Me3Ge
Bu3Sn
Cl
Cl
Cl
Cl
Cl
I
9
10
11
12
13
14
reagents in synthetic chemistry, would be synthesized
efficiently via gem-silylborylation of halomethyllithium
bearing heteroatom(s). Reported herein are facile synth-
esis of chalcogen, halogen, or metal-substituted bory-
l(silyl)methanes and their application to the first synth-
esis of boryl(germyl)(silyl)(stannyl)methanes (Scheme
2).
1c
1a 2j
2i
1a 2k Bu3Sn
1a 2l Ph3Pb
I
For entries 1Á
in THF (3 ml) was treated with a solution of LDA (1.1 mmol) in THF
(1 ml) at ꢁ98 8C and the resulting mixture was allowed to warm to
room temperature. For entries 5Á7, a solution of 1a (1.0 mmol), 2 (1.5
mmol) in THF (3 ml) was treated with a solution of LDA (1.4 mmol)
in THF (1.4 ml) at ꢁ98 8C and the resulting mixture was allowed to
/
4 and 8Á14, a solution of 1 (1.0 mmol), 2 (1.1 mmol)
/
/
/
/
2. Results and discussion
warm to room temperature.
a
Isolated yields are given.
ME: 2-methoxyethyl.
SE: 2-(trimethylsilyl)ethyl.
b
2.1. Silylborylation of heteroatom-substituted methanes
c
Since halomethyllithiums were thermodynamically
labile [7], generation and reaction of such carbenoids
were carried out in the presence of silylborane 1. Thus, a
THF solution of 1 and halomethane 2 was treated with
silylborylated in moderate yields, respectively (entries 3
and 4). Silylborylation of such dihalomethanes as
dichloro- and dibromo-, and diiodomethanes (2eÁ
also proceeded to give 3ae, 3af, and 3ag in 20, 47, and
69% yields, respectively (entries 5Á7). When halo-
/g)
lithium diisopropylamide (LDA) at ꢁ98 8C and the
/
/
resulting solution was allowed to warm to room
temperature before quenching with saturated aqueous
NH4Cl solution (Eq. (1)). The results are summarized in
Table 1. Reaction of (dimethylphenylsilyl)(pinacolato)-
borane (1a) and methoxymethyl chloride (2a) gave the
corresponding product 3aa in low yield, probably
because chloro(methoxy)methyllithium was extremely
unstable under the conditions (entry 1), while chloro-
methyllithium generated from (2-methoxyethoxy)methyl
chloride (2b) reacted with 1a to afford 3ab in moderate
yield (entry 2). Improvement of the yield may be
attributed to the stabilization of the carbenoid inter-
mediate by chelation between two ethereal oxygens and
a lithium [8]. Similarly, 2-(trimethylsilyl)ethoxymethyl
chloride (2c) and methylthiomethyl chloride (2d) were
methanes bearing a metal element were employed,
trimetalated methanes were isolated by purification
with column chromatography on silica gel in moderate
to good yields. Lithiation of chloromethyltrimethylsi-
lane (2h) and subsequent silylborylation with 1a gave
bis(silyl)(boryl)methane 3ah in 88% yield (entry 8).
(Dimethylphenylsilyl)(trimethylgermyl)(pinacolatobor-
yl)methane (3ai) was obtained from chloromethyltri-
methylgermane (2i) and 1a in 76% yield (entry 9). With
2i, (methyldiphenylsilyl)(pinacolato)borane (1b) and
(pinacolato)(triphenylsilyl)borane (1c) were also applic-
able to the present silylborylation albeit the yields were
lower than that with 1a (entries 10 and 11). Tin-
substituted boryl(silyl)methane 3aj was prepared from
chloro- and iodomethanes 2j and 2k in 51 and 67%
yields, respectively (entries 12 and 13), while iodo-
methyltriphenylplumbane [9] was transformed to boron,
lead, and silicon-substituted methane 3al in 62% yield
(entry 14). On the other hand, reaction of iodo-
methyl(pinacolato)borane (2m) [10] with 1a did not
take place at all. Since no consumption of 2m was
observed, treatment of 2m with LDA might cause the
formation of the corresponding borate and such com-
plexation would retard the deprotonation, i.e. genera-
tion of the carbenoid.
Scheme 2. gem-Silylborylation approach for tri- and tetrametal-
methanes.

288
M. Shimizu et al. / Journal of Organometallic Chemistry 686 (2003) 286Á293
/
Table 2
Silylborylation of tri- and tetrahalomethanes 2
2.2. Synthesis of boryl(germyl)(silyl)(stannyl)methanes
4 and 5
a
Yield (%)
Entry
2
Z
X
Method
3
With trimetalated methanes in hand, we scrutinized
the synthesis of methanes substituted by such four
different kinds of metal elements as B, Ge, Si, and Sn.
To our knowledge, no example of the four different
metals-substituted methanes was available [11].
1
2
3
4
5
6
2n
H
Cl
Cl
Br
A
B
A
B
A
B
3an
3an
3ap
3ap
3ar
3ar
70
64
86
93
42
19
2o Cl
2p
H
2q Br Br
2r
2s
H
I
I
I
At first, deprotonation of 3ak with BuLi followed by
germylation with Me3GeBr was attempted to synthesize
Method A: a solution of 1 (1.0 mmol), 2 (1.1 mmol) in THF (3 ml)
was treated with a solution of LDA (1.1 mmol) in THF (1 ml) at
boryl(germyl)(silyl)(stannyl)methane 4. TinÁlithium ex-
/
change, however, took place in preference to the
deprotonation and 3aj was produced in 58% yield.
Then, 3ak was treated with LDA in THF at 60 8C and
then the methyllithium was trapped with Me3GeBr to
produce B-, Ge-, Si-, and Sn-substituted methane 4 in
34% yield as a colorless oil (Eq. (3)). Alternatively,
lithiation of 3aj and subsequent stannylation leading to
another tetrametalated methane 5 was also examined
(Eq. (4)). When 3aj was lithiated with BuLi or lithium
2,2,6,6-tetramethylpiperidide (LiTMP) and stannylated
with Me3SnCl at 60 8C, 5 was isolated in moderate yield
ꢁ98 8C and the resulting mixture was allowed to warm to room
temperature. Method B: a solution of 1a (1.0 mmol), 2 (1.2 mmol) in
THF (2 ml) in diethyl ether (1 ml) was treated with a solution of BuLi
/
(1.2 mmol) in hexane (1.56 M, 0.77 ml) at ꢁ110 8C and the resulting
/
mixture was allowed to warm to room temperature.
a
Isolated yields are given.
ð1Þ
(entries 1 and 2). In case of LDA, boronÁlithium
/
We next examined silylborylation of tri- and tetra-
halomethanes leading to boryl(dihalo)(silyl)methanes
(Scheme 3). Trihalomethanes 2n, 2p, and 2r were
silylborylated with 1a under the same conditions for
exchange also occurred in some extent and Ge-, Si-,
and Sn-substituted methane 6 was co-produced in 23%
yield. On the other hand, a superbase consisting of BuLi
and t-BuOK was found highly effective for the lithiation
and the following stannylation afforded 5 in 81% yield
(entry 3). These are the first synthesis of B-, Ge-, Si-, and
Sn-substituted methanes.
2aÁ
converted to the corresponding trihalomethyllithiums
by halogenÁlithium exchange with BuLi in THF/Et2O
at ꢁ110 8C, which reacted with coexisting 1a. Dichloro-
and dibromomethanes 3an and 3ap were isolated in
acceptable to good yields (Table 2, entries 1Á4).
/2l, while tetrahalomethanes 2o, 2q, and 2s were
/
/
/
Especially silylborylation of 2q proceeded giving rise
to 3ap in 93% yield (entry 4). On the other hand,
diiodomethane 3ar was obtained in low to moderate
yields (entries 5 and 6). In all cases, no diboryl(disi-
lyl)methane, double silylborylated product, formed.
ð3Þ
ð4Þ
Silylborylation via chlorineÁlithium exchange was ap-
/
plicable to trichloromethylbenzene (2t), giving rise to
benzyl chloride 3at in 65% yield (Eq. (2)).
ð2Þ
Entry
1
Conditions
(1) BuLi, THF, ꢁ
Yield (%)
39
/78 to 0 8C
(2) Me3SnCl, 60 8C
2
3
(1) LiTMP, TMEDA, THF, 60 8C
(2) Me3SnCl, 60 8C
30
81
(1) BuLi/t-BuOK, THF, ꢁ78 to ꢁ40 8C
/
/
(2) Me3SnCl, ꢁ78 8C to r.t.
/
Recrystallization of 5 from methanol, fortunately,
afforded single crystals suitable for X-ray diffraction
Scheme 3.

M. Shimizu et al. / Journal of Organometallic Chemistry 686 (2003) 286Á
/
293
289
analysis [12]. ORTEP drawing of 5 is shown in Fig. 1. The
bond lengths of C(1)ÃB(1) and C(1)ÃSi(1) were 1.558(6)
and 1.882(4) A, both of which were almost the same as
/
/
˚
˚
normal bond lengths being 1.56 and 1.87 A [13],
respectively. On the other hand, the C(1)ÃGe(1) bond
being 2.041(4) A was longer than normal value being
/
˚
˚
1.94 A [13], while the distance between C(1) and Sn(1)
˚
being 2.132(5) A was found shortened by comparison
˚
with the normal C(1)Ã
Sn(1)ÃC(1)ÃSi(1)
(111.7(3)8), and Ge(1)Ã
angles were larger than an ideal angle (109.58) of a
tetrahedral carbon, while the bond angles of B(1)ÃC(1)Ã
Ge(1) (105.1(3)8) and B(1)ÃC(1)ÃSn(1) (106.4(3)8) were
smaller than the typical angle. These observations
indicate that steric repulsions between the boryl and
the silyl groups, and the silyl and the stannyl groups are
larger than those between the boryl and the germyl
groups, and the germyl and the stannyl groups pre-
sumably due to the bulkier substituents on boron and
silicon atoms.
/
Sn bond length (2.17 A) [13]. The
/
/
(112.2(2)8),
B(1)Ã
/
C(1)Ã
/
Si(1)
/
C(1)ÃSi(1) (111.8(2)8) bond
/
Fig. 1. ORTEP drawing of 5. Hydrogen atoms are omitted for clarity.
/
/
˚
Selected bond lengths (A): C(1)Ã
C(1)ÃGe(1), 2.041(4); C(1)ÃSn(1), 2.132(5). Selected angles (8): B(1)Ã
C(1)ÃSi(1), 111.7(3); B(1)ÃC(1)ÃSn(1), 106.4(3); B(1)ÃC(1)ÃGe(1),
105.1(3); Si(1)ÃC(1)ÃSn(1), 112.2(2); Si(1)ÃC(1)ÃGe(1), 111.8(2);
Ge(1)ÃC(1)ÃSn(1), 109.26(18).
/
B(1), 1.558(6); C(1)ÃSi(1), 1.882(4);
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
diethyl ether were distilled from benzophenone and
sodium under an argon atmosphere. Butyllithium was
purchased from Sigma-Aldrich Co. Inc., and titrated
with N-pivaloyl-o-toluidine as an indicator. Silylbo-
ranes 1aÁ
[14].
/
c were prepared by the reported procedure
3. Experimental
All manipulations of oxygen- and moisture-sensitive
materials were conducted with a standard Schlenk
technique under a purified argon atmosphere (deoxyge-
nated by passing through BASF-Catalyst R3-11 column
3.1. Typical procedure for silylborylation of
halomethanes: synthesis of
1
at 80 8C). H-NMR spectra were measured on a Varian
(dimethylphenylsilyl)(4,4,5,5-tetramethyl-1,3,2-
dioxaborolan-2-yl)(trimethylsilyl)methane (3ah)
Mercury 200 (1H, 200 MHz) spectrometer. Chemical
1
shifts of H-NMR are expressed in parts per million
downfield relative to an internal tetramethylsilane (dꢂ
/
0
To a solution of chloromethyltrimethylsilane (2h, 0.13
g, 1.10 mmol) and (dimethylphenylsilyl)(pinacolato)bor-
ppm) or chloroform (dꢂ7.26 ppm). Splitting patterns
/
are indicated as s, singlet; d, doublet; t, triplet; q,
quartet; m, multiplet; brs, broad singlet. 13C-NMR
spectra were measured on a Varian Mercury 200 (13C,
50 MHz) spectrometer and JEOL JMN ECP-500 (13C,
125 MHz) spectrometer with tetramethylsilane as an
ane (1a, 0.26 g, 1.00 mmol) in THF (3.0 ml) at ꢁ98 8C
was added a solution of LDA (1.10 mmol) in THF (1
ml). The reaction mixture was stirred for 10 min at
/
ꢁ98 8C and then allowed to gradually warm to room
/
temperature before quenching with saturated aqueous
NH4Cl solution (0.5 ml). The resulting mixture was
diluted with diethyl ether (20 ml), and then washed with
water (10 ml). The organic layer was dried over
anhydrous magnesium sulfate, and concentrated in
vacuo. Purification of the crude product by column
chromatography on silica gel (hexane/ethyl acetate 9:1)
internal standard (dꢂ0 ppm). Infrared spectra (IR)
/
were recorded on a Shimadzu FTIR-8400 spectrometer.
GC-MS analyses were obtained with a JEOL JMS-700
spectrometer by electron ionization at 70 eV. Elemental
analyses were carried out with a YANAKO MT2 CHN
CORDER machine at Kyoto University Elemental
Analysis Center. Melting points were determined using
a YANAKO MP-500D. TLC analyses were performed
by means of Merck Kieselgel 60 F254 and Rf values were
given. Column chromatography was carried out using
Wakogel C-200. Preparative recycling gel permeation
chromatography (GPC) was performed with a JAI LC-
908 chromatograph equipped with JAIGEL-1H and -
2H columns (chloroform as an eluent). Cooling a
afforded 3ah (0.31 g, 88% yield) as a colorless oil. Rf:
1
0.48 (hexane/ethyl acetate 9:1). H-NMR: d ꢁ
/
0.01 (s,
9H), 0.15 (s, 1H), 0.35 (s, 3H), 0.38 (s, 3H), 1.07 (s, 6H),
1.12 (s, 6H), 7.27Á7.37 (m, 3H), 7.50Á
7.60 (m, 2H). 13C-
NMR: d ꢁ0.3, 0.3, 1.5, 24.9, 25.1, 82.6, 127.4, 128.5,
133.7, 141.1. IR: nmax 2975, 1349, 1308, 1245, 1142,
1110, 1023, 848, 732, 699 cmꢁ1. MS: m/z 333 [Mꢀꢁ
/
/
/
/
Me], 251, 233, 191 59, 135, 83. Anal. Calc. for
C18H33O2BSi2: C, 62.05; H, 9.55. Found: C, 62.12; H,
9.53%.
reaction vessel at ꢁ
pentane with liquid nitrogen, or methanol with liquid
nitrogen respectively. Ethereal solvents like THF, and
/
110 or ꢁ98 8C was effected using
/

290
M. Shimizu et al. / Journal of Organometallic Chemistry 686 (2003) 286Á293
/
3.2. Spectral data of 3
1H), 7.30Á
d ꢁ4.0, ꢁ
136.2. IR: nmax 2978, 1379, 1339, 1250, 1140, 1115, 968,
/
7.40 (m, 3H), 7.55Á
/
7.65 (m, 2H). 13C-NMR:
/
/3.6, 24.7, 24.8, 84.2, 127.7, 129.6, 134.1,
3.2.1. (Dimethylphenylsilyl)(methoxy)(4,4,5,5-
tetramethyl-1,3,2-dioxaborolan-2-yl)methane (3aa)
Colorless oil. Rf: 0.26 (hexane/ethyl acetate 9:1). H-
NMR: d 0.36 (s, 3H), 0.38 (s, 3H), 1.17 (s, 6H), 1.20 (s,
846, 820, 785, 733, 700 cmꢁ1. MS: m/z 313 [Mꢀꢀ
/3],
312 [Mꢀꢀ2], 311 [Mꢀꢀ1], 310 [Mꢀ], 309 [Mꢀꢁ
/
/
/1],
1
135. Anal. Calc. for C15H24O2BClSi: C, 57.99; H, 7.79.
Found: C, 57.82; H, 7.84%.
6H), 3.18 (s, 1H), 3.33 (s, 3H), 7.30Á
/
7.42 (m, 3H), 7.57Á
4.1, ꢁ3.7, 24.4, 25.1, 62.6,
/
7.67 (m, 2H). 13C-NMR: d ꢁ
/
/
83.5, 127.5, 129.0, 134.0, 137.7. IR: nmax 3065, 2977,
1455, 1348, 1334, 1239, 1143, 798 cmꢁ1. MS: m/z 306
3.2.6. Bromo(dimethylphenylsilyl)(4,4,5,5-tetramethyl-
1,3,2-dioxaborolan-2-yl)methane (3af)
[Mꢀ], 291 [Mꢀꢁ
Me], 191, 135, 84. FAB HRMS: m/z
/
1
Colorless oil. Rf: 0.48 (hexane/ethyl acetate 9:1). H-
NMR: d 0.48 (s, 6H), 1.16 (s, 6H), 1.18 (s, 6H), 2.54 (s,
Calc. for C16H27BO3Si [Mꢀ]: 306.1823. Found
306.1823.
1H), 7.30Á
d ꢁ3.5, ꢁ
136.4. IR: nmax 2977, 1381, 1330, 1247, 1144, 786 cmꢁ1
MS: m/z 339 [Mꢀꢁ
Me], 275, 135, 83. Anal. Calc. for
/
7.40 (m, 3H), 7.52Á
/
7.62 (m, 2H). 13C-NMR:
/
/3.4, 24.5, 24.6, 84.0, 127.6, 129.4, 133.9,
3.2.2. (Dimethylphenylsilyl)(2-
.
methoxyethoxy)(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-
2-yl)methane (3ab)
Purified by GPC. Colorless oil. Rf: 0.23 (hexane/ethyl
/
C15H24O2BBrSi: C, 50.73; H, 6.81. Found: C, 50.91; H,
7.09%.
1
acetate 10:1). H-NMR: d 0.36 (s, 3H), 0.39 (s, 3H),
1.16, (s, 6H), 1.27 (s, 6H), 3.28Á
/
3.78 (m, 9H), 7.30Á7.65
/
(m, 5H). 13C-NMR: d ꢁ
/
4.1, ꢁ3.8, 24.3, 25.2, 58.9, 72.0,
/
3.2.7. (Dimethylphenylsilyl)(iodo)(4,4,5,5-tetramethyl-
1,3,2-dioxaborolan-2-yl)methane (3ag)
73.7, 83.4, 127.5, 129.0, 134.1, 137.4. IR: nmax 3069,
2978, 1456, 1348, 1330, 1245, 1113, 837 cmꢁ1. MS: m/z
1
Colorless oil. Rf: 0.42 (hexane/ethyl acetate 9:1). H-
NMR: d 0.49 (s, 3H), 0.51 (s, 3H), 1.12 (s, 6H), 1.16 (s,
335 [Mꢀꢁ
/
Me2O], 277, 191, 135, 83. FAB HRMS: m/z
Calc. for C17H28BO4Si [Mꢀ]: 355.1850. Found
355.1845.
/
6H), 2.05 (s, 1H), 7.28Á
13C-NMR: d ꢁ
2.8, ꢁ2.2, 24.3, 24.4, 83.8, 127.7, 129.4,
133.9, 137.0. IR: nmax 2965, 1366, 1153, 1111, 781 cmꢁ1
MS: m/z 402 [Mꢀ], 387 [Mꢀꢁ
Me], 207, 135, 84. Anal.
/
7.40 (m, 3H), 7.50Á7.60 (m, 2H).
/
/
/
.
3.2.3. (Dimethylphenylsilyl)(4,4,5,5-tetramethyl-1,3,2-
dioxaborolan-2-yl)[2-(triethylsilyl)ethoxy]methane
(3ac)
Purified by GPC. Colorless oil. Rf: 0.23 (hexane/ethyl
1
acetate 10: 1). H-NMR: d 0.02 (s, 9H), 0.33 (s, 3H),
/
Calc. for C15H24O2BISi: C, 44.80; H, 6.02. Found: C,
44.81; H, 6.14%.
0.39 (s, 3H), 1.13, (s, 6H), 1.18 (s, 6H), 3.21Á
4H), 4.66 (s, 2H), 7.28Á
7.62 (m, 5H). 13C-NMR: d ꢁ
3.9, ꢁ1.4, 18.3, 24.3, 25.2, 64.9, 71.7, 83.3, 127.5, 128.9,
134.0, 138.0. IR: nmax 2977, 1427, 1381, 1330, 1247,
/
3.65 (m,
3.2.8. (Dimethylphenylsilyl)(4,4,5,5-tetramethyl-1,3,2-
dioxaborolan-2-yl)(trimethylgermyl)methane (3ai)
/
/
1
Colorless oil. Rf: 0.53 (hexane/ethyl acetate 9:1). H-
/
NMR: d 0.13 (s, 9H), 0.33 (s, 3H), 0.35 (s, 3H), 1.09 (s,
1144, 786 cmꢁ1. MS: m/z 377 [Mꢀꢁ
Me], 349, 191, 135,
/
6H), 1.12 (s, 6H), 7.27Á
/
7.37 (m, 3H), 7.52Á7.62 (m, 2H).
/
73. FAB HRMS: m/z Calc. for C20H38BO3Si2 [MHꢀ]:
393.2452. Found 393.2455.
13C-NMR: d ꢁ
/0.3, 0.5, 1.0, 25.0, 25.1, 82.5, 127.4,
128.5, 133.6, 141.2. IR: nmax 2985, 1357, 1316, 1267,
1250, 1148, 1115, 852, 816, 734, 701 cmꢁ1. MS: m/z 379
[Mꢀꢁ
Me], 281, 279, 278, 277, 275. Anal. Calc. for
C18H33O2BGeSi: C, 55.02; H, 8.46. Found: C, 55.32; H,
8.24%.
/
3.2.4. (Dimethylphenylsilyl)(methylthio)(4,4,5,5-
tetramethyl-1,3,2-dioxaborolan-2-yl)methane (3ad)
1
Colorless oil. Rf: 0.30 (hexane/ethyl acetate 9:1). H-
NMR: d 0.43 (s, 3H), 0.44 (s, 3H), 1.16 (s, 6H), 1.19 (s,
6H), 1.82 (s, 1H), 2.12 (s, 3H), 7.30Á
/
7.42 (m, 3H), 7.55Á
/
7.65 (m, 2H). 13C-NMR: d ꢁ
83.5, 127.6, 129.2, 133.9, 137.4. IR: nmax 2980, 1373,
1325, 1249, 1146, 1117, 971, 852, 821, 780, 737, 701
/
3.1, ꢁ2.8, 19.4, 24.7, 24.9,
/
3.2.9. (Methydilphenylsilyl)(4,4,5,5-tetramethyl-1,3,2-
dioxaborolan-2-yl)(trimethylgermyl)methane (3bi)
Colorless needles. M.p. 48.8 8C (dec.). Rf: 0.42
cmꢁ1. MS: m/z 324 [Mꢀꢀ
/
2], 323 [Mꢀꢀ
/
1], 322 [Mꢀ],
(hexane/ethyl acetate 10:1). H-NMR: d 0.08 (s, 9H),
7.65 (m, 10H). 13C-
1
207, 191, 135. Anal. Calc. for C16H27O2BSSi: C, 59.62;
H, 8.44. Found: C, 59.38; H, 8.63%.
0.73 (s, 3H), 1.03 (s, 12H), 7.31Á
/
NMR: d ꢁ2.4, 1.1, 25.0, 25.1, 82.6, 127.3, 127.4, 128.6,
/
128.6, 134.1, 134.5, 139.0, 139.3. IR: nmax 2976, 2906,
1427, 1313, 1252, 1144, 1109, 849, 799, 698 cmꢁ1. MS:
3.2.5. Chloro(dimethylphenylsilyl)(4,4,5,5-tetramethyl-
1,3,2-dioxaborolan-2-yl)methane (3ae)
Colorless oil. Rf: 0.34 (hexane/ethyl acetate 9:1). H-
NMR: d 0.46 (s, 3H), 0.47 (s, 3H), 1.18 (s, 12H), 2.90 (s,
m/z 441 [Mꢀꢁ
/
Me], 341, 237, 135, 83, 73. FAB HRMS:
m/z Calc. for C22H32BGeO2Si [Mꢀꢁ
Me]: 441.1476.
Found 441.1474.
1
/

M. Shimizu et al. / Journal of Organometallic Chemistry 686 (2003) 286Á
/
293
291
3.2.10. (4,4,5,5-Tetramethyl-1,3,2-dioxaborolan-2-
yl)(trimethylgermyl)(triphenylsilyl)methane (3ci)
Colorless needles. M.p. 65.6 8C (dec.). Rf: 0.39
ꢁ
/
2.2, 24.3, 85.1, 127.1, 129.6, 134.8, 135.4. IR: nmax
2976, 1371, 1303, 1267, 1140, 1113, 849 cmꢁ1. FAB MS:
m/z 529 [Mꢀꢀ
/
1], 528 [Mꢀ], 527 [Mꢀꢁ
1], 135. FAB
/
1
(hexane/ethyl acetate 10:1). H-NMR: d 0.01 (s, 9H),
7.67 (m, 15H). 13C-
HRMS: m/z Calc. for C15H23BI2O2Si [Mꢀ]: 527.9650.
Found 527.9655.
0.93 (s, 6H), 1.03 (s, 6H), 7.31Á
/
NMR: d 1.1, 24.9, 25.0, 82.8, 127.4, 128.9, 136.0, 136.8.
IR: nmax 2976, 2908, 1427, 1310, 1264, 1143, 1113, 849,
3.2.14. Dichloro(dimethylphenylsilyl)(4,4,5,5-
tetramethyl-1,3,2-dioxaborolan-2-yl)methane (3an)
Pale yellow oil. Rf: 0.51 (hexane/ethyl acetate 10:1).
788, 700 cmꢁ1. FAB MS: m/z 518 [Mꢀ], 503 [Mꢀꢁ
Me], 135, 83. FAB HRMS: m/z Calc. for
/
C28H37BGeO2Si [Mꢀ]: 518.1868. Found 518.1866.
1H-NMR: d 0.60 (s, 6H), 1.22 (s, 12H), 7.26Á
/
7.70 (m,
5.0, 24.5, 24.6, 85.3, 100.5, 127.5,
129.9, 133.6, 135.0. IR: nmax 2978, 1373, 1319, 1251,
1136, 1110, 970 cmꢁ1. MS: m/z 348 [Mꢀꢀ
4], 347
[Mꢀꢀ3], 346 [Mꢀꢀ2], 345 [Mꢀꢀ1], 344 [Mꢀ], 343
[Mꢀꢁ
5H). 13C-NMR: d ꢁ
/
3.2.11. (Dimethylphenylsilyl)(4,4,5,5-tetramethyl-1,3,2-
dioxaborolan-2-yl)(tributylstannyl)methane (3aj)
/
1
Colorless oil. Rf: 0.53 (hexane/ethyl acetate 9:1). H-
/
/
/
NMR: d 0.13 (s, 1H), 0.31 (s, 3H), 0.33 (s, 3H), 0.70Á
0.88 (m, 6H), 0.85 (t, Jꢂ7.0 Hz, 9H), 1.11 (s, 6H), 1.12
(s, 6H), 1.14Á
/
/
1], 229, 135. HRMS: m/z Calc. for
/
C15H23BCl2O2Si [Mꢀ]: 344.0937. Found 344.0937.
/
1.50 (m, 12H), 7.26Á
/
7.35 (m, 3H), 7.50Á
/
7.60 (m, 2H). 13C-NMR: d 0.5, 11.0, 13.6, 25.0, 25.1,
27.4, 28.9, 82.3, 127.4, 128.4, 133.5, 141.9. IR: nmax 2957,
2930, 1351, 1311, 1294, 1262, 1247, 1146, 1113, 851, 818,
733, 700 cmꢁ1. FAB MS: m/z 564 [Mꢀ], 549 [Mꢀꢁ
3.2.15. Dibromo(dimethylphenylsilyl)(4,4,5,5-
tetramethyl-1,3,2-dioxaborolan-2-yl)methane (3ap)
Pale yellow oil. Rf: 0.48 (hexane/ethyl acetate 10:1).
/
1H-NMR: d 0.65 (s, 6H), 1.25 (s, 12H), 7.35Á
/
7.76 (m,
3.9, 24.4, 85.3, 127.4, 129.9, 134.2,
135.3. IR: nmax 2982, 1470, 1390, 1373, 1315, 1248, 1137,
2],
Me], 191, 135, 83. Anal. Calc. for C18H33O2BSiSn: C,
57.37; H, 9.09. Found: C, 57.65; H, 8.79%.
5H). 13C-NMR: d ꢁ
/
1117, 970 cmꢁ1. MS: m/z 436 [Mꢀꢀ
/
4], 434 [Mꢀꢀ
/
3.2.12. (Dimethylphenylsilyl)(4,4,5,5-tetramethyl-1,3,2-
dioxaborolan-2-yl)(triphenylplumbanyl)methane (3al)
Colorless oil. Rf: 0.39 (hexane/ethyl acetate 10:1). 1H-
432 [Mꢀ], 421, 419, 417, 334, 253, 135. HRMS: m/z
Calc. for C15H23BBr2O2Si [Mꢀ]: 431.9927. Found
431.9934. Anal. Calc. for C15H23BBr2O2Si: C, 41.51;
H, 5.34. Found: C, 41.79; H, 5.30%.
NMR: d 0.39 (s, 3H), 0.51 (s, 3H), 1.09, (s, 12H), 7.43Á
/
7.83 (m, 20H). 13C-NMR: d 0.5, 24.6, 25.1, 82.8, 127.4,
128.0, 128.9, 129.5, 129.7, 129.9, 133.6, 136.9, 137.1,
137.4, 137.9, 141.0, 148.2, 150.9, 151.3, 154.5. IR: nmax
3047, 2976, 1429, 1313, 1263, 1143, 849 cmꢁ1. FAB MS:
m/z 714 [Mꢀ], 191, 135, 83. FAB HRMS: m/z Calc. for
C32H36BO2PbSi [Mꢀ]: 699.2344. Found 699.2343.
3.2.16. [(Chloro)(dimethylphenylsilyl)(4,4,5,5-
tetramethyl-1,3,2-dioxaborolan-2-yl)methyl]benzene
(3at)
Colorless oil. Rf: 0.42 (hexane/ethyl acetate 10:1). 1H-
NMR: d 0.39 (s, 3H), 0.43 (s, 3H), 1.22 (s, 6H), 1.25 (s,
6H), 7.12Á
/
7.44 (m, 10H). 13C-NMR: d ꢁ
/
4.7, ꢁ4.5,
/
3.2.13. Typical procedure of method B for silylborylation
of tetrahalomethanes: synthesis of (dimethylphenyl-
silyl)(diiodo)(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-
yl)methane (3ar)
To a solution of tetraiodomethane (2s, 0.62 g, 1.20
mmol) and (dimethylphenylsilyl)(pinacolato)borane (1a,
0.26 g, 1.00 mmol) in a mixture of THF (5.0 ml) and
24.5, 24.7, 84.4, 125.3, 126.3, 127.0, 127.5, 129.4, 135.2,
135.3, 139.0, 139.3. IR: nmax 2978, 2931, 1495, 1427,
1373, 1323, 1269, 1141, 1114, 974 cmꢁ1. MS: m/z 388
[Mꢀꢀ
/
2], 387 [Mꢀꢀ1], 386 [Mꢀ], 286, 244, 135.
/
HRMS: m/z Calc. for C21H28BClO2Si [Mꢀ]: 386.1640.
Found 386.1646. Anal. Calc. for C21H28BClO2Si: C,
65.21; H, 7.30. Found: C, 64.94; H, 7.23%.
diethyl ether (2.5 ml) at ꢁ
M, 0.77 ml, 1.20 mmol). The reaction mixture was
stirred for 10 min at ꢁ110 8C and then allowed to
/
110 8C was added BuLi (1.56
3.3. (Dimethylphenylsilyl)(4,4,5,5-tetramethyl-1,3,2-
dioxaborolan-2-
yl)(tributylstannyl)(trimethylgermyl)methane (4)
/
gradually warm to room temperature before quenching
with saturated aqueous NH4Cl solution (0.5 ml). The
resulting mixture was diluted with diethyl ether (25 ml),
and then washed with water (10 ml). The organic layer
was dried over anhydrous magnesium sulfate and
concentrated in vacuo. Purification of the crude product
by column chromatography on silica gel (hexane/ethyl
acetate 9:1) afforded 3ar (0.10 g, 19% yield) as a
colorless oil.
To a solution of 3ak (0.41 g, 0.73 mmol) in THF (5
ml) was added LDA (0.76 mmol) in THF at room
temperature and the resulting mixture was heated at
60 8C for 1.5 h. Bromotrimethylgermane (0.21 ml, 1.6
mmol) was added to the mixture at 60 8C and stirred for
1 h at 60 8C before quenching with saturated aqueous
NH4Cl solution. Usual workup followed by purification
with silica gel column chromatography (hexane only)
gave 4 (0.17 g, 34% yield).
1
Rf: 0.47 (hexane/ethyl acetate 10:1). H-NMR: d 0.70
(s, 6H), 1.27 (s, 12H), 7.36Á
7.81 (m, 5H). 13C-NMR: d
/

292
M. Shimizu et al. / Journal of Organometallic Chemistry 686 (2003) 286Á
/
293
1
Colorless oil. Rf: 0.28 (hexane). H-NMR: d 0.11 (s,
9H), 0.41 (s, 3H), 0.42 (s, 3H), 0.74Á0.96 (m, 6H), 0.87
(t, Jꢂ6.9 Hz, 9H), 1.23 (s, 12H), 1.2Á1.5 (m, 12H),
7.25Á7.34 (m, 3H), 7.58Á
7.68 (m, 2H). 13C-NMR: d 2.4,
organotetrametallic reagent for asymmetric synthesis of
a quaternary carbon.
/
/
/
/
/
2.5, 3.8, 13.2, 13.6, 25.5, 27.7, 29.3, 82.5, 127.2, 128.4,
134.5, 142.5. IR: nmax 2958, 2926, 1284, 1259, 1141, 855,
817 cmꢁ1. Anal. Calc. for C30H59O2BGeSiSn: C, 52.83;
H, 8.72. Found: C, 52.67; H, 8.80%.
5. Supplementary material
Crystallographic data for the structural analysis has
been deposited with the Cambridge Crystallographic
Data Centre, CCDC No. 207409 for compound 5.
Copies of this information may be obtained free of
charge from The Director, CCDC, 12 Union Road,
3.4. (Dimethylphenylsilyl)(4,4,5,5-tetramethyl-1,3,2-
dioxaborolan-2-yl)(trimethylgermyl)
(trimethylstannyl)methane (5)
Cambridge, CB2 1EZ UK (Fax: ꢀ44-1223-336033 or e-
/
mail: deposit@ccdc.cam.ac.uk or www: http://
www.ccdc.cam.ac.uk).
To a suspension of t-BuOK (0.25 g, 2.25 mmol) in
THF (3 ml) was added BuLi (1.56 M in hexane, 1.44 ml,
2.25 mmol) at ꢁ
mmol) in THF (0.5 ml) was added to the solution at ꢁ
78 8C and the resulting mixture was allowed to warm to
/
78 8C. A solution of 3aj (0.15 g, 0.45
/
Acknowledgements
ꢁ
/
40 8C over a period of 7 h. The mixture was cooled to
This work was supported by Grant-in-Aids for COE
Research on Elements Science, No. 12CE2005 and for
Young Scientists (B), No. 14750678 from Ministry of
Education, Culture, Sports, Science, and Technology,
Japan. Japan Society for the Promotion of Science
(JSPS) is highly acknowledged for the financial support
to T.K. as a predoctoral research student.
ꢁ
/
78 8C, treated with chlorotrimethylstannane (1 M in
THF, 2.25 ml, 2.25 mmol), and allowed to warm to
room temperature before quenching with saturated
aqueous NH4Cl solution. Usual workup followed by
purification with silica gel column chromatography
afforded 5 (0.19 g, 81% yield).
Colorless needles. M.p. 130 8C (dec). 1H-NMR: d
0.03 (s, 9H), 0.14 (s, 9H), 0.42 (s, 3H), 0.43 (s, 3H), 1.23
(s, 12H), 7.26Á
NMR: d ꢁ4.2, 1.9, 2.2, 3.5, 25.4, 25.5, 82.5, 127.3,
/
7.34 (m, 3H), 7.58Á
7.68 (m, 2H). 13C-
/
References
/
128.5, 134.4, 142.1. IR: nmax 2928, 2855, 1461, 1379,
1282, 1260, 1141, 857, 820 cmꢁ1. Anal. Calc. for
C21H41O2BGeSiSn: C, 45.38; H, 7.44. Found: C,
45.09; H, 7.17%.
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/
(b) Review on three metal(metalloid)s-substituted methanes: V.D.
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/
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/
503.;
Isolated by column chromatography on silica gel
1
(hexane). Colorless oil. Rf: 0.43 (hexane). H-NMR: d
/
ꢁ
/
0.25 (s, 1H), 0.02 (s, 9H), 0.13 (s, 9H), 0.31 (s, 3H),
0.32 (s, 3H), 7.27Á7.36 (m, 3H), 7.44Á
7.53 (m, 2H). 13C-
NMR: d ꢁ5.9, ꢁ2.9, 1.2, 1.5, 2.7, 127.6, 128.5, 133.4,
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/
/
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/
[2] Selected examples of bis-, tris-, or tetrakis(boryl)methanes: (a)
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813, 769, 733, 700 cmꢁ1. Anal. Calc. for C15H30GeSiSn:
C, 41.92; H, 7.04. Found: C, 41.66; H, 6.80%.
6541Á
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/
4. Summary
/
We have demonstrated that heteroatom-substituted
boryl(silyl)methanes could be prepared efficiently by a
reaction with silylboranes of halomethyllithiums sub-
stituted by such heteroatoms as chalcogens, halogens,
germanium, lead, silicon, and tin. Moreover, we have
synthesized B-, Ge-, Si-, and Sn-substituted methanes
for the first time, which may act as a versatile C1
/
/
67.
(g) Bis-, tris-, or tetrakis(silyl)methanes: R.L. Merker, M.J. Scott,
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2244.
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/
/
/
/866.
¨
(l) I. Fleming, C.D. Floyd, J. Chem. Soc., Perkin 1, (1981) 969Á
/
/
976.
/
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/
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/
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¨
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/
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/
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/
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/
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(w) J.A. Soderquist, B. Santiago, I. Rivera, Tetrahedron Lett., 31
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(x) E.J. Corey, A. Guzman-Perez, S.E. Lazerwith, J. Am. Chem.
Soc., 119 (1997) 11769Á11776.
(y) G. Zou, Y.K. Reddy, J.R. Falck, Tetrahedron Lett., 42 (2001)
7213Á7215.
Silyl(stannyl)methanes: (z) K. Itami, M. Mineno, T. Kamei, J.-i.
Yoshida, Org. Lett., 4 (2002) 3635Á3638.
[3] (a) P. Knochel, J. Am. Chem. Soc. 112 (1990) 7431Á
(b) M.J. Rozema, A. Sidduri, P. Knochel, J. Org. Chem. 57 (1992)
1956Á1958.
[4] T. Watanabe, N. Miyaura, A. Suzuki, J. Organomet. Chem. 444
(1993) C1ÁC3.
/1010.
[11] A small amount of [(propan-1,3-diolato)boryl](triphenylger-
myl)(triphenylplumbyl)(triphenylstannyl)methane was reportedly
isolated, but not fully characterized. See Ref. 2d.
/
[12] Crystal data of 5: colorless plates: C23H41BGeO2SiSn, Mꢂ
579.74, monoclinic, space group P2(1)/n, aꢂ9.8162(10), bꢂ
99.577(2)8, Vꢂ2708.1(5)
1.777 g cm3, F(0 0 0)ꢂ
1480, Tꢂ293 K,
60.128, Rꢂ0.070, Rwꢂ0.23,
1.095; Number of dataꢂ21 140, Number of
7521 (Rint 0.0733).
/
/
/
/
˚
15.7264(15), cꢂ
/
17.7906(18) A, bꢂ
/
/
/
3
˚
/
A , Zꢂ
l(MoÁKa)ꢂ
Goodness of fitꢂ
unique dataꢂ
/
5, Dcalc
ꢂ
/
/
˚
/
/
0.71073 A, 2qmaxꢂ
/
/
/
/
/
/
/7433;
/
ꢂ/
[13] J. Emsley, The Elements, third ed., Oxford University Press,
Oxford, 1998, p. 292.
[14] M. Suginome, T. Matsuda, Y. Ito, Organometallics 19 (2000)
/
/
4647Á4649.
/