Synthesis and reactions of stannole anions

Article abstract of DOI:10.1002/ejic.200600629

The synthesis of stannole anions bearing various substituents on the tin atom is described. The reduction of hexaphenylstannole by the proper amount of lithium gave 1,2,3,4,5-pentaphenylstannole anion 1. The reaction of 1 with 1,n-dihaloalkanes (n = 1, 3,

Full text of DOI:10.1002/ejic.200600629

FULL PAPER
DOI: 10.1002/ejic.200600629
Synthesis and Reactions of Stannole Anions
Ryuta Haga,[a] Masaichi Saito,*[a] and Michikazu Yoshioka[a]
Keywords: Anions / Aromaticity / Lithium / Metallacycles / Tin
The synthesis of stannole anions bearing various substituents
on the tin atom is described. The reduction of hexaphen-
ylstannole by the proper amount of lithium gave 1,2,3,4,5-
pentaphenylstannole anion 1. The reaction of 1 with 1,n-di-
haloalkanes (n = 1, 3, 4, 5, 6) gave the corresponding 1,n-
bis(1-stannacyclopentadien-1-yl)alkanes. In contrast, the re-
action of 1 with 1,2-dihaloalkanes gave the 1,1Ј-bistannole.
The reactions of stannole dianion 3 with an equimolar
amount of bulky alkyl, aryl, silyl, and stannyl halides gave
the corresponding stannole anions.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2007)
2 with lithium (Scheme 1).[8] However, it was difficult to
manipulate the stoichiometry or reaction conditions to pro-
Introduction
Metalolyl anions of heavier group 14 elements have re- duce stannole anion 1 without stannole dianion 3 from the
ceived considerable attention in view of their potential aro- 1,1Ј-bistannole 2 because no sufficient amount of 2 could
matic character as heavier congeners of the cyclopen- be obtained in several steps from diphenylacetylene.[7–9] To
tadienyl anion,[1] since the first report on the generation of investigate the chemistry of stannole anions, alternative
a silole anion in 1958.[2] Over the past few decades, silole methods for the synthesis of stannole anions using an easily
and germole anions have already been synthesized by de- accessible starting material were required. Very recently, we
protonation, dehalogenation, or transmetallation of the reported an efficient synthesis of the first tin-containing
corresponding metaloles, and their structures have been dis- carbocyclic aromatic stannole dianion 3 by the reaction of
cussed extensively by NMR, or X-ray structural analy- hexaphenylstannole (4) with excess lithium and discussed
sis.[3–6] Boudjouk reported the first NMR characterization its aromaticity by the aid of NMR studies, X-ray analysis
of a silole anion.[5] The negative charge was concluded to and theoretical calculations (Scheme 2).[10,11] Furthermore,
delocalize in the silole ring. In contrast to Boudjouk’s silole we reported the oxidation of the stannole dianion 3 to the
anion, in some silole and germole anions, the negative 1,1Ј-bistannole dianion 5 as a novel method for the synthe-
charge localizes on the central atom, as evidenced by sis of a stannole anion.[12]
NMR[4] and/or X-ray structural analyses.[6] Although re-
Herein we describe novel methods for the preparation of
markable progress has been made on silicon and germa- stannole anions: (i) the reduction of hexaphenylstannole (4)
nium analogues, no stannole anion had been reported be- with the proper amount of lithium, and (ii) the reaction of
fore we undertook a study on such species a few years the stannole dianion 3 with various halogen reagents. NMR
ago.[7] First, we reported the synthesis of 1,2,3,4,5-penta- studies on stannole anions and their reactions are also re-
phenylstannole anion 1 by the reaction of 1,1Ј-bistannole ported.
Scheme 1.
Results and Discussion
[a] Department of Chemistry, Graduate School of Science and
Synthesis and Reactions of 1,2,3,4,5-Pentaphenylstannole
Anion (1)
Engineering, Saitama University
Shimo-okubo, Sakura-ku, Saitama-City, Saitama,
338-8570 Japan
Fax: +81-48-858-3698
E-mail: masaichi@chem.saitama-u.ac.jp
Supporting information for this article is available on the
WWW under http://www.eurjic.org or from the author.
Synthesis of Stannole Anion 1 from Hexaphenylstannole 4
Treatment of hexaphenylstannole (4) with 3 equiv. of lith-
ium[13] in THF at room temperature gave a dark-red solu-
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R. Haga, M. Saito, M. Yoshioka
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Scheme 2.
tion, suggesting the formation of an anion species. After stannole dianion 3, recrystallization of the reaction mixture
stirring the reaction mixture for 6 h, addition of excess to purify the stannole anion 1 was not successful. Thus, the
methyl iodide to this reaction mixture gave 1-methyl- degree of aromaticity of 1 using the 7Li chemical shift could
1,2,3,4,5-pentaphenylstannole (6)[8] in 55% yield, indicating not be estimated because intermolecular exchange of lith-
the effective formation of pentaphenylstannole anion 1 ium cations between 1 and phenyllithium could not be sup-
from 4 (Scheme 3). Treatment of 1 thus obtained with pressed. Although the yield of 1 could not be estimated, the
1.8 equiv. of chlorotriphenylstannane at –100 °C gave 1-tri- yields of the trapping products 6 and 7, and the NMR spec-
phenylstannyl-1,2,3,4,5-pentaphenylstannole (7) in 66% tra of 1, especially the 119Sn NMR spectrum, suggest that
yield.
the generation efficiency should be very high.
Reaction of Stannole Anion 1 with Dihaloalkanes
Connecting two stannole skeletons with a hydrocarbon
chain is a subject of interest because two stannole rings
could face each other to reveal unique electronic properties
resulting from through-space π-facial interactions.[15]
Reaction of
1 with excess dichloromethane gave
bis(1,2,3,4,5-pentaphenyl-1-stannacyclopentadien-1-yl)meth-
ane (8) in 79% yield (Scheme 4). Compound 8 was proved
to have a symmetrical structure having an Sn–C–Sn skel-
eton by J(Sn–Sn) of 284 Hz in the 119Sn NMR spectrum.
2
Scheme 3.
The bis(stannoles) 9–12, whose two stannole rings are con-
nected by a saturated hydrocarbon chain were also synthe-
sized by the reaction of 1 with 0.5 equiv. of the correspond-
ing 1,n-dibromoalkanes (n = 3–6) in moderate yields
(Scheme 4). The structures of all the bis(stannoles) thus ob-
tained were determined by NMR spectroscopy and elemen-
tal analysis. These results are similar to the formation of
1,3-bis(triphenylstannyl)propane from triphenylstannyl
anion and 1,3-dibromopropane.[16]
The reaction of 4 with 3 equiv. of lithium was monitored
by NMR spectroscopy. In the 119Sn NMR spectrum, only
one signal was observed at δ = –28.6 ppm in the same re-
gion as that in the previous synthesis from the 1,1Ј-bistan-
nole 2,[8,9] suggesting the formation of 1. In contrast to the
reduction of 1,1Ј-bistannole 2 to form both stannole anion
1 and the stannole dianion 3, the 13C NMR spectrum re-
vealed the clean formation of the stannole anion 1. Al-
though some unidentifiable signals were observed, the sig-
nals due to the stannole anion 1 could be completely as-
signed by the comparison of the chart of the mixture of the
stannole anion 1 and the stannole dianion 3 obtained by
the reduction of the 1,1Ј-bistannole 2.[14] A phenyl group of
hexaphenylstannole (4) was eliminated probably as phen-
yllithium, as in the reduction of hexaphenylstannole (4) to
form the stannole dianion 3,[10] although the signals due to
phenyllithium were not observed in the reaction mixture.
The signal assignable to the α-carbon atom in the five-mem-
bered ring was observed at δ = 176.5 ppm, judging from the
large tin–carbon coupling constant of about 171 Hz. The
low-field resonance of the α-carbon atom could be ex-
plained by paramagnetic contribution of a tin–carbon bond
as was observed in the stannole dianion 3.[10] In the 7Li
NMR spectrum, a single resonance was observed at δ =
On the other hand, reactions of the stannole anion 1 with
1,2-dihaloethanes gave bi(1,2,3,4,5-pentaphenyl-1-stanna-
cyclopentadien-1-yl) (2)[8,9] in about 70% yields. Oxidation
–0.64 ppm. In contrast to the successful isolation of the Scheme 4.
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Synthesis and Reactions of Stannole Anions
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Scheme 5.
of the stannole anion 1 by air also gave 2 in high yield chromophore. Namely, the absorption is derived from the
(Scheme 5). The formation of 2 can be reasonably interpre- π–π* transition of the stannole ring.[18] The π–π* transi-
ted in terms of the dimerization of stannole radical 13 re- tions of group 14 metaloles are observed in the same region
sulting from oxidation of 1 by air or dihaloethanes. Evi- at about 360 nm because the contribution of the diene moi-
dently, dihaloethanes function as one-electron oxidants in ety to both HOMO and LUMO is more predominant than
these reactions.[17]
that of the metal moiety.[18] This spectral feature suggests
no significant through-space interaction between the two
stannole rings in solution. Compound 14 displays two
shoulder absorption bands at about 310 and 370 nm. The
latter band can be assigned to π–π* transition of the stan-
nole ring. The shorter band can be assigned to the transi-
tion of σ(Sn–Sn) to π* of the diene moiety because the cor-
responding band is absent in other bis(stannoles), 8–12 with
no tin–tin bond.[9]
Reaction of Stannole Anion 1 with Di-tert-
butyldichlorostannane
Reaction of the stannole anion 1 with di-tert-butyldichlo-
rostannane at –100 °C gave di-tert-butylbis(1,2,3,4,5-penta-
phenyl-1-stannacyclopentadien-1-yl)stannane (14) in 49%
yield (Scheme 6). In the 119Sn NMR spectrum, two signals
are observed with an intensity ratio of 2:1, resulting from
the two equivalent terminal and one central tin atoms,
respectively.
Table 1. UV/Vis absorptions of stannole 4 and bis(stannoles) 8–12,
14 in CH2Cl2.
Compound
λmax/nm (ε)
4
355 (12000)
359 (20000)
353 (10600)
353 (8800)
353 (16500)
349 (4100)
315 (12000) 373 (6800)
8 (n = 1)
9 (n = 3)
10 (n = 4)
11 (n = 5)
12 (n = 6)
14
Scheme 6.
Photophysical Properties of Bis(stannoles) 8–12 and 14
Synthesis of Stannole Monoanions from Stannole Dianion 3
We examined the photophysical properties of the newly
obtained bis(stannoles) 8–12 and 14 whose two stannole
rings are connected by a saturated hydrocarbon or a stannyl
chain. UV/Vis absorption spectra for 4,[16] 8–12, and 14 are
Alkylation of Stannole Dianion 3
Because the reaction of 3 with methyl iodide gave 1,1-
listed in Table 1. The absorption maxima of 8–12 appear at dimethylstannole,[8] tert-butyl chloride was chosen as a
almost the same wavelength as that of 4, reflecting the same bulkier alkylating reagent than methyl iodide.[19] When
Scheme 7.
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1 equiv. of tert-butyl chloride was added to a diethyl ether
We examined the synthesis of the stannole anions 21 and
solution of the stannole dianion 3, the color of the reaction 22 having an m-terphenyl group, ArЈ = C6H3-2,6-Mes2
mixture changed from deep red to bright red. By treatment (Mes = C6H3-2,4,6-Me3) and ArЈЈ = C6H3-2,6-Tip2 (Tip =
of the reaction mixture with methyl iodide, the 1-tert-butyl- C6H3-2,4,6-iPr3), respectively, as a more bulky group than
1-methylstannole 15[19] was obtained in 55% yield, suggest- a Tip group on the tin atom (Scheme 9). The NMR spectra
ing the formation of the stannole anion 16 bearing a tert- of these reaction mixtures suggest the formation of 21 or
butyl group on the tin atom (Scheme 7). The formation of 22 (vide infra), although trapping of 21 and 22 with appro-
16 from 3 is reasonably explained by an electron-transfer priate reagents was not successful.
mechanism, as observed in the reaction of the tributylstan-
nyl anion with tert-butyl halides.[20] The reaction of 3 with
tert-butyl chloride followed by exposure of the reaction
mixture to air gave the 1,1Ј-bistannole 17[8,9] in 27% yield.
The formation of 17 is interpreted in terms of the dimeriza-
tion of the 1-tert-butylstannole radical resulting from the
oxidation of 16, as was observed in the oxidation of penta-
phenylstannole anion 1 (Scheme 5).
Scheme 9.
Arylation of Stannole Dianion 3
The formation of 19 from 3 can be also explained by an
electron-transfer mechanism, as observed in the reaction of
3 with tert-butyl chloride (Scheme 7) because electrophilic
substitution reactions rarely occur in simple aryl halides.
Next we examined the synthesis of 1-arylstannole anions
by the reaction of the stannole dianion 3 with aryl halides.
Reactions with small aryl halides, however, became compli-
cated because of the formation of mono- and disubstituted
products. Thus, bromo-2,4,6-triisopropylbenzene was cho-
Silylation or Stannylation of Stannole Dianion 3
sen as a bulky aryl halide. On treatment of the stannole
dianion 3 with 1 equiv. of 1-bromo-2,4,6-triisopropylben-
On treatment of the stannole dianion 3 with 1 equiv. of
zene in diethyl ether at room temperature, the color of the chlorotriisopropylsilane in diethyl ether at room tempera-
reaction mixture remained deep red, indicating the existence ture, the color of the reaction mixture remained deep red.
of an anion species. After addition of methyl iodide to the The NMR spectra of the reaction mixture reveal the pres-
reaction solution, the color of the reaction mixture changed ence of only one species which can be assigned to the 1-
to green. After usual workup, the 1-methyl-1-(2,4,6-triiso- silyl-substituted stannole anion 23 (Scheme 10). Trapping
propylphenyl)stannole 18 was obtained in 29% yield, indi- of 23 by methyl iodide, however, gave a complex mixture.
cating the formation of the intermediary stannole anion 19 The reaction of the stannole dianion 3 with 1 equiv. of chlo-
bearing a 2,4,6-triisopropylphenyl group on the tin atom rotriphenylstannane in diethyl ether at room temperature
(Scheme 8). Treatment of 3 with 1-bromo-2,4,6-triisopro- gave a dark-brown solution. The formation of the 1-stan-
pylbenzene followed by exposure of the reaction mixture to nyl-substituted stannole anion 24 was evidenced by a chem-
air gave a complex mixture without the formation of the ical trapping reaction. Addition of methyl iodide or chloro-
expected 1,1Ј-bistannole 20. The dimerization of the inter- triphenylstannane to the solution of 24 gave the 1-methyl-
mediary stannole radical generated by oxidation of 19 is 1-(triphenylstannyl)stannole 25 and the 1,1-bis(triphenyl-
suppressed due to the steric congestion around the tin stannyl)stannole 26 in 47 and 39% yields, respectively
atom, preventing the formation of 20.
(Scheme 10).
Scheme 8.
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Synthesis and Reactions of Stannole Anions
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Scheme 10.
NMR Studies of the Newly Obtained Stannole Anions
tion efficiency of 16 is relatively high, although the isolation
of 16 by recrystallization was not successful. The resonance
is at lower field than that of hexaphenylstannole (4) (δ =
–88 ppm) or pentaphenylstannole anion 1 (δ = –28.6 ppm).
The 119Sn NMR signal of the stannyl anion (tBu2HSn–
SntBu2Li) appears at low field (δ = 107.8 ppm in D2O/
THF).[21] Thus, the low-field shift of the stannole anion 16
The structure in solution of the stannole anions was charac-
terized by 1H, 13C, 119Sn and 7Li NMR spectroscopy
(Table 2). In the 119Sn NMR spectra, there appears only
one signal assignable to the 1-tert-butyl-substituted stan-
nole anion 16 at δ = 30.4 ppm, suggesting that the genera-
7
Table 2. Selected 13C, 119Sn and Li NMR chemical shifts of stannole anions (ppm).
[a] Not identified.
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can be explained by the substituent effect of the tert-butyl be also achieved. The formation of the anions was clearly
group on the tin atom. On the other hand, the 119Sn NMR evidenced by NMR analysis and chemical trapping reac-
7
signals of the stannole anions 19, 21 and 22, bearing an tions. The Li NMR signals of these stannole anions are
aryl group on the tin atom are observed at δ = –49.6 (Ar = observed at δ ≈ 0 ppm. The aromaticity of the newly ob-
Tip), –50.2 (ArЈ = C6H3-2,6-Mes2) and –47.1 (ArЈЈ = C6H3- tained stannole anions can not be presently discussed by
2,6-Tip2) ppm in the region similar to that of pentaphen- using 7Li NMR spectroscopy because of the involvement of
ylstannole anion 1. Although the isolation of 19, 21 and 22 exchange of lithium cations as well as a small possibility of
by recrystallization was not successful, the 119Sn NMR sig- η5-coordination of a lithium cation to the stannole anion.
nals due to 19, 21 and 22 were major in each reaction mix-
ture. Thus, the generation efficiency of 19, 21 and 22 was
Experimental Section
estimated to be relatively high. The signal assignable to 1-
silyl-substituted stannole anion 23 was observed at δ =
–218 ppm with a coupling constant of 380 Hz resulting
from a tin–silicon bond. The high-field resonance is charac-
teristic of silyl-substituted stannanes.[22] Although the isola-
General Procedures: All experiments were performed under argon
using a usual glass apparatus or a glovebox. THF, diethyl ether and
[D6]benzene were distilled from sodium/benzophenone or a potas-
sium mirror. 1H (400 MHz) and 13C (101 MHz) NMR spectra were
tion of 23 by recrystallization was not successful, the gener- recorded with a Bruker AM-400 or a Bruker DRX-400 spectrome-
ter in CDCl3 or a mixture of THF or diethyl ether and [D6]benzene.
ation efficiency of 23 was estimated to be very high, judging
from the clean 119Sn, 13C, and 1H NMR spectra of the reac-
tion mixture. The 119Sn NMR spectrum of the 1-stannyl-
substituted stannole anion 24 reveals two signals at δ =
–98.7 and –240.5 ppm, assignable to the triphenylstannyl
and the stannole moieties, respectively. Each signal has a
coupling constant of about 3800 Hz resulting from a tin–
tin bond. Although hexaphenyldistannane was also gener-
ated in the reaction mixture as a minor product, probably
7
119Sn (149 MHz) and Li (156 MHz) NMR spectra were recorded
with a Bruker DRX-400 spectrometer in CDCl3 or a mixture of
THF or diethyl ether and [D6]benzene. Wet column chromatog-
raphy (WCC) was carried out with Kanto silica gel 60N. Prepara-
tive gel permeation chromatography (GPC) was carried out with
an LC-918 (Japan Analytical Ind. Co., Ltd.) with JAIGEL-1H
and -2H columns with chloroform as the eluent. All melting points
were determined with a Mitamura Riken Kogyo MEL-TEMP ap-
paratus and are uncorrected. Elemental analyses were carried out
because stannole dianion 3 functions as a reductant for tri- at the Microanalytical Laboratry of Molecular Analysis and Life
Science Center, Saitama University.
phenylstannyl chloride, the generation efficiency of 24 was
estimated to be relatively high.
Synthesis of 1,2,3,4,5-Pentaphenylstannole Anion (1) from
1,1,2,3,4,5-Hexaphenylstannole (4): A THF (4 mL) solution of
The 13C NMR signals due to 16, 19, 23 and 24 could be
assigned completely. In particular, a characteristic low-field hexaphenylstannole (4) (370 mg, 0.59 mmol) was treated with lith-
ium (10 mg, 1.45 mmol) at room temperature. After the reaction
mixture was stirred for 6 h, an aliquot (1.0 mL) of the reaction
mixture was placed in an NMR tube with [D6]benzene (0.2 mL)
and the tube was degassed by freeze-pump-thaw cycles and sealed.
signal assignable to the α-carbon atom in 16, 19 and 24 was
observed at δ ≈ 170 ppm with a large tin–carbon coupling
constant of about 90–150 Hz, as was observed in the stan-
nole dianion 3 and pentaphenylstannole anion 1. Interest-
ingly, the α-carbon atom of 23 (δ = 156.0 ppm), assigned
by a large tin–carbon coupling constant of about 190 Hz,
appears at higher field than those of other stannole anions,
probably due to the effect of the silyl group on the tin atom.
The 13C NMR signals due to the α-carbon atom of 21 and
1
1: H NMR (THF/C6D6): δ = 6.45–6.49 (m, 2 H), 6.55–6.58 (m, 2
H), 6.61–6.67 (m, 7 H), 6.70–6.74 (m, 4 H), 6.75–6.78 (m, 6 H),
6.86–6.90 (m, 3 H), 7.71–7.74 (m, 1 H) ppm. 13C NMR (THF/
C6D6): δ = 121.36 (d), 123.51 (d), 124.10 (d), 126.44 (d), 126.56 (d),
126.59 (d), 128.54 (d), 131.58 (d), 138.66 (d), 145.59 (s), 150.24 (s),
150.66 (s, JC,Sn = 33 Hz), 161.96 (s), 176.47 (s, JC,Sn = 171 Hz)
7
22 could be observed at δ = 170.34 ppm for 21 and δ = ppm. 119Sn NMR (THF/C6D6): δ = –28.6 ppm. Li NMR (THF/
170.33 ppm for 22. Other signals in the 13C NMR spectra,
C6D6): δ = –0.64 ppm.
however, are too complicated to be assigned, probably due
to steric congestion around the tin atom. The Li NMR
Reaction of Pentaphenylstannole Anion 1 with Methyl Iodide: To a
THF (5 mL) solution of 1 prepared from 4 (148 mg, 0.235 mmol)
7
signals of all the stannole anions are observed at δ ≈ 0 ppm. and lithium (4 mg, 0.61 mmol) was added an excess amount of
methyl iodide (1.0 mL, 1.61 mmol) at room temperature. After re-
moval of volatile substances, the residue was subjected to column
chromatography (hexane/ethyl acetate, 10:1) to afford 1-methyl-
Conclusions
1,2,3,4,5-pentaphenylstannole (6) (80 mg, 0.13 mmol, 55%). 6:
M.p. 139–140 °C (decomp.) (CH2Cl2
+
MeOH). 1H NMR
We have succeeded in an efficient synthesis of pentaphen-
ylstannole anion 1 by the reaction of hexaphenylstannole
(4) with 3 equiv. of lithium. The stannole anion 1 reacted
with 1,n-dihaloalkanes (n = 1, 3, 4, 5 and 6) to give the
corresponding adducts, as do common organostannyl
(CDCl3): δ = 0.86 (s, JH,Sn = 56 Hz, 3 H), 6.79–6.88 (m, 8 H), 6.94–
7.06 (m, 12 H), 7.34–7.41 (m, 3 H), 7.51–7.67 (m, 2 H) ppm. 13C
NMR (CDCl3): δ = –9.06 (q), 125.19 (d), 125.77 (d), 127.30 (d),
127.80 (d), 128.76 (d), 129.15 (d), 129.20 (d), 130.29 (d), 136.45 (d),
139.50 (s), 140.71 (s), 142.55 (s), 143.62 (s), 154.59 (s) ppm. 119Sn
anions. On the other hand, 1,2-dihaloethanes reacted with NMR (CDCl3): δ = –38.8 ppm. C38H34Sn (609.42): calcd. C 74.10,
H 4.97; found C 73.84, H 4.96.
1 as one-electron oxidants. The UV/Vis spectra of the newly
obtained bis(stannoles) reveal no significant interaction be-
tween the two stannole rings in solution. The synthesis of
Reaction of Pentaphenylstannole Anion 1 with Chlorotriphenylstan-
nane: To a THF (4 mL) solution of 1 prepared from 4 (178 mg,
a variety of stannole anions from stannole dianion 3 could 0.28 mmol) and lithium (6 mg, 0.85 mmol) was added chlorotri-
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Synthesis and Reactions of Stannole Anions
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phenylstannane (202 mg, 0.52 mmol) at –100 °C. After being
warmed to room temperature, the reaction mixture was stirred
overnight. After removal of volatile substances, the residue was
chromatographed (hexane/ethyl acetate, 10:1) to give 1,2,3,4,5-
pentaphenyl-1-(triphenylstannyl)stannole (7) (169 mg, 0.19 mmol,
66%). 7: M.p. 189 °C (decomp.). 1H NMR (CDCl3): δ = 6.73–6.84
(m, 8 H), 6.85–6.92 (m, 6 H), 6.94–7.00 (m, 6 H), 7.25–7.38 (m, 12
H), 7.40–7.53 (m, 8 H) ppm. 13C NMR (CDCl3): δ = 125.18 (d),
125.79 (d), 127.30 (d), 127.77 (d), 128.76 (d), 128.92 (d), 128.96 (d),
129.00 (d), 129.15 (d), 129.54 (d, JC,Sn = 21 Hz), 130.35 (d), 137.38
(d, JC,Sn = 9, 41 Hz), 136.15 (s), 140.80 (s), 142.57 (s), 146.97 (s),
142.84 (s, JC,Sn = 45 Hz), 144.21 (s, JC,Sn = 390, 408 Hz), 154.69 (s,
JC,Sn = 81 Hz) ppm. 119Sn NMR (CDCl3): δ = –47.3 ppm.
C72H58Sn2 (1160.70): calcd. C 74.51, H 5.04; found C 74.00, H
5.09.
Reaction of Pentaphenylstannole Anion 1 with 1,5-Dibromopentane:
1,5-Dibromopentane (0.046 mL, 0.35 mmol) was added to a THF
(5 mL) solution of 1 prepared from 4 (430 mg, 0.68 mmol) and lith-
ium (14 mg, 2.0 mmol) at room temperature. After removal of vola-
tile substances, the residue was subjected to GPC to afford 1,5-
bis(1,2,3,4,5-pentaphenyl-1-stannacyclopentadienyl)pentane (11)
(152 mg, 0.13 mmol, 38%). 11: M.p. 85–87 °C (decomp.). 1H NMR
(CDCl3): δ = 1.31–1.43 (m, 2 H), 1.43–1.58 (m, 4 H), 1.58–1.77 (m,
4 H), 6.63–6.84 (m, 16 H), 6.84–7.00 (m, 24 H), 7.29–7.42 (m, 6
H), 7.42–7.63 (m, 4 H) ppm. 13C NMR (CDCl3): δ = 13.27 (t,
154.23 (s) ppm. 119Sn NMR (CDCl3): δ = –125.0 (1JSn,Sn
=
3573 Hz), –111.5 (1JSn,Sn = 3573 Hz) ppm. C52H40Sn2 (902.32):
calcd. C 69.22, H 4.47; found C 68.81, H 4.36.
3
2
1JC,Sn = 355, 372 Hz), 26.26 (t, JC,Sn = 24 Hz), 37.98 (t, JC,Sn
=
Reaction of Pentaphenylstannole Anion 1 with Dichloromethane: To
a THF (5 mL) solution of 1 prepared from 4 (250 mg, 0.40 mmol)
and lithium (7 mg, 1.05 mmol) was added excess dichloromethane
(5 mL, 79 mmol) at room temperature. After removal of volatile
substances, the residue was chromatographed (hexane/ethyl acetate,
10:1) to give bis(1,2,3,4,5-pentaphenyl-1-stannacyclopentadienyl)-
methane (8) (88 mg, 0.079 mmol, conv. 79%). The starting 4 was
recovered in 50% yield. 8: M.p. 226–228 °C (decomp.) (CH2Cl2 +
54 Hz), 125.10 (d), 125.71 (d), 127.28 (d), 127.79 (d), 128.74 (d),
129.14 (d, JC,Sn = 20 Hz), 129.14 (d), 130.29 (d), 136.72 (d, JC,Sn
44 Hz), 139.63 (s), 140.75 (s, JC,Sn = 63 Hz), 142.90 (s, JC,Sn
=
=
44 Hz), 144.32 (s, JC,Sn = 389, 406 Hz), 154.63 (s, JC,Sn = 79 Hz)
ppm. 119Sn NMR (CDCl3): δ = –46.5 ppm. C73H60Sn2 (1174.73):
calcd.C 74.64, H 5.15; found C 74.59, H 5.15.
Reaction of Pentaphenylstannole Anion 1 with 1,6-Dibromohexane:
1,6-Dibromohexane (0.04 mL, 0.27 mmol) was added to a THF
(4 mL) solution of 1 prepared from 4 (338 mg, 0.54 mmol) and lith-
ium (11 mg, 1.59 mmol) at room temperature. After removal of vol-
atile substances, the residue was subjected to GPC to afford 1,6-
1
EtOH). H NMR (CDCl3): δ = 1.14 (s, JH,Sn = 64 Hz, 2 H), 6.71–
6.77 (m, 16 H), 6.90–6.95 (m, 24 H), 7.28–7.33 (m, 6 H), 7.42–7.52
(m, 4 H) ppm. 13C NMR (CDCl3): δ = –15.37 (t, JC,Sn = 253,
256 Hz), 125.30 (d), 125.82 (d), 127.25 (d), 127.90 (d), 128.82 (d,
JC,Sn = 39 Hz), 129.15 (d), 129.35 (d, JC,Sn = 22 Hz), 130.38 (d),
136.28 (d, JC,Sn = 41 Hz), 140.36 (s, JC,Sn = 18 Hz), 140.68 (s, JC,Sn
bis(1,2,3,4,5-pentaphenyl-1-stannacyclopentadienyl)hexane
(12)
(151 mg, 0.13 mmol, 47%). 12: M.p. 75–80 °C (decomp.). 1H NMR
(CDCl3): δ = 1.15–1.30 (m, 4 H), 1.51–1.75 (m, 8 H), 6.70–6.86 (m,
16 H), 6.86–7.05 (m, 24 H), 7.26–7.35 (m, 6 H), 7.45–7.63 (m, 4 H)
ppm. 13C NMR (CDCl3): δ = 13.63 (t, 1JC,Sn = 358, 373 Hz), 26.78
(t, 3JC,Sn = 24 Hz), 33.45 (t, 2JC,Sn = 50 Hz), 125.08 (d), 125.70 (d),
127.28 (d), 127.78 (d), 128.74 (d), 129.05 (d, JC,Sn = 20 Hz), 129.05
(d), 130.29 (d), 136.71 (d, JC,Sn = 45 Hz), 139.71 (s), 140.77 (s, JC,Sn
= 63 Hz), 142.89 (s, JC,Sn = 45 Hz), 144.41 (s, JC,Sn = 388, 407 Hz),
154.61 (s, JC,Sn = 78 Hz) ppm. 119Sn NMR (CDCl3): δ =
–46.6 ppm. C74H62Sn2 (1188.76): calcd. C 74.77, H 5.26; found C
75.01, H 5.39.
= 70 Hz), 142.05 (s, JC,Sn = 47 Hz), 143.47 (s), 154.53 (s, JC,Sn
=
89 Hz) ppm. 119Sn NMR (CDCl3): δ = –29.5 (2JSn,Sn = 284 Hz)
ppm. C69H52Sn2(1118.61): calcd. C 74.09, H 4.69; found C 74.20,
H 4.57.
Reaction of Pentaphenylstannole Anion 1 with 1,3-Dibromopropane:
1,3-Dibromopropane (0.03 mL, 0.30 mmol) was added to a THF
(5 mL) solution of 1 prepared from 4 (350 mg, 0.56 mmol) and lith-
ium (11 mg, 1.64 mmol) at room temperature. After removal of vol-
atile substances, the residue was subjected to GPC to afford 1,3-
bis(1,2,3,4,5-pentaphenyl-1-stannacyclopentadienyl)propane
(9)
(104 mg, 0.091 mmol, 33%). 9: M.p. 90–95 °C (decomp.). 1H NMR
(CDCl3): δ = 1.65–1.86 (m, 4 H), 2.10–2.35 (m, 2 H), 6.73–6.85 (m,
16 H), 6.85–7.00 (m, 24 H), 7.27–2.36 (m, 6 H), 7.40–7.60 (m, 4 H)
Reaction of Pentaphenylstannole Anion 1 with 1,2-Dichloroethane:
Excess 1,2-dichloroethane (2 mL, 32 mmol) was added to a THF
(4 mL) solution of 1 prepared from 4 (252 mg, 0.40 mmol) and lith-
ium (9 mg, 1.30 mmol) at room temperature. After volatile sub-
stances were removed, the residue was washed with hexane to give
1,1Ј-bistannole 2[8,9] (298 mg, 0.27 mmol, 71%).
1
ppm. 13C NMR (CDCl3): δ = 13.13 (t, JC,Sn = 340, 356 Hz, 3JC,Sn
2
= 70 Hz), 24.63 (t, JC,Sn = 21 Hz), 125.14 (d), 125.72 (d), 127.26
(d), 127.83 (d), 128.78 (d), 129.05 (d, JC,Sn = 21 Hz), 129.09 (d),
130.30 (d), 136.75 (d, JC,Sn = 38 Hz), 139.26 (s), 140.66 (s, JC,Sn
=
Reaction of Pentaphenylstannole Anion 1 with 1,2-Dibromoethane:
Excess 1,2-dibromoethane (0.5 mL, 5.8 mmol) was added to a THF
(5 mL) solution of 1 prepared from 4 (303 mg, 0.48 mmol) and lith-
ium (11 mg, 1.59 mmol) at room temperature. After volatile sub-
stances were removed, the residue was washed with hexane to give
1,1Ј-bistannole 2[8,9] (196 mg, 0.18 mmol, 74%).
63 Hz), 142.72 (s, JC,Sn = 45 Hz), 144.02 (s, JC,Sn = 391, 409 Hz),
154.75 (s, JC,Sn = 79 Hz) ppm. 119Sn NMR (CDCl3): δ =
–49.9 ppm. C71H56Sn2 (1146.67): calcd. C, 74.37, H 4.92; found C
74.07, H 4.92.
Reaction of Pentaphenylstannole Anion 1 with 1,4-Dibromobutane:
1,4-Dibromobutane (0.019 mL, 0.16 mmol) was added to a THF
(3 mL) solution of 1 prepared from 4 (200 mg, 0.32 mmol) and lith-
ium (6 mg, 0.89 mmol) at room temperature. After removal of vola-
tile substances, the residue was subjected to GPC to afford 1,4-
Formation of 2 by Oxidation of Pentaphenylstannole Anion 1: A
THF (7 mL) solution of 1 prepared from 4 (408 mg, 0.65 mmol)
and lithium (12 mg, 1.69 mmol) was exposed to air for a few min-
utes. After volatile substances were removed, the residue was
washed with hexane to give 1,1Ј-bistannole 2[8,9] (120 mg,
0.11 mmol, conv. 70%). The starting 4 was recovered in 20% yield.
bis(1,2,3,4,5-pentaphenyl-1-stannacyclopentadienyl)butane
(10)
(66 mg, 0.057 mmol, 36%). 10: M.p. 190 °C (decomp.). 1H NMR
(CDCl3): δ = 1.45–1.63 (m, 4 H), 1.68–1.86 (m, 4 H), 6.77–6.83 (m,
16 H), 6.90–7.01 (m, 24 H), 7.30–7.36 (m, 6 H), 7.46–7.58 (m, 4 H) Reaction of Pentaphenylstannole Anion 1 with Di-tert-butyldichloro-
1
ppm. 13C NMR (CDCl3): δ = 12.71 (t, JC,Sn = 369 Hz), 30.92 (t, stannane: A THF (4 mL) solution of 1 prepared from 4 (250 mg,
3
2JC,Sn = 56 Hz, JC,Sn = 24 Hz), 125.13 (d), 125.73 (d), 127.27 (d),
0.40 mmol) and lithium (8 mg, 1.16 mmol) was added to a THF
127.81 (d), 128.77 (d), 129.09 (d, JC,Sn = 20 Hz), 129.09 (d), 130.32 (2 mL) solution of di-tert-butyldichlorostannane (121 mg,
(d), 136.71 (d, JC,Sn = 38 Hz), 139.58 (s), 140.73 (s, JC,Sn = 63 Hz), 0.40 mmol) at –100 °C. The reaction mixture was warmed to room
Eur. J. Inorg. Chem. 2007, 1297–1306
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
1303

R. Haga, M. Saito, M. Yoshioka
FULL PAPER
temperature and stirred overnight. After removal of volatile sub-
stances, the residue was subjected to GPC to afford di-tert-
butylbis(1,2,3,4,5-pentaphenyl-1-stannacyclopentadienyl)stannane
(14) (109 mg, 0.08 mmol, conv. 49%). The starting 4 was recovered
After filtration of materials insoluble in dichloromethane, a com-
plex mixture (293 mg) was obtained.
Preparation of 1-(2,4,6-Triisopropylphenyl)stannole Anion 19: A di-
ethyl ether (10 mL) solution of stannole dianion 3 prepared from
hexaphenylstannole 4 (707 mg, 1.12 mmol) with lithium (77 mg,
11.1 mmol) was added to a diethyl ether (3 mL) solution of 1-
bromo-2,4,6-triisopropylbenzene (317 mg, 1.12 mmol) at room
temperature. After being stirred overnight, the resulting deep-red
solution was degassed by freeze-pump-thaw cycles and sealed. In
a glovebox, after filtration of insoluble materials, the filtrate was
concentrated. The residue was washed with hexane to give 1-lithio-
1-(2,4,6-triisopropylphenyl)-2,3,4,5-tetraphenylstannole (19). 19:
1H NMR (Et2O/C6D6): δ = 1.12–1.17 (m, 18 H), 2.66–2.80 (sept,
JH,H = 7 Hz, 2 H), 2.88–2.98 (sept, JH,H = 7 Hz, 1 H), 6.55–6.61
(m, 2 H), 6.61–6.67 (m, 2 H), 6.67–6.77 (m, 8 H), 6.77–6.85 (m, 10
H) ppm. 13C NMR (Et2O/C6D6): δ = 24.25 (q), 25.84 (q), 34.82
(d), 40.93 (d), 122.24 (d), 122.43 (d), 124.22 (d), 124.45 (d), 126.80
(d), 127.04 (d), 127.39 (d, JC,Sn = 14 Hz), 128.53 (d), 128.74 (d,
JC,Sn = 14 Hz), 131.47 (d), 138.60 (d, JC,Sn = 47 Hz), 144.74 (s),
148.97 (s), 149.69 (s, JC,Sn = 35 Hz), 152.23 (s, JC,Sn = 15 Hz),
156.47 (s, JC,Sn = 150 Hz), 161.61 (s), 170.39 (s, JC,Sn = 90 Hz)
ppm. 119Sn NMR (Et2O/C6D6): δ = –49.6 ppm. 7Li NMR (Et2O/
C6D6): δ = 0.95 ppm. The elemental analysis of 19 could not be
carried out because of its extremely high reactivity toward water
and oxygen.
1
in 16% yield. 14: M.p. 138–140 °C (decomp.). H NMR (CDCl3):
δ = 1.15 (s, JH,Sn = 7, 77 Hz, 18 H), 6.72–6.83 (m, 24 H), 6.91–6.94
(m, 16 H), 7.25–7.34 (m, 6 H), 7.52–7.66 (m, 4 H) ppm. 13C NMR
(CDCl3): δ = 33.33 (q, JC,Sn = 10 Hz), 35.31 (s, JC,Sn = 31 Hz),
125.10 (d), 125.64 (d), 127.19 (d), 127.60 (d), 128.68 (d, JC,Sn
=
11 Hz), 128.96 (d, JC,Sn = 44 Hz), 129.59 (d, JC,Sn = 20 Hz), 130.93
(d), 137.40 (d, JC,Sn = 41 Hz), 140.99 (s), 141.16 (s, JC,Sn = 54 Hz),
142.73 (s, JC,Sn = 47 Hz), 148.60 (s, JC,Sn = 16 Hz), 154.25 (s, JC,Sn
= 71 Hz) ppm. 119Sn NMR (CDCl3): δ = –103.2 (1JSn,Sn = 329 Hz),
–44.8 (1JSn,Sn = 329 Hz) ppm. C76H68Sn3 (1337.54): calcd. C 68.25,
H 5.12; found C 68.23, H 5.11.
Reaction of 1-tert-Butylstannole Anion 16 with Methyl Iodide: A
diethyl ether (5 mL) solution of stannole dianion 3 prepared from
hexaphenylstannole 4 (270 mg, 0.43 mmol) and lithium (15 mg,
2.18 mmol) was added to a diethyl ether (2 mL) solution of tert-
butyl chloride (0.05 mL, 0.46 mmol) was added at room tempera-
ture. After being stirred for 30 min, the mixture was treated with
methyl iodide (0.03 mL, 0.07 mmol). After filtration of materials
insoluble in dichloromethane, the filtrate was recrystallized from
dichloromethane and methanol to give 1-tert-butyl-1-methyl-
2,3,4,5-tetraphenylstannole (15)[17] (130 mg, 0.24 mmol, 55%). 15:
1
M.p. 75–80 °C (decomp.) (CH2Cl2 + MeOH). H NMR (CDCl3):
Reaction of Stannole Anion 19 with Methyl Iodide: A diethyl ether
(4 mL) solution of stannole dianion 3 prepared from hexaphen-
ylstannole 4 (150 mg, 0.24 mmol) and lithium (16 mg, 2.29 mmol)
was added to a diethyl ether (2 mL) solution of 1-bromo-2,4,6-tri-
isopropylbenzene (66 mg, 0.23 mmol) at room temperature. After
being stirred for 4 h, the mixture was treated with methyl iodide
(0.1 mL, 1.61 mol). After removal of volatile substances, materials
insoluble in dichloromethane were removed by filtration. The resi-
due was subjected to GPC to afford 1-methyl-2,3,4,5-tetraphenyl-
1-(2,4,6-triisopropylphenyl)stannole (18) (48 mg, 0.07 mmol, 29%).
δ = 0.60 (s, JH,Sn = 51 Hz, 3 H), 1.22 (s, JH,Sn = 74 Hz, 9 H), 6.77–
6.79 (m, 4 H), 6.83–6.85 (m, 4 H), 6.93–6.98 (m, 8 H), 7.04–7.08
(m, 4 H) ppm. 13C NMR (CDCl3): δ = –10.57 (q), 29.90 (s), 30.68
(q), 124.86 (d), 125.58 (d), 127.18 (d), 127.74 (d), 129.09 (d), 130.44
(d), 141.01 (s), 143.62 (s), 145.41 (s), 154.47 (s) ppm. 119Sn NMR
(CDCl3): δ = 5.1 ppm. C33H32Sn (547.35): calcd. C 72.42, H 5.89;
found C 72.43, H 5.51.
Preparation of 1-tert-Butylstannole Anion 16: A diethyl ether
(0.7 mL) solution of stannole dianion 3 prepared from hexaphen-
ylstannole 4 (58 mg, 0.09 mmol) with lithium (5 mg, 0.72 mmol)
was added to a diethyl ether (2 mL) solution of tert-butyl chloride
(0.01 mL, 0.09 mmol) at room temperature. The resulting bright-
red solution was degassed by freeze-pump-thaw cycles and sealed.
18: M.p. 188 °C (decomp.). 1H NMR (CDCl3): δ = 0.96 (s, JH,Sn
=
55 Hz, 3 H), 1.05 (d, JH,H = 7 Hz, 12 H), 1.24 (d, JH,H = 7 Hz, 6
H), 2.86 (sept, JH,H = 7 Hz, 1 H), 2.97 (sept, JH,H = 7 Hz, 2 H),
6.73–6.84 (m, 4 H), 6.84–6.95 (m, 12 H), 6.95–7.05 (m, 6 H) ppm.
13C NMR (CDCl3): δ = –3.04 (q, JC,Sn = 323 Hz), 23.88 (q), 24.93
(q), 34.14 (d), 38.13 (d, JC,Sn = 33 Hz), 121.50 (d, JC,Sn = 49 Hz),
1
16: H NMR (Et2O/C6D6): δ = 1.25 (s, 9 H), 6.61–6.78 (m, 12 H),
6.80–6.83 (m, 4 H), 6.88–6.90 (m, 4 H) ppm. 13C NMR (Et2O/
C6D6): δ = 28.64 (s), 33.71 (q), 122.22 (d), 124.04 (d), 126.80 (d),
127.07 (d), 129.35 (d), 131.59 (d), 145.05 (s), 150.35 (s), 151.78 (s),
170.66 (s, JC,Sn = 113 Hz) ppm. 119Sn NMR (Et2O/C6D6): δ =
124.90 (d), 125.49 (d), 127.07 (d), 127.62 (d), 128.93 (d, JC,Sn
=
20 Hz), 130.30 (d), 137.17 (s), 140.93 (s, JC,Sn = 63 Hz), 143.12 (s,
JC,Sn = 45 Hz), 147.09 (s, JC,Sn = 406 Hz), 150.12 (s, JC,Sn = 10 Hz),
153.08 (s, JC,Sn = 84 Hz), 155.92 (s, JC,Sn = 43 Hz) ppm. 119Sn
NMR (CDCl3): δ = –66.0 ppm. C44H46Sn (693.60): calcd. C 76.20,
H 6.69; found C 76.19, H 6.71.
7
30.4 ppm. Li NMR (Et2O/C6D6): δ = 0.92 ppm.
Formation of 17 by Oxidation of 1-tert-Butylstannole Anion 16: A
diethyl ether (4 mL) solution of stannole dianion 3 prepared from
hexaphenylstannole 4 (197 mg, 0.31 mmol) with lithium (21 mg,
3.03 mmol) was added to a diethyl ether (2 mL) solution of tert-
butyl chloride (0.04 mL, 0.34 mmol) at room temperature. After
being stirred for 30 min, the resulting bright-red solution was ex-
posed to air for a few minutes. After filtration of materials insoluble
in dichloromethane, the filtrate was recrystallized from dichloro-
methane and methanol to give bi(1-tert-butyl-2,3,4,5-tetraphenyl-
1-stannacyclopentadienyl) (17)[9] (45 mg, 0.042 mmol, 27%).
Oxidation of Stannole Anion 19: A diethyl ether (4 mL) solution of
stannole dianion 3 prepared from hexaphenylstannole 4 (310 mg,
0.49 mmol) and lithium (32 mg, 4.61 mmol) was added to 1-bromo-
2,4,6-triisopropylbenzene (139 mg, 0.49 mmol) at room tempera-
ture. After being stirred for 8 h, the resulting solution was exposed
to air for a few minutes. After filtration of materials insoluble in
diethyl ether, a complex mixture (410 mg) was obtained.
Preparation of 1-[2,6-Bis(2,4,6-trimethylphenyl)phenyl]stannole
Anion 21: A diethyl ether (7 mL) solution of stannole dianion 3
prepared from hexaphenylstannole 4 (770 mg, 1.22 mmol) and lith-
Reaction of Stannole Dianion 3 with Bromobenzene: A diethyl ether
(7 mL) solution of stannole dianion 3 prepared from hexaphen- ium (86 mg, 12.3 mmol) was added to a diethyl ether (3 mL) solu-
ylstannole 4 (404 mg, 0.64 mmol) and lithium (53 mg, 7.57 mmol)
was added to a diethyl ether (2 mL) solution of bromobenzene
(0.067 mL, 0.64 mmol) at room temperature. After being stirred for
5 h, the resulting solution was exposed to air for a few minutes.
tion of 1-iodo-2,6-bis(2,4,6-trimethylphenyl)benzene[23] (450 mg,
1.09 mmol) at room temperature. After being stirred for 3 d, the
resulting deep-red solution was degassed by freeze-pump-thaw cy-
cles and sealed. After removal of insoluble materials by filtration,
1304
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© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2007, 1297–1306

Synthesis and Reactions of Stannole Anions
FULL PAPER
the filtrate was concentrated in a glovebox to give 1-[2,6-bis(2,4,6-
= 3801 Hz) ppm. 7Li NMR (Et2O/C6D6): δ = –0.74, 0.62 ppm. The
elemental analysis of 24 could not be carried out because of its
extremely high reactivity toward water and oxygen.
trimethylphenyl)phenyl]-1-lithio-2,3,4,5-tetraphenylstannole (21).
1
The H and 13C NMR signals due to 21 are too complicated to be
assigned probably because of steric congestion. However, in the 13
C
Reaction of 1-(Triphenylstannyl)stannole Anion 24 with Methyl
Iodide: A diethyl ether (2 mL) solution of the stannole dianion 3
(102 mg, 0.21 mmol) and chlorotriphenylstannane (80 mg,
0.21 mmol) was stirred in a glovebox at room temperature for 2 h,
and the resulting mixture was treated with methyl iodide (0.1 mL,
1.61 mmol). After removal of volatile substances, insoluble inor-
ganic salts were filtered off. The residue was subjected to GPC to
NMR spectrum, the signal assignable to the α-carbon atom was
observed at δ = 170.34ppm. 21: 119Sn NMR (Et2O/C6D6): δ =
–50.2 ppm. 7Li NMR (Et2O/C6D6): δ = 0.15 ppm. The elemental
analysis of 21 could not be carried out because of its extremely
high reactivity toward water and oxygen.
Preparation of 1-[2,6-Bis(2,4,6-triisopropylphenyl)phenyl]stannole
Anion 22: A diethyl ether (5 mL) solution of stannole dianion 3
from hexaphenylstannole 4 (319 mg, 0.50 mmol) and lithium
(35 mg, 5.07 mmol) was added to a diethyl ether (2 mL) solution
of 1-iodo-2,6-bis(2,4,6-triisopropylphenyl)benzene[24] (230 mg,
0.48 mmol) at room temperature. After being stirred for 3 d, the
resulting deep-red solution was degassed by freeze-pump-thaw cy-
cles and sealed. After removal of insoluble materials by filtration,
the filtrate was concentrated in a glovebox to give 1-[2,6-bis(2,4,6-
triisopropylphenyl)phenyl]-1-lithio-2,3,4,5-tetraphenylstannole
afford
1-methyl-2,3,4,5-tetraphenyl1-(triphenylstannyl)-stannole
(25) (80 mg, 0.097 mmol, 47%). 25: M.p. 143 °C (decomp.). 1H
NMR (CDCl3): δ = 0.89 (s, JH,Sn = 15, 53 Hz, 3 H), 6.70–6.80 (m,
8 H), 6.88–6.97 (m, 12 H), 7.25–7.34 (m, 9 H), 7.34–7.49 (m, 6 H)
ppm. 13C NMR (CDCl3): δ = –7.59 (q, JC,Sn = 59 Hz), 125.08 (d),
125.70 (d), 127.26 (d), 127.78 (d), 128.67 (d), 128.79 (d, JC,Sn
=
11 Hz), 129.39 (d, JC,Sn = 21 Hz), 130.34 (d), 137.34 (d, JC,Sn = 8,
41 Hz), 139.13 (s, JC,Sn = 55 Hz), 140.86 (s, JC,Sn = 5, 58 Hz),
142.77 (s, JC,Sn = 47 Hz), 147.78 (s), 153.50 (s, JC,Sn = 21 Hz) ppm.
1
(22). The H and 13C NMR signals for 22 are too complicated to
1
119Sn NMR (CDCl3): δ = –87.3 (s, JSn,Sn = 3532 Hz), –127.4 (s,
1JSn,Sn = 3532 Hz) ppm. C47H38Sn2 (840.25): calcd. C 67.18, H
be assigned probably because of steric congestion. However, in the
13C NMR spectrum, the signal assignable to the α-carbon atom
was observed at δ = 170.33ppm. 22: 119Sn NMR (Et2O/C6D6): δ =
–47.1 ppm. 7Li NMR (Et2O/C6D6): δ = 0.61 ppm. The elemental
analysis of 22 could not be carried out because of its extremely
high reactivity toward water and oxygen.
4.56; found C 66.90, H 4.49.
Reaction of the 1-(Triphenylstannyl)stannole Anion 24 with Chloro-
triphenylstannane: A diethyl ether (2 mL) solution of the stannole
dianion
3 (107 mg, 0.22 mmol) and chlorotriphenylstannane
(168 mg, 0.44 mmol) was stirred in a glovebox at room temperature
for 30 min. The color of the reaction mixture changed from dark-
red to yellow. After removal of volatile substances, insoluble inor-
ganic salts were filtered off. The residue was subjected to GPC to
afford 2,3,4,5-tetraphenyl-1,1-bis(triphenylstannyl)stannole (26)
(100 mg, 0.085 mmol, 39%). 26: M.p. 175–177 °C (decomp.). 1H
NMR (CDCl3): δ = 6.48–6.56 (m, 4 H), 6.66–6.75 (m, 8 H), 6.80–
6.88 (m, 2 H), 6.88–7.00 (m, 6 H), 7.11–7.35 (m, 30 H) ppm. 13C
NMR (CDCl3): δ = 124.91 (d), 125.64 (d), 127.21 (d), 127.62 (d),
Preraration of 1-Triisopropylsilylstannole Anion 23: Chlorotri-
isopropylsilane (0.025 mL, 0.12 mmol) was added to a diethyl ether
(1 mL) solution of stannole dianion 3 (54 mg, 0.11 mmol) at room
temperature in a glovebox. After being stirred overnight, the reac-
tion mixture was concentrated in a glovebox to give 1-lithio-2,3,4,5-
tetraphenyl-1-(triisopropylsilyl)stannole (23). 23: 1H NMR (Et2O/
C6D6): δ = 1.20–1.46 (m, 3 H), 6.61–6.64 (m, 4 H), 6.64–6.75 (m,
6 H), 6.81–6.89 (m, 10 H) ppm. The signals due to the methyl
protons of the triisopropylsilyl groups are overlapped with those of
the methyl protons of diethyl ether. 13C NMR (Et2O/C6D6): δ =
15.52 (q), 20.29 (d, JC,Sn = 13 Hz), 124.78 (d), 125.47 (d), 127.35
(d), 127.59 (d), 130.59 (d), 130.94 (d), 142.77 (s, JC,Sn = 37 Hz),
145.50 (s, JC,Sn = 40 Hz), 155.04 (s, JC,Sn = 46 Hz), 156.01 (s, JC,Sn
128.65 (d), 127.86 (d), 128.78 (d, JC,Sn = 11 Hz), 129.59 (d, JC,Sn
=
15 Hz), 137.33 (d, JC,Sn = 8, 42 Hz), 139.06 (s, JC,Sn = 11, 54 Hz),
141.05 (s, JC,Sn = 50 Hz), 142.93 (s, JC,Sn = 45 Hz), 150.22 (s, JC,Sn
= 12 Hz), 153.74 (s, JC,Sn = 19, 63 Hz) ppm. 119Sn NMR (CDCl3):
2
δ = –115.7 (1JSn,Sn = 2159 Hz, JSn,Sn = 615 Hz), –219.8 (1JSn,Sn
=
= 190 Hz) ppm. 119Sn NMR (Et2O/C6D6): δ = –218.5 (1JSn,Si
=
2159 Hz) ppm. The elemental analysis of 26 could not be carried
out because of its instability. For the 1H, 13C, and 119Sn NMR
spectra of 26, see Supporting Information.
380 Hz) ppm. 7Li NMR (Et2O/C6D6): δ = 0.48 ppm. The elemental
analysis of 23 could not be carried out because of its extremely
high reactivity toward water and oxygen.
Supporting Information (see footnote on the first page of this arti-
cle): All NMR spectroscopic data of compounds, 1, 16, 19, 21, 22,
23, 24, and 26. Experimental details for control experiment of the
reduction of 1,1Ј-bistannole 1 with lithium to give stannole anion
1 and dianion 3.
Reaction of the 1-Triisopropylsilylstannole Anion 23 with Methyl
Iodide: In a glovebox, a diethyl ether (3 mL) solution of stannole
dianion
3
(94 mg, 0.19 mmol) and chlorotriisopropylsilane
(0.041 mL, 0.19 mmol) was stirred at room temperature overnight
and the resulting mixture was treated with methyl iodide (0.1 mL,
1.61 mmol). After removal of materials insoluble in diethyl ether, a
complex mixture (101 mg) was obtained.
Acknowledgments
Preparation of 1-Triphenylstannylstannole Anion 24: Chlorotri-
phenylstannane (55 mg, 0.16 mmol) was added to a diethyl ether
(2 mL) solution of stannole dianion 3 (70 mg, 0.14 mmol) at room
temperature in a glovebox. After being stirred overnight, the reac-
tion mixture was concentrated in a glovebox to give 1-lithio-2,3,4,5-
This work was partially supported by a Grant-in-Aid for Young
Scientists (B), No. 17750032 (M. S.) from the Ministry of Educa-
tion, Culture, Sports, Science and Technology of Japan. M. S. ac-
knowledges a research grant from Toray Science Foundation. R. H.
thanks Research Fellowships of the Japan Society for the Pro-
motion of Science for Young Scientists.
1
tetraphenyl-1-(triphenylstannyl)stannole (24). 24: H NMR (Et2O/
C6D6): δ = 6.55–6.80 (m, 16 H), 6.80–6.94 (m, 4 H), 6.94–7.06 (m,
9 H), 7.35–7.46 (m, 6 H) ppm. 13C NMR (Et2O/C6D6): δ = 122.48
(d), 124.10 (d), 126.73 (d), 126.82 (d), 127.09 (d), 127.71 (d), 129.58
(d), 131.76 (d), 138.51 (d, JC,Sn = 37, 188 Hz), 144.83 (s), 148.85
(s), 149.70 (s), 151.99 (s), 172.03 (s, JC,Sn = 148 Hz) ppm. 119Sn
NMR (Et2O/C6D6): δ = –98.7 (1JSn,Sn = 3801 Hz), –240.5 (1JSn,Sn
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1305

R. Haga, M. Saito, M. Yoshioka
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Published Online: February 20, 2007
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