Ketene organoelement derivatives. Synthesis of bis(1-R-2-oxovinyl)silanes and germanes (R = SiMe3, GeMe3, SnMe3)

Article abstract of DOI:10.1007/s11172-009-0098-z

abs Earlier unknown 1,3-bisketene organoelement derivatives RMeE(C(E'Me₃)=C=O)₂ (E = Si, Ge; E' = Si, Ge, Sn) have been synthesized by the reaction ofbis(alkoxyethynyl)silanes and -germanes with Me₃E' Hal. Bis(1-trimethyls

Full text of DOI:10.1007/s11172-009-0098-z

Russian Chemical Bulletin, International Edition, Vol. 58, No. 4, pp. 805—809, April, 2009
805
Ketene organoelement derivatives.
Synthesis of bis(1ꢀRꢀ2ꢀoxovinyl)silanes and germanes
(R = SiMe3, GeMe3, SnMe3)
S. V. Gruener, R. N. Ezhov, and V. S. Petrosyan
Department of Chemistry, M. V. Lomonosov Moscow State University,
1 Leninskie Gory, 119992 Moscow, Russian Federation.
Fax: +7 (495) 939 5546. Eꢀmail: svgrun@org.chem.msu.ru
Earlier unknown 1,3ꢀbisketene organoelement derivatives RMeE(C(E´Me3)=C=O)2
(E = Si, Ge; E´ = Si, Ge, Sn) have been synthesized by the reaction of bis(alkoxyethynyl)silanes
and ꢀgermanes with Me3E´Hal. Bis(1ꢀtrimethylsilylꢀ2ꢀoxovinyl)silane is also formed by the
reaction of trimethylsilylꢀ and (dimethylsilylene)bisketenes with dimethylsilylene bistriflate
and trimethylsilyl triflate, respectively. Addition of nucleophiles to the ketene fragment of
compounds synthesized has been studied.
Key words: ketenes, alkynyl ethers, organosilicon compounds, organogermanium comꢀ
pounds, organotin compounds.
Scheme 1
In continuation of our studies on the properties of
bis(alkoxyethynyl)silanes and ꢀgermanes,1—3 we studied
reactions of the latter with Me3E´Hal (E´ = Si, Ge, Sn).
The present work is aimed at obtaining new types of
organoelement bisketenes, the first stable representative
of which, dimethylsilylenebis(ketene), has been syntheꢀ
sized relatively not long ago.1,2
It is known4—6 that the reaction of silyl(germyl)monoꢀ
alkoxyacetylenes with Me3E´Hal leads to the correspondꢀ
ing biselementꢀsubstituted ketenes. We studied reactions
of bis(alkoxyethynyl)silanes and ꢀgermanes 1 with triꢀ
methylsilylꢀ, trimethylgermylꢀ and trimethylstannyl iodiꢀ
des 2—4 (Scheme 1). The reaction was carried out by
stirring of the reagents in dichloromethane or acetonitrile,
which resulted in the corresponding organoelement bisꢀ
ketenes 5 and 6 in good yields.
Unlike the reaction of compounds 2—4 with siliꢀ
con and germanium monoalkoxyethynyl derivatives,4—6
similar reaction of 1a—e proceeds considerably slower
(24—290 h) and requires significant excess of Me3E´I
(>50%) (Table 1).
E´ = Si (2, 5a, 6a,c), Ge (3, 6b,d), Sn (4, 5g, 6f)
Comꢀ
E
R
R´
Comꢀ
E
R
R´
Initially the reaction presumably proceeds at one of
the alkoxyethynyl groups, which was clearly shown by the
reaction of 1a with 2* in dichloromethane. Monitoring of
the reaction course was carried out using the IR spectra of
the reaction mixture, namely, from the decrease in intenꢀ
pound
pound
1e, 6e
1e, 6f
1b, 5g
1a, 5a, 6a
1b, 6b
1c, 6c
1d, 6d*
Si
Si
Si
Si
Me
Me
H
Me
Et
Me
Et
Ge
Ge
Si
Me
Me
Me
Et
Et
Et
H
sity of the absorption band for the C≡C bond (2190 cm–1
)
* Reaction with bromotrimethylgermane.
and increase in intensity of the absorption band for the
ketene group in the region 2100—2050 cm–1. Though, the
band for the C≡C bond almost disappeared after stirring
for 88 h, it was unambiguously shown (1H, 13C, and
* Iodotrimethylsilane (2) is an excellent silylating agent for orꢀ
ganic carbonyl compounds.7
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 789—793, April, 2009.
1066ꢀ5285/09/5804ꢀ0805 © 2009 Springer Science+Business Media, Inc.

806
Russ.Chem.Bull., Int.Ed., Vol. 58, No. 4, April, 2009
Gruener et al.
29Si NMR spectroscopy) that the product distilled in vacuo,
along with bisketene 6a, contained ~30% of compound
with a single ketene group (5a).
the attack by the second molecule 4 on the remained
ethoxyethynyl group. In the case of 1e, such hindrance
apparently is absent, since the Ge—C≡ bond distance in
1e is longer than the Si—C≡ bond distance in 1b and the
Me3Sn— group in 1e does not create steric hindrance.
The reaction of the partial pyrolysis product 1b (see
Ref. 1), dimethyl(ethoxyethynyl)silyl ketene (7b), using
excess iodotrimethylgermane gave monogermylated bisꢀ
ketene 8 (Scheme 2).
The IR spectrum of a distilled mixture of compounds
5a and 6a exhibits intensive absorption bands at 2190 cm–1
(the C≡С bond in 5a) and 2095 cm–1 (C=C=O in 5a and
6a), with intensity of the C≡C absorption band being much
1
lower than that for C=C=O. The H NMR spectrum, in
addition to two singlets at δ 0.13 (Me3Si—) and 0.25
(Me2Si—), contains the singlet at δ 3.13 corresponding to
the —OMe group in compound 5a. The 13C NMR specꢀ
trum, in addition to chemical shifts for the carbon atꢀ
oms in C=C=O (see Ref. 8) in compound 5a, also exhibꢀ
its signals typical of the carbon atoms of the fragment
C≡C—OMe. The 29Si spectrum for 5a contains the resoꢀ
nance signals at δ –21.0 (Me2Si—) and 20.9 (Me3Si—),
whereas for 6a, at δ –3.3 (Me2Si—) and 0.3 (Me3Si—).
A mixture of compounds 5a and 6a was isolated by distilꢀ
lation, rather than a mixture of 1a and 6a, which was
confirmed by the 29Si NMR spectral data (for 1a δ –38.7 1).
In another experiment (a large excess of 2 and longer
reaction time), only bisketene 6a was isolated in 56% yield.
When the reaction was run in acetonitrile with molar ratio
of reagents 1 : 3, its yield increased (70%) and the reaction
time noticeably decreased (see Table 1). Note that in the
IR spectrum, there are observed two absorption bands of
equal intensity characteristic of the ketene group vibraꢀ
tions, at 2082 and 2100 cm–1. Compounds 6b and 6c were
synthesized similarly in 27 and 73% yields, respectively.
Further, we studied reaction of acetylene 1d with
bromotrimethylgermane. The reaction was carried out in
acetonitrile with a large excess of bromotrimethylgermane
(50%) (monitoring by the IR spectra of the reaction mixꢀ
ture). In contrast to 1a, the reaction proceeds significantly
slower and comes to completion after 528 h (the yield of
compound 6d was 48%).
The reaction of compounds 1e and 3 took place under
the same conditions and with the same amounts of startꢀ
ing reagents that in the reaction of 1a with 2. The full
completion of the reaction required 168 h. In this case, the
reaction proceeds considerably faster than the germylation
of 1d with bromotrimethylgermane. Similar reactions were
run between 1b,e and 4. In case of 1b, we failed in carrying
out the reaction to completion, despite a prolonged (380 h)
stirring with a 2ꢀfold excess of 4. The IR spectrum of the
reaction mixture exhibits the absorption bands for acetyꢀ
lene (2180 cm–1) and ketene groups (2050 cm–1). Fracꢀ
tional distillation afforded the product bearing only one
ethoxyethynyl group in 5g (see Scheme 1).
Scheme 2
Conditions for the synthesis of compounds 5a,g, 6a—f,
and 8 are given in Table 1.
Molecular structures of compounds 6a,b,f were studꢀ
ied by electron diffraction in the gas phase. Conformation
analysis was performed using ab initio quantum chemical
methods and DFT. The theoretical calculations in agreeꢀ
ment with the experiment show that compounds under
study exist as two conformers of the type gaucheꢀgauche
and synꢀgauche relatively to the ketenyl groups.9
In the literature, there is described10 an original way to
synthesize bis(trimethylsilyl) ketene by the reaction of
trimethylsilyl triflate with trimethylsilyl ketene in the presꢀ
ence of triethylamine. Earlier, we have found11 that reacꢀ
tions of monosilyl ketenes with trialkylsilyl triflates bearꢀ
ing bulky substituents (both in ketenes and in triflates)
lead either to the corresponding bis(silyl) ketenes or to
a mixture of these ketenes with isomeric silyl ynol ethers.
The latter are capable of a slow isomerization into the
corresponding bis(silyl) ketenes. These both classes of
Table 1. Synthesis of compounds 5a, 5g, 6a—f, and 8
Comꢀ
pound
Starting
reagents
Solꢀ
vent
Excess of
reagents
2—4 (%)
Reaction
time
(h)
5а + 6а 1a + 2
6а
СН2Cl2
СН2Cl2
MeCN
MeCN
MeCN
25
50
50
45
56
50
50
90
100
50
88
115
24
220
290
528
168
180
380
200
1а + 2
6b
6c
6d
6e
6f
1b + 3
1c + 2
Unlike the reaction of 1b, the reaction between 1e and
4 proceeds to completion to form product 6f (monitoring
by the IR spectra of the reaction mixture).
The experimental data obtained can be explained by
the fact that in the intermediate product 5g formed,
the trimethylstannyl group creates steric hindrance to
1d + Me3GeBr MeCN
1e + 3
1f + 4
1b + 4
7 + 3
MeCN
MeCN
MeCN
MeCN
5g
8

Si, Ge, Snꢀsubstituted bisketenes
Russ.Chem.Bull., Int.Ed., Vol. 58, No. 4, April, 2009
807
compounds are important objects for study in organoꢀ
element chemistry.12—14 Their relative thermodynamic
stability and the use of these compounds in organic and
organoelement syntheses are of special interest.15,16
All of this prompted us to study reactions of dimethylꢀ
silylenebis(ethylenone) (9)1,2 with trimethylsilyl triflate
(10) (ratio of the reagents, 1 : 2) in order to explore alterꢀ
native ways for the synthesis of 6a and a possible formaꢀ
tion of isomeric to it bis(trimethylsiloxyethynyl)dimethylꢀ
silane (11) (Scheme 3).
mediate, which partially decomposes and partially isomerꢀ
izes into 6a, which explains the low yield of the ketene
isolated.
We have studied reactions of ketenes obtained with
nucleophiles. For instance, the reaction of compound 6b
with 2 equiv. of benzylamine in hexane gives N,N´ꢀdibenꢀ
zylꢀ2,2´ꢀ(dimethylsilylene)bis[2ꢀ(trimethylgermyl)acetꢀ
amide] (14) in good yield (Scheme 4).
Scheme 4
Scheme 3
The reaction of bisketene 6b with excess water in diꢀ
oxane in the presence of catalytic amount of H2SO4 gave
The reaction of compounds 9 and 10 could have been
expected to result in the formation of compound 11 with
further isomerization into 6a. The reaction was carried out
in diethyl ether at –10 °C with subsequent rising the temꢀ
perature to ambient. Monitoring of the reaction was perꢀ
formed using the IR and 13C NMR spectra of the reaction
mixture. In 24 h after mixing of the reagents, the IR specꢀ
trum exhibited two absorption bands: for the C≡C bond at
2190 cm–1 (of medium intensity) and for the ketene group
at 2090 cm–1. However, in the 13C NMR spectrum of the
reaction mixture aliquot, the signals characteristic of 11
were not observed. On standing of the reaction mixture
(20 °C), the absorption band at 2190 cm–1 decreased down
to entire disappearance after 16 h. Fractional distillation
of the reaction mixture afforded compound 6a only.
The reaction of trimethylsilyl ketene (12) with bisꢀ
(trifluoromethanesulfonyloxy)dimethylsilane (13) (ratio of
reagents, 2 : 1) (see Scheme 3) occured similarly: in the
IR spectrum of the reaction mixture (in 24 h after mixing
of the reagents), two absorption bands were also recorded,
for the C≡C bond at 2190 cm–1 and intensive absorption
band for the ketene group at 2090 cm–1. Fractional distilꢀ
lation of the reaction mixture also gave compound 6a only.
In both cases, compound 6a was isolated in low yield
(15 and 9%, respectively).
Table 2. Characteristics of compounds synthesized
Comꢀ Yield B.p./°C
pound (%) (p/Torr) Calculated
Found
Molecular
formula
(%)
[m.p./°C]
C
H
6а
6b
6c
6d
6e
6d
5g
8
56
73
27
48
38
73
22
77
45—46
(0.02)
68
(0.02)
43
50.56
50.56
38.18
38.58
46.25
46.72
37.43
36.97
34.12
34.47
28.65
28.18
39.45
39.91
46.80
46.36
8.59 С12Н24О2Si3
8.50
6.42 С12Н24О2Ge2Si
6.48
7.93 C11H22O2Si3
8.49
6.29 C11H22O2Ge2Si
6.16
5.75 C11H24O2Ge3
5.79
4.94 C11H24O2GeSn2
4.69
5.98 C11H20O2SiSn
6.09
6.08 C9H16O2GeSi
6.05
(0.02)
59
(0.02)
71—72
(0.02)
95—98
(0.02)
73
(0.02)
39
(22)
14*
15
62 [104—105] 53.33
53.15
40 [133—135] 36.23
36.81
7.45 C26H42N2O2Ge2Si
7.20
6.81 C11H28O4Ge2Si
6.69
Thus, it can be only suggested that if compound 11 is
formed in these reactions, then only as an unstable interꢀ
* Found (%): N, 4.73. Calculated (%): N, 4.76.

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Russ.Chem.Bull., Int.Ed., Vol. 58, No. 4, April, 2009
Gruener et al.
Table 3. IR and 1H and 13C NMR spectra of compounds 5, 6, 8, 14, and 15
Comꢀ
pound
IR,
ν/cm–1
NMR, δ
1H
13C, {29Si}, [119Sn]
6a
2082,
2100
0.26 (s, 6 H, Me2Si);
0.14 (s, 18 H, Me3Si)
1.1 (Me3Si); 2.4 (Me2Si); 2.7 (C=C=O); 167.5 (C=C=O);
{–3.3 (Me2Si)}; {0.3 (Me3Si)}
5a + 6а
2190,
2095
0.20 (s, 9 H, Me2Si, 5a);
0.34 (s, 6 H, Me2Si, 5a);
3.13 (s, 3 H, OMe, 6a);
0.13 (s, 18 Н, Me3Si, 6a);
0.25 (s, 6 H, Me2Si, 6a)
1.1, 2.5 (оба Me2Si, 5a); 2.7 (C=C=O, 5a); 35.0 (SiC≡C, 5a);
65.2 (OMe, 5a); 112.5 (SiC≡C, 5a); 167.8 (C=C=O, 5a);
{–20.9 (Me3Si, 5a)}; {–21.0 (Me2Si, 5a)};
1.1, 2.5 (оба Me2Si, 6a); 2.7 (C=C=O, 6a); 35.0 (SiC≡C, 6a);
65.2 (OMe, 6a); 112.5 (SiC≡C, 6a); 167.5 (C=C=O, 6a);
{20.9 (Me3Si, 6a)}; {–21.0 (Me2Si, 6a)}
6b
6c
2090
2090
0.28 (s, 18 H, Me3Ge);
0.25 (s, 6 H, Me2Si)
1.6 (C=C=O); 1.2 (Me3Ge); 2.6 (Me2Si);
167.0 (C=C=O)
0.40 (d, 3 H, MeHSi);
0.24 (s, 18 H, Me3Si);
4.74 (k, 1 H, MeHSi)
0.0 (Me3(H)Si); 0.8 (Me3Si); 1.0 (C=C=O);
167.1 (C=C=O);
{–20.8 (Me(H)Si)}; {1.2 (Me3Si)}
6d
2086,
2092
0.27 (s, 18 H, Me3Ge);
0.30 (s, 3 H, MeSi];
–0.7 (MeSi); 0.5 (C=C=O); 1.0 (Me3Ge); 167.0 (C=C=O);
{–22.2 (MeSi)}
4.70 (k, 1 H, MeSi(H))
6e
6f
2080
2050
0.28 (s, 18 H, Me3Ge);
0.40 (s, 6 H, Me2Ge)
0.1 (C=C=O); 1.4 (Me3Ge); 3.1 Me2Ge); 168.0 (C=C=O)
0.37 (s, 18 H, Me3Sn);
0.55 (s, 6 H, Me2Ge)
–6.5 (Me3Sn); –5.2 (C=C=O); 3.7 Me2Ge; 164.0 (C=C=O);
[33.4 (Me3Sn)]
5g
2060,
2180
0.27 (s, 6 H, Me2Si);
0.37 (s, 9 H, Me3Sn);
1.37 (t, 3 H, OCH2Me);
4.13 (k, 2 H, OCH2Me)
–6.2 (Me3Sn); 3.0 (Me2Si); 3.7 (C=C=O); 14.4 (OCH2Me);
36.6 (SiC≡C); 75.2 (OCH2Me); 110.3 (SiC≡C); 163.6 (C=C=O)
8
2080,
2090
0.16 (s, 6 H, Me2Si);
0.24 (s, 9 H, Me3Ge);
1.53 (s, 1 H, CH=C=O)
1.3 (Me3Ge); 1.6 (Si(Ge)C=C=O); 2.1 (Me2Si];
167.0 (Si(Ge)C=C=O); 179.9 (SiCH=C=O)
14
—
0.31 (s, 18 H, Me3Ge);
0.38 (s, 6 H, Me2Si);
1.57 (s, 2 H, SiCHCO);
4.19 (m, 4 H, NHCH2Ph);
5.03 (t, 2 H, NHCH2Ph);
7.13 (m, 10 H, NHCH2Ph)
0.5 (Me2Si); 0.6 (Me3Ge); 31.1 (SiCHCO);
44.3 (NHCH2Ph); 127.8, 129.0, 129.1, 140.8 (Ph);
174.0 (SiCHCO)
15
—
0.15 (s, 6 H, Me2Si);
0.24 (s, 18 H, Me3Ge);
1.62 (s, 2 H, SiCHCO);
11.38 (s, 2 H, COOH)
0.0 (Me3Ge); 0.7 (Me2Si); 29.2 (SiCHCO);
175.7 (SiCHCO)
dimethylsilylenebis[(2ꢀtrimethylgermyl)acetic] acid (15)
(see Scheme 4).
Experimental
Using 6b as an example, it was shown that the eleꢀ
mentꢀsubstituted bisketenes react completely with nucleoꢀ
philes similarly to elementꢀsubstituted monoketenes,
rather somewhat slower.
The constants, yields, and elemental analysis data for
compounds 5g, 6a—f, 8, 14, and 15 are given in Table 2,
the spectral data, in Table 3.
In conclusion, the reaction of acetylenes 1a—e with
trimethylsilicon, ꢀgermanium, and ꢀtin halides 2—4 leads
to promising silylated, germylated, and stannylated monoꢀ
and bisketenes.
IR spectra were recorded on a Perkin—Elmer 983G and
IKSꢀ22 spectrometers (0.1ꢀmm thick cuvette, CaF2 plates),
1H, 13C, 29Si, and 119Sn NMR spectra were recorded on
a Bruker ACꢀ200P (200 MHz), Bruker ARXꢀ250 (250 MHz),
and Bruker Avanceꢀ400 (400 MHz) spectrometers using CDCl3,
C6D6, and DMSOꢀd6 as the solvents. All operations were
performed under dry argon. The starting acetylenes 1a—e and
ketene 5 were synthesized according to the procedures deꢀ
scribed earlier.1 Iodotrimethylsilane 2,17 bromo(iodo)trimethylꢀ
germane,18 compounds 4,19 12,20 and 1321 were synthesized
following known procedures, compound 10 was purchased
from Aldrich.

Si, Ge, Snꢀsubstituted bisketenes
Russ.Chem.Bull., Int.Ed., Vol. 58, No. 4, April, 2009
809
References
5ꢀMethoxyꢀ3,3ꢀdimethylꢀ2ꢀtrimethylsilylꢀ3ꢀsilapentꢀ1ꢀenꢀ4ꢀ
ynꢀ1ꢀone (5a) (in a mixture with 6a). Reagent 2 (2.1 g, 10 mmol)
was added to compound 1a (0.7 g, 4 mmol) in dichloromethane
(6 mL) followed by stirring for 88 h. IR, ν/cm–1: 2190 (—C≡C—),
2095 (C=C=O); after stirring for another 12 h: 2190 (shoulꢀ
der of —C≡C—), 2095 (C=C=O). Distillation in vacuo gave
a 5a + 6a product mixture (ratio 1 : 2) (0.8 g, 67%), b.p. 40—42 °C
(0.02 Torr).
2,2´ꢀ(Dimethylsilylene)bis[(trimethylsilyl)ethylenone] (6a).
A. Reagent 2 (2.4 g, 12 mmol) was added to compound 1a (0.7 g,
4 mmol) in dichloromethane (6 mL) followed by stirring for
115 h. Distillation in vacuo gave product 6a (0.7 g, 56%), b.p.
45—46 °C (0.02 Torr).
B. A mixture of compound 10 (2.5 g, 12 mmol) and triꢀ
ethylamine (1.8 g, 18 mmol) in anhydrous diethyl ether (10 mL)
was added to a solution of compound 9 (0.8 g, 6 mmol) in anꢀ
hydrous diethyl ether (5 mL) at –10 °C followed by stirring
for 24 h at 20 °C. IR of the reaction mixture, ν/cm–1: 2090
(Si(C=C=O)2 from 6a), 2190 (Si(C≡COSi)2 from 11). The
ethereal layer was separated, the subsequent distillation in vacuo
gave compound 6a (0.3 g, 15%), b.p. 47 °C (0.02 Torr). The
spectral data of compound obtained completely agree with
those obtained as above.
C. A mixture of compound 13 (1.4 g, 4 mmol) and triethylꢀ
amine (1.2 g, 12 mmol) in anhydrous diethyl ether (10 mL) was
added to a solution of compound 12 (0.9 g, 8 mmol) in anhyꢀ
drous diethyl ether (5 mL) at –10 °C with stirring. The reaction
mixture was stirred for 6 days at 20 °C. IR of the reaction mixꢀ
ture, ν/cm–1: 2090 (Si(C=C=O)2 from 6a), 2190 (Si(C≡COSi)2
from 11). The ethereal layer was separated, the subsequent fracꢀ
tional distillation gave compound 6a (0.2 g, 9%), b.p. 47 °C
(0.02 Torr). The spectral data of compound obtained completely
agree with those obtained as above.
Similarly to the synthesis of compound 6a (method A), the
following compounds were obtained: 5ꢀethoxyꢀ3,3ꢀdimethylꢀ2ꢀ
trimethylstannylꢀ3ꢀsilapentꢀ1ꢀenꢀ4ꢀynꢀ1ꢀone (5g), 2,2´ꢀ(diꢀ
methylsilylene)bis[(trimethylgermyl)ethylenone] (6b), 2,2´ꢀ(meꢀ
thylsilylene)bis[(trimethylsilyl)ethylenone] (6c), 2,2´ꢀ(methylꢀ
silylene)bis[(trimethylgermyl)ethylenone] (6d), 2,2´ꢀ(dimethylꢀ
germylene)bis[(trimethylgermyl)ethylenone] (6e), and 2,2´ꢀ(diꢀ
methylgermylene)bis[(trimethylstannyl)ethylenone] (6f).
N,N´ꢀDibenzylꢀ2,2´ꢀ(dimethylsilylene)bis[2ꢀ(trimethylgerꢀ
myl)acetamide] (14). Benzylamine (0.43 g, 4 mmol) was added
to a solution of compound 6b (0.5 g, 1.3 mmol) in hexane (20 mL)
with stirring. A precipitate formed was filtered off to obtain prodꢀ
uct 14 (0.47 g, 62%) with m.p. 104—105 °C.
2,2´ꢀ(Dimethylsilylene)bis[2ꢀ(trimethylgermyl)acetic] acid
(15). Water (0.05 g, 2.7 mmol) and concentrated sulfuric
acid (0.01 g) were added to a solution of compound 6b (5 g,
1.3 mmol) in 1,4ꢀdioxane (50 mL) with stirring. A precipitate
formed was filtered off to obtain diacid 15 (2.3 g, 42%) with m.p.
133—135 °C.
1. S. V. Gruener, B. Wrackmeyer, R. N. Ezhov, V. S. Petrosyan,
Izv. Akad. Nauk, Ser. Khim., 2003, 1641 [Russ. Chem. Bull.,
Int. Ed., 2003, 52, 1730].
2. K. Sung, T. T. Tidwell, J. Am. Chem. Soc., 1996, 118, 2768.
3. A. Joffler, G. Himbert, Synthesis, 1992, 495.
4. S. V. Ponomarev, M. B. Erman, S. A. Lebedev, S. Ya.
Pechurina, I. F. Lutsenko, Zh. Obshch. Khim., 1971, 41, 127
[J. Gen. Chem. USSR (Engl. Transl.), 1971, 41].
5. M. A. Kazankova, V. A. Ilyushin, I. F. Lutsenko, Zh. Obshch.
Khim., 1980, 50, 690 [J. Gen. Chem. USSR (Engl. Transl.),
1980, 50].
6. I. V. Efimova, M. A. Kazankova, I. F. Lutsenko, Zh. Obshch.
Khim., 1985, 55, 1647 [J. Gen. Chem. USSR (Engl. Transl.),
1885, 55].
7. R. D. Miller, D. R. Mckean, Synthesis, 1979, 730.
8. Yu. K. Grishin, S. V. Ponomarev, S. A. Lebedev, Zh. Org.
Khim., 1974, 404 [J. Org. Chem. USSR (Engl. Transl.), 1974].
9. K. B. Borisenko, R. N. Yezhov, S. V. Gruener, H. E.
Robertson, D. W. H. Rankin, Inorg. Chim. Acta, 2008,
361, 467.
10. W. Uhlig, A. Tzschach, Z. Chem., 1988, 28, 409.
11. S. V. Ponomarev, A. S. Zolotareva, R. N. Ezhov, Yu. V.
Kuznetsov, V. S. Petrosyan, Izv. Akad. Nauk, Ser. Khim.,
2001, 1045 [Russ. Chem. Bull., Int. Ed., 2001, 50, 1093].
12. B. L. Groh, G. R. Magrum, T. J. Barton, J. Am. Chem. Soc.,
1987, 109, 7568.
13. R. L. Danheiser, A. Nishida, S. Savariar, M. P. Trova, Tetꢀ
rahedron Lett., 1988, 29, 4917.
14. S. Akai, S. Kitagaki, T. Naka, K. Jamamoto, Y. Tsusuki,
K. Matsumoto, Y. Kita, J. Chem. Soc., Perkin Trans. 1,
1996, 1705.
15. H. Kai, K. Iwamoto, N. Chatani, Sh. Murai, J. Am. Chem.
Soc., 1996, 118, 7634.
16. G. Maas, M. Regitz, R. Rahm, J. Schneider, P. J. Stang,
Ch. M. Crittell, J. Chem. Soc., Chem. Commun., 1990, 1456.
17. M. G. Voronkov, Yu. I. Khudobin, Izv. Akad. Nauk SSSR,
Ser. Khim., 1956, 714 [Bull. Acad. Sci. USSR, Div. Chem. Sci.
(Engl. Transl.), 1956, 5].
18. V. F. Mironov, A. L. Kravchenko, Izv. Akad. Nauk SSSR,
Ser. Khim., 1965, 1096 [Bull. Acad. Sci. USSR, Div. Chem.
Sci. (Engl. Transl.), 1965, 14].
19. D. Seyferth, N. Kahlen, J. Org. Chem., 1960, 25, 809.
20. L. L. Shchukovskaya, R. I. Pal´chik, A. N. Lazarev, Dokl.
Akad. Nauk SSSR, 1965, 164, 357 [Dokl. Chem. USSR
(Engl. Transl.), 1965].
21. E. J. Corey, H. Cho, Ch. Rucker, D. H. Hua, Tetrahedron
Lett., 1981, 22, 3455.
Received November 7, 2007;
in revised form October 7, 2008