The exhaustive silylation of 5-nitro-pentan-2-one: Novel processes and opportunities

Article abstract of DOI:10.1016/S0040-4020(01)00055-2

Treatment of 5-nitro-pentan-2-one (1) with Me₃SiOTf/Et₃N leads to initial silylation of the C(O)Me-group to give regioisomeric silyl enol ethers 2a and 2b followed by double silylation of the NO₂-group furnishing a mixture of N,N-bis(silyloxy)enamine 4a and enoxime TMS ether 6. Employment of a large excess of Me₃SiOTf/Et₃N triggers a cascade of eliminations and silylations to give a mixture of (E)-4-trimethylsilyloxy-2-trimethylsilyl-pent-2,4-dienenitrile (8) and 3-oxo-1-(1,1,1-trimethylsilyl)-1-cyclobutanecarbonitrile (9). The use of Me₃SiCl/DBU changes the selectivity of silylation of 1 to give silyl nitronate 2c.

Full text of DOI:10.1016/S0040-4020(01)00055-2

TETRAHEDRON
Pergamon
Tetrahedron 57 (2001) 2221±2230
The exhaustive silylation of 5-nitro-pentan-2-one: novel processes
and opportunities
Alexander A. Tishkov,p Il'ya M. Lyapkalo, Sema L. Ioffe,p Yuri A. Strelenko and
Vladimir A. Tartakovsky
N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky prosp. 47, 117913 Moscow, Russian Federation
Received 6 October 2000; revised 8 December 2000; accepted 4 January 2001
AbstractÐTreatment of 5-nitro-pentan-2-one (1) with Me3SiOTf/Et3N leads to initial silylation of the C(O)Me-group to give regioisomeric
silyl enol ethers 2a and 2b followed by double silylation of the NO2-group furnishing a mixture of N,N-bis(silyloxy)enamine 4a and enoxime
TMS ether 6. Employment of a large excess of Me3SiOTf/Et3N triggers a cascade of eliminations and silylations to give a mixture of (E)-4-
trimethylsilyloxy-2-trimethylsilyl-pent-2,4-dienenitrile (8) and 3-oxo-1-(1,1,1-trimethylsilyl)-1-cyclobutanecarbonitrile (9). The use of
Me3SiCl/DBU changes the selectivity of silylation of 1 to give silyl nitronate 2c. q 2001 Elsevier Science Ltd. All rights reserved.
1. Introduction
2. In¯uence of the nature of the silylating reagent
The silylation of aliphatic nitro compounds (ANC) is a
promising method to broaden their reactivity.1 The most
interesting and unusual results could be obtained upon silyl-
ation of different functionalized nitro compounds. Thus, the
reactivity of readily available g-functionalized derivatives
of the general formula RCHX±CHY±CHZ(NO2) (RˆH,
alkyl or aryl; Xˆelectron-withdrawing group; Y, ZˆH,
alkyl, aryl, functional group)2 upon silylation depends on
several factors, such as the nature of R, X, Y, Z and the
silylating reagents, as well as the conditions of silylation.
The silylation of these compounds could lead to
enoximes,3±6 N,N-bis(silyloxy)enamines,4,7 N,N-bis(silyl-
oxy)amino-dihydrofurans and cyclopropanes,8 b-function-
alized N,N-divinylhydroxylamines.6
Treatment of ketone 1 with Me3SiCl/DBU9 gives silyl
nitronate 2c in high yield (Scheme 1).
The reaction proceeds chemoselectively affecting only the
CH2NO2 moiety.
Utilization of a stronger silylating reagent, Me3SiBr/Et3N,
for the silylation of ketone 1 resulted in the formation of a
complicated mixture of unidenti®ed products, which
contained ca. 20% of enoxime 6. It is noteworthy that
b-aryl-g-nitroketones were transformed under the same
reaction conditions into dihydrofurans8 or a-oxymino-
styrenes10, while a related analog of ketone 1, methyl
4-nitrobutanoate, underwent facile double silylation.4
Such diversity of transformations and crucial dependence of
reaction pathway on a multitude of factors complicate a
prediction of the result in each new case. Therefore, more
experimental data on the effect of varying the substituents is
required in order to be able to control the process outcome.
In this study, 5-nitro-pentan-2-one (1) was chosen as a
model polyfunctional compound, having both a nitro- and
a carbonyl group capable to undergo silylation.
To obtain a more unambiguous result, we used 4 equiv. of
one of the most powerful silylating reagent Me3SiOTf/Et3N.
However, even in this case we observed the formation of
complicated mixtures of products. Nevertheless, the
employment of more than 10-fold excess of silylating
reagent allowed us to isolate the nitriles 8 (44%) and 9
(17%).
Products of such kind have never been isolated before upon
silylation of ANC. This unexpected result prompted us to
investigate in detail the silylation of nitro-ketone 1 using
Me3SiOTf/Et3N and varying the temperature of the process
and the ratio of reagents. The main results are presented in
Scheme 1 and Table 1.
Keywords: silylation; nitro ketones; N,N-bis(silyloxy)enamines; elimina-
tion; E,Z-isomerization.
Corresponding authors. Tel.: 17-095-938-36-23; fax: 17-095-135-53-
p
Attempts to monitor directly the course of silylation by
NMR failed because the presence of excess of silylating
28; e-mail: tishkov@cacr.ioc.ac.ru
0040±4020/01/$ - see front matter q 2001 Elsevier Science Ltd. All rights reserved.
PII: S0040-4020(01)00055-2

2222
A. A. Tishkov et al. / Tetrahedron 57 (2001) 2221±2230
Scheme 1. (i) Me3SiOTf/Et3N in CH2Cl2; the ratios are presented in Table 1 (2a/2bˆ1:1). (ii) (1) (Me3Si)2NLi (2.5 equiv.) in THF; (2) Me3SiCl (3.5 equiv.);
(3) H2O; (2a/2bˆ1:2.6). (iii) DBU/Me3SiCl in CH2Cl2, 0!208C. (iv) NH4F in MeOH, 108C. (v) Silica gel, 208C.
reagent hampered the spectral registration as the precipitate
manner. The residue, after solvent evaporation, was mixed
with an internal standard for further NMR analysis.
1
²
of Me3SiNEt3 OTf2 formed. Therefore, an alternative
procedure was employed.
The reagents were mixed at 2788C. The reaction mixture
was stirred for the time period stated in Table 1 at the
indicated temperature, and then quenched at 2308C by
adding ®rst petroleum ether, and then methanol and water
(the quenching was made at 2788C in case of entry 2, Table
1). The organic layer was separated and washed in a regular
²
The mild quenching conditions are meant to avoid desilylation of all
products formed upon silylation of ketone 1 with Me3SiOTf/Et3N. The
exception is the compounds containing silyl nitronate moiety
CHvN(O)OSiMe3, which should easily transform into CH2NO2-group
upon such quenching.

A. A. Tishkov et al. / Tetrahedron 57 (2001) 2221±2230
Table 1. The silylation of substrates with Me3SiOTf/Et3N
2223
Entry
Substrate for silylation (SS)
Mol. ratio SS:TMSOTf:Et3N
T, 8C/time, h
The yields of products and intermediates (%)
2a
2b
4a
5
6
7
8
9
1a
2
3
4
5
6
7
8
1
1
1
1:1.1:1.4
1:4.2:4.5
1:4.2:4.5
1:3.2:4.5
1:4.2:4.5
1:7.0:8.0
1:11.0:12.0
1:3.0:3.5
1:7.0:8.0
1:7.0:8.0
278/4
278/2
230/1
230/1
0/3
20/24
20/50
20/6
47b
41c
±
±
±
±
±
±
±
47b
41c
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
±
40b
24b
±
8b
2b
21b
±
51b,d
72b,e
61b,f
±
2a,b (2a/2bˆ1:2.6)
1
1
1
±
±
±
±
±
±
±
51b,g
±
14b
52b,h
±
22b
20b
±
±
±
±
±
±
±
±
±
E-11
E-11
E-11
85c
20b
±
9
10
5/30
20/55
68b
80c
±
±
±
±
±
a
In NMR tube in CD2Cl2.
By 1H NMR spectrum with internal standard ClCH2CH2Cl (the accuracy is ^3%).
Yield for distilled product.
(4a15):6ˆ1:1.06; syn-6:anti-6,1:3.3.
(4a15):6ˆ1:2.7; syn-6:anti-6,1:3.3.
syn-6:anti-6,1:3.4.
Contained the traces of E-11 and 10.
Contained the traces of 10.
b
c
d
e
f
g
h
3. Mechanism of silylation of nitro-ketone 1 upon
treatment with Me3SiOTf/Et3N
a-protons in the 1- and 3-positions of 1 undergo facile
exchange for deuterium under acidic conditions (DCl in
D2O), whereas the CH2NO2 moiety remains intact.12 At
the same time, the CH-acidity of ANC (pKa,8±10) exceeds
substantially the CH-acidity of ketones (pKa,19±20).13
Therefore, the `nucleophilic' silylating reagents preferen-
tially attack the CH2NO2 moiety of functionalized ANC.
In contrast to this, `electrophilic' silylating reagents should
silylate the carbonyl group. In this connection, the nucleo-
philic Me3SiCl/Et3N in benzene is widely used for the
preparation of silyl nitronates from primary ANC at
208C.14 The same Me3SiCl/Et3N silylates ketones only
under harsh conditions and heating in highly polar DMF
is required.15 The use of more basic DBU instead of Et3N
facilitates the silylation of CH2NO2 moiety ((iii), Scheme
1). The mixture of Me3SiOTf and Et3N exists, especially at
low temperature, as the salt [Et3NSiMe3]1 OTf2,16 i.e. it
possesses a highly electrophilic character. This might be a
reason why Me3SiOTf/Et3N silylates selectively the
carbonyl group in nitro-ketone 1 in the presence of the
CH2NO2 moiety at low temperature.
As was mentioned above, the silylation of nitro-ketone 1
with Me3SiOTf/Et3N is an exceptionally complicated
process, which has no precedent in the practice of ANC
silylation. However, the data on effects of the variation of
temperature, reaction time and ratio of reagents on the
reaction outcome enable us to de®ne the nature of the inter-
mediates formed in the sequence of the transformations
leading to the main isolable products, namely silyl enol
ethers 2, the mixture of oximes 5 and 6, and the mixture
of nitriles 8 and 9 (Scheme 1, Table 1).
The silylation at 2788C proceeds chemoselectively affect-
ing the carbonyl group, independent of the ratio of reagents
and furnishes a mixture of silyl enol ethers 2a and 2b (only
the E-isomer was formed) in the ratio 1:1. The mixture of 2a
and 2b with a different ratio (1:2.6, respectively) could be
prepared by method (ii) in Scheme 1.
The employment of excess of Me3SiOTf/Et3N does not
affect the result of silylation of nitro-ketone 1 at 2788C
(cf. entries 1 and 2, Table 1).
The initially formed silyl enol ethers 2a and 2b undergo
double silylation at the CH2CH2NO2 moiety upon tempera-
ture increase up to 2308C to give the mixture of 4a and 6
(entries 3 and 4, Table 1). Oxime 6 was observed as a
mixture of syn- and anti-isomers. All products were
obtained as E-isomers around the internal C,C-double
bond. The reaction mixture contained also a small amount
of oxime 5. The overall yield of products is close to quanti-
tative and the ratio 4a/6 is predetermined by the ratio of silyl
enol ethers 2a and 2b, respectively (cf. entries 3 and 4,
Table 1). Hence one may conclude, that N,N-bis(silyloxy)-
enamine 4a emerged from 2a and oxime 6 from 2b.
³
Thus, the chemoselectivity of silylation of nitro-ketone 1
entirely changes, when Me3SiCl/DBU is substituted by
Me3SiOTf/Et3N. This result could be rationalized from the
standpoint of the difference in the electrophilicity of the
silylating reagents employed.
The carbonyl group in the starting nitro-ketone 1 is more
basic than the nitro group (for RNO2H1 pKa,212; for
RR0CvOH1 pKa,27).11 It should be noted also, that ®ve
³
The absence of silyl nitronates 3 in the reaction mixture
does not seem unexpected, as the rate of silylation of silyl
nitronates with Me3SiOTf/Et3N exceeds the rate of initial
silylation of starting ANC, as was previously reported.17
The high stereoselectivity of the formation of the C,C-
double bond in N,N-bis(silyloxy)enamines upon silylation
It is reasonable to suppose, that the employment of large excess of
Me3SiOTf/Et3N gives rise to the mixture of silyl nitronates 3a and 3b,
which transforms into the mixture of nitro compounds 2a and 2b upon
quenching. However, the quenching of the reaction mixture (entry 2,
Table 1) with MeOD (the enrichment is more then 60%) does not lead
to the introduction of deuterium in the nitro compounds 2a and 2b
1
(according to H and 13C NMR).

2224
A. A. Tishkov et al. / Tetrahedron 57 (2001) 2221±2230
Scheme 2.
is well known,7,17,18 as well as the fact that N,N-bis(silyl-
oxy)enamines are prone to rearrange into 2-silyloxy-
oximes.17 Therefore, the stereoselectivity of formation of
N,N-bis(silyloxy)enamine 4a and the observation of the
product of its rearrangement in the reaction mixture seems
to be a rather expected result.
time (entries 6 and 7, Table 1). The ®rst step of this process
is the stereoselective elimination of Me3SiOH from the
CHvN fragment with retention of con®guration of the
internal C,C-double bond. The transformation of oximes
into nitriles upon treatment with Me3SiOTf/Et3N was
previously unknownk. Taking into account the formation
of 9, we assume, that this process might be general.
Additional comments are warranted in order to explain the
presence of silylated oxime 6 among the products of silyl-
ation. It is beyond any doubt, that the main precursor of 6
under these conditions is a tentative intermediate 4b, which
formed from silyl enol ether 2b upon double silylation.
Apparently, N,N-bis(silyloxy)enamine 4b undergoes stereo-
selective elimination of Me3SiOH to give the E-isomer of
oxime 6 and the ease of this process can be explained by the
facile formation of stabilized cation A (Scheme 2). The
driving force behind this reaction is the cleavage of a
weak N,O-single bond in electron enriched N,N-bis(silyl-
oxy)enamine 4b along with formation of the thermo-
dynamically stable unsaturated oxime 6.
The second step of the observed transformation 6!8 is of
considerable interest. It consists of the stereoselective silyl-
ation of the dienenitrile 7 affecting the a-carbon atom
relative to the CN-group¶. This step proceeds with entire
inversion of con®guration of the internal C,C-double bond
in dienenitrile 7. The transformation 7!8 most likely
includes the intermediacy of cation B, which eliminates
tri¯ic acid to give linear intermediate C. The latter suffers
a smooth rearrangement into the thermodynamically stable
E-isomer of nitrile 8 (Scheme 3). An alternative mechanism
of the transformation 7!8 is possible (Scheme 4).
The desilylation of nitrile 8 could be realized in high yield
and with entire retention of con®guration of the C,C-double
Further increase of the temperature of silylation up to 08C
and a longer exposure allows us to obtain the mixture of
oximes 5 and 6 with high overall yield (entry 5, Table 1). In
the light of the above mentioned, the formation of these
products does not require additional explanations. However,
it should be noted, that the ratio of 5 and 6 is 1:2.9, which
does not correlate with the starting ratio of silyl enol ethers
2a and 2b (1:1). This discrepancy might be due to well-
known fact of the low yields of the rearrangement of N,N-
bis(silyloxy)enamines. Obviously, the increase of the yield
of 6 is connected with the competitive elimination of
Me3SiOH from 4a.§
²²
bond (Schemes 1 and 3). Owing to this, the found process
could appear to be a convenient way for the E,Z-isomerisa-
tion of b-substituted conjugated enenitriles. However, we
have isomerised the known enenitrile E-11 into Z-11 with an
overall yield of 75% (Scheme 3, 80% for the step E-11!8,
entries 9 and 10, Table 1, and 91% for the step 8!Z-11).
The intermediacy of nitrile 7 also was rigorously established
(entry 8, Table 1).
It seems reasonable to discuss brie¯y the other potential
option for the application of enenitrile 8 and related struc-
tures. a-Silylated enenitriles are the only known equivalents
of vinyl carbanions of the general type [RR0CvC±CN]2
and they react with some electrophiles in the presence of
F2 anions.20 Therefore, the silylation of enenitriles or their
The desilylation of the mixture 516 upon treatment with
NH4F in MeOH allows us to isolate the E-isomer of the
known enoxime 1219 with satisfactory yield (Scheme 1).
³³
precursors enaldoximes with Me3SiOTf/Et3N might be a
As was mentioned in the ®rst part of the article, the eleva-
tion of temperature and the increase of excess of silylating
reagent leads to the realization of hitherto unknown
processes giving rise to nitriles 8 and 9. The precursors of
these nitriles are the oximes 6 and 5, respectively. The rates
of these reactions are essentially lower than those for
already discussed transformations. Me3SiOTf serves as
Lewis acidic mediator of the transformations of 5 and 6
into 9 and 8.
k
A similar elimination was postulated once when ANC have been treated
with Me3SiI (the aldoximes have been generated in situ from primary
nitro compounds). However, this process was not smooth: Olah, G. A.;
Narang, S. C.; Field, L. D.; Fung, A. P. J. Org. Chem. 1983, 48, 2766 -
2767.
¶
We know only two somewhat similar silylations of a,b-unsaturated
nitriles mediated by Me3SiI/Et3N at 1208C to give moderate yields of
a-silylated nitriles (see: Yamashita, H.; Reddy, N. P.; Tanaka, M. Bull.
Chem. Soc. Jpn. 1994, 67, 1510 - 1513). However, the authors proposed a
different mechanism, which includes initial g-C±H deprotonation.
Obviously, this mechanism could not be operative in our case.
The intermediacy of the E-isomer of dienenitrile 7 in the
transformation of 6 into 8 is unambiguously established
upon variation of the ratio of reagents and the reaction
²²
This is in accordance with the normal way of protodesilylation in alkenyl
silanes, indicating no free linear carbanions generation in reaction condi-
tions (see: Weber, W. P. Silicon Reagents for Organic Synthesis,
Springer, Berlin, 1983, 85).
§
³³
A similar process has been reported previously for the example of
MeOOCCH2CHvCHN(OSiMe3)2, see Ref. 4
For the preparation of a,b-unsaturated aldoximes from ready available
ANC via silylation see: ref.3±6

A. A. Tishkov et al. / Tetrahedron 57 (2001) 2221±2230
2225
Scheme 3.
Scheme 4.
Scheme 5.
convenient method for the preparation of these interesting
building blocks.
It is likely that the step 5!9 proceeds via the generation of
cationic intermediate D, which suffers intramolecular
cyclization into ketone 14 followed by transformation of
the CHvNOSiMe3-group into the CN-group and silylation
of the resulting nitrile affecting the a-carbon atom likewise
the discussed reaction 6!8 (Scheme 5).§§
The formation of nitrile 9 is the other interesting process,
which was found upon silylation of nitro-ketone 1 with an
excess of Me3SiOTf/Et3N. The obvious pathway of its
formation could be represented by the sequence
1!2a!3a!4a!5!9.
§§The sequence of steps was chosen arbitrary and the initial formation of the
nitrile group followed by cyclization is possible.

2226
A. A. Tishkov et al. / Tetrahedron 57 (2001) 2221±2230
5. Conclusion
The entire utilization of the oxidizing potential of the nitro
group was accomplished upon silylation of the sterically
unhindered nitro-ketone 1 via cleavage of the weak N±O
bonds. The formation of new multiple C,C- and C,N-bonds
took place.
Several interesting reactions were disclosed. Further
research will be focused on the application of these
processes in organic synthesis.
Figure 1.
The mixture of nitriles 8 and 9 could be separated by ¯ash
chromatography at low temperature (2788C), as the regular
separation at room temperature is complicated by the
desilylation of nitrile 8 into keto-nitrile 10, which has the
same Rf as its cyclic isomer 9.kk The conversion of 8 into 10
on silica gel at room temperature is 80% in 1.5 h and keto-
nitrile 10 could be obtained with good yield at prolonged
exposure.
6. Experimental
6.1. General
NMR spectra were recorded on Bruker AM-300 instrument.
Chemical shifts were measured relative to solvent residual
1
peak (7.26 ppm for H and 77.16 ppm for 13C)23, internal
The complete desilylation of nitrile 9 upon the treatment
with NH4F in MeOH proceeds with good yield to give the
known keto-nitrile 13.21
reference (SiMe4, 0 ppm, for 29Si) and external reference
(MeNO2, 0 ppm, for 14N). The INEPT pulse sequence24
was used for 29Si signals observation. IR spectra were
recorded on Bruker `VECTOR 22'.
4. Determination of the structure and double bond
con®guration of the products and intermediates
Reagents: commercially available Et3N, Me3SiCl, DBU,
and (Me3Si)2NH were freshly distilled with CaH2,
Me3SiOTf was distilled and stored with few drops of
SiMe4, Me3SiBr was freshly distilled and stored with Cu
shavings. n-BuLi in hexane (ca. 1.5 mol/L) was used as
purchased from `Merck'. Reactions were carried out in
dry argon atmosphere using CH2Cl2 freshly distilled with
CaH2. Dry THF and Et2O were obtained by boiling with Na/
Ph2CvO followed by distillation. All other solvents were
distilled prior to use.
All obtained products and intermediates of silylation of
ketone 1 were characterized with NMR and IR spectra.
The composition of isomeric silyl enol ethers 2a and 2b,
nitriles 8 and Z-11 was con®rmed by means of micro-
analysis. The structure of compounds 9 and 10 was
con®rmed by their transformations into known nitrile 13
and described herein Z-11, respectively.
Merck TLC plates were used for chromatographic analysis
and Fisher silica gel (particle size 32±63 mm) was used for
¯ash column chromatography. The ¯ash-chromatography at
2788C was carried out using a column equipped with
freezing jacket ®lled with dry ice/acetone.
The recorded NMR and IR spectra for all known products
were in good agreement with literature data.
The con®guration of the internal disubstituted C,C-double
bond in compounds 4a, 6, 7, E-11, Z-11 and 12 was de®ned
using the values of corresponding 3JH,H coupling constants.¶¶
The E-con®guration of the trisubstituted C,C-double bond
in compounds 2b, 8 and 10 was assigned by means of
nuclear Overhauser effect measurements (Fig. 1).
Starting 5-nitro-pentan-2-one 125 and E-4-oxo-pent-2-
enenitrile E-1126 were obtained according to the known
procedures. 1, colourless liquid, bp 118±1208C/10 (lit.25
bp 117±1298C/10 Torr); nmax (KBr) 1716 (s, CvO), 1554
(s, NO2), 1372 (m, NO2) cm21 (in agreement with lit.25
The con®guration of the C,N-double bond in oximes 6 and
12 was determined on the basis of the values of the chemical
shift of the proton in the CHvN-moieties using the rule,
that this proton in the syn-isomer is shifted 0.5±0.6 ppm
up®eld compared with the analogous signal in the anti-
isomer.22 The anti-con®guration of product 5 was assigned
by comparing the observed chemical shift of the CHvN
proton with the chemical shifts of the same protons in
known similar compounds.17
3
data); dH (300.13 MHz, CDCl3) 4.40 (2H, t, Jˆ6.5 Hz,
3
CH2NO2), 2.58 (2H, t, Jˆ6.5 Hz, CH2C(O)), 2.21 (2H,
3
qt, Jˆ6.5 Hz, CH2), 2.15 (3H, s, MeC(O)) (in agreement
with lit.25 data); dC (75.47 MHz, CDCl3) 206.5 (CvO), 74.3
14N
(CH2NO2), 39.0 (CH2C(O)), 29.6 (Me), 20.9 (CH2); d
(21.69 MHz, CDCl3) 0.7 (Dn1/2 90 Hz, NO2). E-11,
yellowish solid, 75±808C/40 Torr (lit.26 bp 738C/11 Torr);
mp 26±278C (lit.26 mp 278C); nmax (KBr) 2226 (w, CN),
1709 (s, CvO) cm21 (in agreement with lit.27 data); dH
(300.13 MHz, CDCl3) 6.94 (1H, d, 3Jˆ16.5 Hz,
CHvCHCN), 6.31 (1H, d, 3Jˆ16.5 Hz, CHvCHCN),
2.37 (3H, s, Me) (in agreement with lit.28 data); dC
(75.47 MHz, CDCl3) 194.5 (CvO), 145.1 (CHvCHCN),
kkEmployment of rapid ¯ash chromatography at 208C gives rise to slight
conversion of 8 into 10 (max. 10%) and this method is the most conve-
nient for the isolation of 8.
¶¶ The large value of the 3JH±H coupling constant (13.4±16.4) is typical for
trans a,b-disubstituted alkenes: Hesse, M.; Meier, H.; Zeeh, B. Spectro-
skopische Methoden in der Organischen Chemie, Georg. Thieme Verlag,
Stuttgart , 1995, 108 (in German).
14N
d
115.9 (CN), 110.9 (CHvCHCN), 28.9 (Me);
(21.69 MHz, CDCl3) 2106 (Dn1/2 520 Hz, CN).

A. A. Tishkov et al. / Tetrahedron 57 (2001) 2221±2230
2227
6.2. General procedure for silylation with Me3SiOTf/
Et3N (GP)
Na2SO4 and evaporated in vacuo to give the mixture of two
title compounds 2a and 2b (93 mg, 89% by NMR, mol. ratio
1:2.6, respectively, yellowish oil), which was suf®ciently
pure for utilization in following transformation.
To a vigorously stirred solution of starting compound
(1.50 mmol) in CH2Cl2 (1.5 mL) at 2788C (dry ice/acetone)
was added in one portion the de®ned amount of neat Et3N.
Then the de®ned amount of Me3SiOTf in CH2Cl2 (1 mL)
was added dropwise in 10 min at 2788C. Dry ice/acetone
bath was removed (unless the reaction was carried out at
2788C) and the reaction mixture was stored at stirring in
conditions indicated in Table 1. For quenching the reaction
mixture was recooled to 2308C and petroleum ether
(10 mL) was added (the quenching at 2788C was made in
case of silylation at 2788C, see entry 2, Table 1). MeOH
(0.5 mL) was added to vigorously stirred solution, reaction
mixture was maintained for 5 min and then poured into the
two-phase mixture of H2O (20 mL) and petroleum ether
(10 mL). The organic phase was washed consecutively
with the solution of NaHSO4´H2O (0.11 g) in H2O
(20 mL), H2O (10 mL), and brine (10 mL), dried with
Na2SO4 and concentrated in vacuo to provide the crude
product. The yields were determined by means of 1H
NMR with a quantitative standard (ClCH2CH2Cl, the
accuracy is ^3%) or by distillation in short-path
apparatus.
6.2.2. Mixture of O-(1,1,1-trimethylsilyl)-N-[(1,1,1-tri-
methylsilyl)oxy]-N-{(1E)-4-[(1,1,1-trimethyl-silyl)oxy]-
1,4-pentadienyl}hydroxylamine (4a), 2,4-bis[(1,1,1-
trimethylsilyl)oxy]-4-pentenal O1-(1,1,1-trimethylsily-
l)oxime (5) and (2E)-4-[(1,1,1-trimethylsilyl)oxy]-2,4-
pentadienal O1-(1,1,1-trimethylsilyl)oxime (6). a. Treat-
ment of the ketone 1 (197 mg, 1.50 mmol) with Me3SiOTf
(1.20 mL, 6.32 mmol) and Et3N (0.94 mL, 6.75 mmol)
according to GP (2308C, 1 h) gave the mixture of three
1
title compounds 4a, 5 and 6 (447 mg, overall 99% by H
NMR, mol. ratio 5:1:6.4, respectively; syn-6:anti-6ˆ1:3.3,
yellowish oil). For 4a dH (300.13 MHz, CDCl3) 6.03 (1H,
3
3
dt, Jˆ13.5, 1.5 Hz, CHvCHN), 5.52 (1H, dt, Jˆ13.5,
7.5 Hz, CHvCHN), 4.05 (2H, m, CH2vC), 2.71 (2H, d,
3Jˆ7.5 Hz, CH2), 0.20 (9H, s, COSiMe3), 0.19 (18H, s,
NOSiMe3); dC (75.47 MHz, CDCl3) 157.4 (CH2vC),
144.3 (CHvCHN), 118.1 (CHvCHN), 90.5 (CH2vC),
29Si
CDCl3) 25.9 (NOSiMe3), 17.5 (COSiMe3). For 5 dH
36.4 (CH2), 0.9 (SiMe3), 0.3 (SiMe3); d
(59.63 MHz,
3
(300.13 MHz, CDCl3) 7.35 (1H, d, Jˆ7.5 Hz, CHvN),
4.46 (1H, m, CHOSiMe3), 4.07 (2H, m, CH2vC), 2.30
(2H, m, CH2), 0.20 (SiMe3), 0.14 (SiMe3), 0.11 (SiMe3);
dC (75.47 MHz, CDCl3) 156.5 (CHvN), 154.7 (CH2vC),
92.2 (CH2vC), 68.1 (CHOSiMe3), 43.8 (CH2), 1.5 (SiMe3),
6.2.1. Mixture of trimethyl-[1-(3-nitro-propyl)vinyloxy]-
silane (2a) and (E)-trimethyl-(1-methyl-4-nitro-but-1-
enyloxy)-silane (2b). a. Treatment of the ketone 1
(197 mg, 1.50 mmol) with Me3SiOTf (1.20 mL,
6.32 mmol) and Et3N (0.94 mL, 6.75 mmol) according to
GP (2788C, 2 h) gave the mixture of two title compounds
2a and 2b (167 mg, overall 82% after distillation, mol. ratio
1:1, colourless oil), bp 44±458C/0.1 Torr; (Found: C, 47.3;
H, 8.5; N, 6.9; Si, 14.0. C8H17NO3Si requires C, 47.26; H,
8.43; N, 6.89; Si, 13.81%); nmax (KBr) 1555 (s, NO2), 1381
(m, NO2), 1254 (m, SiMe3), 847 (s, SiMe3) cm21. For 2a dH
29Si
0.1 (SiMe3), 20.6 (SiMe3); d (59.63 MHz, CDCl3) 25.1
(NOSiMe3), 18.7 (COSiMe3), 17.2 (COSiMe3). For anti-6
3
4
dH (300.13 MHz, CDCl3) 7.86 (1H, dd, Jˆ10.0 Hz, Jˆ
0.5 Hz, CHvCH±CHvN), 6.51 (1H, ddt, 3Jˆ10.0,
5
3
15.5 Hz, Jˆ0.5 Hz, CHvCH±CHvN), 6.26 (1H, d, Jˆ
15.5 Hz, CHvCH±CHvN), 4.47 (2H, m, CH2vC), 0.25
(9H, s, SiMe3), 0.23 (9H, s, SiMe3); dC (75.47 MHz, CDCl3)
154.8 (CHvCH±CHvN), 154.5 (CH2vC), 136.1
(CHvCH±CHvN), 123.3 (CHvCH±CHvN), 98.7
3
(300.13 MHz, CDCl3) 4.40 (2H, t, Jˆ7.0 Hz, CH2NO2),
29Si
CDCl3) 25.6 (NOSiMe3), 19.6 (COSiMe3). For syn-6 dH
(CH2vC), 0.1 (SiMe3), 20.7 (SiMe3); d
(59.63 MHz,
4.09 (2H, m, CH2vC), 2.16 (4H, m, (CH2)2), 0.21 (9H, s,
SiMe3); dC (75.47 MHz, CDCl3) 156.7 (CH2vC), 91.4
(CH2vC), 74.7 (CH2NO2), 33.2 (CH2), 24.7 (CH2), 0.1
3
(300.13 MHz, CDCl3) 7.30 (1H, d, Jˆ9.5 Hz, CHvCH±
CHvN), 7.09 (1H, dd, 3Jˆ9.5, 15.5 Hz, CHvCH±
CHvN), 6.32 (1H, d, 3Jˆ15.5 Hz, CHvCH±CHvN),
4.54 (2H, m, CH2vC), 0.21 (9H, s, SiMe3), 0.20 (9H, s,
SiMe3); dC (75.47 MHz, CDCl3) 154.4 (CH2vC), 151.8
(CHvCH±CHvN), 136.7 (CHvCH±CHvN), 117.4
(CHvCH±CHvN), 100.5 (CH2vC), 20.2 (SiMe3), 20.9
29Si
(SiMe3); d
(59.63 MHz, CDCl3) 18.1 (COSiMe3). For
2b dH (300.13 MHz, CDCl3) 4.40 (1H, m, CHvC), 4.32
(2H, t, 3Jˆ7.0 Hz, CH2NO2), 2.66 (2H, qd, 3Jˆ7.0,
1.0 Hz, CH2), 1.79 (3H, m, Me), 0.20 (9H, s, SiMe3); dC
(75.47 MHz, CDCl3) 150.7 (CHvC), 101.2 (CHvC),
29Si
75.3 (CH2NO2), 24.0 (CH2), 22.6 (Me), 0.8 (SiMe3); d
29Si
(SiMe3); d
(COSiMe3).
(59.63 MHz, CDCl3) 25.2 (NOSiMe3), 19.5
(59.63 MHz, CDCl3) 17.5 (COSiMe3). For both 2a and 2b
(21.69 MHz, CDCl3) 4.8 (Dn1/2 110 Hz, NO2).
14N
d
b. Treatment of the mixture of 2a and 2b (76 mg,
0.37 mmol, molar ratio 1:2.6, respectively) with Me3SiOTf
(0.23 mL, 1.21 mmol) and Et3N (0.23 mL, 1.67 mmol)
according to GP (2308C, 1 h) gave the mixture of three
b. To a stirred solution of (Me3Si)2NH (0.31 mL, 1.50
mmol) in THF (4 mL) a solution of n-BuLi in hexane
(0.83 mL of ca. 1.5 mol/L, 1.25 mmol) was added at 08C.
The mixture was stirred for 20 min at 08C and cooled down
to 2788C. A solution of nitro ketone 1 (66 mg, 0.50 mmol)
in THF (10 mL) was then added dropwise and the reaction
mixture was stirred for 1 h at 2788C. After the addition of
the solution of Me3SiCl (0.21 mL, 1.67 mmol) in THF
(1 mL) the resulting mixture was allowed to warm to
ambient temperature and evaporated carefully in vacuo.
The residue was diluted with petroleum ether (20 mL) and
poured into H2O (20 mL). The organic layer was separated,
washed with H2O (10 mL) and brine (10 mL), dried with
1
title compounds 4a, 5 and 6 (102 mg, overall 98% by H
NMR, mol. ratio 12:1:36, respectively, syn-6/anti-6ˆ1:3.3;
yellowish oil).
c. Treatment of the ketone 1 (197 mg, 1.50 mmol) with
Me3SiOTf (1.20 mL, 6.32 mmol) and Et3N (0.94 mL,
6.75 mmol) according to GP (08C, 3 h) gave the mixture
of two title compounds 5 and 6 (230 mg, overall 82% by
1H NMR, mol. ratio 1:2.9, respectively, brown oil).

2228
A. A. Tishkov et al. / Tetrahedron 57 (2001) 2221±2230
1
pent-2,4-dienenitrile (8) (30 mg, overall 72% by H NMR,
6.2.3. (E)-4-Trimethylsilyloxy-pent-2,4-dienenitrile (7).
a. Treatment of the nitrile E-11 (71 mg, 0.75 mmol) with
Me3SiOTf (0.43 mL, 2.26 mmol) and Et3N (0.37 mL,
2.66 mmol) according to GP (208C, 6 h) gave the title
compound 7 (106 mg, 85% after distillation, colourless
liquid); bp 45±508C/0.2 Torr (lit.28 bp 548C/2 Torr); nmax
(KBr) 2219 (w, CN), 1256 (m, SiMe3), 850 (s, SiMe3)
mol. ratio 1:2.6, respectively, contained traces of 10, brown
oil). The resulting mixture was distilled at 50±608C/0.1 Torr
and then subjected to rapid ¯ash-chromatography at 2788C
to give title compound 9 (5.4 mg, 17%, yellowish oil, Rf
(EtOAc/petrol. ether 1:3) 0.20) and (E)-4-trimethylsily-
loxy-2-trimethylsilyl-pent-2,4-dienenitrile (8) (22 mg,
49%, colourless liquid).
3
cm21; dH (300.13 MHz, CDCl3) 6.82 (1H, d, Jˆ16.0 Hz,
CHvCHCN), 5.63 (1H, dt, 3Jˆ16.0, 5Jˆ0.5 Hz,
2
5
CHvCHCN), 4.65 (1H, dd, Jˆ1.5, Jˆ0.5 Hz, CH2vC),
For 9. nmax (KBr) 2220 (w, CN), 1796 (s, CvO), 1258 (m,
SiMe3), 847 (s, SiMe3) cm21; dH (300.13 MHz, CDCl3) 3.66
2
5
4.63 (1H, dd, Jˆ1.5, Jˆ1.0 Hz, CH2vC), 0.24 (9H, s,
SiMe3); dC (75.47 MHz, CDCl3) 152.5 (CH2vC), 147.8
(CHvCHCN), 118.0 (CN), 103.0 (CHvCHCN), 97.5
2
4
(2H, ddd, Jˆ15.5, Jˆ3.5, 2.5 Hz, CHMHM'), 3.26 (2H,
ddd, 2Jˆ15.5, 4Jˆ3.5, 2.5 Hz, CHAHA'), 0.27 (9H, s,
CSiMe3); dC (75.47 MHz, CDCl3) 200.4 (CvO), 124.0
29Si
(CH2vC), 0.0 (SiMe3); d
14N
(59.63 MHz, CDCl3) 21.7
(21.69 MHz, CDCl3) 2115 (Dn1/2
29Si
(CN), 54.8 (2 CH2), 11.7 (CSiMe3), 24.4 (SiMe3); d
(COSiMe3);
760 Hz, CN).
d
(59.63 MHz, CDCl3) 11.5 (CSiMe3); the 14N signal is too
broad to be observed.
b. Treatment of the ketone 1 (98 mg, 0.75 mmol) with
Me3SiOTf (1.00 mL, 5.26 mmol) and Et3N (0.84 mL,
6.03 mmol) according to GP (208C, 24 h) gave the mixture
of the title compound 7, (E)-4-trimethylsilyloxy-2-
trimethylsilyl-pent-2,4-dienenitrile (8) and 3-oxo-2-
trimethylsilyl-cyclobutane-carbonitrile (9) (59 mg, overall
87% by 1H NMR, mol. ratio 3.6:1:1.6, respectively,
contained traces of nitriles E-11 and 10, brown oil).
6.2.6. 5-aci-nitro-pentan-2-one trimethylsilyl ether (2c).
To the stirred solution of ketone 1 (66 mg, 0.50 mmol) in
CH2Cl2 (1 mL) at 08C neat DBU (0.09 mL, 0.60 mmol) was
added. The reaction mixture was stirred for 15 min at 08C,
then Me3SiCl (0.15 mL, 1.18 mmol) was added. The result-
ing mixture was allowed to warm to ambient temperature
and then concentrated in vacuo. The solid residue was
treated with dry petroleum ether (10 mL), ®ltered in a dry
atmosphere, and the precipitate of DBU´HCl was washed
with petroleum ether (5 mL). The combined ®ltrate was
concentrated in vacuo to give the title compound 2c
(102 mg, 90%, colorless oil) (Caution, the silyl nitronate
2c is sensitive to moisture and should be stored in Ar
atmosphere). dH (300.13 MHz, CDCl3) 6.17 (1H, t,
6.2.4. (E)-4-Trimethylsilyloxy-2-trimethylsilyl-pent-2,4-
dienenitrile (8). a. Treatment of the nitrile E-11 (71 mg,
0.75 mmol) with Me3SiOTf (1.00 mL, 5.26 mmol) and
Et3N (0.84 mL, 6.03 mmol) according to GP (208C, 55 h)
gave the title compound 8 (144 mg, 80% after distillation,
colourless liquid); bp 50±558C/0.1 Torr; (Found: C, 55.3;
H, 8.9; N, 5.9; Si, 23.6. C11H21NOSi2 requires C, 55.17; H,
8.84; N, 5.85; Si, 23.46%); nmax (KBr) 2192 (w, CN),
1254 (s, SiMe3), 846 (s, SiMe3) cm21; dH (300.13 MHz,
3
3Jˆ6.5 Hz, CHvN), 2.70 (2H, t, Jˆ7.0 Hz, CH2C(O)),
2.44 (2H, q, 3Jˆ6.5 Hz, CH2), 2.13 (3H, s, Me), 0.27
(SiMe3); dC (75.47 MHz, CDCl3) 206.0 (CvO), 115.2
(CHvN), 38.5 (CH2C(O)), 29.2 (Me), 20.4 (CH2), 20.4
29Si 14N
(SiMe3); d (59.63 MHz, CDCl3) 25.7 (NOSiMe3); d
(21.69 MHz, CDCl3) 287.0 (Dn1/2 590 Hz, N(O)OSiMe3).
2
CDCl3) 6.52 (1H, s, CHvCCN), 4.64 (1H, d, Jˆ1.5 Hz,
2
CH2vC), 4.61 (1H, d, Jˆ1.5 Hz, CH2vC), 0.31 (9H, s,
SiMe3), 0.25 (9H, s, SiMe3); dC (75.47 MHz, CDCl3) 154.4
(CH2vC), 150.8 (CHvCHCN), 118.6 (CN), 112.5
(CHvCSiMe3), 102.5 (CH2vC), 0.0 (SiMe3), 22.1
6.2.7. (E)-4-Oxopent-2-enal oxime (12). The mixture of 5,
syn-6 and anti-6 (230 mg, 1.23 mmol, mol. ratio 5/6ˆ1:2.9,
respectively) obtained by GP (see entry 5, Table 1) was
dissolved in MeOH (3 mL). NH4F (10 mg, 0.27 mmol)
was added and the reaction mixture was stirred at 108C
for 3 h. Then it was evaporated in vacuo, and the residue
was subjected to ¯ash-chromatography and then distilled in
short-path apparatus to give the title compound 12 (95 mg,
overall 56%, the mixture of anti-12 and syn-12, mol. ratio
8.5:1, respectively, white solid); bp 60±1108C/0.1 Torr
(lit.19 bp 80±1008C/0.1 Torr for pure E,anti-12); mp 40±
438C (lit.19 mp 458C for pure E,anti-12); nmax (KBr) 3263
(br, s, OH), 1671 (s, CvO), 1640 (m, CvN), 982 (s, N±O)
cm21. For anti-12 dH (300.13 MHz, CDCl3) 9.53 (1H, br, s.,
29Si
(SiMe3); d
(CSiMe3);
1085 Hz, CN).
(59.63 MHz, CDCl3) 21.5 (COSiMe3), 2.3
(21.69 MHz, CDCl3) 2114 (Dn1/2
14N
d
b. Treatment of the ketone 1 (25 mg, 0.19 mmol) with
Me3SiOTf (0.40 mL, 2.11 mmol) and Et3N (0.32 mL,
2.30 mmol) according to GP (208C, 50 h) gave the mixture
of title compound 8 and 3-oxo-2-trimethylsilyl-cyclo-
1
butane-carbonitrile (9) (30 mg, overall 72% by H NMR,
mol. ratio 2.6:1, respectively, contained traces of 10,
brown oil). The resulting mixture was distilled at
50±608C/0.1 Torr and then subjected to rapid ¯ash-
chromatography to give pure title compound 8 (20 mg,
44%, colourless liquid, Rf (EtOAc/petrol. ether 1:3) 0.55)
and the mixture of compounds 9 and 10 (5 mg, overall 15%,
mol. ratio 1:1, yellowish oil, Rf (EtOAc/petrol. ether 1:3)
0.20 for both)
3
OH), 7.88 (1H, d, Jˆ10.0 Hz, CHvCH±CHvN), 7.16
3
(1H, dd, Jˆ10.0, 16.0 Hz, CHvCH±CHvN), 6.38 (1H,
3
d, Jˆ16.0 Hz, CHvCH±CHvN), 2.34 (3H, s, Me); dC
(75.47 MHz, CDCl3) 198.7 (CvO), 150.0 (CHvCH±
CHvN), 136.5 (CHvCH±CHvN), 135.3 (CHvCH±
CHvN), 27.4 (Me). For syn-12 dH (300.13 MHz, CDCl3)
9.53 (1H, br, s, OH), 7.67 (1H, dd, 3Jˆ9.5, 16.5 Hz,
CHvCH±CHvN), 7.29 (1H, d, 3Jˆ9.5 Hz, CHvCH±
CHvN), 6.34 (1H, d, 3Jˆ16.5 Hz, CHvCH±CHvN),
2.38 (3H, s, Me); dC (75.47 MHz, CDCl3) 199.5 (CvO),
6.2.5. 3-Oxo-2-trimethylsilyl-cyclobutane-carbonitrile (9).
The silylation of the ketone 1 (25 mg, 0.19 mmol) according
to GP (208C, 50 h) with Me3SiOTf (0.40 mL, 2.11 mmol)
and Et3N (0.32 mL, 2.30 mmol) gave the mixture of title
compound 9 and (E)-4-trimethylsilyloxy-2-trimethylsilyl-

A. A. Tishkov et al. / Tetrahedron 57 (2001) 2221±2230
2229
146.9 (CHvCH±CHvN), 136.0 (CHvCH±CHvN),
127.8 (CHvCH±CHvN), 27.4 (Me).
title compound 13 and enenitrile Z-11 (30 mg, overall
88%, mol. ratio 1:1, respectively, yellowish oil, Rf
(EtOAc/petroleum ether 1:1) 0.39 for both 13 and Z-11).
For 13: dH (300.13 MHz, CDCl3) 3.56 (4H, m, 2 CH2),
3.27 (1H, m, CHCN); dH (80 MHz on `Bruker WP-80',
CDCl3) 3.50 (5H, m, 2 CH21CHCN) (in agreement with
lit.21 dH (60 MHz on `Varian V-60', CDCl3) 3.47 (5H, m, 2
CH21CHCN)); dC (75.47 MHz, CDCl3) 200.1 (CvO),
6.2.8. (Z)-4-Oxo-2-trimethylsilyl-pent-2-enenitrile (10).
The enenitrile 8 (30 mg, 0.13 mmol) was brought on the
column packed with silica gel (4 g in petroleum ether) and
maintained for 2.5 h. Then it was eluted with EtOAc/petro-
leum ether 1:1. The eluent was concentrated in vacuo to give
the title compound 10 (18 mg, 80%, yellowish oil, Rf
(EtOAc/petrol. ether 1:3) 0.20), nmax (KBr) 2197 (w, CN),
1702 (s, CvO), 1254 (m, SiMe3), 847 (s, SiMe3) cm21; dH
(300.13 MHz, CDCl3) 6.79 (1H, s, CHvCCN), 2.46 (3H, s,
Me), 0.32 (9H, s, SiMe3); dC (75.47 MHz, CDCl3) 194.8
(CvO), 150.0 (CHvCCN), 127.1 (CHvCCN), 117.5
14N
d
121.1 (CN), 53.5 (2 CH2), 12.4 (CHCN);
(21.69 MHz, CDCl3) 2124 (Dn1/2 440 Hz, CN).
Acknowledgements
29Si
(21.69 MHz, CDCl3) 2126
(CN), 29.8 (Me), 22.4 (CSiMe3); d
14N
(59.63 MHz,
This work was performed at the Scienti®c Educational
Center for young chemists and supported by Russian
Foundation of Basic Research (grant nos. 98-03-33002,
00-15-97455), and Federal Program Integration (project
no. A0082).
CDCl3) 4.5 (CSiMe3); d
(Dn1/2 650 Hz, CN).
6.2.9. (Z)-4-Oxo-pent-2-enenitrile (Z-11). a. The distilled
nitrile 8 (35 mg, 0.15 mmol) was dissolved in MeOH
(0.3 mL). NH4F (2 mg, 0.05 mmol) was added, and the reac-
tion mixture was stirred for 3 h at 108C. The solvent was
removed in vacuo and the residue was extracted with warm
petroleum ether (5£1 mL). The resulting solution was
cooled and the analytically pure title compound Z-11 was
crystallized (13 mg, 91%, white solid), mp 34±358C;
(Found: C, 63.2; H, 5.3; N, 14.8. C5H5NO requires C,
63.15; H, 5.30; N, 14.73%); nmax (KBr) 2225 (w, CN),
1693 (s, CvO) cm21; dH (300.13 MHz, CDCl3) 6.78 (1H,
d, 3Jˆ11.5 Hz, CHvCHCN), 5.84 (1H, d, 3Jˆ11.5 Hz,
CHvCHCN), 2.46 (3H, s, Me); dC (75.47 MHz, CDCl3)
194.5 (CvO), 144.7 (CHvCHCN), 115.1 (CN), 107.3
References
1. For the discussion of this problem see: Ioffe, S. L.; Lyapkalo,
I. M.; Makarenkova, L. M. J. Org. Chem. Russ. 1998, 34,
1141±1148 (Russ.); Russ. J. Org. Chem. 1998, 34, 1085±
1092 (Engl. transl.).
2. For the review of the preparative methods see: von Schecken,
O.; Apel, G.; Schwarz, H. G.; Segnitz, A. In Methoden der
Organischen Chemie (Houben-Weyl), Part I, X; George
Thieme: Stuttgart, 1971; pp 181±245.
14N
(CHvCHCN), 30.1 (Me); d (21.69 MHz, CDCl3) 2108
(Dn1/2 340 Hz, CN).
3. Danilenko, V. M.; Ioffe, S. L.; Strelenko, Yu. A.; Karpenko,
N. F.; Kalinin, A. V.; Tartakovsky, V. A. Bull. Acad. Sci.
USSR. Div. Chem. Sci. (Russ.) 1987, 2638±2639 1987,
2453±2454 (Engl. transl.). Ioffe, S. L.; Danilenko, V. M.;
Strelenko, Yu. A.; Tartakovsky, V. A. J. Org. Chem. Russ.
(Russ.) 1995, 31, 1253±1254 Russ. J. Org. Chem. 1995, 31,
1144±1145 (Engl. transl.).
b. The nitrile 10 (10 mg, 0.06 mmol) was dissolved in
MeOH (0.1 mL). NH4F (0.5 mg, 0.01 mmol) was added,
and the reaction mixture was stirred for 3 h at 108C. The
solvent was removed in vacuo and the residue was extracted
with warm petroleum ether (2£0.5 mL). The solvent was
removed in vacuo to give the title compound Z-11
(5.2 mg, 91%, white solid).
4. Tishkov, A. A.; Lyapkalo, I. M.; Ioffe, S. L.; Strelenko, Yu. A.;
Tartakovsky, V. A. Russ. Chem. Bull. (Russ.) 1997, 46, 210±
212 1997, 205±206 (Engl. transl.).
5. Tishkov, A. A.; Lyapkalo, I. M.; Ioffe, S. L.; Strelenko, Yu.
A.; Tartakovsky, V. A. 11th European Symposium on Organic
Chemistry; 1999 Goteborg, O64.
6.2.10. 3-Oxo-cyclobutanecarbonitrile (13). The obtained
after rapid ¯ash-chromatography at 2788C nitrile 9 (5 mg,
0.03 mmol) was dissolved in MeOH (0.05 mL). NH4F
(0.3 mg, 0.008 mmol) was added, and the reaction mixture
was stirred for 3 h at 108C. The solvent was carefully
removed in vacuo and the residue was extracted with
warm petroleum ether (2£0.5 mL). The solvent was
removed in vacuo to give the title compound 13 (2.3 mg,
80%, yellowish oil). nmax (KBr) 2245 (w, CN), 1798 (s,
CvO) cm21 (in agreement with lit.21 data).
6. Ioffe, S. L.; Lyapkalo, I. M.; Tishkov, A. A.; Danilenko, V. M.;
Strelenko, Yu. A.; Tartakovsky, V. A. Tetrahedron 1997, 53,
13085±13098.
7. Dilman, A. D.; Tishkov, A. A.; Lyapkalo, I. M.; Ioffe, S. L.;
Kachala, V. V.; Strelenko, Yu. A.; Tartakovsky, V. A.
J. Chem. Soc., Perkin Trans. 1 2000, 2926±2929.
8. Tishkov, A. A.; Kozintsev, A. V.; Lyapkalo, I. M.; Ioffe, S. L.;
Kachala, V. V.; Strelenko, Yu. A.; Tartakovsky, V. A.
Tetrahedron Lett. 1999, 40, 5075±5078.
b. The obtained after regular ¯ash-chromatography at room
temperature mixture of 10 and 9 (60 mg, 0.36 mmol, mol.
ratio 1:1) was dissolved in MeOH (0.7 mL). NH4F (2 mg,
0.054 mmol) was added, and the reaction mixture was stir-
red for 3 h at 108C. The solvent was removed in vacuo and
the residue was extracted with warm petroleum ether
(5!1 mL). The resulting solution was evaporated and the
crude product was puri®ed by ¯ash-chromatography
(EtOAc/petroleum ether 1:5) to give the mixture of the
9. A general procedure for preparation of silyl nitronates:
Aizipurua, J. M.; Oiarbide, M.; Palomo, C. Tetrahedron
Lett. 1987, 28, 5361±5364.
10. Tishkov, A. A.; Lyapkalo, I. M.; Kozincev, A. V.; Ioffe, S. L.;
Strelenko, Yu. A.; Tartakovsky, V. A. Eur. J. Org. Chem.
2000, 3229±3233.
11. Gordon, A. J.; Ford, R. A. In The Chemist's Companion;
Wiley: New York, 1972; pp 60±61 (a handbook of practical
data, techniques, and references).

2230
A. A. Tishkov et al. / Tetrahedron 57 (2001) 2221±2230
12. Pou, S.; Rosen, G. M.; Wu, Y.; Keana, J. F. J. Org. Chem.
1990, 55, 4438±4443.
528±532. Matsuda, I.; Okada, H.; Izumi, Y. Bull. Chem. Soc.
Jpn 1983, 56, 528±532.
21. Hall, H. K.; Blanchard, Jr., E. P.; Cherkofsky, Jr., S. C.; Sieja,
J. B.; Sheppard, W. A. J. Am. Chem. Soc. 1971, 93, 110±120.
22. Makarenkova, L. M.; Bliznets, I. V.; Ioffe, S. L.; Strelenko,
Yu. A.; Tartakovsky, V. A. Russ. Chem. Bull. (Russ.) 2000,
1265±1272 2000, 49, 1261±1269 (Engl. transl.).
23. Gottlieb, H. E.; Kotlyar, V.; Nudelman, A. J. Org. Chem.
1997, 62, 7512±7515.
13. Gordon, A. J.; Ford, R. A. In The Chemist's Companion;
Wiley: New York, 1972; pp 61±62 (a handbook of practical
data, techniques, and references).
14. Torssell, K.; Zeuthen, O. Acta. Chem. Scand. 1978, B32, 118±
124.
15. House, H. O.; Czuba, L. J.; Gall, M.; Olmstead, H. D. J. Org.
Chem. 1969, 34, 2324±2336.
24. Morris, G. E.; Freeman, R. J. Am. Chem. Soc. 1979, 101, 760±
762.
16. Simchen, G. In Advances in Silicon Chemistry; Larson, G. L.,
Ed.; JAI Press: Greenwich, CT, 1991; 1, pp 189±301.
17. Feger, H.; Simchen, G. Liebigs Ann. Chem. 1986, 1456±1465
Liebigs Ann. Chem. 1986, 428±437.
25. Janowitz, A.; Vavrecka, M.; Hesse, M. Helv. Chim. Acta 1991,
74, 1352±1361.
26. Nesmejanov, A. N.; Rybinskaja, M. I. Dokl. Akad. Nauk SSSR
1957, 115, 315±318; Dokl. Chem. 1957, 112±117, 729±731.
27. Bensen, W. R.; Pohland, A. E. J. Org. Chem. 1964, 29, 385±
391.
18. Dilman, A. D.; Tishkov, A. A.; Lyapkalo, I. M.; Ioffe, S. L.;
Strelenko, Yu. A.; Tartakovsky, V. A. Synthesis 1998, 181±
185.
19. Severin, T.; Adhikary, P.; Brautigam, I. Chem. Ber. 1976, 109,
1179±1183.
28. Hosokawa, T.; Aoki, S.; Murahashi, S.-I. Synthesis 1992,
558±561.
20. Sato, Y.; Hitomi, K. J. Chem. Soc., Chem. Commun. 1983,