Highly efficient desilylation of 3-trimethylsilylprop-2-ynamides by the action of KF-Al2O3

Article abstract of DOI:10.1134/S1070428011120037

A highly effective procedure has been developed for desilylation of 3-trimethylsilylprop-2-ynamides in the presence of KF-Al₂O ₃ as catalyst. The corresponding terminal prop-2-ynamides were obtained in high yield in methanol at 25°C using 5 mol % of the catalyst (reaction time 20 min). Rise in temperature leads to the formation of Z,E-3-methoxyprop-2-enamides or 3,3-dimethoxypropanamides as a result of tandem desilylation-addition of methanol, depending on the conditions.

Full text of DOI:10.1134/S1070428011120037

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2011, Vol. 47, No. 12, pp. 1797–1801. © Pleiades Publishing, Ltd., 2011.
Original Russian Text © M.V. Andreev, L.P. Safronova, A.S. Medvedeva, 2011, published in Zhurnal Organicheskoi Khimii, 2011, Vol. 47, No. 12,
pp. 1761–1765.
Dedicated to Full Member of the Russian Academy of Sciences
M.G. Voronkov on his 90th anniversary
Highly Efficient Desilylation of 3-Trimethylsilylprop-2-ynamides
by the Action of KF–Al2O3
M. V. Andreev, L. P. Safronova, and A. S. Medvedeva
Favorskii Irkutsk Institute of Chemistry, Siberian Division, Russian Academy of Sciences,
ul. Favorskogo 1, Irkutsk, 664033 Russia
e-mail: amedved@irioch.irk.ru
Received June 8, 2011
Abstract—A highly effective procedure has been developed for desilylation of 3-trimethylsilylprop-2-yn-
amides in the presence of KF–Al2O3 as catalyst. The corresponding terminal prop-2-ynamides were obtained in
high yield in methanol at 25°C using 5 mol % of the catalyst (reaction time 20 min). Rise in temperature leads
to the formation of Z,E-3-methoxyprop-2-enamides or 3,3-dimethoxypropanamides as a result of tandem
desilylation–addition of methanol, depending on the conditions.
DOI: 10.1134/S1070428011120037
The synthetic strategy silylation–desilylation of
triple bond is widely used in fine organic synthesis, in
particular in total syntheses of highly efficient natural
antibiotics [1]. This approach was partially reviewed in
[2]. The presence of a trimethylsilyl group at triple
C≡C bond stabilizes the latter so that it becomes
inactive toward nucleophiles [3], organometallic com-
pounds, and transition metal catalysts in various syn-
thetic transformations [4]; as a result, regioselective
cycloaddition of azides at the triple bond of various
trimethylsilylalkynes becomes possible [5], the stabil-
ity of compounds increases, and their solubility in
organic solvents is improved.
even weak bases generated in protic medium from
metal oxides (PbO2, MnO2, Co2O3, Ni2O3) [11].
Despite diversity of desilylating agents, published
data on desilylation of silicon-containing acetylenic
compounds with an activated triple bond are few in
number. Desilylation of such compounds requires mild
conditions, taking into account the possibility for un-
desirable addition of alcohol or water (used as solvent)
at the terminal triple bond in the resulting alkynes by
the action of base in protophilic medium.
In the present work we developed an efficient
procedure for desilylation of trimethylsilylacetylenes
having an activated triple bond. 3-Trimethylsilylprop-
2-ynamides Ia–Ig were selected as substrates, and KF–
Al2O3, as reagent. Solid-phase desilylation of trimeth-
ylsilylalkynes under microwave irradiation required
excess KF–Al2O3 (4 equiv) [12]. There are no pub-
lished data on desilylation of trimethylsilylacetylene
derivatives with an activated triple bond by the action
of KF–Al2O3.
Desilylation of acetylenic compounds can be per-
formed with the use of various reagents, among which
such bases as alkali metal hydroxides [6], alkoxides
[7], and carbonates [8] in protophylic solvents, as well
as potassium [9] and ammonium fluorides [10] are
used most frequently. We recently showed that suc-
cessful desilylation may be achieved with the aid of
Scheme 1.
KF–Al2O3 (5 mol %)
MeOH, 25°C, 20 min
O
O
Me3Si
HC
NR1R2
NR1R2
Ia–Ig
IIa–IIg
R1 = H, R2 = H (a), Ph (b), PhCH2 (c), 2,5-Cl2C6H3 (d), 3-BrC6H4 (e), HOCH2CMe2 (f); R1R2N = morpholino (g).
1797

ANDREEV et al.
1798
In the reactions of amides Ib, Id, and Ie containing
methoxypropanamides IVa and IVb in high yield. The
reaction of trimethylsilylpropynamide Ig with KF–
Al2O3 (5 mol %) under microwave irradiation (700 W,
15 min) resulted in selective addition of one methanol
molecule with formation of 88% of (E,Z)-4-(3-me-
thoxyprop-2-enoyl)morpholine (III, E:Z = 1:2).
an aromatic ring with an equimolar amount of KF–
Al2O3 in diethyl ether at room temperature the yield of
the corresponding terminal propynamides did not ex-
ceed 62%. The efficiency of the process considerably
increased when diethyl ether was replaced by methanol.
Terminal propynamides IIa–IIg were isolated in high
yield (82–99%) by the action of a catalytic amount of
KF–Al2O3 (5 mol %) over a period of 20 min at room
temperature (Scheme 1). N-(2-Hydroxy-1,1-dimethyl-
ethyl)prop-2-ynamide (IIf) was not reported previ-
ously. The developed procedure is advantageous due to
selectivity of the reaction, experimental simplicity,
mild conditions (room temperature), the use of a cata-
lytic amount of desilylating agent, and purity of the
products (no additional purification was necessary).
The process was not accompanied by cleavage of the
amide C–N bond and addition of methanol at the triple
bond of the resulting terminal propynamide.
Scheme 3.
KF–Al2O3
MeOH
O
O
Me3Si
HC
NR1R2
NR1R2
Ic, Ig
IIc, IIg
O
MeO
N
a
O
III
OMe
O
A probable scheme of KF–Al2O3-induced desilyla-
tion of trimethylsilylpropynamides Ia–Ig includes gen-
eration of complex A (Scheme 2) and its protonation
with methanol to produce terminal propynamide,
fluorotrimethylsilane, and potassium methoxide. Potas-
sium fluoride liberated in the reaction of fluorotri-
methylsilane with potassium methoxide returns to the
catalytic cycle.
b
MeO
NR1R2
IVa, IVb
Ic, IVa, R1 = H, R2 = PhCH2; Ig, IVb, R1R2N = morpholino;
a: KF–Al2O3 (5 mol %), MeOH, microwave irradiation
(700 W, 20 min) or KF–Al2O3 (12 mol %), MeOH–MeCN,
reflux, 2 h; b: KF–Al2O3 (5 mol %), MeOH, reflux, 3–7 h.
Insofar as protodesilylation of various silicon-
containing acetylenic amides occurs fairly readily, the
efficiency of the tandem process is determined mainly
by the stage of methanol addition at the terminal triple
bond in intermediate propynamide. Higher reactivity
of amide Ig in this process, as compared to N-benzyl
analog Ic, may be rationalized in terms of higher
basicity of benzylamine (pKa 9.34 in water) as com-
pared to morpholine (pKa 8.70 in water) [13]. The use
of a mixture of methanol with acetonitrile considerably
inhibits methanol addition, and their ratio affects the
Scheme 2.
KF
MeOSiMe3
MeOK
+
Me3SiF
F
Me
Me
Si Me
K+
O
1
reaction selectivity. According to the H NMR data,
HC
O
NR1R2
amide Ig in boiling methanol (5 mol % of KF–Al2O3)
is completely converted into 3,3-dimethoxypropan-
amide (IVb) in 3 h, whereas the reaction in MeOH–
MeCN (1:2) gives a mixture of terminal propynamide
IIg (14%), adduct III (66%), and dimethoxy derivative
IVb (20%). Considerable reduction of the concentra-
tion of methanol (methanol–acetonitrile, 1:9) and in-
crease in the catalyst concentration to 12 mol %
ensures selective addition of methanol with formation
of monomethoxy adduct III (E:Z = 1.0:1.2) in 88%
yield on heating under reflux over a period of 2 h.
NR1R2
IIa–IIg
MeOH
A
O
Me3Si
NR1R2
Ia–Ig
Rise in temperature favors tandem desilylation–
methanol addition process with formation of previ-
ously unknown (Z,E)-3-methoxyprop-2-enamides
(Scheme 3). By heating amides Ic and Ig in boiling
methanol in the presence of KF–Al2O3 (5 mol %) over
a period of 7 or 3 h, respectively, we obtained 3,3-di-
3-Methoxyprop-2-enamides may be regarded as
push–pull vinyl ethers, while 3,3-dimethoxypropan-
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HIGHLY EFFICIENT DESILYLATION OF 3-TRIMETHYLSILYLPROP-2-YNAMIDES
1799
amides are acetals derived from the corresponding
formyl amides, which attract interest as polyfunctional
intermediate products in organic synthesis. β-Keto
amides are used in the synthesis of natural antibiotics
[14]. Terminal propynamides are used as starting
materials in the synthesis of various heterocyclic
compounds possessing a broad spectrum of biological
activity [15].
3.4 mg (5 mol %) of KF–Al2O3, and 5 ml of methanol
was stirred for 20 min at room temperature. The
mixture was then treated with 1 ml of 5% hydrochloric
acid and extracted with diethyl ether (in the synthesis
of IIb–IId) or chloroform (IIe–IIg), and the extract
was dried over MgSO4 and evaporated under reduced
pressure. The residue was propynamide IIb–IIg which
required no additional purification.
N-Phenylprop-2-ynamide (IIb). Yield 99%,
mp 80–81°C [17]. 1H NMR spectrum (CDCl3), δ, ppm:
2.92 s (1H, HC≡), 7.16 t (1H, 4-H, J = 7.60 Hz), 7.34 t
(2H, m-H, J = 7.56 Hz), 7.54 d (2H, o-H, J = 7.52 Hz),
7.92 br.s (1H, NH).
Known methods for the synthesis of terminal
propynamides are based on acylation of amines with
propynoic acid esters [16, 17], chloride [18], and an-
hydride [19] or propynoic acid itself in the presence of
N,N′-dicyclohexylcarbodiimide [20]. A common dis-
advantage of the above procedures is the use of highly
toxic and flammable (inflammation temperature 58°C)
propynoic acid which also acts as skin irritant [21].
Moreover, the presence in propynoic acid esters of
an additional electrophilic center, activated triple bond,
favors formation of aminopropenoates [16, 22, 23].
N-Benzylprop-2-ynamide (IIc). Yield 93%,
mp 88–90°C [23]. 1H NMR spectrum (CDCl3), δ, ppm:
2.80 s (1H, HC≡), 4.50 d (2H, CH2Ph, J = 5.88 Hz),
6.12 br.s (1H, NH), 7.31 m (5H, Ph).
N-(2,5-Dichlorophenyl)prop-2-ynamide (IId).
Yield 99%, mp 112–113°C [18]. IR spectrum (KBr), ν,
cm–1: 3224 (NH, H–C≡), 2109 (C≡C), 1668 (C=O),
1587 (C=Carom), 1522 (C–N, δNH). 1H NMR spectrum
(CDCl3), δ, ppm: 3.00 s (1H, HC≡), 7.07 m (1H, 4-H,
J = 8.56 Hz), 7.31 d (1H, 3-H, J = 8.60 Hz), 8.46 s
(1H, 6-H), 7.90 br.s (1H, NH). 13C NMR spectrum
(CDCl3), δC, ppm: 75.00 (≡C–), 77.41 (HC≡), 120.38
(C2), 121.86 (C6), 125.46 (C4), 129.78 (C3), 134.04
(C5), 134.87 (C1), 149.08 (C=O). Found, %: C 50.09;
H 2.50; Cl 33.26; N 7.03. C9H5Cl2NO. Calculated, %:
C 50.50; H 2.35; Cl 33.13; N 6.74.
To conclude, we have developed a simple and
highly efficient procedure for the synthesis of terminal
propynamides from accessible 3-trimethylsilylprop-2-
ynamides [22, 24] using a catalytic amount of KF–
Al2O3. Conditions have been found for selective one-
step preparation of new mono- and dialkoxy amides
as polyfunctional intermediate products for organic
synthesis.
EXPERIMENTAL
The IR spectra were recorded on a Bruker IFS-25
N-(3-Bromophenyl)prop-2-ynamide (IIe). Yield
90%, mp 124–125°C [18]. IR spectrum (KBr), ν, cm–1:
3271 (H–C≡), 3239 (NH), 2109 (C≡C), 1649 (C=O),
1593 (C=Carom), 1547 (C–N, δNH). 1H NMR spectrum
(CDCl3), δ, ppm: 2.93 s (1H, HC≡), 7.20 t (1H, 5-H,
J = 7.92 Hz), 7.29 d (1H, 4-H, J = 9.04 Hz), 7.46 d
(1H, 6-H, J = 7.60 Hz), 7.73 s (1H, 2-H), 7.46 br.s
(1H, NH). 13C NMR spectrum (CDCl3), δC, ppm: 76.89
(≡C), 77.90 (HC≡), 118.11 (C3), 121.42 and 121.96
(C2, C6), 126.34 (C4), 130.13 (C5), 139.72 (C1), 149.45
(C=O). Found, %: C 48.53; H 2.59; Br 36.02; N 6.38.
C9H6BrNO. Calculated, %: C 48.25; H 2.70; Br 35.66;
N 6.25.
1
spectrometer. The H and 13C NMR spectra were
measured on a Bruker DPX-400 instrument relative to
hexamethyldisiloxane as internal reference. Micro-
wave-assisted reactions were performed in a 25-ml
Teflon high-pressure reactor using an unmodified LG
MS-1904H microwave furnace (700 W). Initial 3-tri-
methylsilylprop-2-ynamides were synthesized accord-
ing to the procedure reported in [24]; KF–Al2O3 (KF
concentration 40%) was prepared as described in [25].
Prop-2-ynamide (IIa). A mixture of 100 mg
(0.71 mmol) of amide Ia, 5.1 mg (5 mol %) of KF–
Al2O3, and 5 ml of methanol was stirred for 20 min at
room temperature. The mixture was then evaporated
under reduced pressure, and the residue was washed
with chloroform and dried. Yield 40 mg (82%),
N-(2-Hydroxy-1,1-dimethylethyl)prop-2-yn-
amide (IIf). Yield 83%, mp 135–136°C. IR spectrum
(KBr), ν, cm–1: 3400 (OH), 3290 (H–C≡), 3210 (NH),
1
1
mp 59–61°C [26]. H NMR spectrum (CDCl3), δ,
2120 (C≡C), 1650 (C=O), 1560 (C–N, δNH). H NMR
ppm: 2.88 s (1H, HC≡), 6.02 br.s and 5.88 br.s (1H
each, NH2).
spectrum (DMSO-d6), δ, ppm: 3.80 s (1H, HC≡),
3.34 s (2H, CH2O), 1.18 s (6H, CH3), 4.69 br.s
(1H, OH), 7.88 br.s (1H, NH). 13C NMR spectrum
(DMSO-d6), δC, ppm: 23.11 (CH3), 55.32 (N–C), 66.78
N-Alkyl(aryl)prop-2-ynamides IIb–IIg (general
procedure). A mixture of 0.47 mmol of amide Ib–Ig,
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 47 No. 12 2011

ANDREEV et al.
1800
(C–O), 73.71 (≡C), 78.98 (HC≡), 151.12 (C=O).
Found, %: C 59.78; H 7.20; N 9.61. C7H11NO2. Cal-
culated, %: C 59.56; H 7.85; N 9.92.
N-Benzyl-3,3-dimethoxypropanamide (IVa).
Yield 90%, oily substance. IR spectrum (film), ν, cm–1:
1640 (C=O), 1580 (C=Carom), 1530 (C–N, δNH), 1110
1
(C–O). H NMR spectrum (CDCl3), δ, ppm: 2.60 d
1-Morpholinoprop-2-yn-1-one (IIg). Yield 95%,
mp 70–72°C [16]. IR spectrum (KBr), ν, cm–1: 3200
(2H, CH2CO, J = 5.36 Hz), 3.39 s (6H, CH3O), 4.47 d
(2H, CH2Ph, J = 5.64 Hz), 4.72 t (1H, CH, J =
5.36 Hz), 7.30 m (5H, Ph), 6.40 br.s (1H, NH).
13C NMR spectrum (CDCl3), δC, ppm: 41.04 (CH2CO),
43.47 (CH2Ph), 54.20 (CH3O), 102.23 (CH); 127.45,
127.58, 128.71, 136.85 (Carom); 169.02 (C=O). Found,
%: C 64.18; H 7.73; N 6.02. C12H17NO3. Calculated,
%: C 64.55; H 7.67; N 6.27.
1
(H–C≡), 2096 (C≡C), 1630 (C=O). H NMR spectrum
(CDCl3), δ, ppm: 3.16 s (1H, HC≡), 3.68 m (4H,
NCH2), 3.74 m (4H, OCH2). 13C NMR spectrum
(CDCl3), δC, ppm: 75.33 (≡C), 79.53 (HC≡), 42.01 and
47.28 (NCH2), 66.44 and 66.86 (OCH2), 151.70
(C=O). Found, %: C 60.01; H 6.50; N 10.05.
C7H9NO2. Calculated, %: C 60.42; H 6.52; N 10.07.
3,3-Dimethoxy-1-morpholinopropan-1-one
(Z,E)-3-Methoxy-1-morpholinoprop-2-en-1-one
(III). a. A Teflon reactor was charged with a mixture
of 60 mg (0.28 mmol) of amide Ig, 2.1 mg (5 mol %)
of KF–Al2O3, and 5 ml of methanol, and the reactor
was placed into a microwave furnace and irradiated at
a power of 700 W over a period of 15 min (in 2–4-min
pulses followed by cooling to room temperature). The
mixture was filtered, and the filtrate was evaporated
under reduced pressure. Yield 43 mg (88%), mp 53–
55°C (from hexane). IR spectrum (KBr), ν, cm–1: 1670
(IVb). Yield 83%, oily substance. IR spectrum (film),
1
ν, cm–1: 1630 (C=O), 1100 (C–O). H NMR spectrum
(CDCl3), δ, ppm: 2.68 d (2H, CH2CO, J = 5.48 Hz),
3.43 s (6H, CH3O), 3.52 m (4H, NCH2), 3.72 m (4H,
OCH2), 4.70 t (1H, CH, J = 5.52 Hz). 13C NMR spec-
trum (CDCl3), δC, ppm: 37.76 (CH2CO), 42.14 and
46.61 (CH2N), 66.98 (CH2O), 54.89 (CH3O), 103.51
(CH), 168.18 (C=O). Found, %: C 53.56; H 8.33;
N 6.94. C9H17NO4. Calculated, %: C 53.19; H 8.43;
N 6.89.
1
(C=O); 1630, 1610 (C=C). H NMR spectrum
(CDCl3), δ, ppm: 3.70 s (3H, CH3O, E), 3.75 s (3H,
CH3O, Z), 4.94 d (1H, =CHCO, J = 7.08 Hz, Z), 5.56 d
(1H, =CHCO, J = 11.72 Hz, E), 6.23 d (1H, OCH=,
J = 7.20 Hz, Z), 7.61 d (1H, OCH=, J = 11.84 Hz, E),
3.45 m and 3.55 m (2H each, NCH2), 3.66 m (4H,
OCH2); (E:Z = 1.0:2.0). 13C NMR spectrum (CDCl3),
δC, ppm: 42.39 and 47.63 (CH2N), 67.51 (CH2O),
61.83 and 58.50 (CH3O), 95.04 and 98.5 (=CHCO),
153.96 and 163.45 (=CHO), 165.57 and 166.81 (C=O).
Found, %: C 56.59; H 7.32; N 8.19. C8H13NO3. Cal-
culated, %: C 56.13; H 7.65; N 8.18.
REFERENCES
1. Clive, D.L.J., Bo, Y., Tao, Y., Daigneault, S., Wu, Y-J.,
and Meignan, G., J. Am. Chem. Soc., 1998, vol. 120,
p. 10332; Thominet, O., Baker, J.R., Britton, H.,
Etheridge, Z.C., Soscia, M.G., and Caddick, S., Org.
Biomol. Chem., 2007, vol. 5, p. 3703; Trost, B.M., Papil-
lon, J.P.N., and Nussbaumer, T., J. Am. Chem. Soc., 2005,
vol. 127, p. 17921; Yamamoto, Y., Yamashita, K.,
Hotta, T., Hashimoto, T., Kikuchi, M., and Nishi-
yama, H., Chem. Asian J., 2007, vol. 2, p. 1388.
2. Siemsen, P., Livingston, R.C., and Diederich, F., Angew.
Chem., Int. Ed., 2000, vol. 39, p. 2632; Zhang, W.
and Moore, J.S., Angew. Chem., Int. Ed., 2006, vol. 45,
p. 4416.
b. A mixture of 60 mg (0.28 mmol) of amide Ig,
4.9 mg (12 mol %) of KF–Al2O3, 1 ml of methanol,
and 9 ml of acetonitrile was heated for 2 h at 65°C.
The mixture was filtered, and the filtrate was evaporat-
ed under reduced pressure to obtain 41 mg (84%) of
compound III as a mixture of E and Z isomers at
a ratio of 1.0:2.0, mp 53–55°C (from hexane).
3. Medvedeva, A.S., Russ. J. Org. Chem., 1996, vol. 32,
p. 272.
4. Pierce, A.E., Silylation of Organic Compounds. A Tech-
nique for Gas-Phase Analysis, Rockford: Pierce
Chemical, 1968, p. 3.
5. Coats, S.J., Link, J.S., Gauthier, D., and Hlasta, D.J., Org.
Lett., 2005, vol. 7, p. 1469; Demina, M.M., Novopa-
shin, P.S., Sarapulova, G.I., Larina, L.I., Smolin, A.S.,
Fundamenskii, V.S., Kashaev, A.A., and Medvede-
va, A.S., Russ. J. Org. Chem., 2004, vol. 40, p. 1804;
Bottaro, J.C., Schmitt, R.J., Bedford, C.D., Gilardi, R.,
and George, C., J. Org. Chem., 1990, vol. 55, p. 1916.
N-Alkyl-3,3-dimethoxypropanamides IVa and
IVb (general procedure). A mixture of 0.47 mmol of
amide Ic or Ig, 3.4 mg (5 mol %) of KF–Al2O3, and
5 ml of methanol was heated at 65°C for 3 (Ig) or 7 h
(Ic). The mixture was evaporated under reduced pres-
sure, the residue was extracted with hot hexane, and
the extract was filtered and evaporated under reduced
pressure.
6. Nishinaga, T., Miyata, Y., Nodera, N., and Komatsu, K.,
Tetrahedron, 2004, vol. 60, p. 3375.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 47 No. 12 2011

HIGHLY EFFICIENT DESILYLATION OF 3-TRIMETHYLSILYLPROP-2-YNAMIDES
1801
7. Casara, P., Danzin, C., Metcalf, B., and Jung, M.,
Angew. Chem., Int. Ed., 2007, vol. 46, p. 3291;
Takao, K., Hayakawa, N., Yamada, R., Yamaguchi, T.,
Saegusa, H., Uchida, M., Samejima, S., and Tadano, K.,
J. Org. Chem., 2009, vol. 74, p. 6452.
J. Chem. Soc., Perkin Trans. 1, 1985, p. 2201.
8. Shi Shun, A.L.K. and Tykwinski, R.R., J. Org. Chem.,
2003, vol. 68, p. 6810.
16. Kanner, C. and Pandit, U., Tetrahedron, 1982, vol. 38,
9. De Meijere, A., Kozhushkov, S.I., Boese, R., Hau-
mann, T., Yufit, D.S., Howard, J.A.K., Khaikin, L.S.,
and Trætteberg, M., Eur. J. Org. Chem., 2002, p. 485.
p. 3597.
17. Sánchez, V., Rebolledo, F., and Gotor, V., Synlett, 1994,
p. 529.
10. Kirkham, J.E.D., Courtney, T.D.L., Lee, V., and Bald-
18. Miller, L., US Patent no. 3210420, 1965; Chem. Abstr.,
win, J.E., Tetrahedron Lett., 2004, vol. 45, p. 5645.
1965, vol. 63, p. 17971h.
19. Undheim, K. and Riege, L., J. Chem. Soc., Perkin
Trans. 1, 1975, p. 1493.
20. Duckworth, D., Lee-Wong, S., Slawin, A., Smith, E.,
and Williams, D., J. Chem. Soc., Perkin Trans. 1, 1996,
p. 815.
11. Tretyakov, E., Romanenko, G., Ikorskii, V., Stass, D.,
Vasiliev, V., Demina, M., Mareev, A., Medvedeva, A.,
and Ovcharenko, V., Eur. J. Org. Chem., 2007, p. 3639;
Tretyakov, E., Tolstikov, S., Mareev, A., Medvedeva, A.,
Romanenko, G., Stass, D., Bogomyakov, A., and Ovcha-
renko, V., Eur. J. Org. Chem., 2009, p. 2548.
21. Raphael, R.A., Acetylenic Compounds in Organic Syn-
thesis, New York: Academic, 1955.
12. Kabalka, G.W., Wang, L., and Pagni, R.M., Arkivoc,
2001, part (iv), p. 5.
22. Safronova, L.P., Medvedeva, A.S., and Vyazankin, N.S.,
Zh. Obshch. Khim., 1983, vol. 53, p. 1313.
23. Coppola, G. and Damon, R., Synth. Commun., 1993,
13. Albert, A. and Serjeant, E., Ionization Constants of
Acids and Bases, London: Methuen, 1962. Translated
under the title Konstanty ionizatsii kislot i osnovanii,
Moscow: Khimiya, 1964, p. 131.
vol. 23, p. 2003.
24. Medvedeva, A.S., Andreev, M.V., and Safronova, L.P.,
Russ. J. Org. Chem., 2010, vol. 46, p. 1466.
25. Yadav, V., Babu, K., and Mittal, M., Tetrahedron, 2001,
14. Iida, T., Hori, K., Nomura, K., and Yoshii, E., Hetero-
cycles, 1994, vol. 38, p. 1839; Boeckman, R.K., Jr.,
Starrett, J.E., Jr., Nickell, D.G., and Sum, P.-E., J. Am.
Chem. Soc., 1986, vol. 108, p. 5549.
vol. 57, p. 7047.
15. Coppola, G. and Damon, R., J. Heterocycl. Chem., 1995,
26. Ferris, T., Lee, P., and Farrar, T., Magn. Reson. Chem.,
vol. 32, p. 1141; Pinto, A., Neuville, L., and Zhu, J.,
1997, vol. 35, p. 571.
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