One-pot synthesis of 3-(trimethylsilyl)propynamides

Article abstract of DOI:10.1134/S1070428010100040

A highly efficient one-pot procedure was developed for the synthesis of 3-trimethylsilylpropynamides by acylation of amines with trimethylsilylpropynoyl chloride generated in situ. Selective N-acylation and N,O-bis-acylation of -amino alcohols with format

Full text of DOI:10.1134/S1070428010100040

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2010, Vol. 46, No. 10, pp. 1466–1470. © Pleiades Publishing, Ltd., 2010.
Original Russian Text © A.S. Medvedeva, M.V. Andreev, L.P. Safronova, 2010, published in Zhurnal Organicheskoi Khimii, 2010, Vol. 46, No. 10,
pp. 1463–1466.
One-Pot Synthesis of 3-(Trimethylsilyl)propynamides
A. S. Medvedeva, M. V. Andreev, and L. P. Safronova
Favorskii Irkutsk Institute of Chemistry, Siberian Division, Russian Academy of Sciences,
ul. Favorskogo 1, Irkutsk, 664033 Russia
e-mail: amedved@irioch.irk.ru
Received January 11, 2010
Abstract—A highly efficient one-pot procedure was developed for the synthesis of 3-trimethylsilylpropyn-
amides by acylation of amines with trimethylsilylpropynoyl chloride generated in situ. Selective N-acylation
and N,O-bis-acylation of β-amino alcohols with formation of, respectively, N-(hydroxyalkyl)propynamides and
2
-methyl-2-[3-(trimethylsilyl)propynoylamino]propyl 3-(trimethylsilyl)propynoate were accomplished with
high yields.
DOI: 10.1134/S1070428010100040
3
-(Trimethylsilyl)propynoic acid amides are valu-
Some α-Si-acetylenic amides exhibit fungicidal, insec-
able intermediates in the synthesis of biologically
important heterocyclic compounds, such as chiral 2-tri-
methylsilyldihydro-1,3-oxazoles [1], trimethylsilyli-
denehydantoins [2], 1,5-trisubstituted 1H-1,2,3-tri-
azoles [3], indoloquinolines [key compounds in the
total synthesis of alkaloids (±)-lysergic acid and
ticidal, and antiphlogistic activity [14, 15].
We previously synthesized a wide series of 3-(tri-
methylsilyl)propynoic acid amides via reaction of
3
-(trimethylsilyl)propynoyl chloride (II) with primary
and secondary amines, amino alcohols, or amino acid
silyl esters [16–19]. However, the overall yield of
(±)-LSD] [4], as well as in the regio- and stereocon-
3
-(trimethylsilyl)prop-2-ynamides IV (calculated on
trolled synthesis of 3-carbamoylcyclopentenones as
chiral synthetic intermediates or ligands [5], tetra-
the initial acid I) did not exceed 60% due to formation
of by-product, (E,Z)-3-chloro-3-trimethylsilylprop-2-
enoyl chloride, in the chlorination of 3-(trimethylsilyl)-
propynoic acid (I) with thionyl chloride [20].
(
hexa)hydrofuro[3,4-e]isoindol-6-ones as intermediate
products in the synthesis of antibiotic lactonamycin
[
6], and unsaturated γ- [7] and δ-lactams [8].
The goal of the present study was to develop a new
one-pot procedure for the synthesis of 3-(trimethyl-
silyl)propynoic acid amides bypassing isolation of acid
chloride II so as to avoid side formation of propenoyl
chloride.
The presence of a trimethylsilyl group at the triple
bond favors stabilization of carbofunctional acetylene
derivatives and their adducts, deactivates the triple
bond toward nucleophiles [9], and ensures regioselec-
tive cycloaddition of azides at the triple of bond of
various trimethylsilylalkynes with formation of the
corresponding 4-trimethylsilyl-1H-1,2,3-triazoles
Cevallos et al. [1] reported on a one-pot procedure
for the synthesis of N-(1-benzyl-2-hydroxyethyl)-3-
(
trimethylsilyl)prop-2-ynamide from 3-(trimethylsilyl)-
[
3, 10] and cycloaddition of norbornadiene to the
propynoic acid and 2-amino-3-phenylpropan-1-ol by
the action of N,N′-dicyclohexylcarbodiimide and N-hy-
droxysuccinimide (25°C, 15 h, 93%). However, an at-
tempt to obtain trimethylsilylpropynamides by succes-
sive reactions of 3-(trimethylsilyl)propynoic acid with
pivaloyl chloride and 10,2-bornanesultam lithium salt
involved side formation of pivaloyl sultam; if sym-
metric 3-(trimethylsilyl)propynoic acid anhydride
(generated by the action of N,N′-dicyclohexylcarbodi-
imide) was used as acylating agent, the initial anhy-
dride was recovered from the reaction mixture [11].
Co (CO) complex with (trimethylsilylpropynoyl)oxa-
2
8
zolidine or sultam according to the Pauson–Khand
reaction [5].
Desilylation of 3-(trimethylsilyl)propynoic acid
amides can be performed by the action of bases under
mild conditions; this reaction underlies an important
preparative procedure for the synthesis of terminal
propynamides [6, 11, 12]. In the presence of Lewis
acids tandem processes could occur with formation of
C–C bond without isolation of terminal alkynes [13].
1
466

ONE-POT SYNTHESIS OF 3-(TRIMETHYLSILYL)PROPYNAMIDES
1467
Scheme 1.
(
(
1) ClCOCOCl, DMF (4 mol %), 25°C
2) R R NH (IIIa–IIIg)
O
1
2
O
Me Si
Me Si
3
3
a
NR R2
1
OH
I
IVa–IVg
O
1
2
SOCl , 60°C
R R NH
2
Me Si
3
b
Cl
II
1
2
1
2
R = H, R = H (a), Ph (b), PhCH
2
(c), 2,5-Cl
2
C
6
H
3
(d), HOCH
2
CH
2
(e), HOCH
2
C(Me)
2
(f); R R N = morpholino (g).
The target amide was formed in a good yield only in
the reaction of sultam with mixed pivalic 3-(trimethyl-
silyl)propynoic anhydride (generated in situ) in the
presence of lithium chloride.
The above data indicate that search for new one-pot
procedures for the synthesis of 3-(trimethylsilyl)pro-
pynoic acid amides, including those functionalized at
the nitrogen atom, is an important problem. The lack
of such highly efficient and simple procedures re-
strains development of synthetic potential of both
diethyl ether to give mixtures of silicon-containing
acetylenic N-hydroxyalkyl amides and their desilyla-
tion products with terminal triple bond [17]. Prelimi-
nary N,O-silylation of amino alcohols ensured high
yields of target hydroxy amides without heterolysis of
the Si–C bond. By carrying out the reaction in ben-
sp
zene as solvent we succeeded in obtaining N-(2-hy-
droxyethyl)-3-(trimethylsilyl)propynamide (IVe) in
one-pot reaction (yield 73%) without preliminary
silylation of the initial amino alcohol.
3
-(trimethylsilyl)propynamides and their analogs with
Using 2-amino-2-methylpropan-1-ol (IIIf) as an ex-
ample, we showed that addition of the amine to acid
chloride II generated in situ (changed order of mixing
of the reactants) leads to the formation of N,O-bis-
acylation product, previously unknown amido ester V,
in 90% yield (Scheme 2).
terminal triple bond.
We have developed a one-pot procedure for the
synthesis of 3-(trimethylsilyl)propynamides IVa–IVg
(Scheme 1, method a) by reaction of equimolar
amounts of 3-(trimethylsilyl)propynoic acid (I) and
oxalyl chloride in the presence of dimethylformamide
as catalyst (4 mol %), followed by acylation of amines
IIIa–IIIg (2 equiv) with 3-(trimethylsilyl)propynoyl
chloride (II) generated in situ. The reaction took 1.5 h
at room temperature, and target compounds IVa–IVg
were isolated in 73–87% yield, which is higher by
To conclude, we have developed a highly efficient
economic one-pot procedure for the synthesis of 3-(tri-
methylsilyl)propynoic acid amides via acylation of
amines with 3-(trimethylsilyl)propynoyl chloride gen-
erated in situ from 3-(trimethylsilyl)propynoic acid by
the action of oxalyl chloride. The proposed procedure
2
5–34% than the overall yield in two-step procedure b
(
see table).
1
2
Yields of amides Me
two-step syntheses (b)
3
SiC≡CCONR R in one-pot (a) and
Undoubtedly, the proposed one-pot procedure for
the synthesis of amides IVa–IVg is advantageous, for
it does not require isolation and purification of toxic,
readily hydrolyzable, and volatile 3-(trimethylsilyl)-
propynoyl chloride (II); in addition, the procedure is
characterized by mild conditions (25°C), short reaction
time, and considerably increased overall yield of the
target products, and it is applicable to the preparation
of 3-(trimethylsilyl)propynamides functionalized at the
nitrogen atom. The use of oxalyl chloride as chlorinat-
ing agent ensures effective generation of acid chloride
II under mild conditions without formation of by-
products [20].
a
Overall yield, %
Amide
no.
1
2
R
R
a
b
IVa
IVb
IVc
IVd
IVe
IVf
IVg
H
H
H
H
H
H
H
82
84
85
82
73
74
87
54 (98)
53 (97)
51 (93)
53 (96)
–
Ph
PhCH
2
2,5-Cl
2
C
6
H
3
HOCH
HOCH
2
2
CH
2
C(Me)
2
48 (88)
53 (97)
1
2
R R N = morpholino
a
We previously showed that 3-(trimethylsilyl)pro-
The yield in the reaction of 3-(trimethylsilyl)propynoyl chloride
pynoyl chloride (II) reacts with β-amino alcohols in
(II) with amine is given in parentheses.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 46 No. 10 2010

1
468
MEDVEDEVA et al.
Scheme 2.
O
SiMe3
Me
ClCOCOCl
DMF (4 mol %), 25°C
HOCH C(Me) NH (IIIf)
Me
2
2
2
O
Et O, 25°C
O
2
I
Me Si
N
H
3
Cl
Me Si
O
3
II
V
makes it possible to perform under mild conditions
selective N- or N,O-acylation of β-amino alcohols with
formation of polyfunctional silicon-containing acety-
lenic amides in high yields.
N-Phenyl-3-(trimethylsilyl)prop-2-ynamide
(IVb). Yield 84%, mp 121–122°C (from hexane) [14].
IR spectrum (KBr), ν, cm : 1670 (C=O), 1580
–
1
(C–Carom), 1530 (C–N, δNH), 1240, 850 (Me Si).
3
1
H NMR spectrum, δ, ppm: 0.25 s (9H, Me Si), 7.15 t
3
EXPERIMENTAL
(
1H, p-H, J = 7.20 Hz), 7.33 t (2H, m-H, J = 7.60 Hz),
.82 d (2H, o-H, J = 8.08 Hz), 8.05 br.s (1H, NH).
7
The IR spectra were recorded in KBr or from thin
13
C NMR spectrum, δ , ppm: –0.67 (Me Si); 92.69 and
1
13
C
3
films on a Specord 75IR spectrometer. The H and C
NMR spectra were measured from solutions in CDCl3
on a Bruker DPX-400 instrument using cyclohexane as
internal reference.
9
1
6.88 (C≡C); 120.0, 124.99, 129.14, 137.23 (Carom);
29
50.39 (C=O). Si NMR spectrum: δ –14.76 ppm.
Si
N-Benzyl-3-(trimethylsilyl)prop-2-ynamide
(
IVc). Yield 85%, mp 73–74°C (from hexane) [21]. IR
3
-(Trimethylsilyl)prop-2-ynamide (IVa). A mix-
–1
spectrum (KBr), ν, cm : 1630 (C=O), 1590 (C–Carom),
1
ture of 0.50 g (3.5 mmol) of 3-(trimethylsilyl)pro-
pynoic acid (I), 0.49 g (3.85 mmol) of oxalyl choride,
and 4 mol % of DMF was stirred for 30 min at room
temperature, excess oxalyl chloride was distilled off
under reduced pressure, the residue was dissolved in
1
510 (C–N, δ ), 1250, 830, 750 (Me Si). H NMR
NH 3
spectrum, δ, ppm: 0.23 s and 0.25* s (9H, Me Si),
3
4
7
.48 d and 4.60* d (2H, CH , J = 5.84 Hz), 7.29–
.36 m (5H, Harom), 6.30 br.s (1H, NH). C NMR
2
13
spectrum, δ , ppm: –0.66 (Me Si); 91.97 and 97.47
C
3
2
0 ml of diethyl ether, and gaseous ammonia was
(
(
C≡C); 43.93 (CH ); 127.90, 128.07, 128.88, 137.22
Carom); 152.68 (C=O). Si NMR spectrum:
2
passed through the solution over a period of 30 min.
The mixture was stirred for 1 h at room temperature,
the precipitate of ammonium chloride was filtered off,
and the solvent was removed from the filtrate under
reduced pressure. Yield 0.41 g (82%), mp 54–55°C
29
δSi –15.02 ppm.
N-(2,5-Dichlorophenyl)-3-(trimethylsilyl)prop-2-
ynamide (IVd). Yield 82%, mp 118–119°C (from
–
1
–
1
hexane) [18]. IR spectrum (KBr), ν, cm : 1640 (C=O),
(
(
from hexane) [16]. IR spectrum (KBr), ν, cm : 1660
1
1
1
510 (C–N, δ ), 1250, 840, 730 (Me Si). H NMR
C=O), 1610 (C–N, δ ), 1260, 850 (Me Si). H NMR
NH 3
NH
3
spectrum, δ, ppm: 0.27 s (9H, Me Si), 7.03 d (1H, 3-H,
spectrum, δ, ppm: 0.24 s (9H, Me Si), 5.88, 6.35 br.s
3
3
1
3
J = 7.80 Hz), 7.26 d (1H, 4-H, J = 8.56 Hz), 8.41 m
(
2H, NH ). C NMR spectrum, δ , ppm: –0.71
2
C
1
3
(
1H, 6-H), 7.81 br.s (1H, NH). C NMR spectrum, δ ,
(
Me Si), 93.10 and 96.94 (C≡C), 154.86 (C=O).
C
3
2
9
ppm: –0.72 (Me Si); 97.30 and 93.80 (C≡C); 120.34,
Si NMR spectrum: δ –14.82 ppm.
3
Si
1
21.55, 125.03, 130.08, 133.75, 134.91 (Carom); 149.68
N-Alkyl(aryl)-3-(trimethylsilyl)prop-2-ynamides
IVb–IVd and IVg (general procedure). A mixture of
2
9
(C=O). Si NMR spectrum: δ –14.43 ppm.
Si
N-[3-(Trimethylsilyl)prop-2-ynoyl)morpholine
IVg). Yield 87%, mp 86–88°C (from hexane) [16]. IR
3
3
.50 mmol of 3-(trimethylsilyl)propynoic acid (I),
.85 mmol of oxalyl choride, and 4 mol % of DMF
(
–
1
spectrum (KBr), ν, cm : 1630 (C=O), 1230, 830, 750
was stirred for 30 min at room temperature, excess
oxalyl chloride was distilled off under reduced pres-
sure, the residue was dissolved in 10 ml of diethyl
ether, and the resulting solution was added dropwise to
a solution of 7 mmol of amine IIIb–IIId or IIIg in
1
(
Me Si). H NMR spectrum, δ, ppm: 0.24 s (9H,
3
Me Si), 3.63–3.66 m and 3.68–3.72 m (4H, CH N),
3
2
1
3
3
.74–3.76 m (4H, CH O). C NMR spectrum, δC,
2
ppm: –0.60 (Me Si), 41.90 and 47.34 (CH N), 66.51
3
2
and 66.91 (CH O), 98.39 and 95.30 (C≡C), 152.61
2
0 ml of diethyl ether. The mixture was stirred for 1 h
2
2
9
at room temperature, treated with 5% hydrochloric
acid, and extracted with diethyl ether. The extract was
(C=O). Si NMR spectrum: δSi –15.00 ppm.
N-(Hydroxyalkyl)-3-(trimethylsilyl)prop-2-yn-
amides IVe and IVf (general procedure). A mixture of
dried over MgSO , and the solvent was removed under
4
reduced pressure to obtain amide IVb–IVd or IVg in
8
2–87% yield.
* Rotamer fraction 15%.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 46 No. 10 2010

ONE-POT SYNTHESIS OF 3-(TRIMETHYLSILYL)PROPYNAMIDES
1469
3
3
.5 mmol of 3-(trimethylsilyl)propynoic acid (I),
.85 mmol of oxalyl chloride, and 4 mol % of DMF
ether. The extract was dried over MgSO , and the
solvent was distilled off under reduced pressure. Yield
4
was stirred for 30 min at room temperature, excess
oxalyl chloride was distilled off under reduced pres-
sure, the residue was dissolved in 10 ml of benzene,
and the resulting solution was added dropwise to
a solution of 7 mmol of amino alcohol IIIe or IIIf in
0.53 g (90%), mp 92–94°C. IR spectrum (KBr), ν,
cm : 3230, 3340 (NH), 2170 (C≡C), 1710 (C=O,
–
1
ester), 1630 (C=O, amide), 1560, 1520 (C–N, δ ),
NH
1
1250, 840 (Me Si). H NMR spectrum, δ, ppm: 0.22 s
3
and 0.25 s (18H, Me Si), 1.38 s (6H, Me), 4.28 s (2H,
3
1
3
2
0 ml of benzene at room temperature. The mixture
CH O), 5.74 br.s (1H, NH). C NMR spectrum, δC,
2
was heated for 4 h at 80°C, cooled to room tempera-
ture, and treated with 3 ml of 5% hydrochloric acid.
The organic phase was separated, the aqueous phase
was extracted with diethyl ether, and the combined
ppm: –0.27 and –0.10 (Me Si); 24.45 (CH C); 54.72
3
3
(N–C); 70.21 (C–O); 90.62, 94.77, 95.68, 98.77
2
9
(C≡C); 152.79, 153.43 (C=O). Si NMR spectrum, δ ,
Si
ppm: –15.31, –14.30. Found, %: C 56.42; H 8.31;
N 4.21; Si 16.50. C H NO Si . Calculated, %:
extracts were dried over MgSO and evaporated under
4
16 27
3
2
reduced pressure.
C 56.93; H 8.06; N 4.15; Si 16.64.
N-(2-Hydroxyethyl)-3-(trimethylsilyl)prop-2-yn-
amide (IVe). Yield 73%, oily substance [17]. IR spec-
trum (film), ν, cm : 3400 (OH), 3250 (NH), 2180
REFERENCES
–
1
1
. Cevallos, A., Rios, R., Moyano, A., Pericás, M.A., and
Riera, A., Tetrahedron: Asymmetry, 2000, vol. 11,
p. 4407.
(
(
(
C≡C), 1640 (C=O), 1520 (C–N, δNH), 1260, 850
1
Me Si). H NMR spectrum, δ, ppm: 0.21 s and 0.24* s
3
9H, Me Si), 3.43 m and 3.20* m (2H, CH N, J = 4.14
3
2
2. Coppola, G. and Damon, R., J. Heterocycl. Chem., 1995,
Hz), 3.72 t and 3.54* t (2H, CH O, J = 3.96 Hz),
2
vol. 32, p. 1141.
1
3
6
–
.78 br.s (1H, NH). C NMR spectrum, δ , ppm:
C
3. Coats, S.J., Link, J.S., Gauthier, D., and Hlasta, D.J.,
Org. Lett., 2005, vol. 7, p. 1469.
. Saá, C., Crotts, D.D., Hsu, G., and Vollhardt, K.P.C.,
0.68 (Me Si), 42.46 (CH N), 61.33 (CH O), 92.27
3
2
2
2
9
and 97.46 (C≡C), 153.69 (C=O). Si NMR spectrum:
δSi –15.06 ppm.
4
Synlett, 1994, p. 487.
N-(2-Hydroxy-1,1-dimethylethyl)-3-(trimethyl-
silyl)prop-2-ynamide (IVf). Yield 74%, mp 105–
5. Fonquerna, S., Moyano, A., Pericás, M.A., and
Riera, A., J. Am. Chem. Soc., 1997, vol. 119, p. 10225.
6. Parsons, P., Waters, A., Walter, D., and Board, J., J. Org.
Chem., 2007, vol. 72, p. 1395.
–
1
1
3
07°C (from hexane) [17]. IR spectrum (KBr), ν, cm :
500 (OH), 3200 (NH), 2170 (C≡C), 1630 (C=O),
7
8
9
. Urabe, H., Nakajima, R., and Sato, F., Org. Lett., 2000,
vol. 2, p. 3481.
. Brummond, K.M., Painter, T.O., Probst, D.A., and
Mitasev, B., Org. Lett., 2007, vol. 9, p. 347.
1
545, 1500, 1530 (C–N, δNH), 1250, 840 (Me Si).
3
1
H NMR spectrum, δ, ppm: 0.23 s (9H, Me Si), 1.33 s
3
(
6H, Me), 3.61 s (2H, CH O), 5.91 br.s (1H, NH).
2
1
3
C NMR spectrum, δ , ppm: –0.74 (Me Si); 24.29
C
3
. Medvedeva, A.S., Russ. J. Org. Chem., 1996, vol. 32,
(
9
Me); 57.10 (CH N); 69.84 (CH O); 92.70, 93.04,
6.94, 97.00 (C≡C); 153.26 (C=O). Si NMR spec-
2 2
2
9
p. 272.
1
0. Demina, M.M., Novopashin, P.S., Sarapulova, G.I.,
Larina, L.I., Smolin, A.S., Fundamenskii, V.S., Kasha-
ev, A.A., and Medvedeva, A.S., Russ. J. Org. Chem.,
trum: δ –15.10 ppm.
Si
2
-Methyl-2-[3-(trimethylsilyl)prop-2-ynoyl-
amino]propyl 3-(trimethylsilyl)prop-2-ynoate (V).
A mixture of 0.5 g (3.50 mmol) of 3-(trimethylsilyl)-
propynoic acid (I), 0.49 (3.85 mmol) of oxalyl
chloride, and 4 mol % of DMF was stirred for 30 min
at room temperature, excess oxalyl chloride was dis-
tilled off under reduced pressure, the residue was
dissolved in 20 ml of diethyl ether, and a solution of
2
004, 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.
1
1. Fonquerna, S., Moyano, A., Pericás, M.A., and
Riera, A., Tetrahedron: Asymmetry, 1997, vol. 8,
p. 1685.
12. Coppola, G. and Damon, R., Synth. Commun., 1993,
0
.31 g (3.5 mmol) of 2-amino-2-methylpropan-1-ol
vol. 23, p. 2003.
(
IIIf) and 0.15 g (1.75 mmol) of pyridine in 10 ml of
13. Siemsen, P., Livingston, R.C., and Diederich, F., Angew.
Chem., Int. Ed., 2000, vol. 39, p. 2632; Yamamoto, Y.,
Chem. Rev., 2008, vol. 108, p. 3199; Ito, H., Arimo-
to, K., Sensui, H.-O., and Hosomi, A., Tetrahedron Lett.,
diethyl ether was added dropwise. The mixture was
stirred for 1 h at room temperature, treated with 3 ml
of 5% hydrochloric acid, and extracted with diethyl
1
997, vol. 38, p. 3977; Montel, F., Beaudegnies, R.,
*
Rotamer fraction 8%.
Kessabi, J., Martin, B., Muller, E., Wendeborn, S., and
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 46 No. 10 2010

1
470
MEDVEDEVA et al.
Jung, P.M.J., Org. Lett., 2006, vol. 8, p. 1905;
17. Medvedeva, A.S., Andreev, M.V, Safronova, L.P.,
Sarapulova, G.I., Pavlov, D.V., and Afonin, A.V., Russ.
J. Org. Chem., 2002, vol. 38, p. 10.
Yamazaki, S., Morikawa, S., Miyazaki, K., Takebaya-
shi, M., Yamamoto, Y., Morimoto, T., Kakiuchi, K., and
Mikata, Y., Org. Lett., 2009, vol. 11, p. 2796.
1
8. Safronova, L.P., Medvedeva, A.S., Klyba, L.V., Boch-
karev, V.N., and Andreev, M.V., Russ. J. Org. Chem.,
2000, vol. 36, p. 184.
1
4. Medvedeva, A.S., Safronova, L.P., Vyazankin, N.S.,
Voronkov, M.G., Andreeva, E.I., Fursenko, E.I.,
Ponomareva, E.E., Sanin, M.A., Andrianova, N.I.,
Gushchin, B.E., Chumakova, E.I., Erokhova, L.N., and
Tsareva, I.S., USSR Inventor’s Certificate no. 1531403,
19. Safronova, L.P., Andreev, M.V., Afonin, A.V., and
Medvedeva, A.S., Russ. J. Org. Chem., 2002, vol. 38,
p. 788; Andreev, M.V., Medvedeva, A.S., Safrono-
va, L.P., Afonin, A.V., and Sarapulova, G.I., Russ. J.
Org. Chem., 2003, vol. 39, p. 1706.
20. Medvedeva, A.S., Andreev, M.V., Safronova, L.P., and
Afonin, A.V., Russ. J. Org. Chem., 2005, vol. 41,
p. 1463.
1
989; Byull. Izobret., 1989, no. 47.
1
1
5. Safronova, L.P., Medvedeva, A.S., Vyazankin, N.S.,
Zaks, A.S., and Yushkov, V.V., USSR Inventor’s
Certificate no. 1048757, 1983; Byull. Izobret., 1983,
no. 38.
6. Safronova, L.P., Medvedeva, A.S., and Vyazankin, N.S.,
21. Coppola, G. and Damon, R., J. Heterocycl. Chem., 1995,
Zh. Obshch. Khim., 1983, vol. 53, p. 1313.
vol. 32, p. 1133.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 46 No. 10 2010