A new procedure for synthesis of phosphorylated ynamines

Full text of DOI:10.1007/s11176-008-1031-0

ISSN 1070-3632, Russian Journal of General Chemistry, 2008, Vol. 78, No. 1, pp. 157 159.
Pleiades Publishing, Ltd., 2008.
Original Russian Text
N.I. Svintsitskaya, A.V. Aleksandrova, A.V. Dogadina, B.I. Ionin, 2008, published in Zhurnal Obshchei Khimii, 2008, Vol. 78,
No. 1, pp. 165 167.
LETTERS
TO THE EDITOR
A New Procedure for Synthesis of Phosphorylated Ynamines
N. I. Svintsitskaya, A. V. Aleksandrova, A. V. Dogadina, and B. I. Ionin
St. Petersburg State Institute of Technology,
Moskovskii pr. 26, St. Petersburg, 190013 Russia
e-mail: bi@thesa.ru
Received September 11, 2007
DOI: 10.1134/S1070363208010313
Phosphorylated ynamines are commonly formed in
reactions of chloroethynylphosphonates with secon-
dary [1] or tertiary amines [2]. In the reactions with
secondary amines, the parent amine taken in a double
molar excess serves as acceptor of the evolved hyd-
rogen chloride. However, while the reactions with
chloroethynylphosphonates with highly basic sec-
ondary amines, such as diethylamine (pKa 10.58)
[1, 3], morpholine (pKa 8.51), or piperidine (pKa
11.22) [4], in an apolar solvent (anhydrous carbon
tetrachloride) proceed vigorously with heat release and
afford phosphorylated ynamines in quantitative yields,
attempted synthesis of ynamines using secondary
amines of moderate or low basicity did not lead to an
unequivocal result. In the cited works, the basicities
of amines were estimated using the Marvin Sketch
program, version 3.5.7 (ChemAxon, http://chemaxon.
com/marvin). The pKa values calculated by this
program for aromatic amines well fit reference values.
We explored the progress of the reaction of di-
methyl chloroethynylphosphonate with 1,2,3,4-tetra-
hydroquinoline (pKa 5.00) in anhydrous CCl4 (reagent
1
molar ratio 1:2) by means of H and 31P NMR spec-
1
troscopy and H {31P} double resonance (decoupling
and INDOR experiments). One hour after reagent
1
mixing, the H {31P} INDOR spectrum of the reac-
tion mixture shows two signals: one at
(characteristic of phosphorylated ynamines) and the
1.5 ppm
P
1
second, stronger signal at
spectrum of the reaction mixture contains a downfield
doublet at 5.3 ppm (JHP 11 Hz). This observation
11 ppm. The H NMR
P
together the above phosphorus chemical shift suggests
formation of a compound with an sp2 carbon atom
attached to phosphorus and bearing hydrogen. We can
thus conclude that the second product is an ynamine
hydrochlorinated by the triple bond:
-
P
-| N
|
-
|
-
|
+ HCl
P C CCl + 2
P C CN
-|-| Cl
CCl4
H
N
H
+1 + 2 ppm
+11 ppm
P
P
Probably, because of the insufficiently high basi-
city, 1,2,3,4-tetrahydroquinoline is incapable of fast
binding the evolved HCl, and, as a result, the latter
adds across the triple bond of the forming amino-
ethynylphosphonate. On further heating for 1.5 h, a
precipitate formed, probably, amine hydrochloride.
The 1H NMR spectrum of the reaction mixture
showed already two characteristic doublet signals split
by coupling with phosphorus: Along with the down-
field doublet at
5.3 ppm, a doublet in an upper
H
157

158
SVINTSITSKAYA et al.
field and with a smaller JHP constant is observed at
4.63 ppm (JHP 7.4 Hz). According to the INDOR ex-
periment, this new doublet corresponds to the phos-
Thus, the reaction of chloroethynylphosphonate
with 1,2,3,4-tetrahydroquinoline is not strictly chemo-
selective and should be studied in mode detail to solve
the problem of fast binding the evolved HCl.
phorus resonance at
25 ppm, which implies
P
It was found that the reaction of dimethyl chloro-
ethynylphosphonate with secondary amines, such as
1,2,3,4-tetrahydroquinoline (pKa 5.00), N-methylani-
line (pKa 4.85), and N-benzylaniniline (pKa 3.92), in
the presence of anhydrous potassium carbonate (HCl
acceptor) at an equimolar reagent ratio in a polar sol-
vent (anhydrous acetonitrile) results in quantitative
formation of phosphorylated ynamines Ia Ic.
formation of a 2,2-bis-aminated vinylphosphonate via
reaction of excess amine with the phosphorylated
ynamine. Knowing that addition of secondary amines
to aminoethynylphosphonates readily occurs in the
presence of acid catalysts [5, 6], we can suggest that
the latter reaction is catalyzed by the formed HCl or
amine hydrochloride.
K2CO3,
P C CCl + HNRR
CH3CN
P C CNRR + KCl + KHCO3,
Ia Ic
N
CH2C6H5
C6H5
CH3
(b), N
(c).
(a), N
P
NRR :
: (CH3O)2P
O
C6H5
After reaction completion, the inorganic salts were
filtered off, and the solvent was removed in a vacuum.
Since ynamines readily add water to form amides [5],
the formed ynamines were not isolated and immedia-
tely introduced in further syntheses. Nevertheless, the
purity and quantitative formation of compounds Ia Ic
solved in acetonitrile was immediately brought in
further transformations.
Dimethyl (1,2,3,4-tetrahydroqunolyl)ethynyl-
phosphonate (Ia). 1H NMR spectrum, , ppm
2
3
(CDCl3): 1.90 q (2H, CH2), 2.67 t (2H, CH2), 3.63 t
(2H, NCH2), 3.69 d (6H, CH3O, 3JHP 12.5 Hz), 6.81 t
(1H, H6), 6.94 d (1H, H8), 7.06 t (1H, H7), 7.13 d (1H,
H5). 13C NMR spectrum, C, ppm (CDCl3): 20.68
1
were confirmed by H, 13C, and 31P NMR spectro-
scopy. The spectra of the reaction mixtures show no
other signals than those of the phosphorylated
ynamines. The 13C NMR spectra are the most infor-
mative; they contain two typical doublet signals
corresponding to the carbon atoms of the triple bond:
2
(C2), 26.12 (C3), 49.95 (C1), 52.69 d (CH3O, JCP
1
5.4 Hz), 57.88 d (CP, JCP 321.5 Hz), 99.92 d (CN,
2JCP 65.1 Hz), 115.33 (C6), 121.99 (C8), 123.96 (C4),
The signal at
57 ppm with a large coupling
C
127.06 (C7), 129.19 (C5), 136.76 (C9). 31P NMR spec-
trum, P, ppm (CDCl3): 1.62.
constant (1JCP 320 Hz) belongs to the carbon atoms
directly bound to phosphorus and that at
100 ppm
(2JCP 64 65 Hz) to the carbon atom boCund to the
amine fragment. The phosphorus chemical shift of
ynamines Ia Ic is close to zero, as expected. These
data fit well the spectral characteristics of phosphoryl-
ated ynamines obtained earlier [1, 3, 4].
1
2
6
3
5
(CH3O)2PC CN
4
9
O
8
7
Aminoethynylphosphonates
Ia Ic
(general
procedure). To a solution of 1 g of dimethyl chloro-
ethynylphosphonate in 3 ml of anhydrous acetonitrile,
1 g of anhydrous potassium carbonate was added,
after which an equimolar amount (5.93 mmol) of the
corresponding secondary amine in 2 ml of anhydrous
acetonitrile was slowly added dropwise with vigorous
stirring. The reaction mixture was refluxed for 2 h.
The inorganic salts were then filtered off, and the
quantitatively formed phosphorylated ynamine dis-
Dimethyl (N-methyl-N-phenylamino)ethynyl-
phosphonate (Ib). 1H NMR spectrum, , ppm
(CDCl3): 3.22 (3H, CH3Ph), 3.67 d (6H, CH3O, JHP
3
12.5 Hz), 6.92 t (1H, p-CH, Ph), 6.99 d (2H, o-CH,
Ph), 7.22 t (2H, m-CH, Ph). 13C NMR spectrum,
,
C
2
ppm (CDCl3): 38.22 (CH3Ph), 52.67 d (CH3O, JCP
1
5.4 Hz), 56.63 d (CP, JCP 320.1 Hz), 100.60 d (CN,
2JCP 63.8 Hz), 114.61 (o-CH, Ph), 122.40 (p-CH, Ph),
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 78 No. 1 2008

A NEW PROCEDURE FOR SYNTHESIS OF PHOSPHORYLATED YNAMINES
159
129.03 (m-CH, Ph), 141.53 (ipso-C, Ph). 31P NMR
spectrum, P, ppm (CDCl3): 0.46.
(13C) and 81.014 MHz (31P), solvent CDCl3, internal
reference TMS (1H, 13C), external reference 85%
1
1
phosphoric acid (31P). Preliminary H and H {31P}
NMR spectra were registered on a Tesla BS-497
instrument at 100 MHz.
Dimethyl (N-benzyl-N-phenylamino)ethynyl-
phosphonate (Ic). 1H NMR spectrum, , ppm
(CDCl3): 3.57 d (6H, CH3O, 3JHP 12.5 Hz), 4.68 (2H,
CH2Ph), 6.87 t (1H, p-CH, Ph), 7.02 d (2H, o-CH,
Ph), 7.08 t (1H, p-CH, PhCH2), 7.15 t (2H, m-CH,
Ph), 7.19 m (4H, o,m-CH, PhCH2). 13C NMR spec-
trum, C, ppm (CDCl3): 52.64 d (CH3O, 2JCP 5.4 Hz),
54.61 (CH2Ph), 57.47 d (CP, 1JCP 317.4 Hz), 100.23 d
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2
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1
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