Dialkyl (1-ethoxycarbonyl-2,2,2-trifluoro-1-phenylsulfonylaminoethyl)- phosphonates

Article abstract of DOI:10.1007/s11172-011-0262-0

A number of fluorine-containing a-amino phosphonates of the general formula (RO)₂P(O)C(CF₃)(COOC₂H₅)NHSO ₂Ph were obtained and found to irreversibly inhibit four serine hydrolases: acetyl- and butyrylcholinesterases, neuropathy target esterase, and carb-oxylesterase.

Full text of DOI:10.1007/s11172-011-0262-0

Russian Chemical Bulletin, International Edition, Vol. 60, No. 8, pp. 1769—1771, August, 2011
1769
Dialkyl (1ꢀethoxycarbonylꢀ2,2,2ꢀtrifluoroꢀ1ꢀphenylsulfonylaminoethyl)ꢀ
phosphonates
A. Yu. Aksinenko, V. B. Sokolov, T. V. Goreva, and G. F. Makhaeva
Institute of Physiologically Active Compounds, Russian Academy of Sciences,
142432 Chernogolovka, Moscow Region, Russian Federation.
Fax: +7 (496) 524 9508. Eꢀmail: alaks@ipac.ac.ru
A number of fluorineꢀcontaining αꢀamino phosphonates of the general formula
(RO)2P(O)C(CF3)(COOC2H5)NHSO2Ph were obtained and found to irreversibly inhibit
four serine hydrolases: acetylꢀ and butyrylcholinesterases, neuropathy target esterase, and carbꢀ
oxylesterase.
Key words: organofluorine compounds, αꢀamino phosphonates, serine hydrolase inhibitors.
Scheme 1
αꢀAmino phosphonic acids and their esters, which are
structural analogs of αꢀamino carboxylic acids, have been
thoroughly studied as biologically active compounds.1,2
Reviews dealing with the synthesis and biological activity
of fluorinated phosphonates contain almost exhaustive
data for 2007,3,4 including fluorinated derivatives of
αꢀamino phosphonic acids. The latter can inhibit various
enzymes.3 For instance, it has been shown that some fluꢀ
orinated esters of αꢀamino fluorophosphonic acids and
phosphine oxides act as inhibitors of cholinesterases5,6 and
thrombin,7 in contrast to their nonfluorinated analogs.
Earlier, we have obtained a number of fluorinated
αꢀamino phosphonates of the general formula
(RO)2P(O)C(CF3)2NHSO2Ph and demonstrated8,9 that
they irreversibly inhibit serine hydrolases via phosphorylꢀ
ation of serine at the active center of the enzymes with
cleavage of the P—C bond. Here we describe the synthesis
of new fluorinated representatives of αꢀamino phosꢀ
phonates (Scheme 1) and present preliminary data on their
reactions with four serine hydrolases that are essential for
the physiological effects of organophosphorus compounds
(OPC): acetylcholinesterase (EC 3.1.1.7, AChE, target
for the acute toxicity of OPC), neuropathy target esterase
(EC 3.1.1.5, NTE, target for the OPC induced delayed
neuropathy, OPIDN), butyrylcholinesterase (EC 3.1.1.8,
BChE), and carboxylesterase (EC 3.1.1.1, CE), which are
secondary scavenger targets. As potential serine hydrolase
inhibitors, the phosphonates studied have a distinctive feaꢀ
ture: their molecules contain no typical leaving group
(F, SAlk, OAr, etc.) characteristic of anticholinesterase
compounds.
R = Me (a), Et (b), Pr (c), Pri (d), Bu (e), Bui (f), nꢀC5H11 (g),
iꢀC5H11 (h)
Phosphonates 3a—h are crystalline solids. Their comꢀ
positions and structures were proved by elemental analysis
and H, 19F, and 31P NMR spectroscopy. The H NMR
spectra of phosphonates 3a—h show a characteristic douꢀ
blet at δ 6.9—9.2 (NH, JH,P = 8.0 Hz). The 19F NMR
spectra contain a doublet at δ 9—12 (CF3, JF,P ≈ 5 Hz).
Accordingly, the 31P NMR spectra show quartets at
δ 10—12 (JP,F ≈ 5 Hz).
1
1
Kinetic studies of human erythrocyte acetylcholinestꢀ
erase, hen brain neuropathy target esterase, horse serum
butyrylcholinesterase, and pig liver carboxylesterase, the
details and analysis of which would be published elseꢀ
where, showed that phosphonates 3a—h, like previously
examined compounds containing two trifluoromethyl
groups at the αꢀC atom,8,9 act as irreversible inhibitors of
all the above esterases with the inhibition kinetics typical
of organophosphorus compounds. The bimolecular inhibiꢀ
Reactions between equimolar amounts of sulfonylꢀ
imine 1 (derived from ethyl trifluoropyruvate) and dialkyl
phosphites 2a—h gave the corresponding fluorinated
αꢀamino phosphonates 3a—h in 60—90% yields.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1741—1743, August, 2011.
1066ꢀ5285/11/6008ꢀ1769 © 2011 Springer Science+Business Media, Inc.

1770
Russ.Chem.Bull., Int.Ed., Vol. 60, No. 8, August, 2011
Aksinenko et al.
with SiMe4 as the internal standard (1H) and with CF3COOH
(19F) and H3PO4 (31P) as the external standards. Melting points
were determined in glass capillaries.
Ethyl 3,3,3ꢀtrifluoroꢀ2ꢀphenylsulfonyliminopropionate (1)
was prepared according to a known procedure.10 Dialkyl phosꢀ
phites (Aldrich) were used as purchased.
tion constants ki (L mol–1 min–1) range from 6.8•102 (3d)
to 6.4•105 (3e,f) for AChE, from 8.9•10 (3d) to 3.9•105 (3g)
for NTE, from 8.3•102 (3a) to 6.8•105 (3e) for BChE,
and from 2.7•103 (3d) to 6.8•105 (3e) for CE. Apparently,
the presence of two strong electronꢀwithdrawing substituꢀ
ents (CF3 and COOEt) at the αꢀC atom makes the P—C
bond more labile as demonstrated earlier for αꢀamino
phosphonates containing two CF3 groups8,9 and the irreꢀ
versible inhibition of serine hydrolases, which is evident
from the kinetic data, is due to the phosphorylation of
serine by compounds 3a—h because of the cleavage of the
P—C bond. An acute toxicity assay revealed that the
αꢀamino phosphonates in question are not very toxic for
the warmꢀblooded: LD50 for 3b is 200 mg kg–1 (mice,
intraperitoneal injection).
Synthesis of phosphonates 3a—h (general procedure). An apꢀ
propriate dialkyl phosphite 2a—h (5 mmol) in anhydrous benꢀ
zene (20 mL) was added to a solution of sulfonylimine 1 (5 mmol)
in anhydrous benzene (20 mL). The reaction mixture was reꢀ
fluxed for 2 h, the solvent was removed, and the residue was
1
recrystallized from hexane—benzene (10 : 1). The H, 19F, and
31P NMR spectra of the compounds obtained are given in Table 1.
Ethyl 2ꢀdimethoxyphosphorylꢀ3,3,3ꢀtrifluoroꢀ2ꢀ(phenylsulfꢀ
onylamino)propionate (3a). Yield 71%, m.p. 82—84 °C. Found (%):
C, 37.46; H, 4.21; N, 3.06. C13H17F3NO7PS. Calculated (%):
C, 37.24; H, 4.09; N, 3.34.
To sum up, we obtained novel fluorinated αꢀamino
phosphonates, which can originate a new type of irreversible
serine hydrolase inhibitors containing no typical leaving
group, as distinct from known anticholinesterase agents.
Ethyl 2ꢀdiethoxyphosphorylꢀ3,3,3ꢀtrifluoroꢀ2ꢀ(phenylsulfꢀ
onylamino)propionate (3b). Yield 60%, m.p. 77—78 °C. Found (%):
C, 43.98; H, 4.82; N, 3.24. C15H21F3NO7PS. Calculated (%):
C, 40.27; H, 4.73; N, 3.13.
Ethyl 2ꢀdiꢀnꢀpropoxyphosphorylꢀ3,3,3ꢀtrifluoroꢀ2ꢀ(phenylꢀ
sulfonylamino)propionate (3c). Yield 72%, m.p. 80—82 °C.
Found (%): C, 42.78; H, 5.18; N, 3.06. C17H25F3NO7PS. Calꢀ
culated (%): C, 42.95; H, 5.30; N, 2.95.
Experimental
1
H, 19F, and 31P NMR spectra were recorded on a Bruker
Ethyl 2ꢀdiisopropoxyphosphorylꢀ3,3,3ꢀtrifluoroꢀ2ꢀ(phenylꢀ
sulfonylamino)propionate (3d). Yield 91%, m.p. 152—153 °C.
DPX 200 instrument (200.13, 188.29, and 81 MHz, respectively)
Table 1. 1H, 19F, and 31P NMR spectra of fluorinated αꢀamino phosphonates 3a—h
Comꢀ
pound
Chemical shifts δ and coupling constants J (Hz)
1H
9F (d, JF,P
)
31P{H} (q, JP,F
)
3aa
3bb
3cа
3db
3ea
1.19 (t, 3 Н, CH3CH2, JH,H = 7.0); 3.79 (d, 6 H, CH3O, JH,P = 11.4);
4.13 (m, 1 H, CH2O); 4.29 (m, 1 H, CH2O); 7.55 (m, 3 H, HAr);
7.92 (m, 2 H, HAr); 9.18 (d, 1 H, NH, JH,P = 7.7)
1.33 (t, 3 Н, CH3CH2OC(O), JH,H = 7.0); 1.37 (t, 6 H, CH3CH2OP(O),
JH,H = 7.0); 4.14—4.46 (m, 6 H, CH2O); 6.28 (d, 1 H, NH, JH,P = 11.9);
10.36
(4.7)
12.37
(4.7)
12.29
(5.2)
10.28
(5.0)
7.47—7.65 (m, 3 H, HAr); 7.92—8.02 (m, 2 H, HAr
)
0.92 (t, 6 H, CH3CH2CH2, JH.H = 7.0); 1.19 (t, 3 Н, CH3CH2O, JH,H = 7.0);
1.66 (m, 4 H, CH3CH2CH2); 3.90—4.14 (m, 5 H, CH2O); 4.29 (m, 1 H, CH2O);
7.54 (m, 3 H, HAr); 7.94 (m, 2 H, HAr); 9.18 (d, 1 H, NH, JH,P = 8.0)
1.12 (m, 12 H, (CH3)2CH); 1.22 (t, 3 Н, CH3CH2O, JH,H = 7.0);
10.48
(4.9)
9.88
(5.0)
11.76
(4.9)
7.62
(4.8)
4.00—4.30 (m, 2 H, CH2O); 4.75 (m, 1 H, CHO); 6.68 (d, 1 H, NH,
JH,P = 8.0); 7.58 (m, 3 H, HAr); 7.92 (m, 2 H, HAr
)
0.92 (t, 6 H, CH3CH2CH2, JH,H = 7.0); 1.10 (t, 3 Н, CH3CH2O, JH,H = 7.0);
1.26 (m, 4 H, CH3CH2CH2); 1.56 (m, 4 H, CH3CH2CH2); 3.90—4.18 (m, 5 H,
CH2O); 4.29 (m, 1 H, CH2O); 7.56 (m, 3 H, HAr); 7.90 (m, 2 H, HAr);
9.24 (d, 1 H, NH, JH,P = 8.0)
0.96 (m, 12 H, (CH3)2CH2CH); 1.24 (t, 3 Н, CH3CH2O, JH,H = 7.0);
1.86 (m, 2 H, CHCH2); 3.86—4.05 (m, 4 H, CH2OP); 4.10 (m, 1 H, CH2OC);
4.30 (m, 1 H, CH2OC); 6.98 (d, 1 H, NH, JH,P = 8.0); 7.56 (m, 3 H, HAr);
9.31
(5.1)
8.64
(5.0)
3fb
9.02
(5.2)
9.92
(5.2)
7.94 (m, 2 H, HAr
)
3ga
3ha
0.88 (t 6 H, CH3CH2CH2, JH,H = 7.0); 1.12 (t, 3 Н, CH3CH2O, JH,H = 7.0);
1.26 (m, 8 H, CH3CH2CH2); 1.55 (m, 4 H, CH2CH2O); 3.83—4.16 (m, 5 H,
CH2O); 4.24 (m, 1 H, CH2O); 7.49 (m, 3 H, HAr); 7.88 (m, 2 H, HAr); 9.04
(d, 1 H, NH, JH,P = 8.0)
0.89 (m, 12 H, (CH3)2CH); 1.14 (t, 3 Н, CH3CH2O, JH,H = 7.0); 1.45 (m, 4 H,
CHCH2); 1.64 (m, 2 H, CHCH2); 3.86—4.37 (m, 6 H, CH2OP + CH2OC);
7.52 (m, 3 H, HAr); 7.93 (m, 2 H, HAr); 9.00 (d, 1 H, NH, JH,P = 7.7)
10.52
(4.9)
10.03
(5.1)
10.43
(5.0)
9.86
(5.0)
a DMSOꢀd6. b CDCl3.

Fluorineꢀcontaining αꢀamino phosphonates
Russ.Chem.Bull., Int.Ed., Vol. 60, No. 8, August, 2011
1771
Found (%): C, 42.69; H, 5.11; N, 3.18. C17H25F3NO7PS. Calꢀ
culated (%): C, 42.95; H, 5.30; N, 2.95.
Ethyl 2ꢀdiꢀnꢀbutoxyphosphorylꢀ3,3,3ꢀtrifluoroꢀ2ꢀ(phenylꢀ
sulfonylamino)propionate (3e). Yield 70%, m.p. 64—66 °C.
Found (%): C, 45.56; H, 6.03; N, 3.04. C19H29F3NO7PS. Calꢀ
culated (%): C, 45.33; H, 5.81; N, 2.78.
4. V. P. Kukhar, V. D. Romanenko, Kem. Ind., 2007, 56, 329.
5. V. V. Kuusk, I. V. Morozova, R. S. Agabekyan, A. Yu.
Aksinenko, T. A. Epishina, V. B. Sokolov, N. V. Kovaleva,
A. N. Razdol´skii, V. I. Fetisov, I. V. Martynov, Bioorg.
Khim., 1990, 16, 1500 [Sov. Bioorg. Chem. (Engl. Transl.),
1990, 16, 1500].
Ethyl 2ꢀdiisobutoxyphosphorylꢀ3,3,3ꢀtrifluoroꢀ2ꢀ(phenylꢀ
sulfonylamino)propionate (3f). Yield 90%, m.p. 95—99 °C.
Found (%): C, 45.15; H, 5.66; N, 2.57. C19H29F3NO7PS. Calꢀ
culated (%): C, 45.33; H, 5.81; N, 2.78.
Ethyl 2ꢀdiꢀnꢀpentyloxyphosphorylꢀ3,3,3ꢀtrifluoroꢀ2ꢀ(phenylꢀ
sulfonylamino)propionate (3g). Yield 68%, m.p. 85—87 °C.
Found (%): C, 47.37; H, 6.33; N, 2.82. C21H33F3NO7PS. Calcuꢀ
lated (%): C, 47.45; H, 6.26; N, 2.64.
Ethyl 2ꢀdiisopentyloxyphosphorylꢀ3,3,3ꢀtrifluoroꢀ2ꢀ(phenylꢀ
sulfonylamino)propionate (3h). Yield 84%, m.p. 98—100 °C.
Found (%): C, 47.69; H, 6.03; N, 2.42. C21H33F3NO7PS. Calcuꢀ
lated (%): C, 47.45; H, 6.26; N, 2.64.
6. O. V. Korenchenko, Yu. Ya. Ivanov, A. Yu. Aksinenko, V. B.
Sokolov, I. V. Martynov, Khim.ꢀFarm. Zh., 1992, 26, 21
[Pharm. Chem. J. (Engl. Transl.), 1992, 26, 489].
7. E. G. Kireeva, S. M. Strukova, T. N. Dugina, V. B. Sokolov,
A. Yu. Aksinenko, Biokhimiya, 1992, 57, 21 [Biochem. (Moscow)
(Engl. Transl.), 1992, 57, 21].
8. G. F. Makhaeva, A. Y. Aksinenko, V. B. Sokolov, I. I. Baskin,
V. A. Palyulin, N. S. Zefirov, N. D. Hein, J. W. Kampf, S. J.
Wijeyesakere, R. J. Richardson, Chem. Biol. Int., 2010,
187, 177.
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Sokolov, N. N. Strakhova, A. N. Razdol´skii, R. J. Richardꢀ
son, I. V. Martynov, Dokl. Akad. Nauk, 2005, 400, 831 [Dokl.
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Received November 17, 2010;
in revised form May 12, 2011