Synthesis and antioxidant activity of substituted-1,3,2-diazaphosphole 1-oxides

Article abstract of DOI:10.1002/ardp.201000280

Synthesis of 1-substituted-1,3,2-diazaphosphole 1-oxides (3a-l) were accomplished via a two-step process. It involves the preparation of diazaphospholo 1-oxide monochloride intermediate (2) and its subsequent reaction with phenols/amino acid esters in dry THF in the presence of triethylamine at 40-45°C. The structures of newly synthesized compounds were characterized by spectral and elemental analysis. The title compounds were evaluated for their in-vitro antioxidant properties. A series of new 1,3,2-diazaphosphole-2-oxides 3a-l have been synthesized and evaluated for their antioxidant properties. Copyright

Full text of DOI:10.1002/ardp.201000280

Arch. Pharm. Chem. Life Sci. 2011, 344, 765–770
765
Full Paper
Synthesis and Antioxidant Activity of Substituted-1,3,2-
Diazaphosphole 1-Oxides
Kalla Reddi Mohan Naidu1, Pasupuleti Visweswara Rao2, Chamarthi Naga Raju1, and
Kambam Srinivasulu3
1 Department of Chemistry, Sri Venkateswara University, Tirupati, India
2 Department of Biotechnology, Sri Venkateswara University, Tirupati, India
3 Department of Nano Materials Division, Graduate School of Science and Technology, Shizuoka University,
Hamamatsu 432-8561, Japan
Synthesis of 1-substituted-1,3,2-diazaphosphole 1-oxides (3a–l) were accomplished via a two-step
process. It involves the preparation of diazaphospholo 1-oxide monochloride intermediate (2) and
its subsequent reaction with phenols/amino acid esters in dry THF in the presence of triethylamine at
40–458C. The structures of newly synthesized compounds were characterized by spectral and
elemental analysis. The title compounds were evaluated for their in-vitro antioxidant properties.
Keywords: Antioxidant activity / 1,3,2-Diazaphosphole 2-oxides
Received: September 26, 2010; Revised: December 16, 2010; Accepted: December 28, 2010
DOI 10.1002/ardp.201000280
Introduction
diazaphospholoiminophosphorane derivatives containing
zidovudine displayed significant antioxidant properties [9].
In view of these reports and various applications of organo-
phosphorus heterocycles, we herein report the synthesis of a
series of novel organophosphorus heterocycles by incorpo-
rating the bioactive groups attached to phosphorus atom,
which fortunately resulted in noticeable antioxidant
properties.
Organophosphorus heterocycles have received much atten-
tion due to their unique structural features and diverse
applications in biological systems [1] particularly as possible
pharmaceuticals [2]. There has been increasing interest in the
role played by oxygen-derived free radicals such as the super-
ꢀ
oxide (O2 ), nitric oxide (NOꢀ), hydroxyl (ꢀOH) and peroxyl
ꢀ
(RO2 ) radicals in human diseases including atherosclerosis,
rheumatoid arthritis and carcinogenesis [3].
Results and discussion
Peroxyl radicals are formed during lipid oxidation chain
reactions. Lipidperoxidation may be initiated by any species
that possesses sufficient reactivity to abstract a hydrogen atom
from a polyunsaturated fatty acid side chain in membrane
lipids [4]. Focus is made on the detailed mechanism of anti-
oxidant action of organophosphorus heterocyclic compounds
and their structure-activity relationship. Phosphite and phos-
phonates act as both primary and secondary antioxidants
[5, 6]. 2-Substituted-thiadiazaphosphol-2-ones exhibited prom-
ising antioxidant properties [7]. Various substituted benzene-
1,4-diamine-bis-dioxaphosphepine-6l5-iminophosphoranes
showed good antioxidant activities [8]. Another series of
Cyclocondensation of 2(ꢁ)aminomethylpiperidine (1) with
phosphorus oxychloride in the presence of TEA in dry THF
at 10–208C gave monochloride 2 which on subsequent reac-
tion with phenols/amino acid esters yielded 3a–l. This
method is advantageous since it does not require the prep-
aration of highly toxic, moisture sensitive and thermally
unstable aryl phosphorodichlorides of the corresponding
phenols and amino acid esters (Scheme 1). The cyclized prod-
ucts (3a–l) were isolated by filtration to remove TEA hydro-
chloride, followed by evaporation of the filtrate in a rotary
evaporator. Further purification was carried out by washing
the residue with hexane followed by column chromatog-
raphy using hexane/ethyl acetate (8:2) mixture as an eluent.
All the compounds 3a–l exhibited IR absorption bands fꢂor1
Correspondence: Chamarthi Naga Raju, Department of Chemistry, Sri
Venkateswara University, Tirupati-517502, India.
E-mail: rajuchamarthi10@gmail.com
–
P O and P-NH in the regions 1269–1214 and 3410–3148 cm
–
[10], respectively. The –NH proton gave a singlet at d 3.55–2.42,
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766
K. R. M. Naidu et al.
Arch. Pharm. Chem. Life Sci. 2011, 344, 765–770
the C-3 methylene hydrogens resonated as multiplets at d
3.40–2.21. The N–CH proton is also appeared as a multiplet
at d 3.68–2.92. In the 13C-NMR spectra, C-3 methylene reson-
ated at d 58.3–45.8. The chemical shifts of the a-carbon to the
amino acid ester group appeared at d 59.8–52.6 [11]. The
remaining carbon resonances were observed in the expected
region. 31P-NMR signals were observed in the region 26.19–
14.30 ppm [12]. The APCI-MS data of all the products showed
their protonated molecular ions.
straight forward synthetic protocol. The structures of 3a–l
were established by elemental analysis, IR, NMR (1H-, 13C-, and
31P-), and mass spectral data. Antioxidant properties were
evaluated for the title compounds (3a–l), the compounds
3g exhibited good antioxidant property when compared to
other members of the series except against SOD. The com-
pound 3l showed maximum antioxidant activity against
SOD. Overall, the title compounds exhibited moderate anti-
oxidant properties when compared to that of vitamin C.
Antioxidant activity
Experimental
Results on the preliminary antioxidant activity of the title
compounds are presented in Table 1. The compound 3g with
a L-valine methylester substitution at phosphorus atom
of octahydro-1,3,2-diazaphospholo[1,5a]pyridine-1-oxide
showed enhanced antioxidant activity by maximum levels
of enzymes like catalase, lipidperoxidation, and glutathione.
Whereas 3g showed a little reduction in superoxide dismu-
tase activity and the compound 3l having a substitution of
phenylglycine ethylester at phosphorus atom of the title
compound exhibited an enhanced superoxide dismutase
activity, followed by catalase activity. But the studies showed
no enhancement of LPO and GSH activities with adminis-
tration of the compound 3l. Further observations reveal that
the compounds 3g, 3h, 3k, and 3l with corresponding amino
acid esters as substituents showed a clear enhancement in
the levels of antioxidant enzyme activities. The compound 3f
with a bis-(2-chloro) ethyl amine substitution showed an
enhanced antioxidant activity as reported earlier [13].
Chemistry
Chemicals were purchased from Sigma-Aldrich, Merck and
Lancaster, and were used as such without further purification.
All solvents used for spectroscopic and other physical studies
were reagent grade and were further purified by literature
methods [14]. Melting points were determined using a calibrated
thermometer by Guna Digital Melting point apparatus. IR spec-
tra were recorded on a Perkin-Elmer FT-IR 240-C spectropho-
tometer using KBr optics. 1H-, 13C-, and 31P-NMR spectra were
recorded on a Bruker 400 MHz NMR spectrometer operating at
500 MHz for 1H-, 125 MHz for 13C-, and 202 MHz for 31P-NMR.
Spectra were recorded in DMSO-d6 and referenced to TMS (1H &
13C) and 85% H3PO4 (31P). APCI mass spectra were recorded on a
Jeol SX102 DA/600 mass spectrometer. Elemental analyses were
performed on a Thermo Finnigan Insturment at University of
Hyderabad, Hyderabad, India.
Synthetic procedure for the intermediate (2)
A solution of phosphoryl chloride (0.002 mol) in 15 mL of dry
THF was added dropwise over a period of 15 min to a stirred
solution of 2(ꢁ)-aminomethyl piperidine (1) (0.002 mol) and tri-
ethylamine (0.004 mol) in 10 mL of THF at 0–58C. After stirring
for 1 h at room temperature, formation of intermediate mono-
chloride 2 was ascertained by TLC analysis run in a 3:7 mixture of
ethyl acetate and hexane, TEA hydrochloride was removed from
the reaction mixture by filtration. The filtrate is evaporated in a
Conclusion
Synthesis of a series of novel 1-substituted-1,3,2-diazaphos-
phole-1-oxides is accomplished by adopting a simple and
Table 1. Antioxidants in brain homogenates of young rats using test compounds 3a–l.
Parameters
SOD
CAT
LPO
GSH
3a
3b
3c
3d
3e
3f
3g
3h
3i
26.23 ꢁ 0.27
26.51 ꢁ 1.47
25.87 ꢁ 1.62
25.91 ꢁ 1.43
26.18 ꢁ 1.39
27.62 ꢁ 1.21
27.29 ꢁ 0.55
27.93 ꢁ 1.88
25.72 ꢁ 1.94
26.23 ꢁ 1.46
27.26 ꢁ 1.32
28.44 ꢁ 0.71
262.21 ꢁ6 .23
259.63 ꢁ 4.17
260.08 ꢁ 5.22
261.92 ꢁ 5.76
260.34 ꢁ 6.23
264.25 ꢁ 6.23
278.16 ꢁ 4.61
272.13 ꢁ 5.78
263.11 ꢁ 4.32
267.18 ꢁ 5.22
272.88 ꢁ 2.18
273.02 ꢁ 5.76
385.46 ꢁ 5.25
403.27 ꢁ 4.76
69.71 ꢁ 3.15
68.02 ꢁ 1.31
66.36 ꢁ 1.45
69.19 ꢁ 2.38
67.22 ꢁ 1.10
72.39 ꢁ 1.66
77.16 ꢁ 1.52
71.44 ꢁ 1.57
62.48 ꢁ 2.77
65.62 ꢁ 1.33
76.22 ꢁ 1.28
72.11 ꢁ 1.82
82.78 ꢁ 1.43
88.06 ꢁ 1.28
4.72 ꢁ 0.74
4.61 ꢁ 1.56
4.52 ꢁ 1.28
4.67 ꢁ 1.90
4.62 ꢁ 1.33
4.81 ꢁ 0.66
4.95 ꢁ 1.51
4.83 ꢁ 1.73
4.59 ꢁ 1.29
4.64 ꢁ 1.50
4.71 ꢁ 1.07
4.68 ꢁ 1.55
8.34 ꢁ 0.74
10.26 ꢁ 0.92
3j
3k
3l
Ascorbic acid 32.45 ꢁ 1.25
Vitamin E
34.06 ꢁ 1.28
Abbreviations: LPO – lipid peroxidation; GSH – reduced glutathione content; SOD – superoxide dismutase; CAT – catalase.
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Arch. Pharm. Chem. Life Sci. 2011, 344, 765–770
Substituted-1,3,2-Diazaphosphole 1-Oxides
767
rotary evaporator to get the intermediate (2). The intermediate
was confirmed by 1H-, 13C-, 31P-NMR and mass spectral
analyses.
(2H, m, NH–CH2), 2.62–2.53 (2H, m, N–CH2), 2.51 (1H, s, NH),
1.56–1.16 (6H, m, –(CH2)3); 13C-NMR (DMSO-d6) d [ppm]: 160.2
(C-20), 149.5 (C-10), 139.1 (C-40), 121.1 (C-50), 120.4 (C-60), 54.9 (C-4),
45.3 (C-3), 43.7 (C-6), 29.8 (C-9), 27.8 (C-7), 23.2 (C-8); 31P-NMR: d
24.20; APCI-MS m/z (%) 255 [M þ 2] (55); Anal. calcd.
for C11H16N3O2P: C, 52.17, H, 6.32, N, 16.9. Found: C, 52.24,
H, 6.37, N, 17.2.
1-Chloro-hexahydro-[1,3,2]diazaphospholo[1,5a]-
pyridine-1-oxide 2
1H-NMR (CDCl3): 3.59–3.49 (1H, m, N-CH), 3.45–3.42 (2H, m,
NH-CH2), 2.26 (1H, s, NH), 1.89–1.84 (2H, m, N–CH2), 1.74–1.68
(6H, m, –(CH2)3); 13C-NMR data: 66.6 (C-4), 44.8 (C-3), 44.3 (C-6),
30.3 (C-9), 29.6 (C-7), 26.6 (C-8); 31P-NMR: d 22.0; APCI-MS m/z (%)
194 [Mþ] (100), 196 [M þ 2] (32).
1-Propyl-hexahydro-[1,3,2]diazaphospholo[1,5a]-
pyridine-1-oxide 3d
Yield 76%ꢂ; 1m.p. 126–1288C IR (KBr) (vmax, cmꢂ1): 3368 (-NH), 1269
–
(P O) cm
;
1H-NMR (MEOD) d [ppm]: 3.53–3.41 (1H, m, N–CH),
–
3.05–3.01 (2H, m, NH–CH2), 2.65–2.53 (2H, m, N–CH2), 2.42 (1H, s,
NH), 1.65–1.50 (6H, m, –(CH2)3), 1.51–1.44 (4H, m, –(CH2)2–), 0.93
(3H, t, J ¼ 6.5 Hz, –CH3); 13C-NMR (MEOD) d [ppm]: 60.9 (C-6), 58.3
(C-3), 44.1 (C-4), 30.4 (C-9), 26.5 (C-7), 22.3 (C-10), 22.1 (C-8), 17.3
(C-20), 15.9 (C-30); 31P-NMR: d 26.19; APCI-MS m/z (%) 203 [MH]þ
(100); Anal. calcd. for C9H19N2OP: C, 53.46, H, 9.40, N, 13.86.
Found: C, 53.38, H, 9.45, N, 13.92.
Synthetic procedure for the title compounds (3a–l)
To a stirred solution of various phenols and amino acid ester
hydrochlorides in dry THF (10 mL) and TEA (0.002 mol), the
intermediate monochloride (2) in dry THF was added dropwise
at 08C. After the addition, the temperature was slowly raised to
40–458C and the mixtures were stirred for 2 h. The progress of
the reaction was monitored by TLC conducted on a 3:7 mixture of
ethylacetate and hexane with an average Rf value 0.65. The
reaction mixtures were filtered to remove TEA hydrochloride
and the filtrate on evaporation in a rotary evaporator yielded
the crude products. These were further purified by column
chromatography on silica gel (60–120 mesh) with ethyl
acetate/hexane (1:9) as eluent. The title compounds were charac-
1-Phenyl-hexahydro-[1,3,2]diazaphospholo[1,5a]-
pyridine-1-oxide 3e
Yield 81%; viscous liquid, IR (KBr) (vmax, cmꢂ1): 3148 (-NH), 1262
(P O) cmꢂ1; 1H-NMR (DMSO-d6) d [ppm]: 7.75–7.27 (5H, m, Ar-H),
–
–
1
terized by IR, H-, 13C-, 31P-NMR and mass spectral analyses.
3.68–3.61 (1H, m, N–CH), 2.95–2.86 (2H, m, NH–CH2), 2.71–2.65
(2H, m, N–CH2), 2.55 (1H, s, NH), 1.59–1.30 (6H, m, –CH2)3); 13C-
NMR (DMSO-d6) d [ppm]: 130.4 (C-30, C-50), 129.5 (C-40), 127.5 (C-20,
C-60), 129.6 (C-10), 58.2 (C-4), 46.1 (C-3), 42.2 (C-6), 30.5 (C-9), 29.0 (C-
7), 21.6 (C-8); 31P-NMR: d 22.83; APCI-MS m/z (%) 237 [MH] þ (100);
Anal. calcd. for C12H17N2OP: C, 61.01, H, 7.17, N, 11.81. Found: C,
61.06, H, 7.21, N, 11.87.
1-(4-Chlorophenoxy)-hexahydro-[1,3,2]-
diazaphospholo[1,5a]pyridine-1-oxide 3a
Yield 80%; m.p. 127–298C; IR (KBr) (vmax, cmꢂ1): 3315 (–NH), 1250
(P O), 1210, 950 (P–O–Caryl) cmꢂ1
;
1H-NMR (DMSO-d6) d [ppm]:
–
–
7.41 (2H, d, J ¼ 7.8 Hz, Ar-H), 7.29 (2H, d, J ¼ 7.4 Hz, Ar-H), 3.34–
3.03 (1H, m, N-CH), 2.96–2.93 (2H, m, NH-CH2), 2.74–2.62 (2H, m,
N–CH2), 2.51 (1H, s, NH), 1.56–1.16(6H, m, –(CH2)3); 13C-NMR
(DMSO-d6) d [ppm]: 151.2 (C-10), 129.3 (C-30, C-50), 124.0 (C-40),
122.2 (C-20, C-60), 55.6 (C-4), 45.8 (C-3), 44.7 (C-6), 30.7 (C-9), 28.0
(C-7), 23.4 (C-8); 31P-NMR: d 22.0; APCI-MS m/z (%) 286 [Mþ] (100),
288 [M þ 2] (32), 287.3 [M þ H]þ (13.2); Anal. calcd. for
C12H16ClN2O2P: C, 50.26, H, 5.58, N, 9.77. Found: C, 50.21, H,
5.53, N, 9.85.
N,N-bis(2-chloroethyl)-hexahydro-[1,3,2]-
diazaphospholo[1,5a]pyridine-1-amine 1-oxide 3f
Yield 79%;ꢂv1iscous liquid, IR (KBr) (vmax, cmꢂ1): 3367 (-NH), 1233
;
1H-NMR (DMSO-d6) d [ppm]: 4.19–3.85 (4H, m,
–
(P O) cm
–
–CH2–Cl), 3.68–3.54 (1H, m, N–CH), 3.40–3.35 (4H, m, N–CH2),
2.85–2.72 (2H, m, NH–CH2), 2.62–2.54 (2H, m, N–CH2), 2.47 (1H, s,
NH), 1.89–1.16 (6H, m, –(CH2)3); 13C-NMR (DMSO-d6) d [ppm]: 64.5
(C-4), 53.8 (C-10), 48.1 (C-3), 47.0 (C-6), 43.2 (C-20), 30.5 (C-9), 26.2 (C-
7), 21.8 (C-8); 31P-NMR: d 26.02; APCI-MS m/z (%); 299 [Mþ] (100),
301 [M þ 2] (65), 303 [M þ 4] (8.3); Anal. calcd. for C10H20
Cl2N3OP: C, 40.01, H, 6.66, N, 14.02. Found: C, 40.12, H, 6.61,
N, 14.08.
1-(4-Nitrophenoxy)-hexahydro-[1,3,2]-
diazaphospholo[1,5a]pyridine-1-oxide 3b
Yield 82%; m.p. 135–378C; IR (KBr) (vmax, cmꢂ1): 3275 (-NH), 1263
(P O), 1212, 968 (P–O–Caryl) cmꢂ1
;
1H-NMR (DMSO-d6) d [ppm]:
–
–
8.11 (2H, d, J ¼ 9.0 Hz, Ar-H), 6.92 (2H, d, J ¼ 9.0 Hz, Ar-H), 3.30–
3.25 (1H, m, N–CH), 2.89–2.74 (2H, m, NH–CH2), 2.61 (1H, s, NH),
2.59–2.54 (2H, m, N–CH2), 1.27–1.13 (6H, m, –(CH2)3); 13C-NMR
(DMSO-d6) d [ppm]: 164.3 (C-10), 126.3 (C-30, C-50), 140.6 (C-40), 116.4
(C-20, C-60), 55.1 (C-4), 48.9 (C-3), 43.2 (C-6), 31.7 (C-9), 29.4 (C-7), 22.8
(C-8); 31P-NMR: d 22.83; APCI-MS m/z (%) 298 [MH]þ (100); Anal.
calcd. for C12H16N3O4P: C, 48.48, H, 5.38, N, 14.14. Found: C,
48.51, H, 5.42, N, 14.17.
Methyl-2-methyl-1-[(1-oxido-hexahydro-[1,3,2]-
diazaphospholo[1,5a]pyridine-1-yl)amino] butanoate 3g
Yield 82%; viscous liquid, IR (KBr) (vmax, cmꢂ1): 3426 (-NH), 3152
1
(-NH), 1721 (C O), 1204 (P O) cmꢂ1; H-NMR (DMSO-d6) d [ppm]:
–
–
–
–
3.82 (3H, s, –OCH3), 3.75–3.68 (1H, m, NH–CH–CO), 3.65–3.60
(1H, m, N–CH), 3.55 (2H, s, NH), 2.71–2.64 (2H, m, N–CH2),
2.35–2.21 (2H, m, NH–CH2), 1.55–1.44 (6H, m, –(CH2)3), 1.37–
1.26 (1H, m, –CH–(CH3)2), 1.13 (6H, d, J ¼ 6.5 Hz, –CH–(CH3)2);
13C-NMR (DMSO-d6) d [ppm]: 165.3 (C-50), 61.6 (C-4), 59.8 (C-10), 55.8
(C-3), 52.7 (C-60), 45.8 (C-6), 41.5 (C-20,), 30.7 (C-9), 27.8 (C-7), 23.5
(C-8), 18.3 (C-30, C-40); 31P-NMR: d 23.10; APCI-MS m/z (%) 290 [MH]þ
(60); Anal. calcd. for C12H24N3O3P: C, 49.82, H, 8.30, N, 14.53.
Found: C, 49.89, H, 8.34, N, 14.57.
1-(Pyridin-3-yloxy)-hexahydro-[1,3,2]diazaphospholo-
[1,5a]pyridine-1-oxide 3c
Yield 78%; viscous liquid, IR (KBr) (vmax, cmꢂ1): 3248 (–NH), 1260
(P O), 1217, 958 (P–O–Caryl) cmꢂ1
7.41–7.29 (4H, m, Ar-H), 3.34–3.03 (1H, m, N–CH), 2.96–2.90
;
1H-NMR (DMSO-d6) d [ppm]:
–
–
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www.archpharm.com

768
K. R. M. Naidu et al.
Arch. Pharm. Chem. Life Sci. 2011, 344, 765–770
9
6
3
2
4
8
7
R-OH, R-H&R-NH2
THF, Et3N, 40-45 0C
POCl3, Et3N
THF 0-20 0C
NH2
NH
NH
1
NH
N
N
5
P
P
Cl
R
O
O
(3a-l)
(2)
(1)
Compd
3a
Compd
3g
R
2′
R
3′
5′
COOCH3
NH CH CH CH3
1′
4′ Cl
O
CH3
6′
COOCH3
NH CH CH2 CH
H3C
O
CH3
3h
NO2
3b
COOCH3
N
NH CH CH2 C6H4-OH (4′)
O
3i
3c
3d
3e
COOCH2CH3
CH2 CH
S
NH2
3j
3k
CH2-CH2-CH3
COOCH2CH3
NH CH
C6H4-OH(4′)
Cl
COOCH2CH3
N
3f
NH CH
3l
C6H5
Cl
Scheme 1. Synthesis of title compounds 3a–l.
3.05–2.94 (2H, m, N–CH2), 2.86–2.74 (2H, m, NH–CH2), 2.6 (2H, d,
J ¼ 6.6 Hz, Ar–CH2–CH–), 1.80–1.40 (6H, m, –(CH2)3); 13C-NMR
(DMSO-d6) d [ppm]: 168.5 (C-90), 151.4 (C-60), 129.5 (C-40, C-80),
117.4 (C-50, C-70), 56.2 (C-4), 52.4 (C-100), 50.2 (C-10), 49.0 (C-3),
45.6 (C-6), 39.0 (C-20), 28.5 (C-9), 25.2 (C-7), 22.1 (C-8); 31P-NMR: d
21.17; APCI-MS m/z (%) 354 [MH]þ (60); Anal. calcd.
for C16H24N3O4P: C, 52.78, H, 7.03, N, 12.31. Found: C, 52.84,
H, 7.09, N, 12.35.
Methyl-3-methyl-1-[(1-oxido-hexahydro-[1,3,2]-
diazaphospholo[1,5a]pyridine-1-yl)amino] pentanoate 3h
Yield 79%; viscous liquid, IR (KBr) (vmax, cmꢂ1): 3259 (–NH), 3152
(–NH), 1740 (C O), 1230 (P O) cmꢂ1; 1H-NMR (DMSO-d6) d [ppm]:
–
–
–
–
3.80 (3H, s, –OCH3), 3.70–3.65 (1H, m, NH–CH–CO), 3.45–3.32
(1H, m, N–CH), 3.32 (2H, s, NH), 3.01–2.96 (2H, m, N–CH2),
2.30–2.24 (2H, m, NH–CH2), 1.60–1.45 (6H, m, –(CH2)3), 1.37–
1.26 (1H, m, –CH–(CH3)2), 1.15 (6H, d, J ¼ 6.5Hz, –CH–(CH3)2),
1.89 (2H, t, J ¼ 8.2 Hz, CH–CH2–CH); 13C-NMR (DMSO-d6) d [ppm]:
169.6 (C-60), 55.5 (C-4), 54.8 (C-70), 53.4 (C-3), 52.6 (C-10), 45.7 (C-6),
41.7 (C-20), 30.6 (C-9), 27.7 (C-7), 25.8 (C-30), 23.5 (C-8), 22.6 (C-50, C-
40); 31P-NMR: d 22.93; APCI-MS m/z (%) 304 [MH]þ (60); Anal. calcd.
for C13H26N3O3P: C, 51.48, H, 8.58, N, 13.86. Found: C, 51.56, H,
8.61, N, 13.90.
Ethyl-2-amino-1-[(1-oxido-hexahydro-[1,3,2]-
diazaphospholo[1,5a] pyridine-1-yl)sulfonyl] propanoate 3j
Yield 78%; viscous liquid, IR (KBr) (vmax, cmꢂ1): 3516 (-OH), 3372
(–NH), 3182 (–NH), 1735 (C O), 1231 (P O) cmꢂ1; 1H-NMR (DMSO-
–
–
–
–
d6) d [ppm]: 3.72 (2H, s, –OCH2), 3.03–2.92 (1H, m, N–CH), 3.37
(2H, s, NH2), 2.85–2.76 (2H, m, NH–CH2), 2.67–2.52 (2H, m,
N–CH2), 2.42 (1H, s, –NH), 1.95–1.83 (2H, s, S–CH2), 1.52–1.34
(6H, m, –(CH2)3), 1.12 (3H, t, J ¼ 6.5 Hz, –CH3), 3.19–3.04
Methyl-2(4-hydroxyphenyl)-1-[(1oxido-hexahydro-[1,3,2]-
diazaphospholo[1,5a]pyridine-1-yl)amino] propanoate 3i
Yield 76%; viscous liquid, IR (KBr) (vmax, cmꢂ1): 3512 (–OH), 3326
13
(1H, m, –CH–NH2); C-NMR (DMSO-d6) d [ppm]: 169.9 (C-30),
(–NH), 3162 (–NH), 1746 (C O), 1214 (P O) cmꢂ1; 1H-NMR (DMSO-
–
–
–
–
61.1 (C-40), 55.8 (C-4), 49.4 (C-3), 41.7 (C-10), 45.2 (C-6), 42.6 (C-
20), 30.1 (C-9), 28.7 (C-7), 22.5 (C-8), 31P-NMR: d 22.12; APCI-MS m/z
(%) 308 [MH]þ (60); Anal. calcd. for C11H22N3O3PS: C, 42.99, H,
7.16, N, 13.68. Found: C, 43.05, H, 7.21, N, 13.72.
d6) d [ppm]: 10.10 (1H, s, Ar–OH), 7.81 (2H, d, J ¼ 9.0 Hz, Ar–H),
6.92 (2H, d, J ¼ 9.0 Hz, Ar-H), 3.82 (3H, s, –OCH3), 3.72–3.64
(1H, m, NH–CH–CO), 3.52–3.45 (1H, m, N–CH), 3.37 (2H, s, NH),
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Arch. Pharm. Chem. Life Sci. 2011, 344, 765–770
Substituted-1,3,2-Diazaphosphole 1-Oxides
769
ꢀ Catalase activity:
OD of the sample ꢃ Volume of assay
13:6 ꢃ Volume of enzyme source ꢃ mg of protein
Ethyl (4-hydroxyphenyl)-1-[(1-oxido-hexahydro-[1,3,2]-
diazaphospholo[1,5a]pyridine 1-yl)amino]acetate 3k
Yield 80%; viscous liquid, IR (KBr) (vmax, cmꢂ1): 3514 (–OH), 3326
CAT ¼
(–NH), 3182 (–NH), 1738 (C O), 1265 (P O) cmꢂ1; 1H–NMR (DMSO-
–
–
–
–
d6) d [ppm]: 9.90 (1H, s, Ar–OH), 7.12 (2H, d, J ¼ 9.0 Hz, Ar–H), 6.76
(2H, d, J ¼ 9.0 Hz, Ar–H), 3.80 (2H, s, –OCH2), 3.89–3.74 (1H, m,
NH–CH), 3.47–3.30 (1H, m, N–CH), 3.32 (1H, s, NH), 2.96–2.82
(2H, m, N–CH2), 2.89–2.72 (2H, m, NH–CH2), 1.52–1.36 (6H, m,
–(CH2)3), 1.12 (3H, t, J ¼ 7.0 Hz, –CH3); 13C–NMR (DMSO–d6) d
[ppm]: 167.8 (C-80), 151.7 (C-50), 128.5 (C-30, C-70), 127.2 (C-20),
115.2 (C-40, C-60), 62.2 (C-90), 56.4 (C-4), 51.8 (C-10), 48.6 (C-3), 44.9
(C-6), 29.2 (C-9), 24.6 (C-7), 23.4 (C-8), 16.2 (C-100); 31P-NMR: d 23.02;
APCI-MS m/z (%) 354[MH]þ (60); Anal. calcd. for C16H24N3O4P: C,
54.39, H, 6.79, N, 11.89. Found: C, 54.46, H, 6.82, N, 11.94.
where OD ¼ optical density
Brain tissues of rat were homogenized 1:40 (w/v) in 0.1 M
phosphate buffer, pH 7.4, containing 1 mM EDTA. Total gluta-
thione (GSH þ GSSG) [15] and reduced glutathione (GSH) and the
activities of GSH-PX [16] and GST [17] were assayed. Protein
content of the homogenates was determined by the method of
Lowry et al. [18] and the GSH-PX and GST activities were expressed
in terms of U/g protein. For estimation of ascorbic acid the tissue
were homogenized 1:9 (w/v) in ice-cold 5% trichloroacetic acid.
Ascorbic acid assay is based on oxidation of ascorbic acid to
dehydroascorbic acid followed by treatment with 2,4-dinitrophe-
nylhydrazine to form the bis-dinitrophenylhydrazone [19].
Ethyl-[(1-oxido-hexahydro-[1,3,2]diazaphospholo[1,5a]-
pyridine-1-yl)amino]phenyl acetate 3l
Yield 81%; viscous liquid, IR (KBr) (vmax, cmꢂ1): 3410 (–NH), 3172
The authors express their grateful thanks to UGC, New Delhi, for
sanctioning a major Research Project (F.No. 34–356/2008(SR) and Prof.
C. D. Reddy, Department of Chemistry, Sri Venkateswara University,
Tirupati, for his helpful discussion.
(–NH), 1728 (C O), 1237 (P O) cmꢂ1; 1H–NMR (DMSO–d6) d [ppm]:
–
–
–
–
7.29–6.31 (5H, m, Ar–H), 3.92–3.85 (1H, m, NH–CH), 3.71 (2H, s,
–OCH2), 3.32–3.26 (1H, m, N–CH), 2.85–2.71 (2H, m, NH–CH2),
2.92–2.84 (2H, m, N–CH2), 2.55 (2H, s, NH), 1.57–1.31 (6H, m,
–(CH2)3), 1.15 (3H, t, J ¼ 7.5 Hz, –CH3); 13C–NMR (DMSO–d6) d
[ppm]: 169.4 (C-80), 133.2 (C-20), 128.2 (C-30, C-70), 127.9 (C-40,
C-60), 125.2 (C-50), 61.7 (C-90), 55.6 (C-4), 51.4 (C-10), 46.6 (C-3),
44.2 (C-6), 28.1 (C-9), 25.4 (C-7), 22.1 (C-8), 16.6 (C-100); 31P-NMR:
The authors have declared no conflict of interest.
d
14.53; APCI-MS m/z (%) 338 [MH]þ (100); Anal. calcd.
References
for C16H24N3O3P: C, 56.97, H, 7.12, N, 12.46. Found: C, 57.03,
H, 7.16, N, 12.51.
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Net rate ꢂ Intercept
GSH ¼
ꢁ Dilution factor
Slope
ß 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.archpharm.com

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K. R. M. Naidu et al.
Arch. Pharm. Chem. Life Sci. 2011, 344, 765–770
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