Synthetic approach for novel bis(α-aminophosphonic acid) derivatives of chromone containing 1,2,4,3-triazaphosphole moieties

Article abstract of DOI:10.1002/hc.20520

Terephthalic acid hydrazide (1) was reacted with phenylphosphonic dichloride to yield bis(1,3,4,2-oxadiazaphosphole) derivative 3, which was condensed with α-aminophosphonic acid derivative 4 to afford bis[(1,2,4,3-triazaphospholyl) (chromonyl)methylphosp

Full text of DOI:10.1002/hc.20520

Heteroatom Chemistry
Volume 20, Number 3, 2009
Synthetic Approach for Novel
Bis(α-aminophosphonic acid) Derivatives
of Chromone Containing 1,2,4,3-
Triazaphosphole Moieties
Tarik E. Ali1 and Silvia S. Halacheva2
1Department of Chemistry, Faculty of Education, Ain Shams University, Roxy, 11711, Cairo, Egypt
2Institute of Polymers, Bulgarian Academy of Science, Sofia, Bulgaria
Received 26 September 2008; revised 19 February 2009
range of biological activities. A large volume of
ABSTRACT: Terephthalic acid hydrazide (1) was
research on their synthesis and biological activi-
reacted with phenylphosphonic dichloride to yield
ties has been reported during the last 20 years.
bis(1,3,4,2-oxadiazaphosphole) derivative 3, which
Several α-aminophosphonate derivatives are bioac-
was condensed with α-aminophosphonic acid deriva-
tive. They display antiviral, antimicrobial, antifun-
tive 4 to afford bis[(1,2,4,3-triazaphospholyl)(chro-
gal, and antitumor activities [1–7]. At the same
monyl)methylphosphonic acid] derivative 5. The
time, we noticed that phosphorus-containing hete-
addition of diethyl phosphite to Schiff bases 9
rocyclic systems also possess a wide range of bi-
and 10 derived from the condensation of bis(4-
ological and pharmacological activities [8–13]. On
amino-1,2,4,3-triazaphosphole) derivative 6 or bis(4-
the other hand, the chromone nucleus is an im-
phosphorylamino-1,2,4,3-triazaphosphole) derivative
portant feature in a variety of natural products
7
with 3-formyl-6-methylchromone (8) yielded
and medicinal agents [14–19]. Having these facts in
mind and in continuation of our efforts to synthe-
size novel α-aminophosphonate derivatives contain-
ing chromone moieties [20], the present work was
aimed to synthesize novel bis(α-aminophosphonic
acid) derivatives of chromone containing 1,2,4,3-
triazaphosphole moieties.
bis[(1,2,4,3-triazaphospholyl)(chromonyl)amino-
methylphosphonate] derivative 11 and bis[(1,2,4,3-
triazaphospholyl)(chromonyl)phosphorylamino-
methylphosphonate] derivative 12, respectively. The
structures of all products were established by elemen-
ꢀ
C
tal analysis and spectral data. 2009 Wiley Periodicals,
Inc. Heteroatom Chem 20:117–122, 2009; Published on-
line in Wiley InterScience (www.interscience.wiley.com).
DOI 10.1002/hc.20520
RESULTS AND DISCUSSION
The key intermediate in the present study is the
terephthalic acid hydrazide (1), which was prepared
according to a previously described procedure [21].
The reaction of 1 with phenylphosphonic dichloride
in THF and DMF in the presence of sodium hydride
gave the nonisolable intermediate 2, which was con-
verted to 5,5ꢁ-(1,4-phenylene)bis(2-oxo-2-phenyl-2,3-
dihydro-1,3,4,2-oxadiazaphosphole) (3) (Scheme 1).
The structural assignment of compound 3 was es-
tablished by elemental analysis and spectroscopic
INTRODUCTION
α-Aminophosphonic acids, bioisosteres of natural
amino acids, have been found to exhibit a wide
Correspondence to: Tarik E. Ali; e-mail: tarik elsayed1975@
yahoo.com.
c
ꢀ
2009 Wiley Periodicals, Inc.
117

118 Ali and Halacheva
H
H
H2N NH
NH NH2
O
Ph-P(O)Cl2
1:2
O
N
N
N
N
O
Ph
P
P
Ph
THF- DMF
NaH
O
Cl HO
OH Cl
1
2
H
H
N
N
N
N
O
O
HO
HO
O
O
O
P
P
P
HCl is trapped by NaH
H
Ph
Ph
CH3
N
N
H2N
H
OH
H
HO
H
P
H
P
O
N
N
N
N
O
4
O
OH
O
HO
P
P
O
pyridine
1:2
O
O
O
Ph
Ph
O
O
3
CH3
One diastereomeric form meso (R,S ) or racemic (R,R and S,S)
SCHEME 1
H3C
5
studies. Its 1H NMR spectrum showed signals of
were formed. The condensation of compound 6 or 7
with 3-formyl-6-methylchromone (8) in boiling DMF
afforded the corresponding Schiff bases 9 and 10,
respectively (Scheme 2). Structures of compounds
6–10 were deduced on the basis of analytical and
spectral data (see the “Experimental” section). The
chemical shifts of NH2 protons in compounds 6 and
7 were recorded at δ 5.78 and 4.98 ppm, respectively.
NH and aromatic protons at δ 14.16 and 7.23–
1
7.55 ppm, respectively, whereas 31P{ H}NMR spec-
trum showed a singlet at δ 29.4 ppm [22]. In the
IR spectrum of 3, the absorption bands of 1,3,4,2-
oxadiazaphosphole moiety appeared at 3168 (NH),
1654 (C N), and 1224 cm−1 (P O).
Interestingly, bis compound 3 on treatment with
[amino(6-methyl-4-oxo-4H-chromen-3-yl)methyl]-
phosphonic acid (4) in dry pyridine afforded only
one diastereomeric form of 5,5ꢁ-(1,4-phenylene)bis-
[(3-oxo-3-phenyl-2,3-dihydro-4H-1,2,4,3-triazapho-
sphol-4-yl)(6-methyl-4-oxo-4H-chromen-3-yl)]-
methylphosphonic acid) (5) (Scheme 1).
1
Also, H NMR spectra of 9 and 10 showed broad
signals at δ 9.76 and 9.11 ppm for CH N protons,
respectively.
The addition of diethyl phosphite to azomethine
bonds of compounds 9 and 10 on fusion at 80◦C–
100◦C in the presence of a catalytic amount of tri-
ethylamine yielded only one diastereomeric form of
5,5ꢁ-(1,4-phenylene)bis(diethyl[{[3-phenyl-3-oxo-2,3-
dihydro-4H-1,2,4,3-triazaphosphol-4-yl]amino}(4-
oxo-4H-chromen-3yl)methyl]phosphonate) (11) and
two diastereomeric forms of 5,5ꢁ-(1,4-phenylene)bis-
{diethyl[[(3-oxo-3-phenyl-2,3-dihydro-4H-1,2,4,3-
triazaphosphol-4-yl)methylphosphoryl]amino][6-
methyl-4-oxo-4H-chromen-3-yl)methyl]phospho-
nate} (12), respectively, (Scheme 3). IR spectra
of 11 and 12 showed absorption bands for NH
and P O groups at regions 3295–3198 and 1305–
1215 cm−1, respectively. The 1H NMR spectrum
of compound 11 was characterized by a broad
signal for CH P hydrogens at δ 5.36 ppm. Beside
The spectral data are in good agreement with
the proposed structure. Thus, the IR spectrum of
5 showed absorption bands of NH and OH groups
in the region of 2675–3339 cm−1, C O pyrone at
1646 cm−1, and P O groups as strong bands at
1
1287 and 1205 cm−1. 1H and 31P{ H}NMR spec-
tra of the product gave conclusive evidence for α-
1
aminophosphonic moieties. The H NMR spectrum
showed a broad signal at δ 3.40 ppm for hydroxyl
protons and a doublet at δ 6.31 ppm (J = 19.2 Hz) for
1
CH P proton. Furthermore, its 31P{ H}NMR spec-
trum displayed two signals at δ 25.9 and 13.9 ppm
in accordance with 1,3,4,2-triazaphosphole and α-
aminophosphonic acid moieties, respectively [23].
When compound 3 was heated with hydrazine
hydrate or methylphosphonic diamide in absolute
ethanol, bis-amino compounds 6 and 7, respectively,
1
its 31P{ H}NMR spectrum revealed a signal for
α-aminophosphonate moiety at δ 21 ppm. On the
other hand, the 1H NMR spectrum of compound 12
Heteroatom Chemistry DOI 10.1002/hc

Synthetic Approach for Novel Bis(α-aminophosphonic acid) Derivatives of Chromone Containing 1,2,4,3-Triazaphosphole Moieties 119
H
N
spectra, which show only one sharp signal for
α-aminophosphonate moieties for compounds 5
and 11 and two signals for compound 12. Thus,
we conclude that, once again, the synthesis of
bis(aminophosphonate) in most cases is occurring
with high stereoselectivity, yielding as major prod-
uct only one of the diastereomers, as previously ob-
tained in similar reactions [20,25].
H
N
N
N
O
O
P
P
Ph
Ph
O
O
3
NH2-R
EtOH
1:2
H
N
H
N
N
N
O
O
P
P
EXPERIMENTAL
Ph
Ph
N
R
N
R
Melting points of the products were determined on
a Stuart SMP3 apparatus. IR spectra were recorded
on an Elmer 293 spectrophotometer (γ in cm−1),
using KBr disks. 1H NMR spectra were recorded
on a Gemini-200 spectrometer (200 MHz), using
DMSO-d6 as a solvent and TMS (δ = 0.0 ppm) as
6, R = NH2
7, R = -P(O)(CH3)NH2
O
O
H3C
CHO
DMF
an internal standard. 31P{ H}NMR spectra were
1
1:2
recorded on a Varian Inova 500 MHz spectrom-
eter at room temperature with DMSO-d6 as a
solvent and TMS as an internal standard and
85% H3PO4 as an external reference, respectively.
Elemental microanalyses were performed at the
microanalysis center in Bulgarian Academy of
Science, Sofia, Bulgaria. [Amino(6-methyl-4-oxo-
4H-chromen-3-yl)methyl]phosphonic acid (4) [26],
methylphosphonic diamide [27], and 3-formyl-6-
methylchromone (8) [28] were prepared by the pub-
lished methods.
8
H
N
H
N
N
N
O
O
P
P
Ph
Ph
N
N
X
N
X
N
O
O
O
O
5,5ꢁ-(1,4-Phenylene)bis(2-oxo-2-phenyl-2,3-
dihydro-1,3,4,2-oxadiazaphosphole) (3)
H3C
CH3
9, X = bond
10, X = -P(O)CH3
Sodium hydride (480 mg, 20 mmol) was added in
portions to a solution of terephthalic acid hydrazide
(1) (970 mg, 5 mmol) in DMF (20 mL) at room tem-
perature. Phenylphosphonic dichloride (1950 mg,
10 mmol) in THF (5 mL) was added drop wise to
this mixture while the temperature of the reaction
mixture was maintained at 25◦C. The whole mixture
was heated under reflux for 6 h. The mixture was fil-
tered off while hot to remove sodium chloride. The
filtrate was evaporated under reduced pressure to
give thick gum, which is treated by diethyl ether.
The resulting solid was collected by filtration and
crystallized from THF to give pale yellow crystals
in 72% yield, m.p. 88◦C–90◦C. IR (in cm−1): 3168
(NH), 3060 (C Harom), 1654 (C N), 1552 (C C), 1224
SCHEME 2
showed two doublet signals at δ 5.17 (J = 23 Hz)
and 5.24 (J = 23 Hz) ppm for CH P hydrogens.
Beside its 31P{ H}NMR spectrum revealed two
1
signals for α-aminophosphonate moieties at δ 23.1
and 23.5 ppm, which confirmed that compound 12
exists in two diastereomeric forms (∼91%:9%).
The formation of bis(α-aminophosphonate)
derivatives 5, 11, and 12 should yield a mixture
of meso and racemic diastereomers [24]. However,
1H and 31P{ H}NMR spectra do not show the com-
1
1
plexity expected for a mixture of diastereomers
and seem to indicate the presence of only one iso-
mer (one CHP signal, one triplet for ethoxy methyl
group) except compound 12. Furthermore, this in-
(P O), 1055 (P O C). H NMR (DMSO): δ 7.23–
7.55 (m 14H, aromatic protons), 14.16 (s, 2H, 2 NH)
ppm. 31P NMR (DMSO): δ 29.4 ppm. Anal. calcd. for
C20H16N4O4P2 (438.31): C, 54.80; H, 3.68; N, 12.78.
Found: C, 54.43; H, 3.49; N, 12.43.
terpretation is also nicely confirmed by 31P{ H}NMR
1
Heteroatom Chemistry DOI 10.1002/hc

120 Ali and Halacheva
H
H
N
N
N
N
O
O
P
P
Ph
Ph
N
N
X
N
X
N
O
O
O
O
9, X= bond
10, X= -P(O)CH3
H3C
CH3
(EtO)2-P(O)H
Excess
Fusion at 80-100 oC
Et3N
9
10
H
H
N
O
N
N
N
H
H
O
N
N
N
N
O
O
P
P
P
P
Ph
Ph
N
P
N
Ph
Ph
N
N
OEt
O
EtO
O
H3C
EtO
O
H3C
P
HN
H
O
OEt
O
NH
H
HN
H
P
P
O
OEt
P
EtO
NH
H
P
OEt
EtO
O
O
O
O
O
O
O
O
H3C
CH3
11
H3C
12
CH3
One diastereomeric form meso (R,S ) or racemic (R,R and S, S )
Two diastereomeric forms-meso (R,S ) and racemic (R,R and S, S )
SCHEME 3
H-2ꢁ), 13.69 (s, 2H, 2 NH) ppm. 31P NMR (DMSO):
δ 13.9 (O P OH), 25.9 (Ph P O) ppm. Anal. calcd.
for C42H36N6O12P4 (940.66): C, 53.63; H, 3.86; N,
8.93. Found: C, 53.32; H, 3.62; N, 8.69.
5,5ꢁ-(1,4-Phenylene)bis[(3-oxo-3-phenyl-2,3-
dihydro-4H-1,2,4,3-triazaphosphol-4-yl)(6-
methyl-4-oxo-4H-chromen-3-yl)]methyl-
phosphonic acid) (5)
A mixture of compound 3 (2190 mg, 5 mmol) and
[amino(6-methyl-4-oxo-4H-chromen-3-yl)methyl]-
phosphonic acid (4) (2690 mg, 10 mmol) in dry
pyridine (40 mL) was heated under reflux for 12 h.
The reaction mixture was poured into ice–HCl
mixture and stirred for 10 min. The obtained solid
was collected by filtration, dried, and crystallized
from ethanol to give white crystals in 62% yield,
m.p. 238◦C–240◦C. IR (in cm−1): 3339 (NH), 3020
(C Harom), 2979 (C Haliph), 2737, 2675 (OH), 1646
(C O), 1603 (C N), 1581 (C C), 1287, 1205 (2
5,5ꢁ-(1,4-Phenylene)bis(4-amino-3-oxo-3-
phenyl-2,3-dihydro-4H-1,2,4,3-triaza-phosphole)
(6) and 5,5ꢁ-(1,4-Phenylene)bis[P-methyl-P-(3-
oxo-3-phenyl-2,3-dihydro-4H-1,2,4,3-
triazaphosphol-4-yl)phosphinic amide] (7)
Hydrazine hydrate or methylphosphonic diamide
(10 mmol) was added to a solution of compound
3 (2190 mg, 5 mmol) in absolute ethanol (25 mL).
The reaction mixture was heated under reflux for
5 h. The obtained solids were filtered off, dried,
and crystallized from DMF/ethanol to give 6 and 7,
respectively.
1
P O). H NMR (DMSO): δ 2.19 (s, 6H, 2 CH3), 3.40
(br, 4H, P OH), 6.31 (d, J = 19.2 Hz, 2H, 2 CH P),
7.45–8.07 (m, 18H, aromatic protons), 8.57 (s, 1H,
H-5), 8.77 (s, 1H, H-5ꢁ), 9.16 (s, 1H, H-2), 9.20 (s, 1H,
Heteroatom Chemistry DOI 10.1002/hc

Synthetic Approach for Novel Bis(α-aminophosphonic acid) Derivatives of Chromone Containing 1,2,4,3-Triazaphosphole Moieties 121
6: Yellow crystals in 66% yield, m.p. 165◦C–
167◦C. IR (in cm−1): 3147 (NH2, NH), 3048 (C Harom),
1601 (C N), 1559 (C C), 1235 (P O). 1H NMR
(DMSO): δ 5.78 (s, 4H, 2 NH2), 7.53–7.97 (m,
14H, aromatic protons), 13.90 (brs, 2H, NH) ppm.
31P NMR (DMSO): δ 26.0 ppm. Anal. calcd. for
C20H20N8O2P2 (466.37): C, 51.51; H, 4.32; N, 24.03.
Found: C, 51.23; H, 4.09; N, 23.88.
5,5ꢁ-(1,4-Phenylene)bis(diethyl[{[3-oxo-3-
phenyl-2,3-dihydro-4H-1,2,4,3-triaza-phosphol-
4-yl]amino}(6-methyl-4-oxo-4H-chromen-3-
yl)methyl]phosphonate) (11) and
5,5ꢁ-(1,4-Phenylene)bis{diethyl[[(3-oxo-3-
phenyl-2,3-dihydro-4H-1,2,4,3-tri-azaphosphol-
4-yl)methylphosphoryl]amino][6-methyl-4-oxo-
4H-chromen-3-yl) methyl]phosphonate} (12)
7: Yellow crystals in 64% yield, m.p. 202◦C–
205◦C. IR (in cm−1): 3167, 3125 (NH2, NH), 3058
(C Harom), 2948 (C Haliph), 1597 (C N), 1577 (C C),
1251 (P O), 1223 (P O). 1H NMR (DMSO): δ 2.15 (s,
6H, 2 CH3), 4.98 (s, 4H, 2 NH2), 7.50–7.74 (m, 14H,
aromatic protons), 13.80 (brs, 2H, NH) ppm. 31P
NMR (DMSO): δ 19.2 (CH3 P O), 26.2 (Ph P O)
ppm. Anal. calcd. for C22H26N8O4P4 (590.38): C,
44.76; H, 4.44; N, 18.98. Found: C, 44.39; H, 4.19;
N, 18.70.
A mixture of compound 9 or 10 (5 mmol) and di-
ethyl phosphite (2085 mg, 15 mmol) in the pres-
ence of a few drops of triethylamine was heated at
80◦C–100◦C for 10 h. The excess of diethyl phosphite
was removed under reduced pressure and the oily
residue was treated with methanol. The obtained
solids were filtered off, dried, and crystallized from
DMF/methanol to give 11 and 12, respectively.
11: White crystals in 46% yield, m.p. 194◦C–
196◦C. IR (in cm−1): 3295, 3216 (NH), 3096
(C Harom), 2906 (C Haliph), 1661 (C O), 1599 (C N),
1305, 1233 (2 P O), 1075 (P O C). 1H NMR
(DMSO): δ 1.05 (t, J = 6.8 Hz, 6H, 2 OCH2CH3), 1.20
(t, J = 7.2 Hz, 6H, 2 OCH2CH3), 2.29 (s, 6H, 2 CH3),
2.67 (br, 2H, 2 NH P), 3.86 (br, 8H, 4 OCH2CH3),
5.36 (br, 2H, 2 CH P), 7.18–8.10 (m, 22H, aro-
matic protons), 14.15 (br, 2H, 2 NH) ppm. 31P NMR
(DMSO): δ 21.0 (EtO P O), 26.7 (Ph P O) ppm.
Anal. calcd. for C50H54N8O12P4 (1082.90): C, 55.46;
H, 5.03; N, 10.35. Found: C, 55.21; H, 4.84; N, 9.98.
12: Pale yellow crystals in 57% yield, m.p.
220◦C–223◦C. IR (in cm−1): 3198 (NH), 3092, 3036
(C Harom), 2985, 2948 (C Haliph), 1665 (C O), 1583
(C N), 1559 (C C), 1301, 1290, 1215 (3 P O), 1021
(P O C). 1H NMR (DMSO): δ 1.06 (t, J = 6.6 Hz, 6H,
2 OCH2CH3), 1.19 (t, J = 7.0 Hz, 6H, 2 OCH2CH3),
2.15 (s, 3H, CH3-Ar), 2.16 (s, 3H, CH3 Ar), 2.32 (s,
3H, CH3 P), 2.34 (s, 3H CH3 P), 2.44 (d, J = 3.8 Hz,
2H, 2 NH P), 3.97 (q, J = 8.4 Hz, 4H, 2 OCH2CH3),
4.10 (q, J = 6.2 Hz, 4H, 2 OCH2CH3), 5.17 (d, J = 23
Hz, 1H, CH P), 5.24 (d, J = 23 Hz, 1H, CH P), 7.52–
7.77 (m, 18H, aromatic protons), 7.89 (br, 2H, H-5
and H-5ꢁ), 8.49 (br, 2H, H-2 and H-2ꢁ), 13.77 (brs,
2H, 2 NH) ppm. 31P NMR (DMSO): δ 20.0 and 20.5
(90.9%: 9.1%) (CH3 P O), 23.1 and 23.5 (91%: 9%)
(EtO P O), 26.5 (Ph P O) ppm. Anal. calcd. for
C52H60N8O14P6 (1206.92): C, 51.75; H, 5.01; N, 9.28.
Found: C, 51.52; H, 4.83; N, 8.93.
5,5ꢁ-(1,4-Phenylene)bis(6-methyl-3-[{[3-oxo-3-
phenyl-2,3-dihydro-4H-1,2,4,3-triazaphosphol-
4-yl]imino}methyl]-4H-chromen-4-one) (9) and
5,5ꢁ-(1,4-Phenylene)bis{[P-methyl-N-(6-methyl-
4-oxo-4H-chromen-3-yl)methylene]-P-[3-oxo-3-
phenyl-2,3-dihydro-4H-1,2,4,3-triazaphosphol-
4-yl]phosphinic amide} (10)
To a solution of compound 6 or 7 (5 mmol) in DMF
(30 mL), 3-formyl-6-methylchromone (8) (1880 mg,
10 mmol) was added and the solution was heated
under reflux for 4 h, cooled, and filtered off. The
obtained solids were crystallized from DMSO to give
9 and 10, respectively.
9: Pale yellow crystals in 59% yield, m.p. >300◦C.
IR (in cm−1): 3314 (NH), 3062 (C Harom), 2978
(C Haliph), 1640 (C O), 1601 (C N), 1581 (C C),
1281 (P O). 1H NMR (DMSO): δ 2.18 (s, 6H, 2 CH3),
7.57–8.15 (m, 18H, aromatic protons), 8.75 (s, 2H,
H-5 and H-5ꢁ), 9.14 (s, 2H, H-2 and H-2ꢁ), 9.76 (br,
2H, 2 CH N), 13.66 (s, 2H, 2 NH) ppm. 31P NMR
(DMSO): δ 26.0 ppm. Anal. calcd. for C42H32N8O6P2
(806.70): C, 62.53; H, 4.00; N, 13.89. Found: C, 62.29;
H, 3.83; N, 13.61.
10: Pale brown crystals in 71% yield, m.p.
>300◦C. IR (in cm−1): 3409 (NH), 3055 (C Harom),
2923 (C Haliph), 1660 (C O), 1620 (C N), 1571
(C C), 1222, 1168 (2 P O). 1H NMR (DMSO): δ
2.19 (s, 6H, 2 CH3 Ar), 2.39 (s, 6H, 2 CH3 P O),
7.55–7.75 (m, 18H, aromatic protons), 7.92 (s, 2H,
H-5 and H-5ꢁ), 8.75 (s, 2H, H-2 and H-2ꢁ), 9.11 (br,
2H, 2 CH N), 13.65 (br, 2H, 2 NH) ppm. 31P NMR
(DMSO): δ 22.1 (CH3 P O), 26.3 (Ph P O) ppm.
Anal. calcd. for C44H38N8O8P4 (930.71): C, 56.78; H,
4.12; N, 12.04. Found: C, 56.50; H, 3.89; N, 11.79.
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Heteroatom Chemistry DOI 10.1002/hc