A convenient synthesis of chrysin-7-yl aryl N-bis(2-chloroethyl) phosphoramidate

Article abstract of DOI:10.3184/030823410X12790414891526

A series of novel chrysin-7-yl aryl N-bis(2-chloroethyl) phosphoramidates have been synthesised in good yield via phosphorylation reactions and their structures were elucidated by IR, NMR and elemental analysis.

Full text of DOI:10.3184/030823410X12790414891526

JOURNAL OF CHEMICAL RESEARCH 2010
RESEARCH PAPER 407
JULY, 407–409
A convenient synthesis of chrysin-7-yl aryl N-bis(2-chloroethyl)
phosphoramidate
Xiaolan Chena,*, Jinwei Yuanb, Junliang Wanga, Lingbo Qua,b, Zhangqi Yua and Yufen Zhaoa,c
aKey Laboratory of Organic Chemistry and Chemical Biology, Henan Province, Department of Chemistry, Zhengzhou University,
Zhengzhou 450052, P. R. China
bChemistry and Chemical Engineering School, Henan University ofTechnology, Henan Province, Zhengzhou 450052, P. R. China
cKey Laboratory for Bioorganic Phosphorus Chemistry and Chemical Biology, Ministry of Education, Department of Chemistry,
School of Life Sciences and Engineering, Tsinghua University, Beijing 100084, P. R. China
A series of novel chrysin-7-yl aryl N-bis(2-chloroethyl) phosphoramidates have been synthesised in good yield via
phosphorylation reactions and their structures were elucidated by IR, NMR and elemental analysis.
Keywords: chrysin, phosphoramide mustard, phosphorylation
Chrysin (4), which is widely distributed in plants, has antio-
xidant,1 antibacterial,2 anticancer,3 anti-inflammatory,4 antial-
lergic,5 and anxiolytic antivities.6 Efforts to improve the
biological activity of chrysin have led to the development
of derivatives by appropriate modification of chrysin.7,8 The
concept of carrier molecules has been employed in the design
of some of the earliest nitrogen mustard derivatives used in
cancer chemotherapy.9,10 In the past, large numbers of nitrogen
mustards, containing the bis-(β-chloroethyl) amino group have
been synthesised as potential antitumor agents. In the hope of
increasing the biological specificity of these compounds, the
mustard group has been attached to various carrier molecules
such as antimalarial drugs,11 amino acids,12,13 steroids,14 and
carbohydrates.15,16
Given the importance of this functional group in cancer
chemotherapy, our interest was to attach a phosphoramide
mustard group to chrysin, as a carrier molecule. It was hoped
that novel phosphoramide mustard analogues of chrysin could
improve their physicochemical and biological properties. In
the work described here, a series of novel chrysin-7-yl aryl
N-bis(2-chloroethyl) phosphoramidates have been synthesised
via a facile phosphorylation reaction (Scheme 1). The struc-
tures of compounds 3a–e were elucidated by NMR, IR and
elemental analysis. The study of their biological activity is in
progress.
were split into doublet by the nearby phosphorus atom, respec-
tively. In contrast, 5-C at δ 161.97 and 10-C at δ 108.18 were
not split. These facts show that the phosphorylation reaction
has proceeded chemoselectively at the 7-OH of chrysin. This
may be due to the hydrogen bonding of 5-OH group with
carbonyl group. Hydrogen bonding makes the phosphorylation
reaction at 5-OH difficult.
Experimental
1
IR spectra were recorded on a Shimadazu IR-408. H, 13C, 31P NMR
spectra were recorded on a Bruker Avance DPX spectrometer operat-
ing at 400.13, 100.62 and 161.98 MHz, respectively, with 13C and 31
P
spectra being recorded proton-decoupled. All NMR spectra were
recorded in CDCl3 at room temperature (20 3 °C). 1H and 13C chemi-
cal shifts are quoted in parts per million downfield from TMS. 31P
chemical shifts are quoted in parts per million relative to an external
85% H3PO4 standard. J values refer to coupling constants, and signal
splitting patterns are described as singlet(s), doublet(d), triplet(t),
quartet(q), multiplet(m). Elemental analyses were carried out with a
Flash EA 1112 elemental analyzer. TLC was performed on silica
gel plates and preparative chromatography on columns of silica gel
(200–300 mesh). All the reagents used were AR grade.
Preparation of di-(2-chloroethyl)-phosphoramidic dichloride 2;
general procedure
A suspension of bis-(β-chloroethyl)-amine hydrochloride (40 g, 0.23
mmol) in distilled phosphorus oxychloride (174 mL, 1.78 mol, b.p.
105.5–107.5 °C), was refluxed for 24 h until complete solution
resulted. The excess phosphorus oxychloride was removed by distilla-
tion and the residue was crystallised from acetone–petroleum ether.
Di-(2-chloroethyl)-phosphoramidic dichloride (2) was obtained as
white crystal (45 g, yield: 77.5%) m.p. 55–56 °C (lit. 17: yield: 80%,
m.p. 54–56 °C).
Results and discussion
In the synthesis of chrysin-7-yl aryl N-bis(2-chloroethyl)
phosphoramidates (5) (Scheme 1), bis-(β-chloroethyl)-amine
hydrochloride (1) was first reacted with phosphorus oxychlo-
ride under reflux to give di-(2-chloroethyl)-phosphoramidic
dichloride (2). Then di-(2-chloroethyl)-phosphoramidic dich-
loride (2) was coupled to different substituted phenols to
afford aryl-di-(2-chloroethyl) phosphoramidic chlorides (3),
which were purified further by chromatography. Chrysin (4)
was reacted with aryl-di-(2-chloroethyl) phosphoramidic
chloride (3) in tetrahydrofuran in the presence of triethyla-
mine under reflux to form phosphoramide mustard analogues
of chrysin (5). The structures of all the newly synthesised
chrysin derivatives were confirmed by NMR, IR and elemental
analysis.
Aryl-di-(2-chloroethyl) phosphoramidic chloride (3) can
react with two different reaction positions (7-OH and 5-OH) of
chrysin. The result showed that the phosphorylation reaction
occurred chemoselectively at the 7-OH of chrysin. This con-
clusion was confirmed by 13C NMR of compound 5a–e. For
example, 13C NMR of compound 5a showed 7-C at δ 155.50
(J = 6.2), 6-C at δ 103.64 (J = 6.0) and 8-C at δ 99.03 (J = 4.4)
Preparation of aryl-di-(2-chloroethyl) phosphoramidic chloride 3;
general procedure
A solution of the dichlorophosphamide (2) (3 g, 11.58 mmol) and
appropriate phenol (11.58 mmol) in dry toluene (30 mL) was stirred at
0 °C for 20 min, and then added dropwise a solution of dry triethy-
lamine (2.4 mL, 17.37 mmol) and dry toluene (5 mL). The reaction
mixture was stirred at room temperature for 1 h, and then was refluxed
for 8 h. After cooling, the mixture was filtered to remove triethylamine
hydrochloride. The toluene was distilled off under vacuum and the
residue was purified by flash chromatography on silica gel and eluted
using a mixture of dichloromethane and ethyl acetate (10:1 v/v) as the
eluent. The product (3) was obtained as a light yellow oil.
3a: 2.7 g, yield: 75%, 1H NMR (CDCl3) δ: 7.40–7.18 (m, 5H,
Ph-H), 3.55–3.27 (m, 8H, 2 CH2CH2Cl); 31P NMR (CDCl3) δ: –7.31.
3b: 3.5 g, yield: 90%, 1H NMR (CDCl3) δ: 7.28–6.97 (m, 4H,
Ph-H), 3.55–3.26 (m, 8H, 2 CH2CH2Cl), 2.37 (s, 3H, CH3); 31P NMR
(CDCl3) δ: –6.61.
3c: 3.4 g, yield: 84%, 1H NMR (CDCl3) δ: 7.30–6.77 (m, 4H,
Ph-H), 3.56–3.29 (m, 8H, 2 CH2CH2Cl), 3.81 (s, 3H, OCH3); 31P NMR
(CDCl3) δ: –6.71.
3d: 3.5 g, yield: 87%, 1H NMR (CDCl3) δ: 7.19–6.85 (m, 4H, Ph-
H), 3.55–3.26 (m, 8H, 2 CH2CH2Cl), 3.78 (s, 3H, OCH3); 31P NMR
(CDCl3) δ: –6.05.
* Correspondent. E-mail: chenxl@zzu.edu.cn

408 JOURNAL OF CHEMICAL RESEARCH 2010
Scheme 1
3e: 3.1 g, yield: 70%, 1H NMR (CDCl3) δ: 7.36–7.15 (m, 4H,
Ph-H), 3.58–3.33 (m, 8H, 2 CH2CH2Cl); 31P NMR (CDCl3) δ: −6.58.
These data are consistent with the reported data.18,19
CDCl3) δ: −0.37. IR(KBr) ν(cm–1): 3454 (OH), 2961 (CH2), 1657
(C=O), 1281 (P=O), 1030 (P-O-C). Anal. Calcd for C25H22Cl2NO6P:
C, 56.20; H, 4.15; N, 2.62. Found: C, 56.04; H, 4.13; N, 2.63%.
Chrysin-7-yl 3p-(methyl)phenyl N-bis(2-chloroethyl) phosphorami-
dates (5b): Light yellow sticky liquid. 1H NMR (400.13 MHz, CDCl3)
δ: 12.78 (s, 1H, 5-OH), 7.87 (d, 2H, J = 7.8 Hz, 2p6p-H), 7.58–7.49 (m,
3H, 3p, 4p, 5p-H), 7.24 (t, 1H, J = 8.1 Hz, 5q-H), 7.09–7.06 (m, 2H, 2q,
8-H), 7.03–7.01 (m, 2H, 4q, 6q-H), 6.72 (s, 1H, 3-H), 6.66 (d, 1H,
J = 1.7 Hz,6-H),7.06(s,1H,2q-H),3.67–3.56(m,8H,N(CH2CH2Cl)2),
2.36 (s, 3H, 3q-CH3). 13C NMR (100.62 MHz, CDCl3) δ: 182.6 (4-C),
164.7 (2-C), 162.2 (5-C), 157.0 (9-C), 155.7 (d, J = 6.3 Hz, 7-C),
150.1 (d, J = 5.9 Hz, 1q-C), 140.3 (3q-C), 132.1 (4p-C), 130.8 (1p-C),
129.6 (5q-C), 129.1 (3p, 5p-C), 126.3 (2p, 6p, 4q-C), 120.5 (d, J = 4.9 Hz,
2q-C), 116.8 (d, J = 3.7 Hz, 6q-C), 108.4 (10-C), 106.0 (3-C), 103.8
(d, J = 6.4 Hz, 6-C), 99.2 (d, J = 4.5 Hz, 8-C), 49.5 (d, J = 4.1 Hz,
N-CH2), 41.7 (Cl-CH2), 21.3 (3q-CH3). 31P NMR (161.98 MHz,
CDCl3) δ: –0.38. IR(KBr) ν(cm–1): 3437 (OH), 2922 (CH2), 1654
(C=O), 1277 (P=O), 1030 (P-O-C). Anal. Calcd for C26H24Cl2NO6P:
C, 56.95; H, 4.41; N, 2.55. Found: C, 56.76; H, 4.39; N, 2.57%.
Chrysin-7-yl 3p-(methoxy)phenyl N-bis(2-chloroethyl) phosphora-
midates (5c): Yellow sticky liquid. 1H NMR (400.13 MHz, CDCl3) δ:
12.79 (s, 1H, 5-OH), 7.85 (d, 2H, J = 7.1 Hz, 2p, 6p-H), 7.54–7.47 (m,
3H, 3p, 4p, 5p-H), 7.28–7.24 (m, 1H, 5q-H), 7.02 (s, 1H, 8-H), 6.88 (d,
1H, J = 8.6 Hz, 4q-H), 6.83 (s, 1H, 2q-H), 6.76 (d, J = 8.3 Hz, 1H,
6q-H), 6.70 (s, 1H, 3-H), 6.67 (s, 1H, 6-H), 3.78 (s, 3H, 3q-OCH3),
3.68–3.57 (m, 8H, N(CH2CH2Cl)2). 13C NMR (100.62 MHz, CDCl3)
δ: 182.4 (4-C), 164.4 (2-C), 162.0 (5-C), 160.6 (3q-C), 156.8 (9-C),
Preparation of chrysin-7-yl aryl N-bis(2-chloroethyl)
phosphoramidates 5;general procedure
Triethylamine (0.3 mL, 2.0 mmol) was added to a solution appropriate
aryl-di-(2-chloroethyl) phosphoramidic chloride (3) (2.0 mmol) and
chrysin (4) (0.51 g, 2.0 mmol) in dry tetrahydrofuran. The reaction
mixture was stirred and refluxed for 4–5 h. After cooling, the mixture
was filtered to remove trethylamine hydrochloride. Tetrahydrofuran
was distilled off under vacuum. The residue was purified with column
chromatography on silica gel and eluted with dichloromethane:
acetone (30:1, v/v), to give the title compounds (5a–e).
Chrysin-7-yl phenyl N-bis(2-chloroethyl) phosphoramidates (5a):
Yellow sticky liquid. 1H NMR (400.13 MHz, CDCl3) δ: 12.81 (s, 1H,
5-OH), 7.82 (d, 2H, J = 7.0 Hz, 2p, 6p-H), 7.53–7.45 (m, 3H, 3p, 4p, 5p-
H), 7.39–7.33 (m, 2H, 3q, 5q-H), 7.31–7.27 (m, 2H, 2q, 6q-H), 7.25–
7.15 (m, 1H, 4q-H), 7.00 (d, 1H, J = 1.7 Hz, 8-H), 6.68 (s, 1H, 3-H),
6.66 (d, 1H, J = 1.7 Hz, H-6), 3.67–3.55 (m, 8H, N(CH2CH2Cl)2). 13
C
NMR (100.62 MHz, CDCl3) δ: 182.4 (4-C), 164.4 (2-C), 162.0 (5-C),
156.7 (9-C), 155.5 (d, J = 6.2 Hz, 7-C), 150.0 (d, J = 6.8 Hz, 1q-C),
132.0 (4p-C), 130.5 (1p-C), 129.7 (3q, 5q-C), 128.9 (3p, 5p-C), 126.1 (2p,
6p-C), 125.4 (4q-C), 119.8 (d, J = 5.0 Hz, 2q, 6q-C), 108.2 (10-C),
105.8 (3-C), 103.6 (d, J = 6.0 Hz, 6-C), 99.0 (d, J = 4.4 Hz, 8-C), 49.2
(d, J = 4.0 Hz, N-CH2), 41.6 (Cl-CH2). 31P NMR (161.98 MHz,

JOURNAL OF CHEMICAL RESEARCH 2010 409
155.5 (d, J = 6.2 Hz, 7-C), 150.9 (d, J = 6.7 Hz, 1q-C), 132.0 (4p-C),
130.5 (1p-C), 130.1 (5q-C), 128.9 (3p, 5p-C), 126.1 (2p, 6p-C), 111.8 (d,
J = 4.5 Hz, 6q-C), 111.2 (4q-C), 108.2 (10-C), 105.9 (d, J = 5.1 Hz,
2q-C), 105.7 (3-C), 103.7 (d, J = 5.9 Hz, 6-C), 99.1 (d, J = 4.2 Hz,
The authors would like to thank the Chinese National Science
Foundation (No. 20472076), Henan Academic Foundation of
Science and Technology (No. 0512001400) for financial
support.
8-C), 55.3 (3q-OCH3), 49.3 (d, J = 3.7 Hz, N-CH2), 41.6 (Cl–CH2). 31
P
NMR (161.98 MHz, CDCl3) δ: −0.40. IR(KBr) ν(cm–1): 3439 (OH),
2922, 2853 (CH3, CH2), 1654 (C=O), 1278 (P=O), 1033 (P–O–C).
Anal. Calcd for C26H24Cl2NO7P: C, 55.33; H, 4.29; N, 2.48. Found:
C, 55.16; H, 4.26; N, 2.49%.
Received 14 May 2010; accepted 7 June 2010
Paper 1000131 doi:10.3184/030823410X12790414891526
Published online: 28 July 2010
Chrysin-7-yl 4p-(methoxy)phenyl N-bis(2-chloroethyl) phosphora-
midates (5d): Light yellow sticky liquid. 1H NMR (400.13 MHz,
CDCl3) δ: 12.78 (s, 1H, 5-OH), 7.87 (d, 2H, J = 8.0 Hz, 2p, 6p-H),
7.55–7.48 (m, 3H, 3p, 4p, 5p-H), 7.19 (d d, 2H, J = 9.1, 0.9 Hz, 2q, 6q-
H), 7.00 (d, 1H, J = 1.7 Hz, 8-H), 6.89–6.85 (m, 2H, 3q, 5q-H), 6.70
(s, 1H, 3-H), 6.65 (d, 1H, J = 1.9 Hz, 6-H), 3.78 (s, 3H, 4q-OCH3),
3.67–3.55 (m, 8H, N(CH2CH2Cl)2). 13C NMR (100.62 MHz, CDCl3)
δ: 182.6 (4-C), 164.7 (2-C), 162.1 (5-C), 157.0 (4q-C), 156.9 (9-C),
155.7 (d, J = 6.3 Hz, 7-C), 143.6 (d, J = 7.1 Hz, 1q-C), 132.1 (4p-C),
130.7 (1p-C), 129.0 (3p, 5p-C), 126.3 (2p, 6p-C), 120.8 (d, J = 4.6 Hz, 2q,
6q-C), 114.7 (3q, 5q-C), 108.3(10-C), 105.9(3-C), 103.8(d, J = 6.2 Hz,
6-C), 99.1 (d, J = 4.4 Hz, 8-C), 55.5 (4q-OCH3), 49.4 (d, J = 3.9 Hz,
N-CH2), 41.7 (Cl-CH2). 31P NMR (161.98 MHz, CDCl3) δ: 0.15.
IR(KBr) ν(cm–1): 3443 (OH), 2924, 2849 (CH3, CH2), 1655 (C=O),
1275 (P=O), 1031 (P-O-C). Anal. Calcd for C26H24Cl2NO7P: C, 55.33;
H, 4.29; N, 2.48. Found: C, 55.18; H, 4.27; N, 2.46%.
References
1
M. Hecker, C. Preiss, P. Klemm and R. Busse. Br. J. Pharmacol., 1996,
118, 2178.
2
N. Qais, M.M. Rahman, M.A. Rashid, H. Koshino, K. Nagasawa and
T. Nakata. Fitoterapia, 1996, 67, 554.
3
4
S. Habtemariam, J. Nat. Prod., 1997, 60, 775.
R.J. Fishkin and J.T. Winslow. Psychopharmacology (Berl.), 1997, 132,
335.
5
6
7
8
9
F.L. Pearce, A.D. Befs and J. Bienenstock. J. Allegy. Clin. Immunol., 1984,
73, 819.
C. Wolfman, H. Viola, A.C. Paladini, F. Dajas and J.H. Medina. Pharmacol.
Biochem. Behav., 1994, 47, 1.
J.S. Shin, K.S. Kim, M.B. Kim, J.H. Jeong and B.K. Kim. Bioorg. Med.
Chem. Lett., 1999, 9, 869.
K.S. Babu, T.H. Babu, P.V. Srinivas, K.H. Kishore, U.S.N. Murthy and
J.M. Rao. Bioorg. Med. Chem. Lett., 2006, 16, 221.
L.A. Cates, V.S. Li, D.R. Powell and D.V.D. Helm. J. Med. Chem., 1984,
27, 397.
Chrysin-7-yl 4p-(chloro)phenyl N-bis(2-chloroethyl) phosphorami-
1
dates (5e): Yellow sticky liquid. H NMR (400.13 MHz, CDCl3) δ:
12.79 (s, 1H, 5-OH), 7.87 (d, 2H, J = 8.0 Hz, 2p, 6p-H), 7.56–7.50 (m,
3H, 3p, 4p, 5p-H), 7.33 (d, 2H, J = 8.8 Hz, 3q, 5q-H ), 7.22 (d d, 2H,
J = 8.1, 0.7 Hz, 2q, 6q-H), 6.99 (d, 1H, J = 1.9 Hz, 8-H), 6.72 (s, 1H,
3-H), 6.65(d, 1H, J = 1.9 Hz, 6-H), 3.66–3.59(m, 8H, N(CH2CH2Cl)2).
13C NMR (100.62 MHz, CDCl3) δ: 183.1 (4-C), 165.2 (2-C), 162.7
(5-C), 157.5 (9-C), 156.0 (d, J = 6.4 Hz, 7-C), 149.2 (d, J = 6.8 Hz,
1q-C), 132.6 (4p-C), 131.2 (4q-C), 130.4 (3q, 5q-C), 130.3 (1p-C), 129.6
(3p, 5p-C), 126.9 (2p, 6p-C), 121.8 (d, J = 4.9 Hz, 2q, 6q-C), 109.0
(10-C), 106.5 (3-C), 104.2 (d, J = 6.2 Hz, 6-C), 99.6 (d, J = 4.6 Hz,
8-C), 49.9 (d, J = 4.0 Hz, N-CH2), 42.2 (C-CH2). 31P NMR (161.98
MHz, CDCl3) δ: −0.27. IR(KBr) ν(cm–1): 3431 (OH), 2962, 2930
(CH2), 1645 (C=O), 1265 (P=O), 1037 (P-O-C). Anal. Calcd for
C25H21Cl3NO6P: C, 52.79; H, 3.72; N, 2.46. Found: C, 52.63; H, 3.70;
N, 2.44%.
10 W.B. Pratt and R.W. Ruddon. The anticancer drugs, Oxford University
Press: New York, 1979, 64.
11 R.M. Peck, R.K. Preston and H.J. Creech, J. Am. Chem. Soc., 1959, 81,
3984.
12 F. Bergel and J.A. Stock, J. Chem. Soc., 1954, 2409.
13 F. Bergel and R. Wade, J. Chem. Soc., 1959, 941.
14 W.J. Gensler and G.M. Sherman, J. Org. Chem., 1958, 23, 1227.
15 L. Vargha, L. Toldy, O Feher and S. Lendvai, J. Chem. Soc., 1957, 805.
16 R.Y. Chen and X.R. Chen, Heteroat. Chem., 1993, 4, 587.
17 O.M. Friedman and A.M. Sellgman, J. Am. Chem. Soc., 1954, 76, 655.
18 R.Y. Chen, H.L. Wang and J. Zhu, Heteroat. Chem., 1994, 5, 497.
19 V. M. Ovrutskii, I.I. Kuzmenko and L.D. Protsenko, Russ. J. Gen. Chem.,
1977, 47, 307.

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