A new method for the preparation of ifosfamide and cyclophosphamide

Article abstract of DOI:10.1515/znb-1997-0810

The reaction of 2-chloro-3-(2-chloroethyl)-tetrahydro-2H-1,3,2-oxazaphosphorin-2-oxide 1 and 2-chloro-tetrahydro-2H-1,3,2-oxazaphosphorin-2-oxide 2 with 2-(trimethylsilyloxy)ethylamine 3 and bis-[2-(trimethylsiloxy)ethyl]amine 4, respectively, yielded the trimethylsilylated compounds 5 and 6, analogous to ifosfamide and cyclophosphamide. The reaction of 5 and 6 with 2-chloro-1,3,5-trimethyl-1,3,5-triaza-2-phosphorin-4,6-dione 7 led to the diphosphorus compounds 8 and 9 which could be transformed to ifosfamide 11 and cyclophosphamide 12 by treatment with sulfuryl chloride. This synthesis shows that the alkylating agents 2-chloroethylammonium chloride and bis-(2-chloroethyl)ammonium chloride can be avoided and the chlorine atom can be introduced in the final reaction step of the synthesis of 11 and 12.

Full text of DOI:10.1515/znb-1997-0810

A New Method for the Preparation of Ifosfamide and Cyclophosphamide
I. Nedaa, R. Sonnenburga, R. Schmutzler3 *, U. Niemeyerb, B. Kutscherb, J. Engelb,
A. Kleemannb
a Institut für Anorganische und Analytische Chemie der Technischen Universität,
Postfach 3329, D-38023 Braunschweig, Germany
b ASTA Medica AG, Weismüllerstr. 45, D-60314 Frankfurt, Germany
Dedicated to Professor Dr. med. Dr. h. c. Norbert Brock on the occasion of his 85th birthday
Z. Naturforsch. 52 b, 943-946 (1997); received April 24, 1997
Ifosfamide, Cyclophosphamide, Oxazaphosphorines, 2-(Trimethylsiloxy)ethylamines
The reaction of 2-chloro-3-(2-chloroethyl)-tetrahydro-2//-l,3,2-oxazaphosphorin-2-oxide 1
and 2-chloro-tetrahydro-2//-l,3,2-oxazaphosphorin-2-oxide2 with 2-(trimethylsilyloxy)ethyl-
amine 3 and bis-[2-(trimethylsiloxy)ethyl]amine 4, respectively, yielded the trimethylsilylated
compounds 5 and 6, analogous to ifosfamide and cyclophosphamide. The reaction of 5 and
6 with 2-chloro-1,3,5-trimethyl-1,3,5-triaza-2-phosphorin-4,6-dione 7 led to the diphosphorus
compounds 8 and 9 which could be transformed to ifosfamide 11 and cyclophosphamide
12 by treatment with sulfuryl chloride. This synthesis shows that the alkylating agents 2-
chloroethylammonium chloride and bis-(2-chloroethyl)ammonium chloride can be avoided
and the chlorine atom can be introduced in the final reaction step of the synthesis of 11 and 12.
l,3,5-triaza-2-phosphorin-4,6-dion-2-oxide 10 and
the corresponding alkyl chloride [7], the silylated
compounds 5 and 6, consequently, were allowed to
react with 7 to form the cr4A5/cr3A3-diphosphorus
species 8 and 9. Treatment of 8 and 9 with sul-
furyl chloride led to ifosfamide 11 and cyclophos-
phamide 12, respectively, but the compounds were
not stable in the reaction mixture. A 31P NMR
spectrum, recorded after half an hour of reac-
tion time, showed a yield of ca. 75%. On recrys-
tallisation of the product mixtures from diethyl
ether only 2-chloro-1,3,5-trimethyl-1,3,5-triaza-2-
phosphorin-4,6-dion-2-oxide 10 crystallized in a
pure state. Ifosfamide 11 and cyclophosphamide 12,
could be separated by column chromatography of
the ethereal mother liquor; the yield after recrys-
tallisation amounted to 10 - 15%.
The previously known methods for the synthesis
of ifosfamide and cyclophosphamide do not require
chromatographic separation of the products. Our
work has demonstrated an alternative synthesis of
compounds 11 and 12, avoiding the use of the alky-
lating agents, 2-chloroethylammonium chloride and
bis(2-chloroethyl)ammonium chloride, as starting
compounds.
Introduction
Ifosfamide 11 and cyclophosphamide 12 are two
clinically widely used alkylating agents in the
treatment of many types of human cancers [1,
2]. 2-Chloroethylammonium chloride and bis-(2-
chloroethyl)ammonium chloride (nitrogen mustard
HCl-salt) are important educts for the synthesis of
11 [3,4] and 12 [5, 6], respectively. In order to avoid
the use of these alkylating agents we developed a
new synthesis in which chlorine is introduced in the
final reaction step.
Results and Discussion
The substitution of chlorine in
by 2-(trimethylsiloxy)ethylamine
1
and
2
3
and bis-
[2-(trimethylsiloxy)ethyl]amine 4, respectively,
yielded the products 5 and 6 in nearly quanti-
tative yield. Hydrolysis of these silylated com-
pounds led to the corresponding hydroxy com-
pound only in the case of 5. Its direct chlorination
with thionyl chloride gave 11 in low yield. Having
in mind that 2-alkoxy-1,3,5-trimethyl-1,3,5-triaza-
2-phosphorin-4,6-diones react with sulfuryl chlo-
ride with formation of 2-chloro-1,3,5-trimethyl-
* Reprint requests to R. Schmutzler.
0939-5075/97/0800-0943 $ 06.00
©
1997 Verlag der Zeitschrift für Naturforschung. All rights reserved.
K
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944
I. Neda et cd. ■A New Method for the Preparation of Ifosfamide and Cyclophosphamide
+ Et,N
R1
.OSiMe,
+
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G <
- Et3N • HC1
3
R2 = H
5
R1
--------- w C l
R3 = H
4
R2 = '-'N—-OSiMe,
6
R1 =
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R3 = ^ V -O S iM e,
H3C
O
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ii
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CISiMe,
+
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I
w
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HiC
o
10
Experimental
of 2-(trimethylsiloxy)ethylamine 3 (3.27 g, 15 mmol) in
20 ml of dichloromethane was added dropwise during 15
min. After stirring the reaction mixture for 5 h at -15°C
the solvent and all volatile components were removed i. v.
The residue was extracted with 50 ml of diethyl ether, and
triethylammonium chloride was filtered off. After remov-
ing the diethyl ether i. v. 5 was left as a colourless oil;
yield: 4.48 g (94.9%); b.p.: >200°C (1 mm Hg).
All experiments were carried out with exclusion of air
and moisture; solvents were purified and dried accord-
ing to the usual methods [8]. “In vacuo” (i. v.) refers
to a pressure of 0.1 mm Hg at 25°C. - NMR spectra
were recorded on a Bruker AC 200 spectrometer at 200.1
MHz (’H), 50.3 MHz (l3C), and 81.0 MHz (3,P). Chem-
ical shifts 6 are given relative to Si(CH3)4 (TMS) ( 1H,
l3C); 85% H3PO4 (3IP). High-field shifts were given
negative, low-field shifts positive signs. - MS: Finni-
gan MAT 8430. - Elemental analyses: Analytisches La-
boratorium des Instituts für Anorganische und Analyti-
sche Chemie der Technischen Universität, Braunschweig.
'H NMR (CDCI3, 200.1 MHz): Ö = 0.79 (s, 9 H,
Si(C//3)3), 1.83-1.95 (m, 2 H, CH2C //2CH2), 2.90-3.65
(m, 11 H, 3xNCH2, 2xNCH,CH2, NH), 4.13-4.37 (m, 2
H, POC//2). - 13C NMR (CDC13, 50.3 MHz): 6 = -0.63
(s, SiCH3), 26.41 (d, 3/(PC) = 4.6 Hz, PNCH,CH,CH,),
42.01 (d, 27(PC) = 4.0 Hz, PNCH,CH2CH2), 43.22; 62.56
(s; d, 6.4 Hz, PNHCH,CH,OSi), 47.73 (s, CH,C1), 50.15
(d, 27(PC) = 2.7 Hz, PNCH2CH,C1), 67.01 (d, 27(PC)
= 6.8 Hz, POCH,CH,CH,). - 31P NMR (CDC13, 81.0
MHz): 6 = 13.23 (s) - EI-MS: m/z (%) = 314 (4) [M+],
299 (24) [M+- CH3], 211 (100) [M+- CH2OSi(CH3)3],
182 (28) [M+- NHCH,CH2OSi(CH3)3].
-
Precursor compounds: 2-chloro-3-(2-chloroethyl)-
tetrahydro-2//-l,3,2-oxazaphosphorin-2-oxide (1) [9], 2-
chloro-tetrahydro-2//- 1,3,2-oxazaphosphorin-2-oxide
(2) [10], 2-(trimethylsiloxy)ethylamine (3) [11], bis-[2-
(trimethylsiloxy)ethyl]amine (4) [11], 2-chloro-l ,3,5-
trimethyl-1,3,5-triaza-2-phosphorin-4,6-dione (7) [12].
3-(2-Chloroethyl)-2-[2-(trimethylsüoxy)ethylamino]-
tetrahydro-2H-l,3,2 -oxazaphosphorin-2-oxide (5)
CioH24C lN ,0 3PSi (314.82)
Calcd C 38.15 H 7.68 N 8.90%,
Found C 36.88 H 7.45 N 9.28%.
A solution of 1 (2.00 g. 15 mmol) and of triethylamine
(1.52 g, 15 mmol) in 30 ml of dichloromethane was
cooled to -15°C (ethanol/liqu. nitrogen) and a solution
The experimental C-value deviates from the calculated
value, presumably because of the formation of SiC.
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I. Neda et al. • A New Method for the Preparation of Ifosfamide and Cyclophosphamide
945
2-Bis-[2-(trimethylsiloxy)ethylamino]-tetrahydro-2H-
1,3,2-oxazaphosphorin-2-oxide (6)
2/(PC) = 6.8 Hz, POCH2CH2CH2), 153.27 (d, 2/(PC)
= 9.9 Hz, P(NCH3C(:0))2). - 31P NMR (CDC13, 81.0
MHz): 6 = 90.93 (s), 13.06 (s). - EI-MS: m/z (%) =
415 (2) [M+], 380 (10) [M+- Cl], 366 (5) [M+- CH2C1],
225 (100) [M+- 0P{NCH3C(:0)}2NCH3], 211 (42) [M+-
CH20P{NCH3C (:0)}2NCH3].
A solution of 2 (5.80 g, 37mmol) and of triethylamine
(3.77 g, 37 mmol) in 50 ml of dichloromethane was cooled
to 0°C. A solution of bis-[2-(trimethylsiloxy)ethyl]amine
4 (9.30 g, 37 mmol) in 50 ml of dichloromethane was
added dropwise during 1 h. After stirring the reaction
mixture for 18 h at r.t., the solvent and all volatile compo-
nents were removed i. v. The residue was extracted with
100 ml of diethyl ether, and triethylammonium chloride
was filtered off. After removing the diethyl ether i.v. 6
was left as a colourless oil; yield: 12.08 g (88.7%); b.p.:
>200°C (1 mm Hg).
Ci2H24C1N50 5P2 (415.75)
Calcd C 34.67 H 5.82 N 16.85%,
Found C 34.05 H 5.99 N 16.04%.
2-Bis-[2-( 1,3,5-trimethyl-1,3,5,2-triazaphosphorin-4,6-
dion-2-yloxy)ethylamino]-tetrahydro-2H-l ,3,2-oxaza-
phosphorin-2-oxide (9)
'H NMR (CDCb, 200.1 MHz): b = 0.05 (s, 18 H,
Si(C//3)3), 1.62-1.94 (m, 2 H, CH2C //2CH2), 2.87-2.96
(br„ 1 H, NH), 3.02-3.45 (m, 6 H, 3xNCH2), 3.60 (t,
4 H, V(HH) = 6.2 Hz, NCH2C //2OSi), 4.05-4.46 (m, 2
H, POCH2). - l3C NMR (CDCI3, 50.3 MHz): b = -0.89
(s, SiCH3), 25.86 (d, 3/(PC) = 6.4 Hz, PNCH2CH2CH2),
40.90 (d, 2/(PC) = 2.8 Hz, PNCH2CH2CH2), 48.17 (d,
2/(PC) = 4.1 Hz, PN(CH2CH2OSi)2), 60.91 (d, 3/(PC) =
I.1 Hz, PN(CH2CH2OSi)2), 67.08 (d, 2/(PC) = 6.7 Hz,
POCH2CH2CH2). - 31P NMR (CDCI3, 81.0 MHz): b =
13.84 (s). - EI-MS: m/z (%) = 368 (1) [M+], 353 (16)
[M+- CH3], 265 (100) [M+- CH2OSi(CH3)3], 194 (13)
[M+- CH2CH2OSi(CH3)3 -NHCH2CH2CH2].
To a solution of 3.70 g (10 mmol) of 6 in 50 ml of
dichloromethane 4.20 g (20 mmol) of 7 was added. After
stirring the reaction mixture for 1 d at r.t., the solvent and
all volatile components were removed i.v. The residue
was washed with 50 ml of n-hexane and dried i.v.; yield:
4.35 g (76.3%); m.p.:58°C.
‘H NMR (CDC13, 200.1 MHz): b = 1.72-1.88 (m,
2 H, CH
2
CH
2
CH ), 2.61 (br„ 1 H, NH), 2.98-3.33;
2
3.52-3.69 (2 m, 10 H, 3xNCH2, 2xNCH2C //2), 3.09
(d, 12 H, 3/(PH) = 11.6 Hz, P(NC//3)2), 3.27 (s, 6 H,
[C(:0)]2N C//3), 4.07-4.45 (m, 2 H, P (:0 )0 C //2). - l3C
NMR (CDC13, 50.3 MHz): b = 25.72 (d, 3/(PC) = 5.5
Hz, PNCH2CH2CH2), 30.26 (s, [C(:0)]2NCH3), 33.51
(d, 2/(PC) = 36.3 Hz, P(NCH3)2), 41.57 (d, 2/(PC) =
2.9 Hz, PNCH2CH2CH2), 47.40 (d, 2/(PC) = 3.8 Hz,
PN(CH2CH20 -)2), 63.14 (s, PN(CH2CH20 -)2), 67.41 (d,
2/(PC) = 6.8 Hz, POCH2CH2CH2), 153.35 (d, 2/(PC)
= 11.3 Hz, P(NCH3C (:0))2. - 3IP NMR (CDC13, 81.0
MHz): b = 91.67 (s), 13.35 (s). - EI-MS: m/z (%) =
570 (0.4) [M+], 380 (100) [M+- 0P{NCH3C (0)}2NCH3],
366 (5) [M+- CH20P{NCH3C (:0)}2NCH3], 174 (73)
[0P{NCH3C (:0)}2NCH3].
C,3H33N20 4PSi2 (368.56)
Calcd C 42.37 H 9.02 N 7.60%,
Found C 41.39 H 9.03 N7.71%.
The experimental C-value deviates from the calculated
value, presumably because of the formation of SiC.
3-(2-Chloroethyl)-2-[2-( 1,3,5-trimethyl-1,3,5,2-triaza-
phosphorin-4,6-dion-2-yloxy)ethylamino]-tetrahydro-
2H-1,3,2-oxazaphosphorin-2-oxide (8)
C]7H33N80 8P3 (570.42)
To a solution of 3.15 g (10 mmol) of 5 in 50 ml of
dichloromethane 2.10 g (10 mmol) of 7 was added. After
stirring the reaction mixture for 1 d at r.t., the solvent and
all volatile components were removed i.v. The residue
was washed with 50 ml of n-hexane and dried i.v.; yield:
3.60 g (86.5%); m.p.:54°C.
Calcd C 35.80 H 5.83 N 19.64%,
Found C 35.95 H 6.28 N 19.33%.
3-(2-Chloroethyl)-2-[(2-chloroethyl)amino]-tetrahydro-
2H-1,3,2-oxazaphosphorin-2-oxide (Ifosfamide) (11)
and 2-bis-[(2-chloroethyl)amino]-tetrahydro-2H-1,3,2-
oxazaphosphorin-2-oxide (Cyclophosphamide) (12)
'H NMR (CDC13, 200.1 MHz): b = 1.86-1.91 (m,
2 H, CU
2
CH
2
CH ), 2.99-3.62 (m, 11 H, 3xNCH2,
2
2xNCH2CH2, NH), 3.08 (d, 6 H, 3/(PH) = 1 1 .7 Hz,
P(NC//3)2), 3.24 (s, 3 H, [C(:0)]2N C//3), 4.08-4.33 (m,
2 H, P (:0)0C //2). - l3C NMR (CDC13, 50.3 MHz): 6 =
26.32 (d, 3/(PC) = 4.4 Hz, PNCH2CH2CH2), 30.20 (s,
[C(:0)]2NCH3), 33.43 (d, 2/(PC) = 36.3 Hz, P(NCH3)2),
41.60; 41.87; 63.98 (3d, 2/(PC) = 4.2 Hz; 4.6 Hz; 4.8 Hz,
PNCH2CH2CH2, PNHCH2CH2OP), 47.40 (s, CH2C1),
49.92 (d, 2/(PC) = 2.6 Hz, PNCH2CH2C1), 67.07 (d,
To solutions of 2.49 g (6 mmol) of 8 and of 3.42 g
(6 mmol) of 9, respectively, in 50 ml of dichloromethane
sulfuryl chloride (0.81 g, 6 mmol) was added at 0°C. Af-
ter stirring the solutions for 1 h at 0°C, the solvent and all
volatile components were removed i.v. The residues were
dissolved in 30 ml of diethyl ether each and kept overnight
at -20°C. Pure 2-chloro-1,3,5-trimethyl-1,3,5-triaza-2-
phosphorin-4,6-dion-2-oxide 10 crystallized from both
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I. Neda et al. • A New Method for the Preparation of Ifosfamide and Cyclophosphamide
Acknowledgements
solutions, while ifosfamide 11, cyclophosphamide 12 and
other by-products remained in solution. After filtration,
both 11 and 12 were separated by column chromatogra-
phy on silica gel (CfLCb/n-hexane, 5:2) of the ethereal
mother liquor and recrystallized from 5 ml of diethyl ether
each at -20°C. The identity of 10, of ifosfamide 11 and
of cyclophosphamide 12 was established by 'H- and 31P
NMR-spectroscopy [4, 6, 12]; yield: 11: 0.24 g (14.8%);
12: 0.17 g ( 10.9%).
This research was supported through generous gifts of
chemicals by BASF AG, BAYER AG, and HOECHST
AG, and by a grant of the Fonds der Chemischen Indu-
strie.
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