A new method of introducing SCH3 and SCD3 groups to phosphorothioates

Article abstract of DOI:10.1080/10426507.2011.634467

A new synthesis of phosphorothioates starting from phosphites and cyanuric chloride (TCT)-activated DMSO is reported herein. This method enables the incorporation of SCH₃ and SCD₃ groups into phosphorothioates in good yields. The labeling purities of the products are excellent.

Full text of DOI:10.1080/10426507.2011.634467

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Phosphorus, Sulfur, and Silicon and the
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A New Method of Introducing SCH3 and
SCD3 Groups to Phosphorothioates
Tianzhen Liu a , Xiaoxue Cui a , Zhifang Yu a & Chunbao Li a
a Department of Chemistry, College of Science , Tianjin University ,
Tianjin , China
Published online: 27 Mar 2012.
To cite this article: Tianzhen Liu , Xiaoxue Cui , Zhifang Yu & Chunbao Li (2012) A New Method of
Introducing SCH3 and SCD3 Groups to Phosphorothioates, Phosphorus, Sulfur, and Silicon and the
Related Elements, 187:5, 606-611, DOI: 10.1080/10426507.2011.634467
To link to this article: http://dx.doi.org/10.1080/10426507.2011.634467
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Phosphorus, Sulfur, and Silicon, 187:606–611, 2012
Copyright ꢀC Taylor & Francis Group, LLC
ISSN: 1042-6507 print / 1563-5325 online
DOI: 10.1080/10426507.2011.634467
A NEW METHOD OF INTRODUCING SCH3
AND SCD3 GROUPS TO PHOSPHOROTHIOATES
Tianzhen Liu, Xiaoxue Cui, Zhifang Yu, and Chunbao Li∗
Department of Chemistry, College of Science, Tianjin University, Tianjin, China
GRAPHICAL ABSTRACT
TCT (0.8 eq.),
DMSO-d6 (5 eq.)
MeCN, 80oC, 1 h
O
P
S
O
O
O
O
R
P
R
R
R
OH
CD3
Abstract A new synthesis of phosphorothioates starting from phosphites and cyanuric chloride
(TCT)-activated DMSO is reported herein. This method enables the incorporation of SCH3
and SCD3 groups into phosphorothioates in good yields. The labeling purities of the products
are excellent.
Keywords Synthesis; phosphites; phosphates; deuterium-labeled synthesis
INTRODUCTION
Phosphorothioates are well known as pesticides in agriculture1 and a number of
phosphorothioates have been reported as chemotherapeutic agents.2 Diversified meth-
ods have been described on the synthesis of this type of compounds. The follow-
ing methods are known: the reactions of phosphorothioates with alcohols or alkyl
halides,3,4 chlorodimethoxyphosphine oxides with thiols,5 dimethoxyphosphine oxides
with disulfides,6 triethoxyphosphine with alkyl thiocyanates,7 trimethoxyphosphate with
sulfur,8 and S-alkyl phosphorodichloridothiolates with phenols;9 from dimethoxy phos-
phine oxide, unsaturated alcohols, and sulfur;10 and from alcohols, thiols, and phosphorus
oxychloride.11
Although several dozens of 18O- and 14C-labeled phosphorothioates are known, only
two deuterium-labeled phosphorothioates have been reported but without preparation pro-
cedures.12 One reason is that the deuterated starting materials for phosphorothioates such
as deuterated thiols are not commercially available. However, they are important to help
elucidate reaction mechanisms and enzymatic mechanisms and aid DMPK research.
Received 24 September 2011; accepted 17 October 2011.
We thank NSFC for financial support.
Address correspondence to Chunbao Li, Department of Chemistry, College of Science, Tianjin University,
Tianjin 300072, China. E-mail: lichunbao@tju.edu.cn
606

METHOD OF INTRODUCING SCH3 AND SCD3 GROUPS TO PHOSPHOROTHIOATES 607
RESULTS AND DISCUSSION
According to our previous research using TCT (cyanuric chloride)-activated
DMSO,13,14 we speculated that the TCT/DMSO system could be used to introduce SCH3
and SCD3 groups into phosphorothioates. Diethyl phosphite was used as a benchmark
to test this idea. It was treated with TCT and DMSO in various solvents: ethyl acetate,
chloroform, xylene, THF, toluene, DMSO neat, and acetonitrile. At room temperature,
no reactions took places. When the reaction temperatures were elevated, only in xylene,
DMSO, toluene, and acetonitrile did the reaction afford the desired product: O,O-diethyl
S-methyl phosphate. The reaction of the phosphite with TCT (0.8 eq.) and DMSO (5 eq.)
in refluxing acetonitrile gave the best yields. Therefore, a few phosphites were subjected
to this condition. The results are summarized in Table 1. The reaction rates and yields
are roughly the same when the alkyl groups on the phosphites changes from methyl to
steroidyl. The presence of SCH3 groups in the products is supported by the doublets in the
range of 2.19–2.34 ppm in 1H NMR and the doublets in the range of 12.29–12.70 ppm in
13C NMR.
Table 1 The reactions of phosphites with TCT-activated DMSO
Entry
R
Yield (%)
1
2
3
4
5
Me
Et
n-Bu
c-Hex
71
69
63
68
55
6
7
59
60

608
T. LIU ET AL.
Table 2 The reactions of phosphites and TCT-activated dibutylsulfoxide
O
P
S
n-Bu
Bu-n
O
O
TCT, acetonitrile
80 oC, 1 h
O
O
S
O
+
R
R
P
R
R
OH
Bu-n
Entry
R
Yield (%)
1
2
Me
Et
56
54
Replacing DMSO with dibutylsulfoxide produced the corresponding S-butyl phos-
phorothiates in good yields. The results are summarized in Table 2. This demonstrates the
generality of our method for various sulfoxides.
The following mechanism is proposed (Scheme 1): nucleophilic attack of phosphite
on TCT-activated DMSO I leads to II, which is decomposed by the chloride attack to yield
phosphorothioate. The change of the alkoxy groups on the phosphites has little influence on
the nucleophility and the reactivity of II. Therefore, the reaction rates are almost the same
(Tables 1 and 2). The mechanism is supported by trapping MeCl evolved from the reaction
with triethylenediamine (DABCO) in ethanol to produce DABCO ammonium salt.15
Cl
N
O
Cl
TCT + DMSO
N
N
S
H O
OR
P
OR
I
Cl
N
O
Cl
O
RO
OR
Cl
P
S
N
N
S
O
P
OR
OR
II
Scheme 1
According to the mechanism, it is possible to incorporate SCD3 into the phosphoroth-
ioate if DMSO-d6 is used. Therefore, four phosphites were reacted with TCT and DMSO-d6
in acetonitrile. The reactions of the phosphites with TCT (0.8 eq.) and DMSO-d6 (5 eq.)
in refluxing acetonitrile gave the corresponding deuterated phosphorothioates in moderate
yields. The deuterium-labeling purity is excellent according to the NMR spectra. The results
are summarized in Table 3. The deuterated products in Table 3 were synthesized almost in
the same rates and yields as in Table 1.

METHOD OF INTRODUCING SCH3 AND SCD3 GROUPS TO PHOSPHOROTHIOATES 609
Table 3 The reactions of phosphites and TCT-activated DMSO-d6
Entry
R
Yield (%)
1
2
3
Me
c-Hex
67
68
58
4
60
CONCLUSION
We have developed a new synthesis for phosphorothioate starting from phosphite,
TCT, and DMSO or dibutyl sulfoxide. This procedure allows the introduction of SCH3
and SCD3 groups into the phosphorothioates in excellent purity. This represents a practical
synthesis of deuterated phosphorothioates and provides bases for mechanism studies of
bioactive phosphorothioates.
EXPERIMENTAL
General
All chemicals were obtained from commercial sources or prepared according to
1
standard methods. The H NMR (400 MHz), 13C NMR (100 MHz), and 31P NMR (162
MHz) spectra were recorded on a Bruker AM-400 spectrometer. Chemical shifts δ are
reported relative to TMS (1H) or CDCl3 (13C). Chemical shifts δ of 31P are reported relative
to 85% H3PO4 as external standard. IR spectra (KBr, cm−1) were recorded on a BIO-RAD
FTS 3000 spectrometer. Mass spectra (ESI) were obtained on a Finnigan LCQ Advantage
MAX spectrometer. High-resolution mass spectra were obtained on a Bruker micrOTOF-
QII spectrometer. All new compounds were fully characterized, all known compounds
(Table 1, Entries 1–316–18 and Table 2, Entries 1–219,20) were characterized and the data
compared with the literature.
Typical Procedure
The procedure for the reaction of TCT (cyanuric chloride)-activated DMSO and
dicyclohexyl phosphite (Table 1, Entry 4) is representative for all phosphites. To a solution

610
T. LIU ET AL.
of dicyclohexyl phosphite (492 mg, 2 mmol) and TCT (295 mg, 1.8 mmol) in 5 mL
acetonitrile was added DMSO (780 mg, 10 mmol). The mixture was stirred at 80 ◦C and
monitored by TLC until completion (1 h). Then, the reaction mixture was added to ethyl
acetate (30 mL), washed with water (3 × 10 mL). The organic layers were combined and
concentrated in vacuum to give the crude product that was purified by silica gel column
chromatography to afford O,O-dicyclohexyl S-methyl phosphorothioate (395 mg, yield
68% based on the amount of the phosphite used). Oil. IR: 2937, 2859, 1546, 1344, 1251,
1
985, 889, 673. H NMR (CDCl3): δ = 4.35 (m, 2H), 2.29 (d, J = 12 Hz, 3H), 1.98 (m,
4H), 1.75 (m, 4H), 1.55 (m, 6H), 1.33 (m, 6H). 13C NMR (CDCl3): δ = 77.2, 33.4, 25.1,
23.6, 12.7. 31P NMR (CDCl3): δ = 25.9. MS (ESI) m/z (%) 607 [2M + Na]+ (100). HRMS
(ESI): m/z [M + Na]+ calcd for C13H25O3PSNa: 315.1154; found: 315.1159.
O,O-Bis(2-isopropyl-5-methylcyclohexyl) S-methyl phosphorothioate (Table 1,
◦
◦
1
Entry 5): mp 56 C–58 C. IR: 2933, 2929, 1637, 1511, 1329, 1251, 950, 823, 804. H
NMR (CDCl3): δ = 4.25 (m, 2H), 2.32 (d, J = 12 Hz, 3H), 2.18 (m, 2H), 1.76–0.78 (m,
32H). 13C NMR (CDCl3): δ = 79.3, 48.6, 42.7, 34.0, 31.6, 25.4, 22.8, 21.9, 21.1, 15.8, 12.6.
31P NMR (CDCl3): δ = 25.9. MS (ESI) m/z (%) 831 [2M + Na]+ (100). HRMS (ESI): m/z
[M + Na]+ calcd. for C21H41O3PSNa: 427.2412; found: 427.2413.
O,O-Bis(3β-acetoxy-androst-5-en-17β-yl) S-methyl phosphorothioate (Table 1,
Entry 6): mp 230 ◦C–233 ◦C. IR: 3034, 2929, 2830, 1732, 1630, 1472, 1442, 1371, 1259,
1
1152, 1011, 936, 883, 800, 633. H NMR (CDCl3): δ = 5.39 (s, 2H), 4.62 (m, 2H), 4.31
(m, 2H), 2.33 (d, J = 8 Hz, 3H), 2.05 (s, 6H), 1.05 (s, 6H), 0.84 (s, 6H). 13C NMR (CDCl3):
δ = 170.4, 139.8, 122.1, 86.5, 73.8, 42.9, 36.5, 31.8, 31.4, 29.7, 28.5, 27.7, 23.4, 21.4, 20.5,
19.3, 12.7, 11.6. 31P NMR (CDCl3): δ = 27.3. MS (ESI) m/z (%) 779 [M + Na]+ (100).
HRMS (ESI): m/z [M + Na]+ calcd for C43H65O7PSNa: 779.4086; found: 779.4077.
O,O-Bis(3β-acetoxy-5α-androstan-17β-yl) S-methyl phosphorothioate (Table 1,
Entry 7): mp 222 ◦C–226 ◦C. IR: 2929, 2880, 1731, 1472, 1443, 1371, 1341, 1259, 1152,
1
1131, 1011, 935, 883, 633. H NMR (CDCl3): δ = 4.70 (m, 2H), 4.31 (m, 2H), 2.28 (d,
J = 8 Hz, 3H), 2.05 (s, 6H), 0.84 (s, 6H), 0.81 (s, 6H). 13C NMR (CDCl3): δ = 170.6, 86.6,
73.6, 54.2, 50.1, 44.6, 43.2, 36.9, 35.5, 33.9, 31.4, 27.4, 23.4, 21.5, 20.5, 12.2, 11.8. 31P
NMR (CDCl3): δ = 27.2. MS (ESI) m/z (%) 1544 [2M + Na]+ (100). HRMS (ESI): m/z
[M + Na]+ calcd for C43H69O7PSNa: 783.4399; found: 783.4390.
O,O-Dimethyl S-methyl-d3 phosphorothioate (Table 3, Entry 1): In the reaction
of TCT-activated DMSO-d6, DMSO-d6 was used to replace DMSO. Oil. IR: 2940, 2856,
1546, 1384, 1250, 988, 886, 655. 1H NMR (DMSO-d6): δ = 3.72 (d, J = 12 Hz, 6H). 13
C
NMR (DMSO-d6): δ = 54.1. 31P NMR (CDCl3): δ = 32.4. MS (ESI) m/z (%) 341 [2M +
Na]+ (100). HRMS (ESI): m/z [M + Na]+ calcd. for C3H6D3O3PSNa: 182.0093; found:
182.0096.
O,O-Dicyclohexyl S-methyl-d3 phosphorothioate (Table 3, Entry 2): Oil. IR: 2935,
2855, 1548, 1346, 1252, 987, 886, 677. 1H NMR (CDCl3): δ = 4.49 (m, 2H), 1.99 (m, 4H),
1.77 (m, 4H), 1.57 (m, 6H), 1.35 (m, 6H). 13C NMR (CDCl3): δ = 77.2, 33.4, 25.1, 23.6.
31P NMR (CDCl3): δ = 25.9. MS (ESI) m/z (%) 613 [2M + Na]+ (100). HRMS (ESI): m/z
[M + Na]+ calcd. for C13H22D3O3PSNa: 318.1345; found: 318.1341.
O,O-Bis(3β-acetoxy-androst-5-en-17β-yl)
S-methyl-d3
phosphorothioate
◦
(Table 3, entry 3): mp 225◦C–229 C. IR: 3030, 2986, 2896, 1732, 1442, 1401, 1373,
1345, 1252, 1024, 934, 874, 800, 633. 1H NMR (CDCl3): δ = 5.40 (s, 2H), 4.62 (m, 2H),
4.32 (m, 2H), 2.05 (s, 6H), 1.05 (s, 6H), 0.84 (s, 6H). 13C NMR (CDCl3): δ = 170.5, 139.8,
122.1, 86.6, 73.8, 50.4, 49.9, 42.9, 38.1, 36.6, 31.8, 31.3, 28.8, 27.7, 23.4, 21.4, 20.5, 19.3.

METHOD OF INTRODUCING SCH3 AND SCD3 GROUPS TO PHOSPHOROTHIOATES 611
31P NMR (CDCl3): δ = 27.4. MS (ESI) m/z (%) 783 [M + Na]+ (100). HRMS (ESI): m/z
[M + Na]+ calcd. for C43H62D3O7PSNa: 782.4269; found: 782.4268.
O,O-Bis(3β-acetoxy-5α-androstan-17β-yl)
S-methyl-d3
phosphorothioate
◦
◦
(Table 3, entry 4): mp 231 C–234 C. IR: 2929, 2880, 1731, 1451, 1442, 1373, 1259,
1
1153, 1011, 934, 881, 633. H NMR (CDCl3): δ = 4.70 (m, 2H), 4.29 (m, 2H), 2.04 (s,
6H), 0.84 (s, 6H), 0.81 (s, 6H). 13C NMR (CDCl3): δ = 170.6, 86.7, 73.6, 54.2, 50.2, 44.6,
43.2, 35.5, 35.4, 33.9, 31.4, 27.4, 23.4, 21.4, 20.6, 12.2, 11.8. 31P NMR (CDCl3): δ =
27.3. MS (ESI) m/z (%) 1550 [2M + Na]+ (100). HRMS (ESI): m/z [M + Na]+ calcd. for
C43H66D3O7PSNa: 786.4582; found: 786.4577.
REFERENCES
1. (a) Deloude, L.; Laszlo, P. J. Org. Chem. 1996, 61, 6360-6370; (b) Varma, R. S.; Meshram, H.
M. Tetrahedron Lett. 1997, 38, 7973-7976.
2. Uhlman, E.; Peyman, A. Chem. Rev. 1990, 90, 543-584.
3. Han, X. P.; Wu, J. Org. Lett. 2010, 24, 5780-5782.
4. Pandey, L. K.; Mazumder, A.; Pathak, U. Indian. J. Chem. B. 2009, 48, 602-605.
5. Carta, P.; Puljic, N.; Robert, C.; Dhimane, A.; Ollivier, C.; Fensterbank, L.; Lacote, E. Tetrahedron
2008, 64, 11865-11875.
6. Gao, Y.; Tang, G.; Cao, Y.; Zhao, Y. Synthesis 2009, 7, 1081-1086.
7. Piekutowska, M.; Pakulski, Z. Tetrahedron Lett. 2007, 48, 8482-8486.
8. Chandrasekaran, P.; Mague, J. T.; Balakrishna, M. S. Inorg. Chem. 2006, 45, 5893-5897.
9. Jhajharja, P.; Samota, M. K.; Seth, G. Heteroatom. Chem. 2010, 21, 84-88.
10. Han, X.; Zhang, Y.; Wu, J. J. Am. Chem. Soc. 2010, 132, 4104-4106.
11. Yamamoto, T.; Hasegawa, H.; Ishii, S.; Kaji, S.; Masuyama, T. Tetrahedron 2008, 64, 11647-
11660.
12. Cullis, P.; Misra, R.; Wilkins, D. Tetrahedron Lett. 1987, 28, 4211-4214.
13. Chu, G.; Zhang, Y.; Li, C.; Zhang, Y. Synthesis 2009, 22, 3828-3832.
14. Sun, L.; Guo, Y.; Peng, G.; Li, C. Synthesis 2008, 21, 3487-3491.
15. Gao, F.; Zhai, H.; Jin, M.; Chu, G.; Duan, H.; Li, C. Synthesis 2011, 22, 3635-3638.
16. He, Z.; Chen, W.; Ma, F.; Zhou, Z.; Tang, C. Phosphorus, Sulfur, Silicon Relat. Elem. 1998, 142,
49-55.
17. Lu, Z.; Neverov, A. A.; Brown, R. S. Org. Biomol. Chem. 2005, 3, 3379-3387.
18. Zimmerling, R.; Dimmig, T.; Jaeger, G.; Stroehl, D. Z. Chem. 1990, 30, 372-373.
19. Torii, S.; Tanaka, H.; Sayo, N. J. Org. Chem. 1979, 44, 2938-2941.
20. Lyashenko, Y. E.; Sokolov, V. B. Phosphorus, Sulfur, Silicon Relat. Elem. 1993, 78, 153-159.