M. Yamada et al. / Bioorg. Med. Chem. Lett. 20 (2010) 5943–5946
5945
Table 2
9. Nakamura, S.; Yamashita, M.; Yokota, D.; Hirano, I.; Ono, T.; Fujie, M.; Shibata,
K.; Niimi, T.; Suyama, T.; Kasthuraiah, M.; Asai, K.; Yamashita, J.; Iguchi, Y.;
Substituent effect of R1 and/or R2 at 3- and/or 4-positions of 1-phenyl-2-phospholene
1-oxides (2) on anti-proliferative effect by alkyl group of C-3 position
10. Yamada, M.; Asai, K.; Yamashita, J.; Suyama, T.; Niimi, T.; Kasthuraiah M.; Fujie,
M.; Nakamura, S.; Yamashita, M. Phosphorus, Sulfur, Silicon Relat Elem, in press.
11. General procedures and methods: TLC (Silica gel: Wako Chromato Sheet and/or
Merk Kieselgel 60; Eluent: CHCl3/MeOH = 20:1, in Rf value); Melting point
apparatus (Gallenkamp, in °C); MS (MALDI-TOF-MS: GL Science (Voyager-DE
Compound 2
Substituents at 3- and/or 4-position
IC50 (lM)
R1
R2
2a
2b
2c
H
H
>1000
900
350
Porimerix); Matrix: a-cyano-4-hydroxycinnamic acid, in m/z); IR (JASCO FT/IR
CH3
CH3
H
CH3
410 (KBr), in cmꢀ1); 1H NMR (JEOL JNM-AL300 (300 MHz); solvent: CDCl3, in d
(ppm)); and HPLC (JASCO and GL Science HPLC apparatuses, in tR) were used
for analyzing the products.
12. Preparation of 2-phospholenes 2: Synthesis of 3,4-dimethyl-1-phenyl-2-
phospholene 1-oxide (2c): 2,3-dimethyl-1,3-butadiene 10 ml (90 mmol;
1.0 equiv) and phenylphosphonous dichloride 16 ml (120 mmol; 1.30 equiv)
were mixed and reacted at room temperature for 2 weeks. The formed solid
3,4-dimethyl-1-phenyl-2-phospholenium dichloride was dissolved in
chloroform (200 ml) and hydrolyzed at 0 °C by addition of ice. The reaction
mixture was neutralized with sodium hydrogencarbonate and then filtered
and extracted with chloroform (20 ml ꢁ 3). The chloroform extract was
washed with water (50 ml), saturated sodium hydrogencarbonate solution
(50 ml), and saturated sodium chloride solution (50 ml). Drying over the
chloroform extract with anhydrous sodium sulfate followed by filtration,
evaporation of the solvent in vacuo, and distillation under the reduced
pressure afforded 3,4-dimethyl-1-phenyl-2-phospholene 1-oxide (2c, 5.6 g) in
30% yield. Bp: 130–132 °C/0.12 mmHg; Rf = 0.30 (CHCl3/MeOH = 20:1); 1H
NMR (CDCl3, 300 MHz) d = 1.24–1.37 (dd, 3H, C4–CH3), 1.80 (s, 3H, C3–CH3),
2.07–2.17 (ss, 1H, C4), 2.67–2.93 (m, 2H, C5), 5.89–5.97 (dd, 1H, C2), 7.48–7.75
(m, 5H, Ph) MALDI-TOF mass: m/z 205.7 (MH+, 50), 207.7 (MH+, 100); HPLC
(Wakosil 5SIL, CHCl3/MeOH = 20:1, flow rate 0.5 mL/min, k = 254 nm);
tR = 11.04 min.
Table 3
Substituent effect of R1 and/or R2 at 3- and 4-positions of 4-bromo-1-phenyl-2-
phospholene 1-oxides (3) on anti-proliferative effect by alkyl group of C-3 position
Compound 3
Substituents at 3- and/or 4-position
IC50 (lM)
R1
R2
3a
3b
3c
3d
H
CH3
H
H
>1000
87
CH3
CH2CH3
CH3
H
5.6
>1000
tion at the half of the absorbance intensity (IC50) against U937 cells
are shown in Tables 2 and 3. Tables 2 and 3 show that 4-bromo
substituent remarkably enhances the anti-leukemia activity.
Table 2 shows that 3,4-dimethyl-2-phospholene 1-oxide (2c) has
Similarly, 1-phenyl-2-phospholene 1-oxide (2a) and 3-methyl-1-phenyl-2-
phospholene 1-oxide (2b) were prepared.
1-Phenyl-2-phospholene 1-oxide (2a): Registry number: 703-03-7; Rf = 0.38
(CHCl3/MeOH = 20:1); bp 145–152 °C (0.08 mmHg); 1H NMR (CDCl3, 300 MHz)
d = 2.12–2.21 (m, 2H, C5), 2.78–2.94 (dd, 2H, C4), 6.25–6.36 (dt, 1H, C3), 7.05–
7.23 (dt, 1H, C2), 7.47–7.50 (m, 3H, m, p-Ph), 7.64–7.71 (m, 2H, o-Ph); MALDI-
TOF mass: m/z 179.6 (MH+, 100); HPLC (Wakosil 5SIL, CHCl3/MeOH = 20:1, flow
rate 0.5 mL/min, k = 254 nm); tR = 10.88 min.
3-Methyl-1-phenyl-2-phospholene 1-oxide (2b): Registry number: 707-61-9;
Rf = 0.32 (CHCl3/MeOH = 20:1); bp 148–161 °C (0.10 mmHg); 1H NMR (CDCl3,
300 MHz) d = 2.08 (s, 1H, –CH3), 2.17–2.29 (m, 2H, C5), 2.59–2.83 (dd, 2H, C4),
5.90–5.99 (dd, 1H, C2), 7.43–7.71 (m, 5H, Ph); MALDI-TOF mass m/e 193.7
(MH+, 100); HPLC (Wakosil 5SIL, CHCl3/MeOH = 20:1, flow rate 0.5 mL/min,
k = 254 nm); tR = 10.06 min.
3-Ethyl-1-phenyl-2-phospholene 1-oxide (2d): Under Ar atmosphere, to
tetrahydrofuran dehydrate (THF; 10 ml) solution of iodomethane (0.26 mL,
4.0 mmol, 2.0 equiv) was added n-hexane solution (1.6 mol/l; 2.55 ml,
4.0 mmol, 2.0 equiv) at ꢀ78 °C. After 2 h, 2b (384 mg, 2.0 mmol, 1.0 equiv) in
THF was added, and then the reaction mixture was stirred at ꢀ78 °C for 24 h.
After the completion of the reaction, the reaction mixture was allowed to stand
at room temperature and worked up by washing with 10% hydrochloric acid
(3 ml) and saturated ammonium chloride solution (3 ml), and then dried over
with anhydrous sodium sulfate and rotary evaporated. Purification of the
product through silica gel column (CHCl3/MeOH = 30:1–15:1) afforded 3-
ethyl-1-phenyl-2-phospholene 1-oxide (3; 205 mg, 1.00 mmol) in 50% yield.
a
higher activity than 3-methyl-2-phospholene 1-oxide (2b).
Table 3 shows that 3,4-dimethyl-4-bromo-2-phospholene 1-oxide
(3c) has the highest activity among 3 and 3-methyl derivative 3b is
much more active than 3a and 3d, whose R1 is H and C2H5, respec-
tively. The IC50 value of 3c was 5.6 lM. The observed anti-prolifer-
ative effect of 4-bromo-3,4-dimethyl-1-phenyl-2-phospholene
1-oxide 3c on U937 cells is much more efficient than that of
GleevecÒ (IC50 = 500
lM), which is clinically used as a molecule
targeting chemotherapeutical agent.9,10,16In conclusion, unsatu-
rated phospha sugars and unsaturated deoxybromo phospha
sugars or 2-phospholenes 2a–2c and 3a–3d were prepared. The
novel phospha sugar analogues 3b and 3c exerted anti-prolifera-
tive effect against U937 leukemia cells evaluated by MTT in vitro
methods. Especially 4-bromo-3,4-dimethyl-1-phenyl-2-phospho-
lene 1-oxide 3c, whose 3- and 4-positions were substituted with
methyl groups, possesses quite higher anti-cancer activity than
GleevecÒ (clinically being used against).
Formula:
C12H15OP; Exact Mass: 206.09; Registry number: 848484-65-1;
Rf = 0.29 (CHCl3/MeOH = 20:1); 1H NMR (CDCl3, 300 MHz) d = 2.13 (t, 3H, –
CH2CH3), 2.24–2.26 (m, 2H, C5), 2.38 (m, 2H, –CH2CH3), 2.71–2.86 (m, 2H, C4),
5.93–6.01 (dd, 1H, C2), 7.53–7.74 (m, 5H, Ph); MALDI-TOF mass: m/e 207 (MH+,
100).
Acknowledgements
13. Middlemas, E. D.; Quin, L. D. J. Org. Chem. 1979, 44, 2587.
The authors greatly acknowledge financial supports by the Sa-
tellite Shizuoka and the Headquarters of Japan Science and Tech-
nology Agency (JST) as well as Shizuoka Prefecture Industry
Creating Agency.
14. Preparation of 4-bromo-2-phospholenes 3: 4-Bromo-3,4-dimethyl-1-phenyl-2-
phospholene 1-oxide (3c): To a chloroform (3 ml) solution of 3,4-dimethyl-1-
phenyl-2-phospholene 1-oxide (2c; 206.1 mg, 1.00 mmol, 1.0 equiv) and N-
bromosuccinimide (NBS, 213.6 mg, 1.20 mmol, 1.2 equiv) was added dropwise
a chloroform (3 ml) solution of 2,20-azobisisobutyronitrile (AIBN, 24.6 mg,
0.15 mmol, 0.15 equiv) at 60 °C and the reaction mixture was refluxed for 6 h
under Ar atmosphere. The reaction mixture was neutralized with saturated
NaHCO3 aqueous solution (10 ml), washed with water (10 ml) and saturated
NaCl solution (10 ml), and dried over with anhydrous sodium sulfate. The
solvent of the filtrate was evaporated under a reduced pressure to give an oily
residual material. The residue was purified by column chromatography on
silica gel by using chloroform and methanol (20:1) as the eluent to give 4-
References and notes
1. Yamashita, M.; Yamada, M.; Nomoto, H.; Sugiura, M.; Oshikawa, T. Nippon
Kagaku Kaishi (J. Chem. Soc. Jpn.) 1987, 7, 1207.
2. Yamamoto, H.; Hosoyamada, C.; Kawamoto, H.; Inokawa, S.; Yamashita, M.;
Armour, M. A.; Nakashima, T. T. Carbohydrate Res. 1982, 102, 159.
3. Yamamoto, H.; Hanaya, T.; Kawamoto, H.; Inokawa, S.; Yamashita, M.; Armour,
M. A.; Nakashima, T. T. J. Org. Chem. 1985, 50, 3516.
4. Reddy, V. K.; Haritha, B.; Oshikawa, T.; Yamashita, M. Tetrahedron Lett. 2004, 45,
2851.
5. (a) Shan, M.; O’Doherty, G. A. Org. Lett. 2008, 10, 3381; (b) Sollogoub, M.; Sinay,
P. In Organic Chemistry of Sugars; Levy, D. E., Fugedi, P., Eds.; Taylor & Francis,
2006; p 349.
6. Alam, M. A.; Kumar, A.; Vankar, Y. D. Eur. J. Org. Chem. 2008, 4972.
7. Joseph, B.; Rollin, P. Phosphorus, Sulfur, Silicon 1993, 74, 467.
8. Ito, S.; Yamashita, M.; Niimi, T.; Fujie, M.; Reddy, V. K.; Totsuka, H.; Harutha, B.;
Maddali, K.; Nakamura, S.; Asai, K.; Suyama, T.; Yamashita, J.; Iguchi, Y.; Yu, G.;
Oshikawa, T. Heterocycl. Commun. 2009, 15, 23.
bromo-3,4-dimethyl-1-phenyl-2-phospholene
1-oxide
(3c;
0.089 g,
0.314 mmol) in 31% yield; TLC (Silica gel:Wako Chromato Sheet and/or Merk
Kieselgel 60; Eluent: CHCl3/MeOH = 20:1), Rf = 0.59; MS (MALDI-TOF-MS: GL
Science (Voyager-DE Porimerix); Matrix: a-Cyano-4-hydroxycinnamic acid (m/
z)), 285.3 (MꢀH+); 1H NMR (JEOL JNM-AL300 (300 MHz); solvent: CDCl3, d
(ppm)) = 1.73 (s, 3H, C3–CH3), 1.90–2.31 (m, 2H, C5), 2.21 (s, 3H, C4–CH3),
5.97–6.05 (dd, 1H, C-2), 7.48–7.79 (m, 5H, Ph).
Similar procedure for 3c afforded 3a, 3b, and 3d as follows:
4-Bromo-1-phenyl-2-phospholene 1-oxide (3a): Yield, 26 %; Rf = 0.49 (CHCl3/
MeOH = 20:1); MS (m/z), 285.3(MꢀH+); 1H NMR (CDCl3, 300 MHz),
d
(ppm) = 2.12–2.21(m, 2H, C5), 5.30–5.35 (t, 1H, C4), 6.26–6.37 (dt, 1H, C3),
7.06–7.24 (dt, 1H, C2) 7.48–7.71 (m, 5H, Ph).