References and Notes
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Preparation of
Thiophosphates 1a-i Represented by the Preparation of O
,
O-
Diethyl 6-Bromo-2-(diethoxythio-phosphinyl)-4-methylphenylthiophosphonate (1g): A solution of the phenolic derivative 2c (3.70 g, 8.85 mmol), triethylamine (1.48
mL, 10.6 mmol, 1.2 equiv) and DMAP (0.108 g, 0.88 mmol, 0.1 equiv)
in THF (36 mL) was slowly added (15 min) to a solution of O,O-diethylchlorothio-phosphate
(1.67 g, 8.85 mmol) in THF (10 mL). The solution was then stirred
overnight. The obtained suspension was filtered on celite and washed
with Et2O. The filtrate was concentrated and redissolved
in Et2O (80 mL). The organic phase was washed with H2O
(2 × 20 mL) and brine (15 mL), dried over MgSO4,
filtered and concentrated. The obtained crude product was purified
by column chromatography over silica gel (70-230 mesh;
pentane-EtOAc, 100:5) to produce 1g (87% yield)
as a colorless solid; mp 81 ˚C. ¹H
NMR (300 MHz, CDCl3): δ = 1.33, 1.40
(2 × t, ³
J
HH = 7.0
Hz, 12 H, CH
3CH2O),
2.34 (s, 3 H, Me), 4.14, 4.31 (2 × m, 8 H, CH3CH
2O), 7.57 (d, 5
J
HP = 1.8 Hz, 1 H,
H5), 7.92 (d, ³
J
HP = 19.0
Hz, 1 H, H3). ³¹P (81.03 MHz, CDCl3): δ = 62.2
(d, 4
J
PP = 2.7
Hz), 83.5 (d, 4
J
PP = 2.7
Hz). ¹³C (75.48 MHz, CDCl3): δ = 16.0
(m, CH2
CH3), 20.7
(s, Me), 63.3 (d, ³
J
HP = 5
Hz, OCH2CH3), 65.2
(m, OCH2CH3), 117.6
(dd, ³
J
CP = 12 Hz, ³
J
CP = 5 Hz, CBr),
127.6 (dd, ¹
J
CP = 143
Hz, ³
J
CP = 5
Hz, CArP), 136.0-136.42 (m, 2 × CAr),
139.0 (s, CArH), 147.3 (m, CArO). IR (neat):
709, 735, 790, 889, 927, 966, 1018, 1245, 1432, 2979 cm-¹.
Anal. Calcd for C15H25BrO5P2S2:
C, 36.67; H, 5.13; S, 13.05. Found: C, 36.74; H, 5.10; S, 13.02.
<A NAME="RD24208ST-14">14</A>
Synthesis of Thiophosphonate
2-2i from Thiophosphate Represented by the Preparation
of O
,
O
-Diethyl 6-Hydroxy-2-pyridinylthiophosphonate (2f):
n-Butyllithium
(1.5 M in n-hexane, 2.25 mL, 3.38 mmol,
1.1 equiv) was added dropwise to a solution of 1f (1
g, 3.07 mmol) in THF (10 mL) previously cooled to -78 ˚C.
At the end of the addition, the solution was left to warm slowly. Then
an aqueous solution of ammonium chloride was added (10 mL). The
aqueous phase was extracted with Et2O (3 × 30 mL).
The combined organic phases were washed with H2O and
dried over MgSO4. After filtration and concentration
the crude product was purified by column chromatography over silica
gel (PE-EtOAc, 5:1) to produce the pure compound 2f as a white solid in 85% yield;
mp 70 ˚C. ¹H NMR (300 MHz, CDCl3): δ = 1.37
(t, ³
J
HH = 7.0
Hz, 6 H, OCH2CH
3),
4.26 (m, 4 H, OCH
2CH3),
7.31 (dd, ³
J
HH = 7.0
Hz, ³
J
HP = 1.0
Hz, 1 H, C4-H), 7.36 (m, 1 H, C5-H), 8.34 (dt, ³
J
HH = 5.0 Hz, 4
J
HP = 1.0 Hz, 1 H,
C6-H), 9.65 (s, 1 H, OH). ³¹P NMR (81.03 MHz,
CDCl3): δ = 69.7. ¹³C
NMR (75.48 MHz, CDCl3): δ = 16.0 (d, ³
J
CP = 7 Hz, OCH2
CH3), 63.6 (d, ²
J
CP = 6 Hz, OCH2CH3), 126.4
(d, ³
J
CP = 10
Hz, C4), 128.4 (d, 4
J
CP = 4 Hz,
C5), 135.4 (d, ¹
J
CP = 188
Hz, C2), 141.9 (d, ³
J
CP = 20
Hz, C6), 158.3 (d, ²
J
CP = 27
Hz, C3). Anal. Calcd for C9H14NO3PS:
C, 43.72; H, 5.71; N, 5.66; S, 12.87. Found: C, 44.19; H, 5.90;
N, 5.30; S, 12.66. HRMS (ES-TOF): m/z
[M + H] calcd
for C9H15NO3PS: 248.0505; found:
248.0510. IR (neat): 953, 1009, 1306, 1455, 1570, 2733, 2927 cm-¹.