402 J. CHEM. RESEARCH (S), 1999
J. Chem. Research (S),
1999, 402^403y
Phosphorylation of Phenols with Diethyl
Chlorophosphonate on the Surface of Magnesiay
B. Kaboudin*
Inst. for Advanced Studies in Basic Sciences (IASBS), 45195-159, Gava Zang, Zanjan, Iran
Phosphorylation of phenols with diethyl chlorophosphonate on the surface of magnesia is an easy, rapid, safe and
high-yielding reaction.
Surface-mediated solid phase reactions are of growing
interest1 because of their ease of set up and work-up, mild
reaction conditions, rate of the reaction, selectivity, high
yields, lack of solvent and the low cost of the reactions
in comparison with their homogeneous counterparts. As
part of our e¡orts to explore2 the novel utilities of
surface-mediated reactions, here we report a new method
for the phosphorylation of phenols. The synthesis of
phosphate esters is an important objective in organic
synthesis, since they have found wide use in the preparation
of biologically active molecules3 as well as in the reduction
of phenols to aromatic hydrocarbons.4 Mixed phosphonate
As shown in Table 1, o-, m-, p-substituted phenols with
diethyl chlorophosphonate in the presence of magnesia
a¡ord the desired products in excellent yields. These results
clearly show that the reactions seem to be faster with higher
yields when the aromatic part of the phenol molecules carry
electron-withdrawing groups. The reaction also proceeded
with high yields for a- and b-naphthols (products 3i, 3j).
Acidic, neutral, and basic alumina are not as e¡ective as
magnesia and usually give low yields of the corresponding
esters.
Simple work-up, low consumption of solvent, fast
reaction rates, mild reaction condition, good yields, and
selectivity of the reaction make this method an attractive
and a useful contribution to the present methodologies.15
8
esters have been prepared by several methods;5 one of
the best involves the reaction of a dialkyl phosphite with
an alcohol or phenol in the presence of triethyl amine in
carbon tetrachloride.9;10 Other variations have been
13
reported,11
including phase transfer and use of
Experimental
trialkylphosphites with molecular iodine.13 Recently,
phosphorylation of phenols with diethyl cyanophosphonate
in the presence of triethylamine at 0 8C has been reported.14
General.öAll chemicals were commercial products and distilled or
recrystallized before use. IR spectra were measured using a Bruker
Vector 22 spectrometer. 1H NMR spectra were recorded on a Bruker
Avance DPX 250 MHz instrument. Mass spectra were obtained
on GC-MS Shimadzu GP 1000 spectrometer.
We describe here
a
new and easy method for the
phosphorylation
of
phenols with diethyl
1
General Procedure for the Phosphorylation of Phenols with Diethyl
Chlorophosphate on the Surface of Magnesia.öMagnesia (0.3 g)
was added to a mixture of diethyl chlorophosphonate (0.86 ml,
0.006 mol) and the phenol (0.005 mol). This mixture was stirred at
room temperature or 60 8C for 0.25±1 h (Table 1). The solid mixture
was washed with dichloromethane (4 Â 25). The solution was then
washed with a dilute NaOH solution and a saturated sodium chloride
solution and dried over MgSO4. After evaporating of solvent, the
crude product was isolated in a pure state by distillation in vacuo in
85^95% yield.
chlorophosphonate 2 on a magnesia surface without solvent
(Scheme 1). We have found that the reaction of a phenol
with 1.2 equivalents of diethyl chlorophosphonate in the
presence of 1.5 equivalents of magnesia was complete within
1 h. The overall yields of these reactions are given in Table 1.
OH
O
PO (OEt)2
MgO
+
(EtO)2–PO–Cl
The Institute for Advanced Studies in Basic Sciences
(IASBS) is thanked for supporting this work.
X
X
1
2
3
Received, 6th January 1999; Accepted, 17th March 1999
Paper E/9/00183B
Scheme 1
Table 1 Phosphorylation of phenols with diethyl chlorophosphonate in the presence of magnesia
Product
Ar
t/h
Yielda(%)
Product
Ar
t/h
Yielda(%)
3a
3b
3c
3d
3e
Ph
1b
87
90
88
95
90
3f
3g
3h
3i
2,4-Cl2C6H3
m-MeC6H4
o-O2NC6H4
a-C10H7
0.5
1b
90
85
88
85
85
o-ClC6H4
p-MeC6H4
p-O2NC6H4
m-BrC6H4
0.5
0.75b
0.25
0.5
0.5
1b
3j
b-C10H7
1b
a Isolated yield. b Reaction carried out at 60 8C.
References
1
A. Fadel, R. Yefash and J. Salaun, Synthesis, 1987, 37; G.
Rosini, R. Galarini, E. Marotta and R. Righi, J. Org. Chem.,
1990, 55, 781; M. Kodomari, T. Sakamoto and S. Yoshitomi,
J. Chem. Soc., Chem. Commun., 1990, 701; P. J. Kropp, K.
* E-mail: Kaboudin@sultan.iasbs.ac.ir.
y This is a Short Paper as de¢ned in the Instructions for Authors,
Section 5.0 [see J. Chem. Research (S), 1999, Issue 1]; there is
therefore no corresponding material in J. Chem. Research (M).
Kaboudin
