Introduction
<P>Diethyl chlorophosphate [ClP(O)(OEt)
2, DECP] is widely used in the synthesis of vinyl phosphates, which can be prepared
regio- and stereoselectively by phosphorylation of enolate anions generated from the
corresponding ketones under kinetically or thermodynamically controlled conditions.
[
1]
Other important application, include the use of DECP for the phosphorylation of amide
enolates to give α-phosphonoamides.
[
2]
</P><P>Vinyl phosphates can also be synthesized by the Perkow reaction with trialkyl
phosphites, but unlike the above-mentioned method, starting carbonyl compounds must
be α-halo ketones, which are not commercially available and, in some cases very difficult
to be synthesized. Moreover, the nature of the halogen atom and the reaction temperature
have a crucial effect on the final products, i.e. both formation of vinyl phosphate
and vinyl phosphonate can take place at the same time.
[
1c]
[
3]
</P><P>Phenols are converted to the corresponding aryl phosphate in high yields by
reaction of the phenoxide anion with DECP.
[
4]
This method is more successful in most cases than generating diethyl chlorophosphite
in situ.
[
5]
In this sense, the selective phosphorylation of hydroxyphenols has recently been
performed using DECP.
[
6]
</P><P>On the other hand, the scope of phosphorylation in bioorganic chemistry includes
amine precursors in the synthesis of phosphotriesters employing DECP. This synthetic
strategy would make available some interesting unnatural phosphates derived from naturally
occurring amino sugars, alkaloids and amino acids.
[
7]
This reagent can also be used as a coupling agent in the synthesis of oligonucleoside
phosphorodithionates
[
8]
and in the synthesis of diethylphosphoric anhydride employed in the N-protection of
amino acids.
[
9]
</P><P>For the above exposed reasons, DECP has received added interest as phosphorylating
reagent, in organic and bioorganic chemistry such as: synthesis of structurally specific
olefins,
[
1a]
[
b]
[
10]
synthesis of acetylenes,
[
11]
synthesis of phosphonates
[
12]
and bisphosphonates,
[
13]
selective synthesis of thiol esters,
[
14]
cross-coupling reactions in the presence of various heteroatoms,
[
15]
[
1d]
industrial scale synthesis of vinyl halides,
[
16]
displacement of phosphate as leaving group
[
17]
by an anion (e.g. organotin
[
18]
or tellurolate
[
19]
anions) or by alkyl cuprates.
[
20]
</P><P>DECP is commercially available. It can also be prepared by reaction of diethyl
phosphite with chlorine until the liquid assumed a yellow coloration. Excess of gas
is removed by bubbling dry air through the liquid under reduced pressured. The crude
oil is vacuum-distilled. Yield 80-90%, bp 92 °C/17 mm Hg.
[
21]
</P><P>
Caution! DECP is highly toxic by skin contact. It decomposes if exposed to moisture, and thermal
decomposition may produce toxic fumes of phosphorus oxides and phosphines.</P>
