Some unusual reactions in organophosphorus chemistry

Article abstract of DOI:10.1080/10426500212235

Methylenephosphinophosphorane 1 reacts with azides without evolution of nitrogen to give zwitterionic phosphorazide 3 and iminophosphorazide 4, which are in equilibrium to each other; 1 reacts with hexafluoroacetone (HFA) in a different way to give zwitte

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Some Unusual Reactions in Organophosphorus
Chemistry
a
a
a
a
b
I. Shevchenko , V. Andrushko , R. Mikolenko , D. Shakhnin , H. Grützmacher & G.-V.
c
Röschenthaler
a
Institute of Bioorganic Chemistry and Petrochemistry, Kiev, Ukrane
b
ETH-Zentrum, Laboratory of Inorganic Chemistry, Zurich, Switzerland
c
Institute of Inorganic and Physical Chemistry, Bremen, Germany
Version of record first published: 27 Oct 2010.
To cite this article: I. Shevchenko , V. Andrushko , R. Mikolenko , D. Shakhnin , H. Grützmacher & G.-V. Röschenthaler (2002):
Some Unusual Reactions in Organophosphorus Chemistry, Phosphorus, Sulfur, and Silicon and the Related Elements, 177:6-7,
1413-1416
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Phosphorus, Sulfur and Silicon, 2002, Vol. 177:1413–1416
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DOI: 10.1080/10426500290092802
SOME UNUSUAL REACTIONS
IN ORGANOPHOSPHORUS CHEMISTRY
a
a
a
a
I. Shevchenko, V. Andrushko, R. Mikolenko, D. Shakhnin,
b
c
H. Gr u¨ tzmacher, and G.-V. R o¨ schenthaler
Institute of Bioorganic Chemistry and Petrochemistry, Kiev,
a
Ukrane; ETH-Zentrum, Laboratory of Inorganic Chemistry,
b
Zurich, Switzerland; and Institute of Inorganic and Physical
Chemistry, Bremen, Germanyc
(Received July 29, 2001; accepted December 25, 2001)
Methylenephosphinophosphorane 1 reacts with azides without evolu-
tion of nitrogen to give zwitterionic phosphorazide 3 and iminophos-
phorazide 4, which are in equilibrium to each other; 1 reacts with
hexafluoroacetone (HFA) in a different way to give zwitterionic product
0
5
, which may have the ylidic structure 5 . HFA and thio-HFA react anal-
ogously with methylenediphosphines 6 to give corbodiphosphoranes 7.
Reaction of 6 with activated alkenes 9 gives monoylide 10, which is a
useful synthone for the synthesis of fluorosubstituted conjugated triene
1
2 and diylides 13 and 14. Reaction of 10 with TOB gives unusu-
ally stable betaine 15. Reaction of the other activated alkene 16 with 6
unexpectedly gave the unusual zwitterionic compound 17.
Keywords: Hypervalency; phosphorazides; ylides; zwitterions
Among various organophosphorus compounds containing a structural
fragment P CH2 P, those in which a methylene group bridges two
phosphorus atoms with coordination numbers PIII and P are of spe-
cial interest. Such compounds possess unusual chemical properties
accounted for by their ability to add some unsaturated reagents to
the two phosphorus atoms. Each phosphorus atom increases its co-
ordination number by one to give zwitterionic compounds with pos-
itively charged phosphonium and negatively charged phosphorate
centres.
V
We thank the Swiss National Science Foundation and the Deutsche Forschungsge-
meinschaft for the support of this work.
Address correspondence to I. Shevchenko, Institute of Bioorganic Chemistry and
Petrochemistry, Murmanskaya Str. 1, 02094 Kiev, Ukraine.
1
413

1
414
I. Shevchenko et al.
FIGURE 1
Such a type of addition reaction is illustrated, for example, by the
interaction of methylenephosphinophosphorane 1 with isocyanates to
1
give zwitterionic product 2 (Figure 1).
Another interesting example of this kind is the interaction of
methylenephosphinophosphorane 1 with azides. It takes place with-
out evolution of nitrogen to give zwitterionic phosphorazides 3 and
iminophosphorazides 4. In solution these structural isomers are in equi-
librium, the position of which is determined by the electronegativity of
the substituent R. The value of the chemical shift of the phosphorus
atom with the coordination number 5–6 at room temperature is in-
dicative of the position of the equilibrium. When R = C6H5CH2 (a) or
2
C6H5 (b) the equilibrium is almost completely shifted to the zwitteri-
onic phosphorazides 3a (�P = � 154 ppm) or 5b (�P = � 142 ppm), which
can be isolated as a stable crystalline colorless products. With trifluo-
romethylsulfonylazide (R = h), the formation of iminophosphorane 4h
(
�P = � 35 ppm) was observed by nuclear magnetic resonance (NMR)
�
spectroscopy in solution at temperatures below 0 C. With other azides
used the forms 3c–f and 4c–f were registered in P-NMR spectra
simultaneously as common broad signals (for � P) at room tempera-
31
5-6
�
ture or as sharp separate signals at � 50 C.
We reasoned that the reaction of 1 with hexafluoroacetone (HFA)
could give a zwitterionic product analogous to that of 2. However, this

Unusual Reactions in Organophosphorus Chemistry
1415
FIGURE 2
0
3
reaction gave unexpectedly the ylide 5 , which according to the x-ray
data may have an unusual zwitterionic structure 5.
It turned out that this unusual reaction has a more common charac-
ter. For example, methylenediphosphines 6 reacts analogously not only
4
5
with HFA (X = O), but with thio-HFA (X = S) to give carbodiphospho-
ranes 7 (Figure 2). In the latter case (X = S; R = Ph) the carbodiphos-
phorane is unstable and rearranges into ylide 8.
The interaction of methylenediphosphines 6 (R = Alk2N) with
(
CF3)2C CHCN 9 became an interesting continuation of this work,
as 9 can be considered as carbon derivative of HFA or thio-HFA.
In equimolar ratio this reaction gives ylide 10. Further addition of
9
depends on steric hindrance at phosphorus. If R = Me2N, the ex-
pected double ylide 13 can be obtained. If R = Et2N, the reaction
gives conjugated triene 12 and P–F substituted ylide 11. An addi-
tion of HFA to 10 gives the double ylide 14. The oxidation of 10 with
tetrachloro-orthobenzoquinone (TOB) gives the unusual compound 15,
which has a betainic structure with the negatively charged oxygen
atom being situated between the two positively charged phosphorus
atoms.
An unusual result was obtained when we used in this reaction acti-
vated alkene 16, having a carboxymethyl group (Figure 3). This reac-
tion gave unexpectedly zwitterionic compound 17 with two phosphorus
atoms of different coordination numbers and opposite charges. One of
the phosphorus atom of 6 loses its original substituents and transforms

1
416
I. Shevchenko et al.
FIGURE 3
into hexacoordinated state, in which it is connected with one hydrogen
and three fluorine atoms.
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