New applications of Ph3P=N-Li in organic synthesis and heteroatom chemistry

Article abstract of DOI:10.1080/10426500212281

The lithium triphenylaminophosphonium azayldiide 1 proved again to be a very good tool in organic synthesis, allowing further synthesis of various compounds such as vinyl nitriles, aromatic or heteroaromatic nitriles, and mono-, bis-, and trisphosphinimines.

Full text of DOI:10.1080/10426500212281

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Phosphorus, Sulfur, and Silicon and the Related
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New Applications of Ph 3 P=N--Li in Organic Synthesis
and Heteroatom Chemistry
Marc Taillefer a , Nicolas Rahier a , Ewelina Minta a & Henri-Jean Cristau a
a Laboratoire de Chimie Organique , Montpellier Cedex 5, France
Published online: 27 Oct 2010.
To cite this article: Marc Taillefer , Nicolas Rahier , Ewelina Minta & Henri-Jean Cristau (2002) New Applications of Ph 3
P=N--Li in Organic Synthesis and Heteroatom Chemistry, Phosphorus, Sulfur, and Silicon and the Related Elements, 177:6-7,
1847-1850, DOI: 10.1080/10426500212281
To link to this article: http://dx.doi.org/10.1080/10426500212281
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Phosphorus, Sulfur and Silicon, 2002, Vol. 177:1847–1850
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Copyright 2002 Taylor & Francis
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DOI: 10.1080/10426500290093342
NEW APPLICATIONS OF Ph3P N Li IN ORGANIC
SYNTHESIS AND HETEROATOM CHEMISTRY
Marc Taillefer, Nicolas Rahier, Ewelina Minta,
and Henri-Jean Cristau
Laboratoire de Chimie Organique, Montpellier Cedex 5, France
(Received July 29, 2001; accepted December 25, 2001)
The lithium triphenylaminophosphonium azayldiide 1 proved again to
be a very good tool in organic synthesis, allowing further synthesis of
various compounds such as vinyl nitriles, aromatic or heteroaromatic
nitriles, and mono-, bis-, and trisphosphinimines.
Keywords: Azayldiide; metallated ylide; nitrile; triphosphinimine
INTRODUCTION
As part of our works on metallated ylides showing reinforced nucleo-
philic activity, already illustrated in the case of the diphenylphos-
4
phonium diylides and diazaylides,1
we present here our results
concerning the reactivity and the new applications of a third cate-
gory of this type of ylides: the lithium triphenylaminophosphonium
azayldiide 1.
Ph3P N Li
1
Lithium azayldiide Ph3P NLi 1 was until recently used mainly
in coordination chemistry. It was initially prepared by Schmidbaur,5
but we have developed a method allowing direct one-pot prepara-
tion in large scale, by double deprotonation of the corresponding
aminophosphonium salt, which is obtained from gaseous ammonia and
dibromophosphorane.1,6
We thank le Conseil Re´gional de la Re´gion Languedoc Roussillon for financial support.
Address correspondence to Marc Taillefer, Laboratoire de Chimie Organique, UMR
5076 du C.N.R.S., ENSCM, 8 Rue de l’Ecole Normale, 34296 Montpellier Cedex 5, France.
1847

1848
M. Taillefer et al.
RESULTS AND DISCUSSION
The study of the reactivity of 1 allowed us already to find numer-
ous applications for this compound in organic synthesis.1 For in-
stance, we could develop new methods for the synthesis of (1) amines,
(2) aminophosphonium salts precursors of aminoacids, (3) valuable
precursors for the sulfonamide chemistry, (4) N-alkoxycarbonyl and
N-acyltriphenylphosphinimines, and (5) , -unsaturated nitriles.1,7
More recently, we observed that the diethyl phthalate 4 can be con-
verted into the diphosphinimine 5 via nucleophilic substitutions at the
carbonyl groups,7 the corresponding dinitrile 6 being then obtained by
intramolecular aza-Wittig reaction.
In the case of substituted ethyl benzoates the corresponding nitriles
8 can be obtained chemoselectively in good overall yields (61–90%) with
various functional groups (F, I, CF3, OMe, MeCO, and NO2), wherever
their position on the aromatic ring may be. Only the compounds with
the nitro group in the meta or ortho position give a lower yield (20–28%).
It is noteworthy that the kinetic of the two steps of the nitrile
synthesis are different depending on the nature of the substituents.
The first step, the N-acylphosphinimines 7 formation, is accelerated
by electronwithdrawing substituents and, on the contrary, slowed
down by electron-donating groups. The reverse and stronger effects
are verified for the second step, the intramolecular aza-Wittig re-
action. Accordingly, the synthesis of nitriles from the correspond-
ing esters is all in all favored by electron-donating substituents and
not favored by electron-withdrawing substituents on the aromatic
ring.

New Applications of Heteroatom Chemistry
1849
The method has also been successfuly extended to the one-pot syn-
thesis of a large family of functionalized heteroaromatic nitriles 10.
Inanotherfield, wehave recently performed a systematic study of the
reactivity of Ph3PNLi towards PIII and PIV phosphorus electrophiles.
The results show the possibility of obtaining (one-pot), in very good
yields, a large range of N-substituted phosphinimines, which are valu-
able precursors for the (poly-)phosphazene chemistry. Thus, depend-
ing on the cases, mono-, di-, and also triphosphinimines 11 have been
synthesized. Notice that for a same family of phosphorus electrophiles
(X : S , O , or electronic doublet), the trisubstitution is, as expected,
more difficult to reach than the di- or the monosubstitution. More-
over, for a same number of chlorine on the starting phosphorus
electrophile, the ease of substitution increases in the following order:
ClnP(S)R3 n < ClnP(O)R3
ClnPR3 n. Thus, sulfurated diphosphin-
n
imines were difficult to obtain and the corresponding sulfurated
triphosphinimines impossible to reach. Notice that the triphosphin-
imine (PIII, n = 3) is a very basic compound which is similar to a
Schwesinger’s base.
REFERENCES
[1] H. J. Cristau, Chem. Rev., 94, 1299–1313 (1994).
[2] (a) M. Taillefer, N. Inguimbert, L. Ja¨ger, K. Merzweiler, and H. J. Cristau, Chem.
Commun., 565–566 (1999); (b) M. Taillefer, H. J. Cristau, and I. Jouanin, Synthesis,
69–74 (2001).
[3] (a) M. Taillefer, H. J. Cristau, A. Fruchier, and V. Vicente, Journal of Organometal-
lic Chemistry, 624, 307–315 (2001); (b) H. J. Cristau, I. Jouanin, and M. Taillefer,

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M. Taillefer et al.
Journal of Organometallic Chemistry, 584, 68–72 (1999); (c) M. Taillefer and H. J.
Cristau, Tetrahedron Letters, 39, 7857–7860 (1998); (d) H. J. Cristau and M. Taillefer,
Tetrahedron, 54, 1507–1522 (1998).
[4] L. Ja¨ger, V. Maurizot, C. Wagner, M. Taillefer, and H. J. Cristau, Challenges for
Coordination Chemistry in the New Century, 195–200 (2001).
[5] H. Schmibaur and G. Jonas, Chem. Ber., 100, 1120–1128 (1967).
[6] H. J. Cristau, E. Manginot, and E. Torreilles, Synthesis, 382–384 (1991).
[7] H. J. Cristau, A. Hammami, and E. Torreilles, Heteroatom Chemistry, 10, 49–54
(1999).