INVESTIGADORES
MARTIN Sandra Elizabeth
congresos y reuniones científicas
Título:
New Approaches to the Preparation of Phosphanes Containing P-Rfn Bonds. Reactivity of RfnI
Autor/es:
MARIO N. LANTERI; SANDRA E. MARTÍN
Lugar:
Los Cocos, Córdoba, Argentina
Reunión:
Conferencia; 9th Latin American Conference on Physical Organic Chemistry (CLAFQO9); 2007
Resumen:
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NEW APPROACHES TO THE PREPARATION OF PHOSPHANES CONTAINING P-Rfn
BONDS. REACTIVITY OF RfnI
Lanteri,
Mario N. and Martín, Sandra E.
Instituto de Investigaciones en Físico Química de
Córdoba (INFIQC), Departamento de Química Orgánica, Facultad de Ciencias
Químicas, Universidad Nacional de Córdoba.
Ciudad Universitaria. 5000 Córdoba-Argentina. e-mail:
mlanteri@mail.fcq.unc.edu.ar
Organofluorine compounds are well-known for displaying unique reactivities
and selectivities. Both, the high electronegativities and the apolarity of
prefluoroorganyl groups give special properties of solubility and a strong
electron withdrawing effect to phosphane ligands. Our work focused on the
development of strategies to obtain phosphanes with perfluoroalkyl groups (Rfn).
Herein, we report our results of two methods. One approach is based on the Pd-catalyzed
cross-coupling reaction with RfnI as electrophiles, and the other is
the photochemical reaction of the ?P3-? ion with RfnI.
Recently, we
have described the Pd-catalyzed cross-coupling reaction of the stannane n-Bu3SnSePh with
perfluoroalkyl iodides.1 To extend the applications of this
methodology, we have studied the cross-coupling reaction of the phosphorus stannane
n-Bu3SnPPh2 (1). The stannane 1 was synthesized by the
reaction of the Ph2P- anion with n-Bu3SnCl.
Afterwards, the Pd-catalyzed cross-coupling reaction of 1 with RfnI was carried out, all in a one-pot procedure. After
oxidation, the reaction afforded the bisphenylperfluoroalkyl phosphane oxide Ph2P(O)Rfn
(5-48%)(eq. 1).
We
evaluated the effect of different additives (CsF and CuI), ligands (Ph3P,
Ph3As, (o-tol)3P,
(o-furyl)3P), solvents and
catalysts to establish the optimal conditions for the coupling reaction and to
explain the reactivity in the catalyzed reaction of these particularly
electrophiles, RfnI.
On the
other hand, it is known that elemental phosphorus reacts with sodium in liquid
ammonia to produce ?P3-? ion which could act as nucleophile. With
aryl halides under irradiation the corresponding symmetrical triarylphosphanes were
obtained.2 Similarly, this ion could be used to react with RfnI
to obtain triperfluoroalkylphosphanes P(Rfn)3, compounds of
interest as a tunable alternative to the
carbon monoxide ligand. We have studied the overtaking of the formation of ?P3-?
and the photochemical reaction of this anion with RfnI to obtain the
phosphanes P(Rfn)3. After oxidation, we have found only 10-20%
of the product P(O)(Rfn)3. Different aspects of the
reaction were explored to account for the reactivity of the ?P3-?
ion and the RfnI.
[1] Bornancini,
E. R.; Alonso, R. A. and Rossi, R. A. J.
Organomet. Chem. 1984, 270, 177-183.
2 Bonaterra, M.;
Martín, S. E. and Rossi, R. A. Tetrahedron
Lett. 2006, 47, 3511-3515.