through the addition of secondary phosphines to alkynes but
with certain limitations, for example, limitations of the substrate
structure, selectivities, and availability of the catalyst.5-7 We
report here a novel hydrophosphination of carbon-carbon
unsaturated bonds with a silylphosphine in the presence of a
cationic rhodium catalyst, yielding a wide variety of alk-
enylphosphines with high regio- and stereoselectivities.
Regio- and Stereoselective Synthesis of
Alkenylphosphines: A Rhodium-Catalyzed
Hydrophosphination of Alkynes Using a
Silylphosphine
Minoru Hayashi,* Yutaka Matsuura, and Yutaka Watanabe
Department of Materials Science and Biotechnology, Graduate
School of Science and Engineering, Ehime UniVersity, 3
Bunkyo-cho, Matsuyama 790-8577, Japan
Silylphosphines offer considerable potential as synthetic
equivalents of phosphines, masked phosphines, or phosphides,
for the synthesis of several organophosphorus compounds.8-10
However, catalytic reactions of silylphosphines, especially
transition-metal-catalyzed reactions with cleavage of silicon-
phosphorus bonds, are still limited.10 Thus, we first surveyed
suitable catalysts for the addition of a silylphosphine to a
carbon-carbon triple bond via activation of the silicon-
phosphorus bond. The reactivity of each catalyst was evaluated
by using the reaction of (tert-butyldimethylsilyl)diphenylphosphine
1a and ethynylbenzene 2a in benzene under reflux (Table 1).
Several catalysts such as Ru(0), Ru(II), Rh(I), Pd(0), Pd(II),
and Ir(I) complexes, with or without additives or external
ligands, were used in an attempt to realize the coupling
reaction.11 Among the tested catalysts, only cationic rhodium
catalysts, generated by adding AgOTf to chlororhodium com-
plexes, worked as expected to give the corresponding adduct.
ReceiVed August 22, 2006
A novel rhodium-catalyzed hydrophosphination of alkynes
using a silylphosphine as a phosphino group source is
described. A variety of alkynes, both terminal and internal
ones with aryl, alkyl, and carboxyl groups, gave the
corresponding alkenylphosphines in a highly regioselective
and syn-selective manner. Alkenes with an electron-
withdrawing group also gave the corresponding adducts in
good yields.
Surprisingly, the silyl group did not incorporate into the
adduct at all; instead, protodesilylated product 3a was solely
(5) (a) Wicht, D. K.; Glueck, D. S. In Catalytic Heterofunctionalization;
Togni, A., Gru¨tzmacher, H., Eds.; Wiley-VCH: Weinheim, 2001; Chapter
5. (b) Delacroix, O.; Gaumont, A. C. Curr. Org. Chem. 2005, 9, 1851-
1882. (c) Alonso, F.; Beletskaya, I. P.; Yus, M. Chem. ReV. 2004, 104,
3079-3159.
Organophosphorus compounds have received much attention
because of their essential role in various fields of chemistry,
especially when used as ligands in transition-metal catalysis.
Although a variety of sophisticated phosphine ligands have been
prepared for several kinds of catalytic reactions with high
reactivity and/or selectivity, the preparation of these well-
designed phosphorus compounds depends heavily on the clas-
sical phosphination methods using highly reactive organometals
under extreme conditions or on the indirect oxidation-reduction
processes through P(V) derivatives.1 Although alkenylphos-
phines are a promising class of organophosphorus compounds
both as synthetic reagents2 and as ligands, their use is quite
limited mainly because of the difficulties in their synthesis when
using the methods mentioned above.3,4 Some recent reports have
described straightforward preparations of alkenylphosphines
(6) Ni- and Pd-catalyzed hydrophosphination: (a) Kazankova, M. A.;
Efimova, I. V.; Kochetkov, A. N.; Afanas’ev, V. V.; Beletskaya, I. P. Russ.
J. Org. Chem. 2002, 38, 1465-1474. (b) Kazankova, M. A.; Efimova, I.
V.; Kochetkov, A. N.; Afanas’ev, V. V.; Beletskaya, I. P.; Dixneul, P. H.
Synlett 2001, 497-500. Co-catalyzed hydrophosphination, see: ref 4. Ru-
catalyzed hydrophosphination: (c) Je´roˆme, F.; Monnier, F.; Lawicka, H.;
De´rien, S.; Dixneuf, P. H. Chem. Commun. 2003, 9, 696-697. Yb-catalyzed
hydrophosphination: (d) Komeyama, K.; Kobayashi, D.; Yamamoto, Y.;
Takehira, K.; Takaki, K. Tetrahedron 2006, 62, 2511-2519. (e) Takaki,
K.; Komeyama, K.; Kobayashi, D.; Kawabata, T.; Takehira, K. J. Alloys
Compd. 2006, 408-412, 432-436. (f) Komeyama, K.; Kawabata, T.;
Takehira, K.; Takaki, K. J. Org. Chem. 2005, 70, 7260-7266. (g) Takaki,
K.; Koshoji, G.; Komeyama, K.; Takeda, M.; Shishido, T.; Kitani, A.;
Takehira, K. J. Org. Chem. 2003, 68, 6554-6565. (h) Takaki, K.; Takeda,
M.; Koshoji, G.; Shishido, T.; Takehira, K. Tetrahedron Lett. 2001, 42,
6357-6360.
(7) Addition of phosphine-borane to alkynes: Mimeau, D.; Gaumont,
A.-C. J. Org. Chem. 2003, 68, 7016-7022.
(8) For a review, see: Fritz, G.; Scheer, P. Chem. ReV. 2000, 100, 3341-
3401.
(1) (a) Clarke, M. L.; Williams, M. J. In Organophosphorus Reagents;
Murphy, P. J., Ed.; Oxford University Press: New York, 2004; Chapter 2.
(b) Gilheany, D. G.; Mitchell, C. M. In The Chemistry of Organophosphorus
Compounds; Hartley, F. R., Ed.; John Wiley and Sons: Chichester, U.K.,
1990; Vol. 1, pp 151-190.
(2) Alkenylphosphines are reported as versatile synthetic intermediates
for dienes via the Wittig type reaction, see: Ohmiya, H.; Yorimitsu, H.;
Oshima, K. Angew. Chem., Int. Ed. 2005, 44, 2368-2370.
(3) Synthesis of alkenylphosphines by the uncatalyzed addition of lithium
diphenylphosphide to phenylacetylene, see: Aguiar, A. M.; Archibald, T.
G. Tetrahedron Lett. 1966, 5471-5475.
(4) Catalytic addition of P(V)-H to alkynes, see: (a) Han, L.-B.; Tanaka,
M. Chem. Commun. 1999, 395-402. (b) Tanaka, M. Top. Curr. Chem.
2004, 232, 25-54.
(9) (a) Hayashi, M.; Matsuura, Y.; Watanabe, Y. Tetrahedron Lett. 2005,
46, 5135-5138. (b) Hayashi, M.; Matsuura, Y.; Watanabe, Y. Tetrahedron
Lett. 2004, 45, 9167-9169. (c) Hirano, K.; Yorimitsu, H.; Oshima, K. Org.
Lett. 2004, 6, 4873-4875. (d) Kolodiazhnyi, O. I.; Guliaiko, I. V.;
Kolodiazhna, A. O. Tetrahedron Lett. 2004, 45, 6955-6957.
(10) Transition-metal-catalyzed reaction of silylphosphines (a) Pd-
catalyzed cross-coupling with aryl halides: Tunney, S. E.; Stille, J. K. J.
Org. Chem. 1987, 52, 748-753. (b) Ni-catalyzed cross-coupling with
alkenyl halides: Kazankova, M. A.; Chirkov, E. A.; Kochetkov, A. N.;
Efimova, I. V.; Beletskaya, I. P. Tetrahedron Lett. 1999, 40, 573-576. (c)
Yb-catalyzed silylphosphination of alkynes: see ref 6e.
(11) The metal complexes with higher oxidation numbers were expected
to be reduced since the Pd(II) complexes were reported to be reduced to
Pd(0) by the reaction with a silylphosphine.10a
10.1021/jo061739f CCC: $33.50 © 2006 American Chemical Society
Published on Web 11/01/2006
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