Angewandte
Chemie
mixture was heated for 12 hours in the presence of 0.05 mmol
Anhydrous [Co(acac) ] (26 mg, 0.10 mmol), dioxane (3 mL), and 6-
2
dodecyne (1a, 166 mg, 1.0 mmol) were added successively. The
resulting black mixture was heated at reflux for 2 h. The reaction
was quenched with distilled water (1 mL) after the mixture was
cooled to room temperature and S8 (32 mg, 0.10 mmol) was then
added. The reaction mixture was stirred for 15 min at ambient
temperature and then poured into water. The product was extracted
with ethyl acetate (2 ꢀ 20 mL), the combined organic layers were
of [Co(acac) ] and 0.20 mmol of butyllithium.
2
A variety of alkynes were subjected to hydrophosphina-
tion (Table 1), and all reactions afforded the corresponding
syn adducts exclusively irrespective of the substrates. The
regioselectivity was governed by the steric interactions of the
two alkyne substituents and was generally high in the
reactions of 1. The two resulting regioisomers could be
readily separated from each other by chromatographic
purification on silica gel or fractional crystallization from
acetonitrile. The use of 1-aryl-1-propynes as the substrates
provided 1-aryl-2-diphenylthiophosphinyl-1-propenes pre-
dominantly (entries 3–6). The methoxy substituent at the
ortho position hindered the reaction, although no change in
regioselectivity was observed (entry 6). Hydrophosphination
of terminal alkynes was facile (entries 7–13), and addition
across tert-butylacetylene led to the exclusive formation of 2h
1
dried over sodium sulfate, and the solvent was removed. H NMR
spectroscopic analysis with dibenzyl ether as an internal standard
revealed quantitative formation of the corresponding product 2a.
3
1
Only one signal was detected by P NMR spectroscopic analysis.
Purification of the crude oil by column chromatography on silica gel
(hexane/ethyl acetate, 20:1) provided 2a (341 mg, 0.89 mmol) in 89%
yield.
Received: January 22, 2005
Published online: March 14, 2005
Keywords: alkenes · alkynes · cobalt · phosphines ·
(
entry 8). Propargylamine 1i underwent hydrophosphination
.
regioselectivity
with perfect anti-Markovnikov selectivity although the reac-
tion rate was slow (entry 9). The reaction of aryl acetylenes
afforded modest yields of the alkenylphosphine derivatives
[
1] a) D. K. Wicht, D. S. Glueck in Catalytic Heterofunctionalization
Eds.: A. Togni, H. Grꢁtzmacher), Wiley-VCH, Weinheim, 2001,
chap. 5; b) F. Alonso, I. P. Beletskaya, M. Yus, Chem. Rev. 2004,
04, 3079 – 3159.
(
entries 10–12). Interestingly, an amino moiety did not
interfere with the reaction as much as would be expected
entry 12). Triethylsilylacetylene participated in the hydro-
(
(
1
phosphination to yield primarily a 1-silyl-2-thiophosphanyl-
ethene derivative (entry 13). The use of 1,6-heptadiyne as a
substrate resulted in a complex mixture, and addition to
conjugated diyne and diene compounds, such as 4,6-deca-
diyne and 1,3-undecadiene, led to slow conversion rates, thus
giving the corresponding adducts in no more than 20% yield.
The exact mechanism of this reaction, including the role of the
acac ligand, is not clear at this stage. Further investigation is
necessary to clarify the reaction pathway.
We investigated the utility of the products of the hydro-
phosphination reaction (Scheme 1). The isolated free phos-
phane 4 was treated with iodomethane to produce phospho-
nium salt 5 and then benzaldehyde and 1,8-diazabicyclo-
[2] a) L.-B. Han, M. Tanaka, Chem. Commun. 1999, 395 – 402; b) M.
Tanaka, Top. Curr. Chem. 2004, 232, 25 – 54.
[
3] a) M. R. Douglass, T. J. Marks, J. Am. Chem. Soc. 2000, 122,
824 – 1825; b) M. R. Douglass, C. L. Stern, T. J. Marks, J. Am.
1
Chem. Soc. 2001, 123, 10221 – 10238; c) A. M. Kawaoka, M. R.
Douglass, T. J. Marks, Organometallics 2003, 22, 4630 – 4632;
d) K. Takaki, M. Takeda, G. Koshoji, T. Shishido, K. Takehira,
Tetrahedron Lett. 2001, 42, 6357 – 6360; e) K. Takaki, G. Koshoji,
K. Komeyama, M. Takeda, T. Shishido, A. Kitani, K. Takehira, J.
Org. Chem. 2003, 68, 6554 – 6565; f) K. Takaki, K. Komeyama,
K. Takehira, Tetrahedron 2003, 59, 10381 – 10395.
[
4] M. A. Kazankova, I. V. Efimova, A. N. Kochetkov, V. V. Afana-
sꢂev, I. P. Beletskaya, P. H. Dixneuf, Synlett 2001, 497 – 500.
5] Uncatalyzed addition of lithium diphenylphosphide to phenyl-
acetylene: a) A. M. Aguiar, T. G. Archibald, Tetrahedron Lett.
[
[
5.4.0]undec-7-ene (DBU) were added to the salt. The
1966, 5471 – 5475; addition of phosphane–borane under thermal
reaction mixture was heated for two hours to provide the
and palladium-catalyzed conditions wherein under the former
conditions anti addition resulted and under the latter conditions
Markovnikov adducts resulted: b) D. Mimeau, A.-C. Gaumont,
J. Org. Chem. 2003, 68, 7016 – 7022; transition-metal-catalyzed
addition of tertiary phosphines to alkynes: c) M. Arisawa, M.
Yamaguchi, J. Am. Chem. Soc. 2000, 122, 2387 – 2388.
conjugated diene 6a in good yield with concomitant produc-
[
10]
tion of styrene (30%). The preparation of ylides from 1-
alkenylphosphines and their application to the Wittig reaction
are rather difficult processes and have not been established so
[
11]
far.
The present strategy offers a simple synthesis of
[
6] Base or transition-metal-catalyzed hydrophosphination of acti-
vated alkenes: a) T. Bunlaksananusorn, P. Knochel, Tetrahedron
Lett. 2002, 43, 5817 – 5819; b) M. O. Shulyupin, M. A. Kazan-
kova, I. P. Beletskaya, Org. Lett. 2002, 4, 761 – 763; c) Y.
Hayashi, Y. Matsuura, Y. Watanabe, Tetrahedron Lett. 2004,
conjugated dienes and related p-electron systems.
In summary, we have developed a universally stereo-
selective hydrophosphination reaction of alkynes with diphe-
nylphosphane that is mediated by a cobalt catalyst and
butyllithium. The procedure is simple and scaleable; thus, it is
applicable to the practical synthesis of new ligands and
advanced materials.
45, 9167 – 9169; d) A. D. Sadow, I. Haller, L. Fadini, A. Togni, J.
Am. Chem. Soc. 2004, 126, 14704 – 14705, and references
therein.
[
7] We have been exploring the catalytic activity of cobalt salts:
a) K. Wakabayashi, H. Yorimitsu, K. Oshima, J. Am. Chem. Soc.
2001, 123, 5374 – 5375; b) Y. Ikeda, T. Nakamura, H. Yorimitsu,
K. Oshima, J. Am. Chem. Soc. 2002, 124, 6514 – 6515; c) T. Tsuji,
H. Yorimitsu, K. Oshima, Angew. Chem. 2002, 114, 4311 – 4313;
Angew. Chem. Int. Ed. 2002, 41, 4137 – 4139; ; d) T. Fujioka, T.
Nakamura, H. Yorimitsu, K. Oshima, Org. Lett. 2002, 4, 2257 –
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Experimental Section
A typical procedure for the cobalt-catalyzed hydrophosphination of
alkynes 1a: A solution of diphenylphosphane (186 mg, 1.0 mmol) in
anhydrous THF (1 mL) was placed in a 30-mL flask and butyllithium
(1.6m hexane solution, 0.13 mL, 0.20 mmol) was then added under
argon. The mixture turned orange and was stirred for 30 min at 08C.
Angew. Chem. Int. Ed. 2005, 44, 2368 –2370
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