3
bromide was observed in the case of 3u. The bromide on arene
could survive from the condition that a benzyl bromide coupled
with acylphosphine in 84% yield.
Funds for the Central Universities (buctrc 201321, PT1613-07)
for their generous support.
References and notes
Table 4. Substrate scope of alkyl chlorides
5 mol% PdCl2(PhCN)2
R
Cl
Bz PPh2
2
R
PPh2
3
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Phosphorus(III) Ligands in Homogeneous Catalysis: Design and
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Cs2CO3, toluene, 80oC
4
P
P
COOEt
Ph
Ph
Ph
Ph
3q 90%
3k 43%
Reaction conditions: 1 (0.48 mmol, 1.2 eq), 2 (0.4 mmol, 1.0 eq),
PdCl2(PhCN)2 (2.5 mol%), Cs2CO3 (0.48 mmol, 1.2 eq), Toluene (0.4
ml), 12h, 80oC in N2. Isolated yield, characterized by phosphineoxide.
The generality of this coupling reaction was further
demonstrated by using alkyl chlorides as substrates (Table 4).
With ethyl chloroacetate and benzyl chloride as the coupling
partners, the product 3k and 3q were obtained in yields of 43%
and 90% under the same reaction conditions of benzyl bromide,
respectively. With normal alkyl chlorides, this coupling did not
react at all.
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(e) Teichert, J. F.; Feringa, B. L. Angew. Chem. Int. Ed. 2010,
49(14), 2486-2528.
PdCl2(PhCN)2
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Chem. 2014, 10, 1064-1096; (b) Kendall, A. J.; Tyler, D. R.
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Püntener, K.; Stürmer, R.; et al. Tetrahedron Asymmetry. 1997,
8(5), 715-738.
COPh
PPh2
Pd(0)
R
Br
4
1
PPh2-COPh
Oxidative
addition
2
6. (a) Katagiri, K.; Danjo, H.; Yamaguchi, K.; et al. Tetrahedron.
2005, 61(19), 4701-4707; (b) Nechab, M.; Gall, E. L.; Troupel,
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Laureano, H.; et al. C. R. Chimie. 2010, 13(8-9), 1213-1226.
7. (a) Hirao, T.; Masunaga, T.; Ohshiro, Y.; et al. Synthesis. 1981,
1981(1), 56-57; (b) Tappe, F. M. J.; Trepohl, V. T.; Oestreich, M.
Synthesis. 2010, 2010(18), 3037-3062; (c) Shao, C.; Xu, W.; Li,
L.; et al. Chin. J. Org. Chem. 2017, 37, 335-348.
Pd(0)
6
COPh
Br Pd PPh2
Reductive
elimination
R
5
Base
Ph2P
R
3
Figure 2. Plausible mechanism
8. (a) Ager, D. J.; Laneman, S. A. Chem. Commun. 1997, 1997(24),
2359-2360; (b) Butti, P.; Rochat, R.; Sadow, A. D.; et al. Angew.
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A plausible mechanism was proposed as shown in Figure 2.
Pd(0) complex
4
generated from PdCl2(PhCN)2 and
acylphosphine 2 would undergo oxidative addition with alkyl
bromide 1 to form intermediate 5. Reductive elimination then
took place on intermediate 5 to reproduce Pd(0) and desired
product 3. The de-acylation process is not clear yet. Pd(0) and
acylphosphine continued to participate in the catalytic cycle, and
the product alkyl substituted phosphine was generated.
10. (a) Yu, R.; Chen, X.; Wang, Z. Tetrahedron Lett. 2016, 57(30),
3404-3406; (b) Yang, J.; Wu, H.; Wang, Z. J. Saudi. Chem. Soc.
2016, 22(1), 1-5.
In summary, we have developed a palladium-catalyzed
C(sp3)–P(III) bond formation reaction for phosphines
preparation. The acylphosphine was used as the phosphorus
source and reacted with various alkyl bromides and limited alkyl
chlorides. Under relative mild and easily accessible condition,
differential alkyl substituted phosphines were afforded in good
yields. This reaction made up the application of palladium
catalysis in challenging C(sp3)–P(III) bond formation. The
performance of acylphosphine in this reaction also indicated the
acylphosphines family could be regarded as a phosphination
reagent in the synthesis of trivalent phosphines.
Supplementary Material
Supplementary data associated with this article can be found,
in the online version, at….
Declaration of interests
x The authors declare that they have no known
competing financial interests or personal
relationships that could have appeared to influence
the work reported in this paper.
Acknowledg
ments
We thank the National Natural Science Foundation of China
(NSFC 21302010, 21571015) and the Fundamental Research