complex [Pd](NCMe)(Ph2Pꢀ) (31P{1H} NMR: d ꢀ69.7) could
be generated immediately when equivalent Et3N was added
with characteristic color change. However, the phosphido
complex did not react with the enone at ꢀ80 1C to form the
expected product. Therefore the free phosphines play an
important role in driving the catalytic cycle and the palladium
serves as a Lewis acid both for Ph2PH and enone in this
reaction.
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During the preparation of this manuscript, Duan and
co-workers15 reported a similar hydrophosphination reaction
catalyzed by a pincer palladium complex with phosphine-
oxides as the product.
In conclusion, we have developed a novel palladium(II)
catalyzed asymmetric hydrophosphination of aromatic enones
to prepare chiral tertiary phosphines with high yields and
stereoselectivity. The procedure provides practical direct
access to potentially useful optically pure chiral phosphines.
Further work to design a better catalyst and improve selectivity
as well as extension to other substrates is in progress.
We thank Nanyang Technological University for supporting
this research and for a PhD scholarship to Y. H.
9 P. H. Leung, Acc. Chem. Res., 2004, 37, 169.
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11 For recent selected examples, see: (a) Y. Huang, S. A. Pullarkat,
M. Yuan, Y. Ding, Y. Li and P. H. Leung, Organometallics, 2010,
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13 More details see supporting information.
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I. D. Gridnev and N. Miyaura, Organometallics, 2005, 24, 5025;
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c
6952 Chem. Commun., 2010, 46, 6950–6952
This journal is The Royal Society of Chemistry 2010