Organic Letters
Letter
Scheme 4. Plausible Reaction Mechanism in the Presence of
Catalytic Amounts of Et3N, 3, and 4b
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success of this catalytic reaction cycle relies on the extent of
chemoselectivity accomplished at two stages of the cycle via (i)
efficient reduction of 3, thereby preventing the reduction of 1
and 2 catalyzed by 3, and (ii) chemoselective addition of
generated phosphine onto 1 rather than 2 (Table 6, Scheme 3),
leading to efficient generation of furans.
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In summary, we developed a novel protocol to synthesize
highly functionalized furans utilizing catalytic amounts of
phosphine oxide and Et3N under mild conditions. The concept
of recyclable Et3N was employed for the first time in a catalytic
Wittig reaction. An unprecedented activation of phosphine oxide
by silyl chloride and Et3N·HCl for its highly chemoselective
reduction in the presence of acyl chloride and electron-deficient
olefins was achieved. This protocol could prove to be significant
on an industrial scale as it averts the need for using stoichiometric
amounts of phosphine and base. Related work utilizing other
functionalized substrates is underway in our laboratory, and the
results will be published in due course.
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ASSOCIATED CONTENT
* Supporting Information
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S
The Supporting Information is available free of charge on the
Results of the mechanism study, experimental procedures,
characterization data, and spectra for all compounds
AUTHOR INFORMATION
Corresponding Author
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Notes
The authors declare no competing financial interest.
(11) During the reaction progress, corrosion of the needle attached to
the argon inlet was observed, which also indicates release of HCl.
(12) For the detailed experimental study on phosphine oxide
ACKNOWLEDGMENTS
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The authors thank the Ministry of Science and Technology of the
Republic of China (MOST 104-2113-M-003-002-MY3) for
financial support.
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Org. Lett. XXXX, XXX, XXX−XXX