Organic Letters
Letter
Scheme 2. Synthesis of Various Chiral Oxazoline Ligands
AUTHOR INFORMATION
Corresponding Author
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Author Contributions
†T.X. and Y.M. contributed equally to this work.
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
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We are grateful for financial support from the National 973
Program (2015CB856600), NSFC (21472162), the Fundamen-
talResearch FundsfortheCentral Universities(2013QNA3022),
the “Thousand Youth Talents Plan”.
REFERENCES
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Scheme 3. Plausible Mechanism
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oxazoline intermediate B. Finally, reductive elimination provides
the product and regenerates the Pd(0) species.
In summary, we have developed a direct and practical method
to install a chiral oxazoline unit onto aryl/heteroaryl rings via
palladium-catalyzed C−H functionalization at the 2-positions of
oxazolines with a variety of halides. The simple diphosphine
ligand (dppe) could promote reactions efficiently. Pyridyl
bromides or chlorides with a variety of functionalized groups,
such as imino, free alcohols, and trifluoromethyl, were good
partners and reacted with various oxazolines. Additionally,
various of other heteroaryl halides as well as aryl halides
participated. Vinyl bromide was also a good coupling partner.
The reaction could be easily scaled up to 10 g scale. A plausible
catalytic cycle for this coupling reaction is depicted based on the
deuteration studies. Further studies on this transformation using
base metal catalysts and applications in the new chiral ligand
design are ongoing in our laboratory.
́ ́ ́
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ASSOCIATED CONTENT
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* Supporting Information
TheSupportingInformationisavailablefreeofchargeontheACS
Experimental procedures and characterization data for all
C
Org. Lett. XXXX, XXX, XXX−XXX