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Synfacts 2014; 10(1): 0038
DOI: 10.1055/s-0033-1340384
Synthesis of Materials and Unnatural Products
© Georg Thieme Verlag Stuttgart · New York

Quinoxalines Directly from Electron-Deficient Alkynes

Rezensent(en):
Timothy M. Swager
,
Jonathan G. Weis
Okumura S, Takeda Y, * Kiyokawa K, Minakata S. * Osaka University, Japan
Hypervalent Iodine(III)-Induced Oxidative [4+2] Annulation of o-Phenylenediamines and Electron-Deficient Alkynes: Direct Synthesis of Quinoxalines from Alkyne Substrates under Metal-Free Conditions.

Chem. Commun. 2013;
49: 9266-9268
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Publikationsverlauf

Publikationsdatum:
13. Dezember 2013 (online)

 
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Key words

annulation - hypervalent iodine - metal-free reaction - quinoxalines

Significance

The authors report the metal-free oxidative [4+2] annulation of electron-deficient alkynes and ortho-phenylenediamines to synthesize quinoxalines, which are most commonly prepared by condensing diamines with α-diketones. The ­reactions with electron-rich, -neutral, and -poor substrates all proceed with high yield. The synthesis of anhydride 4 demonstrates the utility of this method, as such electron-deficient quinoxalines are challenging to prepare by traditional methods.


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Comment

Initial results with tert-butyl hypoiodite predominately yielded the dearomatized cis,cis-mucononitrile. Phenyliodine diacetate (PIDA) proved to be crucial, despite attempts with several other hypervalent iodine reagents. The reaction is also highly solvent-dependent, proceeding more effectively with increasing solvent polarity.


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