RSS-Feed abonnieren
Bitte kopieren Sie die angezeigte URL und fügen sie dann in Ihren RSS-Reader ein.
https://www.thieme-connect.de/rss/thieme/de/10.1055-s-00000131.xml
Synfacts 2007(6): 0579-0579
DOI: 10.1055/s-2007-968581
DOI: 10.1055/s-2007-968581
Synthesis of Heterocycles
© Georg Thieme Verlag Stuttgart · New York
Synthesis of 2H-Benzopyran via Electrophilic Cyclization
S. A. Worlikar, T. Kesharwani, T. Yao, R. C. Larock*
Iowa State University, Ames, USA
Weitere Informationen
Publikationsverlauf
Publikationsdatum:
22. Mai 2007 (online)
Significance
A general synthesis of benzopyrans from propargylic aryl ethers triggered by electrophilic cyclization using inexpensive electrophiles such as I2, ICl and PhSeBr is reported. The reactions proceed under mild conditions tolerating a small range of substituents in both coupling partners. Starting propargylic ethers are conveniently available from phenols; the product benzopyrans incorporate a handle, R5 = I for further chemistry. The cyclization undoubtedly proceeds by the formation of iodonium or selenonium intermediates followed by electrophilic attack from the electron-rich aromatic ring. Interestingly, the cyclization occurs in a 6-endo-dig mode.