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Intramolecular Direct Arylation of 3-Halo-2-pyrones and 2-Coumarins.
- Source :
-
Journal of Organic Chemistry . 11/6/2015, Vol. 80 Issue 21, p10904-10913. 10p. - Publication Year :
- 2015
-
Abstract
- Direct arylation represents a favorable alternative to traditional cross-coupling and has found widespread use with simple aryls and robust heterocycles. Herein a direct arylation protocol has been optimized and applied to 2-pyrones, which are delicate and privileged biological motifs. Regioselective halogenation at the 3-position allows intramolecular coupling by activation of a pyrone C-Br or C-Cl bond and a phenoxy C-H bond. Importantly, electron-poor phenoxy substrates also worked well. The methodology was extended to 2-coumarins and applied to the synthesis of flemichapparin C and a novel analogue. Deuterium isotope effects, typical of a concerted metalation-deprotonation (CMD) mechanism, were observed in the case of a bromopyrone, but a highly unusual, inverse kinetic isotope effect was evident using a chlorocoumarin, implying that a different mechanism is operating. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 00223263
- Volume :
- 80
- Issue :
- 21
- Database :
- Academic Search Index
- Journal :
- Journal of Organic Chemistry
- Publication Type :
- Academic Journal
- Accession number :
- 110909956
- Full Text :
- https://doi.org/10.1021/acs.joc.5b02027