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Published on: August 1, 2018
Synthesis of indoles via 6pi-electrocyclic ring closures of trienecarbamates
Thomas J Greshock1, Raymond L Funk
1Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
Abstract:
A new method for the preparation of indoles from readily available alpha-haloenones and alpha-(trialkylstannyl)enecarbamates is described. Following a Stille coupling, trienecarbamate 2 is electronically activated to undergo a facile 6pi-electrocyclic ring closure and subsequent oxidation to afford protected aniline 4. Upon deprotection and reductive amination, acid 5 underwent clean cyclization to N-acetylindole 6 (Ac2O, NEt3, 130 degrees C). This method has been used to construct a variety of substituted indoles that are not easily prepared by conventional indole annelation methods.
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