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Facile Preparation of (2Z,4E)-Dienamides by the Olefination of Electron-deficient Alkenes with Allyl Acetate
Published on: June 21, 2017
(Diacyloxyiodo)arenes as Versatile Reagents for the Asymmetric α-Acyloxylation of Aldehydes via Enamine Catalysis
Naoya Nishimoto1, Yu Yamaura1, Morifumi Fujita1
1Department of Material Science, Graduate School of Science, University of Hyogo, Kouto, Kamigori, Hyogo 678-1297, Japan.
Abstract:
Enantioselective α-acyloxylation of aldehydes was successfully developed using hypervalent iodine(III) reagents in enamine catalysis. Investigation of various oxidants revealed that 2,6-dichloro(diacetoxyiodo)benzene serves as a highly efficient electrophile for the α-acetoxylation. When combined with a chiral tritylpyrrolidine catalyst, this protocol afforded the desired products with excellent enantioselectivity (up to >99% ee). A significant advantage of this method is its high versatility; various acyloxy groups can be introduced either by employing specific (diacyloxyiodo)arenes or through the in situ ligand exchange of the 2,6-dichloro reagent with the corresponding carboxylic acids.
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