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Synfacts 2015; 11(1): 0088
DOI: 10.1055/s-0034-1379620
Organo- and Biocatalysis
© Georg Thieme Verlag Stuttgart · New York

Asymmetric β-Hydroxylation of Enals Catalyzed by an N-Heterocyclic Carbene

Contributor(s):
Benjamin List
,
Luping Liu
White NA, Rovis T * Colorado State University, Fort Collins, USA
Enantioselective N‑Heterocyclic Carbene-Catalyzed β-Hydroxylation of Enals Using Nitroarenes: An Atom Transfer Reaction That Proceeds via Single Electron Transfer.

J. Am. Chem. Soc. 2014;
136: 14674-14677
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Further Information

Publication History

Publication Date:
15 December 2014 (online)

 
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Key words

N‑heterocyclic carbenes - hydroxylation - single electron transfer

Significance

White and Rovis report an asymmetric β-hydroxylation of alkyl and aryl enals via oxygen transfer from electron-deficient nitro­arenes. The reaction is catalyzed by an N-heterocyclic carbene to furnish the corresponding β-hydroxy esters in moderate to good yields (up to 73%) and with good to excellent enantioselectivities (er up to 96:4).


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Comment

N-Heterocyclic carbenes are powerful catalysts in organic synthesis, with applications in various transformations. In this report, the authors present a novel NHC-catalyzed reaction that proceeds by a radical pathway. A significantly reduced yield of product was observed when the reaction was conducted in the presence of a radical inhibitor. Investigations of the stereoselectivities of the reaction when using cis and trans enals further support the proposed radical mechanism.


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