Article

Stereochemical control in the reduction of 2-chromanols.

Department of Chemistry, 1251 Wescoe Hall Drive, 2010 Malott Hall, University of Kansas, Lawrence, Kansas 66045-7582, USA.
Organic Letters (impact factor: 5.86). 11/2006; 8(21):4711-4. DOI:10.1021/ol061727g pp.4711-4
Source: PubMed

ABSTRACT [reaction: see text] Reduction of C5-substituted 2-hydroxychromans selectively provides 2,4-cis-chromans using large silane reductants and 2,4-trans-chromans using the smaller silane PhSiH(3). The stereochemical outcome has been rationalized on the basis of a Curtin-Hammett kinetic situation arising from hydride delivery to two different conformations of an intermediate oxocarbenium ion. This method provides a powerful way to control the relative stereochemistry of these substructures which are prevalent in bioactive natural products.

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Keywords

2,4-trans-chromans
 
[reaction
 
C5-substituted 2-hydroxychromans
 
Curtin-Hammett kinetic situation
 
different conformations
 
hydride delivery
 
intermediate oxocarbenium ion
 
powerful way
 
stereochemical outcome
 
substructures
 
text] Reduction