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Origin of 13C complexation shifts in the adduct formation of 2-butyl phenyl ethers with a dirhodium tetracarboxylate complex

✍ Scribed by Edison Díaz Gómez; Helmut Duddeck

Book ID
102527710
Publisher
John Wiley and Sons
Year
2007
Tongue
English
Weight
228 KB
Volume
46
Category
Article
ISSN
0749-1581

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✦ Synopsis

Abstract

Complexation of the oxygen atom in 2‐butyl phenyl ethers to a rhodium atom of the dirhodium tetracarboxylate Rh^(II)^~2~[(R)‐(+)‐MTPA]~4~(Rh*, MTPA‐H = methoxytrifluoromethylphenylacetic acid ≡ Mosher's acid) deshields an sp^3^‐hybridized ^13^C nucleus directly bonded to the ether oxygen; apparently, the inductive effect of the oxygen is enhanced when it is complexed to the rhodium atom. On the other hand, deshielding complexation shifts of aromatic ipso‐carbons (α‐positioned) are minute but ortho‐ and para‐carbon signals are influenced by the resonance effect of oxygen. This effect can be modulated by further substituents at the benzene ring. In turn, this modulation of the resonance correlates linearly ith the magnitude of the inductive effect exerted on the aliphatic α–carbon atoms. Diastereomeric dispersion effects at ^13^C signals can be observed for most compounds, indicating that enantiodifferentiation is possible in this class of ethers. Copyright © 2008 John Wiley & Sons, Ltd.

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