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Carbon-13 nuclear magnetic resonance spectra of brominated catechin derivatives: Stereoelectronic effects on chemical shifts

✍ Scribed by E. Kiehlmann; A. S. Tracey

Publisher
John Wiley and Sons
Year
1988
Tongue
English
Weight
736 KB
Volume
26
Category
Article
ISSN
0749-1581

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✦ Synopsis

The "C NMR spectra of 21 catechin derivatives substituted at C-6/C-S by bromine and/or hydrogen and at oxygen by methyl, acetyl and/or hydrogen have been analysed in deuteriated acetone and chloroform. When a methoxy group is flanked by two bulky orrho substituents (6-Br and C4), the M e 0 and ortho/puru ring carbons (C-4a, C-6, C-8) are deshielded owing to steric inhibition of resonance, which permits a distinction between 6-and &substituted catechin methyl ethers. Hindered acetoxy groups do not give rise to this phenomenon.

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