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13 C NMR chemical shifts and substituent effects transmission in 1,7,7‐trimethyl‐3‐[( E )‐2′‐arylethenyl]‐2‐oxabicyclo[4.4.0]deca‐3,5‐dienes
Author(s) -
Gandhi R. P.,
Ishar M. P. S.,
Kumar Sudhir
Publication year - 1990
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.1260280304
Subject(s) - substituent , chemistry , chemical shift , aryl , resonance (particle physics) , stereochemistry , carbon 13 nmr , medicinal chemistry , organic chemistry , alkyl , physics , particle physics
13 C NMR chemical shifts were determined for all carbons in a number of 1,7,7‐trimethyl‐3‐[( E )‐2′‐arylethenyl]‐2‐oxabicyclo[4.4.0]deca‐3,5‐dienes [aryl = C 6 H 5 , C 6 H 4 CH 3 ‐ p , C 6 H 4 F‐ p , C 6 H 4 Cl ‐ p , C 6 H 4 Br ‐ p , C 6 H 4 CN ‐ p , C 6 H 4 NO 2 ‐ p , C 6 H 4 OCH 3‐ p , C 6 H 3 (OCH 3 ) 2 ‐ m , p and α‐furyl]. Substituent chemical shift (Δδ 13 C) values for C‐1, C‐3, C‐4, C‐5, C‐6, C‐1′, C‐2′, C‐3′ and C‐4′,8′ were correlated with various Hammett parameters by singleparameter analysis. The correlations revealed that the substituent effects are transmitted across three π‐bonds in conjugation with the aryl ring. Dual‐substituent‐parameter treatment of the substituent chemical shifts revealed that resonance plays a major role in the substituent effect transmission. Hammett parameters were also derived for the α‐furyl substituent.