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Optical activity in remotely perturbed exocyclic s‐ cis ‐butadienes. Preparation and circular dichroism of enantiomerically pure 5,6‐dimethylidene‐2‐norbornyl derivatives
Author(s) -
Sonney JeanMarie,
Vogel Pierre
Publication year - 1980
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19800630431
Subject(s) - chemistry , circular dichroism , 2 norbornyl cation , ketone , cotton effect , absorption (acoustics) , chirality (physics) , diene , stereochemistry , medicinal chemistry , organic chemistry , chiral symmetry , physics , nambu–jona lasinio model , acoustics , quark , natural rubber , quantum mechanics
Optically pure 5, 6‐dimethylidene‐ exo ‐2‐norbornanol ((+)‐ 1 ), acetate ((+)‐ 2 ), p ‐bromobenzenesulfonate ((+)‐ 3 ), 5, 6‐dimethylidene‐ endo ‐2‐norbornanol ((+)‐ 4 ), acetate ((+)‐ 5 ), p ‐bromobenzenesulfonate ((+)‐ 6 ) and 5, 6‐dimethylidene‐2‐norbornanone ((+)‐ 7 ) have been prepared. Their chirality was correlated chemically with that proposed by Mislow et al . for (+)‐benzo‐5‐norbornen‐2‐yl acetate ((+)‐ 14 ). The solution CD. spectra of these remotely perturbed exocyclic s‐ cis ‐butadienes are reported and discussed briefly. Unexpectedly, the β,γ‐unsaturated ketone (+)‐ 7 , for which transannular interaction between the ketone and diene functions was revealed by its UV. absorption spectrum, showed (in isooctane) two weak Cotton effects of opposite sign between 265 and 340 nm.