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NMR study of 4‐membered rings. VIII —The sign of the four‐bond couplings in adducts of cyclopentenone with vic‐dichloroethylenes
Author(s) -
Bongini A.,
Lamartina L.,
Mondelli R.,
Tagliabue G.
Publication year - 1975
Publication title -
organic magnetic resonance
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0030-4921
DOI - 10.1002/mrc.1270070706
Subject(s) - ring (chemistry) , coupling constant , cyclopentenone , chemistry , adduct , sign (mathematics) , cyclobutane , double bond , cyclobutanone , crystallography , stereochemistry , computational chemistry , physics , polymer chemistry , organic chemistry , mathematical analysis , mathematics , particle physics
The proton spectra of the four stereoisomers prepared by photocycloaddition of 2‐cyclopentenone to cis and trans dichloroethylene have been analysed using tickling and INDOR techniques in order to obtain the sign of the cross‐ring four‐bond coupling constants in the cyclobutane ring. These parameters are correlated with the relative orientation of the protons involved. The complete NMR analysis of the seven‐spin system of the cycloadduct endo ‐7‐phenoxybicyclo[3.2.0]hept‐2‐en‐6‐one has been carried out and all the four‐bond coupling constants have been obtained and discussed. The sign of the cross‐ring coupling in the cyclobutanone ring has been determined.