NMR study of 4-membered rings. VIII—The sign of the four-bond couplings in adducts of cyclopentenone with vic-dichloroethylenes |
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Authors: | A. Bongini L. Lamartina R. Mondelli G. Tagliabue |
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Abstract: | 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. |
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