TY  - JOUR
A1  - Christl, Manfred
A1  - Herbert, R.
T1  - Unusual Carbon Shielding Effects of Cyclopropanes and Double Bonds in Strained Bicyclo[3.1.0]hexanes and Cyclopentenes
N2  - Carbon-13 shieldings and one-bond \(^{13}\)C-H coupling constants of bicydo[2.1.1]hexane, bicydo[2.l.l]hex- 2-ene, tricydo[3.1.1.0\(^{2.4}\)]heptane and benzvalene are presented and compared. to the data of related. compounds. H a bicydo[3.1.0]hexane system is part of a rigid skeleton, the cydopropane ring exerts spedfk: 'Y substituent eflects of two ldnds. In the case of the bicyclobexane boat form an upfield shift of the C-3 signal is observed and in tbe esse of the chair form a downfield shift of 15-20 ppm. Compared to the corresponding cydopentanes the double bond in strained cydopentenes causes downfield shifts of the C-4 absorption. 1bis eftect increases witb increasing strain, reaching 8 45.9 ppm maximum in benzvalene. Hence it is tbe only known bicydo[l.l.O]butane baving 8 reversed order of carbon shieldings. The downfield shifts are e:xplained by means of simple orbital interaction schemes.
KW  - Organische Chemie
Y1  - 1979
UR  - https://opus.bibliothek.uni-wuerzburg.de/frontdoor/index/index/docId/4991
UR  - https://nbn-resolving.org/urn:nbn:de:bvb:20-opus-58038
ER  -