Effect upon Structure and Properties

The parallel and perpendicular isomers of trans,trans-bicyclo[6,l,0]non-4-enes (542) and (543) have recently been prepared. The cyclopropyl and olefinic groups are not conjugated yet whereas (543a), like cyclo-octa-1,5-diene, 

Deyrup, M. BetkousH W. Szabo M. Mathew, and G. J. Palenik, J. Amer. Chem. Soc., 

There is already substantial experimental evidence and theoretical justification for electronic interaction between cyclopropyl and carbonyl groups. A charge-transfer band in the vapour-phase u.v. spectra of several cyclopropyl ketones has been detected at ca. 180 nm (s ca. 4000). The circular dichroism of several optically active cyclopropyl ketones, together with conformational analysis based upon n.m.r. spectroscopy results and INDO theory, has been used to extend the octant rule for such compounds.  

The known anisotropic n.m.r. shielding effect of the cyclopropyl group has been used empirically to assign the conformational preferences of cyclopropyl methyl ketone ethyleneacetals. In an attempt to put the shielding effect on a more quantitative level, a a ring-current model has been used. Agreement 

Matsumoto, H. Shirahama, A. Ichihara, H. Shin, S. Kagawa, T. Hisamitsu, T. Kamada, and 

---