Synthesis and NMR spectra of - and -tricyclo[3.2.2.02,4]non-6-ene

Orbital-Controlled Stereoselections in Sterically Unbiased Cyclic Systems

“…A cyclopropyl group is known to act as a strong π donor due to a high-lying occupied Walsh orbital, which is frequently regarded as an equivalent of a double bond. ,− Photoelectron spectra of the olefins 40a and 41a were previously measured and the signals assigned. ,− Vertical ionization potentials of the olefin π orbitals of 40a and 41a were found to be higher than those of the unsubstituted parent bicyclo[2.2.2]octene 35a (R 1 = R 2 = H) and 7-methylenenorbornane 28a (R 1 = R 2 = H), respectively, indicating a sizable interaction of the π orbital of the double bond with the occupied Walsh orbital of the fused cyclopropane ring. The previous account of the observed anti facial preference of 41a was based on this interaction, in particular, out-of-phase interaction of the relevant orbitals ( 4.36 ). − However, the corresponding out-of-phase interaction of the olefinic π orbital with the Walsh orbital of the cyclopropyl group ( 4.35 ) does not seem to be relevant to 40a because of the observed reverse syn preference.…”

Palladium‐Catalyzed Cyclopropanation of Unsaturated Endoperoxides. A New Peroxide‐Preserving Reaction

“…Also the spectra of the known carbocyclic analogs were used to confirm the stereochemical assignments. [8] …”

“…In all cases where the cyclopropane ring syn to the peroxo bridge, the secondary proton syn to the peroxo bridge absorbs downfield (1.2 ppm) whereas it absorbs upfield (0.5 ppm) when it is syn to the ethano bridge, in analogy to the carbocyclic system. [8] Moreover, the tertiary cyclopropane protons syn to the ethano bridge in 12 absorb at 1.17 ppm, the same protons syn to the peroxo bridge absorb at 1.65 ppm in 13 . The endo stereochemistry in the case of 21 was readily established by the fact that the secondary cyclopropane proton syn to the benzene ring absorbs upfield, at −0.9 ppm due to the diamagnetic anisotropy of the aromatic ring.…”

Bromination of exo-Tricyclo[3.2.2.02,4]non-6-ene

“…Preparation of exo -Tricyclo[3.2.2.0 2,4 ]non-6-ene 1. exo -Tricyclo[3.2.2.0 2,4 ]non-6-ene ( 1 ) was synthesized by the literature procedure and the identity confirmed by comparison of the 1 H NMR spectra with that reported. exo -Tricyclo[3.2.2.0 2,4 ]non-6-ene (1): a colorless semisolid; bp 165−168 °C; Lit.…”