Olefins derivatives, five-membered ring structure

The expanded capabilities of this catalyst allowed the construction of additional ring systems [44]. A transannular olefin insertion formed a bicyc-lo[3.3.1]nonane structure (Eq. 69). Multiple insertion steps can selectively transform a monocyclic substrate into a propellane derivative (Eq. 70). The catalytic cycle begins at the monosubstituted olefin, followed by the insertion of the remaining double bonds to form five membered rings. 

Nielson1 has correlated the ultra-violet aBsorption spectra and the structure of a/ -unsaturated acids and their derivatives. For alicyclic and acyclic types, each alkyl substituent at the olefinic double bond produces a bathochromic shift of 8—10 m x. For alicyclic acids, an exocyclic double bond produces a bathochromic shift of 5 m/x. A 5 m/x shift is also produced by an endoeyclic double bond in a five- or seven-membered ring. Other factors which shift the Amax in these compounds have also been discussed. The usefulness of the correlation in structural elucidation has been illustrated. 

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