7-Methyl- and 7-phenylcyclohepta-1, 3, 5-trienes from benzvalene via 3, 3a, 4, 5, 6, 6a-hexahydro-4, 5, 6-methenocyclopentapyrazoles and tetracyclo[4. 1. 0. 0.0] heptanes

Sigmatropic Rearrangements and Related Processes Promoted by Silver

“…They can be considered as joined cyclopropanes and as such, readily react in the presence of catalytic amount of silver salts. 27,28 Interestingly, combining such fragmentation and rearrangement with hyperconjugative stabilization of the cyclopropylcarbinyl cation when a silyl or comparable substituent at the adequate position allowed the control of reaction course. [22][23][24] Screening and kinetic investigations of these rearrangements suggested that the argento cationic intermediate formed on interaction of silver ion with one cyclopropane unit could further rearrange through ring opening of the second cyclopropane unit, but that the latter depended on the nature of the substituent.…”