Chapter 10.6, Problem 14PTS

The bicyclic alkene P can be prepared by thermal electrocyclic ring closure from cyclodecadiene Q or by photochemical electrocyclic ring closure from cyclodecadiene R. Draw the structures of Q and R, and indicate the stereochemistry of the process by which each reaction occurs.

Identify two alkenes that react with HBr to form 1-bromo-1-methylcyclohexane without undergoing a carbocation rearrangement.

Alloocimene is a hydrocarbon found in turpentine. It has the molecular formula C₁0H16 and a UV absorption maximum at 290 nm. On hydrogenation with a palladium catalyst, 2,6-dimethyloctane is obtained. Ozonolysis of alloocimene, followed by treatment with zinc and acetic acid, produces the following four fragments: || CH3C-CH i O || || CH3CCH3 HC-CH Propose a structure for alloocimene. O || CH3CH