QuestionOrganic / pinacol rearrangement
The major product formed in the following reaction is:
- (a) 1-Phenylcyclopentyl phenyl ketone
- (b) 2-Phenylcyclopentyl phenyl ketone
- (c) 2,2-Diphenylcyclohexanone
- (d) 2,6-Diphenylcyclohexanone
Answer: (c)
Ionisation gives the more stable diphenyl-stabilised cation. A ring C–C bond migrates to it (ring expansion 5 → 6), and the ring oxygen becomes C=O → 2,2-diphenylcyclohexanone → (c).