Q7(d)(ii). Epoxidation, then acid-catalysed ring expansion to a ketone
Complete the following reactions and give the appropriate mechanisms: (diphenylmethylidene)cyclopentane, C₆H₅CO₃H/CHCl₃ → A, H⁺ → B. [structure given in the paper]
Answer in brief
A: the epoxide, 2,2-diphenyl-1-oxaspiro[2.4]heptane. B: 2,2-diphenylcyclohexanone, an isomer of A formed by ring expansion.
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Coversepoxidationperoxy acidepoxide rearrangementring expansionsemipinacol rearrangementMeinwald rearrangement
All parts of Question 7
- 7(a)(i) Schmidt reaction of a cyclohexanone with an alkyl azide5 marks
- 7(a)(ii) Robinson annulation of 2-methylcyclohexane-1,3-dione5 marks
- 7(b) Oxepin: 6π electrocyclic ring closure, then Diels–Alder addition5 marks
- 7(c) Chloromethylation, then Sommelet–Hauser rearrangement5 marks
- 7(d)(i) Iodolactonisation of a cyclopentenylacetic acid5 marks
- 7(d)(ii) Epoxidation, then acid-catalysed ring expansion to a ketone5 marks