Q7(d)(i). Iodolactonisation of a cyclopentenylacetic acid
Complete the following reactions and give the appropriate mechanisms: [structure of a cis vinyl-substituted cyclopentenylacetic acid given in the paper], KI–I₂/NaHCO₃ → ?
Answer in brief
Iodolactonisation gives the cis-fused γ-lactone with iodine on the next ring carbon, trans to the lactone oxygen; the vinyl group is unchanged.
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Coversiodolactonisationiodonium ionγ-lactoneanti additionhalolactonisation
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