UPSC Civil Services (Mains), Chemistry optional · 2025 · Paper II
Q3(b)(i). Cyclopropane from tert-butyl chloroacetate and ethyl acrylate
Question
Write the steps involved in the following conversion: tert-butyl chloroacetate + CH₂=CH–CO₂Et with t-BuOK → cyclopropane-1,2-diester. [structures given in the paper]
Answer in brief
The ring forms by Michael addition followed by internal SN2: a Michael-initiated ring closure.
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CoversMichael-initiated ring closureMichael additioncyclopropanation3-exo-tetethyl acrylate
All parts of Question 3
- 3(a)(i) Products of two reactions10 marks
- 3(a)(ii) Ketone A from isobutanol alone5 marks
- 3(b)(i) Cyclopropane from tert-butyl chloroacetate and ethyl acrylate10 marks
- 3(b)(ii) Structures of C and D5 marks
- 3(c)(i) Missing reagents and intermediate10 marks
- 3(c)(ii) Photolysis of the α-diazoketone in methanol10 marks