UPSC Combined Geo-Scientist, Mains · 2020 · Mains Paper III
Q8(a). Robinson annulation
Question
Complete PhCH₂COCH₃ + CH₂=CHCOCH₃ with benzyltrimethylammonium hydroxide in water/ether/dioxane, followed by cyclisation.
Answer in brief
The benzylic Michael adduct cyclises to 3-methyl-4-phenylcyclohex-2-en-1-one.
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CoversRobinson annulationMichael addition and aldol condensation
All parts of Question 8
- 8(a) Robinson annulation10 marks
- 8(b) Benzilic acid rearrangement of phenanthrenequinone10 marks
- 8(c)(i) UV maximum of a bicyclic enone5 marks
- 8(c)(ii) UV maximum of a steroidal tetraene5 marks