Q33 · CSIR-NET Chemistry, December 2019

Paper: CSIR-NET December 2019 · Subject: Organic Chemistry · Chapter: Reagents, Reaction Mechanisms & Named Reactions · Topic: Named Reactions · Marks: 2 · Difficulty: Medium

The structure of A in the following reaction is Question structure 1 of 7, ABC26OR0442 1. i) hv Question structure 2 of 7, ABC26OR0442 Question structure 3 of 7, ABC26OR0442 Question structure 4 of 7, ABC26OR0442 Question structure 5 of 7, ABC26OR0442 Question structure 6 of 7, ABC26OR0442 Question structure 7 of 7, ABC26OR0442
(b)Option (b) structure, ABC26OR0442
(c)Option (c) structure, ABC26OR0442
(d)Option (d) structure, ABC26OR0442
(a)Option (a) structure, ABC26OR0442
Answer
Answer: A ✓ checked by 4AB · confidence medium
Explanation
But-2-ynyl acrylate (a) undergoes intramolecular [2+2] photocycloaddition between the alkyne and the acrylate to give a cyclobutene-fused lactone; ozonolysis cleaves the cyclobutene to a 1,4-diketone and NaOEt aldol condensation closes the cyclopentenone — the bicyclic enone lactone shown, which carries no methyl.

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