Q20 · CSIR-NET Chemistry, December 2015

Paper: CSIR-NET December 2015 · Subject: Organic Chemistry · Chapter: Reagents, Reaction Mechanisms & Named Reactions · Topic: Reagents, Reaction Mechanisms & Named Reactions – General · Marks: 2 · Difficulty: Hard

The major structures of A and B in the following reaction sequence are Question structure 1 of 9, ABC26OR0279 Question structure 2 of 9, ABC26OR0279 Question structure 3 of 9, ABC26OR0279 Question structure 4 of 9, ABC26OR0279 Question structure 5 of 9, ABC26OR0279 Question structure 6 of 9, ABC26OR0279 Question structure 7 of 9, ABC26OR0279 Question structure 8 of 9, ABC26OR0279 Question structure 9 of 9, ABC26OR0279
(a)Option (a) structure 1 of 4, ABC26OR0279 Option (a) structure 2 of 4, ABC26OR0279 Option (a) structure 3 of 4, ABC26OR0279 Option (a) structure 4 of 4, ABC26OR0279
(b)Option (b) structure 1 of 4, ABC26OR0279 Option (b) structure 2 of 4, ABC26OR0279 Option (b) structure 3 of 4, ABC26OR0279 Option (b) structure 4 of 4, ABC26OR0279
(c)Option (c) structure 1 of 4, ABC26OR0279 Option (c) structure 2 of 4, ABC26OR0279 Option (c) structure 3 of 4, ABC26OR0279 Option (c) structure 4 of 4, ABC26OR0279
(d)Option (d) structure 1 of 3, ABC26OR0279 Option (d) structure 2 of 3, ABC26OR0279 B = Option (d) structure 3 of 3, ABC26OR0279
Answer
Answer: A ✓ checked by 4AB · confidence high
Explanation
DCC/DMAP benzoylates the less hindered primary alcohol (A); PDC oxidises the secondary alcohol to the ketone and alumina promotes β-elimination of benzoate, giving the α-methylene ketone (a).

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