Q9 · CSIR-NET Chemistry, June 2017

Paper: CSIR-NET June 2017 · Subject: Organic Chemistry · Chapter: Reagents, Reaction Mechanisms & Named Reactions · Topic: Reagents, Reaction Mechanisms & Named Reactions – General · Marks: 2 · Difficulty: Medium

Under review — part of this question (a structure or an option) is not clear in the source scan. 4AB is checking it against the original book; the answer shown may change.
The intermediate A and product B formed in the following sequence are: Question structure 1 of 12, ABC26OR0332 Question structure 2 of 12, ABC26OR0332 Question structure 3 of 12, ABC26OR0332 Question structure 4 of 12, ABC26OR0332 Question structure 5 of 12, ABC26OR0332 Question structure 6 of 12, ABC26OR0332 Question structure 7 of 12, ABC26OR0332 Question structure 8 of 12, ABC26OR0332 Question structure 9 of 12, ABC26OR0332 Question structure 10 of 12, ABC26OR0332 Question structure 11 of 12, ABC26OR0332 Question structure 12 of 12, ABC26OR0332
(a)Option (a) structure 1 of 2, ABC26OR0332 Option (a) structure 2 of 2, ABC26OR0332 $\ominus 0$
(b)Option (b) structure 1 of 2, ABC26OR0332 Option (b) structure 2 of 2, ABC26OR0332
(c)A =
(d)Option (d) structure, ABC26OR0332
Answer
Under review — not yet confirmed.
Answer: D

The source book printed no answer; this one was worked out and checked — see the explanation.

Explanation
DCC couples the acid with N-hydroxypyridine-2-thione to the Barton ester A (an O-acyl thiohydroxamate). Bu₃SnD/AIBN then decarboxylates it to the alkyl radical, which takes D to give an epimeric C–D mixture (d).

Study loop for Reagents, Reaction Mechanisms & Named Reactions

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