Q30 · CSIR-NET Chemistry, December 2019
Paper: CSIR-NET December 2019 · 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.
In the given transformation, the intermediate $[mathrm{A}]$ and the major product B are 
(a)
B = 
B = (b)A = 
B = 
B = (c)
B = 
B = (d)
B = 
B = Answer
Under review — not yet confirmed.
Answer: A
(a) and (c) are drawn almost identically; the mechanism is certain.
Explanation
The copper carbenoid from ethyl diazoacetate is trapped by benzaldehyde oxygen to give the carbonyl ylide [A]; a 1,3-dipolar cycloaddition with a second benzaldehyde gives the 2,4-diphenyl-1,3-dioxolane-5-carboxylate (a).
Study loop for Reagents, Reaction Mechanisms & Named Reactions