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Q.
Number of the following configurations showing mesoisomerism is _____.
Organic Chemistry – Some Basic Principles and Techniques
Solution:
All compounds have two chiral centers.
(i) has a plane of symmetry $\Rightarrow$ Meso
A plane of symmetry $\Rightarrow$ Meso compound
Odd no. of interchanges produces a different compound which is symmetric.
Hence, this compound is not a meso isomer.
(v) has a plane of symmetry $\Rightarrow$ Meso
Hence, this compound is also not a meso isomer similar to (iv).
Therefore, (i), (ii), (iii) and (v) are meso isomers.