For the below given cyclic hemiacetal (X), the correct pyranose structure is:
Biomolecules · Class 12 · JEE Main Previous Year Question
For the below given cyclic hemiacetal (X), the correct pyranose structure is:
- a
Option a
- b
Option b
- c
Option c
- d✓
Option d
Option d
Step 1: Identifying the Hemiacetal — The cyclic hemiacetal form of a sugar can be represented as a pyranose (six-membered) or furanose (five-membered) ring.
Step 2: Mapping Substituents — By following standard conventions (groups on the right of a Fischer projection go down in a Haworth/pyranose form and vice versa), we map each carbon's substituent.
Step 3: Conclusion — Comparing the orientations of the groups and the group leads to structure (d) as the correct pyranose representation.
Key Point: Structure (d) correctly maintains the stereochemistry of the original open-chain or hemiacetal form.
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