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JEE Main · 2025 · 22 Jan 2025 · Shift 2 · Biomolecules

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Identify the number of structure/s from the following which can be correlated to D-glyceraldehyde.
Structure A
A
Structure B
B
Structure C
C
Structure D
D
  1. (A)three✓ Correct
  2. (B)two
  3. (C)four
  4. (D)one

Answer: (A)

Solution

A sugar is correlated with D- or L-glyceraldehyde by comparing the configuration at its lowest stereocenter — the carbon adjacent to the terminal — with that of glyceraldehyde itself. If the on that reference carbon points to the right in the standard Fischer projection ( at top, at bottom), the sugar belongs to the D-series; if it points left, it belongs to the L-series, regardless of the configuration at any other stereocenter.

Checking the four Fischer projections given, the hydroxyl on this reference carbon lies on the right-hand side in three of them and on the left in only one.

Three of the four structures carry the D-configuration and can be correlated with D-glyceraldehyde.

JEE Main · 2025 · 22 Jan 2025 · Shift 2 · Single correct option

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