Q. 58 E - Organic Chemistry (Mcmurry)

Question

One of the steps in fat metabolism is the hydration of crotonate to yield 3-hydroxybutyrate. This reaction occurs by addition of –OH to the Si face at C3, followed by protonation at C2, also from the Si face. Draw the product of the reaction, showing the stereochemistry of each step.

Step-by-Step Solution

Answer

The product of the reaction and the stereochemistry of each step are shown below.

Step 1: Hydration

Hydration is a chemical reaction that involves adding water to a substance. Water is added to the unsaturated substrate, and it can be alkene or alkyne. For example, when water is added to ethylene, it converts to ethanol.

Step 2: The product of the reaction with the stereochemistry

Every carbon which is has Re and Si face. In crotonate, the upper face is Si, and the lower face is Re. The –OH is added to Si face at C3 of crotonate, followed by the protonation at C2; this is also from the Si face. It results in the formation of (S)-3-Hydroxybutyrate, having an S configuration.

The product of the reaction with the stereochemistry