What is Barbier Weiland Degradation?

The Barbier Weiland Degradation (BWD) provides a mean of stepping down one acidic carbon at a time as follows;

what is barbier weiland degradation?

If ketone is a starting material in a chemical reaction, then BWD steps down two carbon atoms as follows;

barbier weiland degradation in case of ketone

How Barbier Weiland Degradation is used to determine the nature of side chain?

In organic chemistry, BWD is frequently used to determine the nature of the side chain of natural products like cholesterol and ergosterol. These two natural products are common examples in organic chemistry concerning Barbier Weiland Degradation.

This topic also covers the application of Barbier Weiland Degradation in organic chemistry.

v SIDE CHAIN OF CHOLESTEROL:

Cholesterol undergoes the following reactions and oxidized into its fragments;

barbier weiland degradation for cholesterol

Now, apply Barbier Weiland Degradation on the side chain of cholesterol following the above mechanism;

barbier weiland degradation for determining nature of side chain of cholesterol

o Formation of ketone in 4th BWD shows that there is an alkyl group at the alpha carbon of the previous acid, otherwise, the acid will be formed in the 4th BWD’s product

The nature of the side chain has been determined. Now, joining the two fragments will give the structure of cholesterol.

formation of cholesterol

v SIDE CHAIN OF ERGOSTEROL:

Ergosterol is oxidized into following fragments;

barbier weiland degradation for ergosterol

BWD is applied to side chain of ergosterol in following way;

barbier weiland degradation for determining side chain of ergsterol

After determining the nature of side chain of ergosterol, structure of ergosterol can also be determined.

The same method can be applied in determining the nature of the side chain of any natural compound, found in organic chemistry.

v REFERENCE:

· I.L Finar, Organic Chemistry, Volume Two, 1959.

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Friday, June 25, 2021