Desymmetrization

Examples

Typical substrates are epoxides, diols, dienes, and cyclic carboxylic acid anhydrides.

One example is the conversion of cis-3,5-diacetoxycyclopentene to monoacetate. This particular conversion utilizes the enzyme cholinesterase.

In another example, a symmetrical cyclic imide is subjected to asymmetric deprotonation resulting in a chiral product with high enantioselectivity.

Partial hydrogenation converts benzil (PhC(O)C(O)Ph) into chiral hydrobenzoin. The process can be implemented enantioselectively using transfer hydrogenation.

PhC(O)C(O)Ph + H₂ → PhCH(OH)C(O)Ph (Ph = C₆H₅)

The precursor benzil has C_2v symmetry, and the product is C₂ symmetric.

Citric acid is also a symmetric molecule that can be desymmetrized by partial methylation.

The alcoholysis of cyclic anhydrides can be conducted enantiosymmetrically using chiral amine catalysts.

A related example is the hydrolysis of prochiral diesters catalyzed by chiral phosphoric acids.