Darzens condensation reaction equation

The Darzens condensation, also known as the Darzens reaction or glycidic ester condensation, is a process in which a ketone or aldehyde reacts with an α-halo ester in the presence of a base to yield an α,β-epoxy ester (comm referred to as a "glycidic ester"). This reaction was discovered in 1904 by the French organic chemist Auguste Georges Darzens and is named after him.

The Darzens condensation is a significant reaction for synthesizing α,β-epoxy esters. It holds great importance in organic synthesis as a key method for constructing natural products, pharmaceutical intermediates, and multifunctional compounds containing epoxy structures.

Reagents: Base
Reactants: Aldehyde or ketone, α-halo ester
Product: α,β-Epoxy ester
Reaction type: Nucleophilic addition, condensation reaction

Experimental Tips:

1. This condensation reaction is also applicable to substrates such as α-halo nitriles, sulfoxides, sulfones, sulfoximines, and amides.

2. The epoxy esters generated via the Darzens reaction can serve as crucial intermediates for further transformations into diverse structural compounds. For example, hydrolysis of the ester group followed by decarboxylation can trigger epoxy ring-opening rearrangements to produce corresponding carbonyl compounds. Additionally, under appropriate conditions, the epoxy structure may induce other types of rearrangement reactions, enabling the construction of diverse molecular frameworks. 

  3.In terms of substrate reactivity: For α-halo esters, bromides (Br) are more reactive than chlorides (Cl); aldehydes exhibit higher reactivity compared to ketones.

Reaction Mechanism

Darzens Condensation

Original literature

• Darzens, G. Compt. Rend. (in French). 1904, 139, 1214.

• Darzens, G. Compt. Rend. (in French). 1905, 141, 766.