Rahul Sharma

Hagemann's ester

Updated on
Share on FacebookTweet on TwitterShare on LinkedIn
Density  1.08 g/cm³
Hagemann's ester httpsuploadwikimediaorgwikipediacommonsthu

Hagemann's ester, or ethyl-2-methyl-4-oxo-2-cyclohexenecarboxylate, is an organic compound that was first prepared and described in 1893 by German chemist Carl Hagemann. The compound is used in organic chemistry as a reagent in the synthesis of many important natural products including sterols, trisporic acids, and terpenoids.

Contents

Hagemann's approach

Methylene iodide and two equivalents of acetoacetic ester react in the presence of sodium methoxide to form the diethyl ester of 2,4-diacetyl pentane. This precursor is treated with base to induce cyclization. Finally, heat is applied to generate Hagemann's ester.

Knovenagel's approach

Soon after Hagemann, Knovenagel presented the following modified procedure. Formaldehyde and two equivalents of acetoacetic ester undergo condensation in the presence of catalytic piperidine to produce the diethyl ester of 2,4-diacetyl pentane. This precursor is treated with base to induce cyclization. Finally, heat is applied to generate Hagemann's ester.

Newman and Lloyd approach

2-Methoxy-1,3-butadiene and ethyl-2-butynoate undergo a Diels Alder reaction to generate a precursor. The precursor is hydrolyzed to obtain Hagemann's ester. By varying the substituents on the butynoate starting material, this approach allows for different C2 alkylated Hagemann's ester derivatives to be synthesized.

Original

Methyl vinyl ketone, acetoacetic ester, and diethyl-methyl-(3-oxo-butyl)-ammonium iodide react to form a cyclic aldol product. Sodium methoxide is added to generate Hagemann's ester.

Variations

Methyl vinyl ketone and acetoacetic ester undergo aldol cyclization in the presence of catalytic pyrrolidinum acetate or Triton B or sodium ethoxide to produce Hagemann's ester.

References

Hagemann's ester Wikipedia


Similar Topics
Memo Aguirre
Koji Onuma
Ellen Fullman
Topics