The Uses of Dimethyl acetylenedicarboxylate

Dimethyl acetylenedicarboxylate (DMAD) is an electron-deficient acetylenic compound having two reactive ester groups. It is a privileged and advantaged molecule, which participates easily and practically in heterocyclization. Due to the presence of two ester electron-withdrawing group, DMAD easily undergoes Michael addition, which is followed by heterocyclization to afford versatile heterocyclic compounds with different ring sizes. DMAD carries out Diels–Alder reactions under mild conditions to give heterocycles, which could not be easily synthesized via conventional heterocyclizations.

Uses

Use of DMAD has opened a precious gateway to synthesize some important fused-ring heterocyclic systems that are neither readily obtained by alternative paths nor by using commercially available starting materials.

Dimethyl acetylenedicarboxylate is a di-ester in which the ester groups are conjugated with a C-C triple bond. As such, the molecule is highly electrophilic, and is widely employed as a dienophile in cycloaddition reactions, such as the Diels-Alder reaction. It is also a potent Michael acceptor.This compound exists as a colorless liquid at room temperature. This compound was used in the preparation of nedocromil.

Preparation

Although inexpensively available, DMAD is prepared today as it was originally. Maleic acid is brominated and the resulting dibromosuccinic acid is dehydrohalogenated with potassium hydroxide yielding acetylenedicarboxylic acid. The acid is then esterified with methanol and sulfuric acid as a catalyst.