Dimethyl acetylenedicarboxylate (DMAD) is an organic compound with the formula CH3O2CC2CO2CH3.

It 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.

[1][2] This compound exists as a colorless liquid at room temperature.

Although inexpensively available, DMAD is prepared today as it was originally.