Alkynes can act as dienophiles in the Diels-Alder reaction. The reaction between diene and alkyne forms a 1,4-cyclohexadiene.

 
diels-alder-alquinos
 
1,3-Butadiene [1]  reacts with diethyl butynedioate [2]  to form diethyl cyclohexa-1,4-diene-1,2-dicarboxylate [3].
 
diels-alder-alquinos