The [2+2] cycloaddition of the 1,1-dimethoxyalkenes 1 and the electron-poor alkynes 2 in dry chloroform affords the functionalized 3,3-dimethoxycyclobutenes 3 in good to excellent yields (40-100%). The latter by electrocyclic ring opening give the dienes 4, starting materials to multifunctional compounds such as the esters 5 and the cyclohexenes 6.