For the first time, the [4 + 3] or [2 + 1] annulation of crotonate-derived sulfur ylides with arylidenemalononitrile or arylidene-1H-indene-1,3(2H)-dione is reported using Na₂CO₃ as the base. This protocol is advantageous as it does not require prior preparation of arylidenemalononitrile or arylidene-1H-indene-1,3(2H)-dione substrates, due to the independent participation of the base in the two reactions. This mild, operationally multicomponent process can be employed for the transformation of a wide variety of commercially available aldehydes into the corresponding indeno[1,2-b]oxepine or cyclopropyl acrylate core in moderate to excellent yields under mild conditions.