An assembly for opening/closing doors including at least a first wing, a second wing and a mechanism adapted to move the wings from a closing position wherein they lie in a vertical plane, to an opening position wherein they are arranged facing each other and lying onto parallel and substantially horizontal planes, and vice versa. The passage from the closing position to the opening position and vice versa occurs through a synchronized and simultaneous rotary-translating motion of the wings. The mechanism includes first and second kinematic arrangements respectively adapted to move the first and second wings, the kinematic arrangements being separate and distinct, kinematically connected through a mechanism for synchronizing and changing the transmission ratio to impart a differential trajectory to the synchronized motion of the first wing with respect to the second wing during closing and opening.