α-Truxilic Acid of Cinnamic Acid is a photodimer of cinnamic acid, belonging to the truxilic acid family of cyclobutane dicarboxylic acids. It is formed through [2+2] cycloaddition upon UV irradiation of cinnamic acid, resulting in a rigid, cyclic structure. This compound is significant in organic synthesis, pharmaceutical research, and polymer chemistry due to its unique stereochemistry and stability.