A new class of photochromic reactions was investigated as a possible trigger for phase transitions in liquid crystals. Chirochromic compounds have two chiral units. One unit is fixed, and the other can be switched with light. A series of diastereomeric compounds based on ketals and acetals of 1,1’-bi-2-naphthol was prepared. In some cases, the absorption spectra of the diastereomers are measurably different. The ketals do not undergo efficient photoepimerization, apparently because the activation barrier for atropisomerism in their triplet state has increased. However, certain of the acetal derivatives do photoepimerize and are chirochromic. These compounds may be developed into triggers.