Valine sulfonamidecinnamic acid asymmetric crystal reactions.

Racemic and homochiral valine sulfonamidecinnamic acids crystallize with components aligned by use of the complementary features of hydrogen bonds and molecular topology to give supramolecular dimers. These discrete motifs effectively organize adjacent olefins for UV initiated single-crystal-to-single-crystal [2+2] photodimerization reactions. The racemic crystals produce inversion related cyclobutane products, while the desymmetrized crystalline architectures of the homochiral phase promote asymmetric photodimerization with 90% conversion.