Supramolecular construction of a cyclobutane ring system with four different substituents in the solid state

Methods to form cyclobutane rings by an intermolecular [2+2] cross-photoreaction (CPR) with four different substituents are rare. This research reports a CPR that generates a cyclobutane ring with four different aryl substituents quantitatively, without side products, and without purification. The authors demonstrate how face-to-face stacking interactions of aromatic rings can be exploited in cocrystallization to stack and align unsymmetrical alkenes in CPRs, affording chiral cyclobutanes with up to four different aryl groups via binary cocrystals. The process is expected to be useful for generating chiral carbon scaffolds important in biological compounds and materials science.

Michael A. Sinnwell, Ryan H. Groeneman, Benjamin J. Ingenthron, Changan Li, Leonard R. MacGillivray