Flow Photochemistry as a Tool for the Total Synthesis of (+)-Epigalcatin.

The first total synthesis of (+)-epigalcatin was completed in a highly stereoselective manner starting from piperonal, 3,4-dimethylbenzaldehyde, and diethyl succinate. l-Prolinol was used as a chiral auxiliary. The crucial step in this procedure involves the construction of the cyclolignan framework by continuous-flow photocyclization of a chiral atropisomeric 1,2-bisbenzylidenesuccinate amide ester.