Diastereoselective photodimerization reactions of chromone-2-carboxamides to construct a C2-chiral scaffold.

Irradiation of three chromone-2-carboxamides with a chiral auxiliary resulted in diastereoselective formation of a C2-chiral anti-HH dimer scaffold. Selection of the solvent polarity and decreasing the temperature resulted in asymmetric induction with up to 84% diastereomeric excess (de).