On the absolute configuration of chiral 1,4-dihydropyridazines synthesized by organocatalysed reactions

A computational investigation of the specific optical rotation and of the electronic circular dichroism spectra of two chiral 1,4-dihydropyridazines was performed and compared with existing experimental data to verify a previous assignment of their absolute configuration based on a well-accepted mechanism of catalysis of the organocatalyst used in their synthesis. Both the optical rotation and circular dichroism calculations indicate that the absolute configuration is opposite to the one assigned on the basis of the mechanism originally assumed. An alternative reaction mechanism is therefore suggested.