Structural dependence on the stereoselective formation of inverted housane in the viscosity-controlled photodenitrogenation of DBH-type azoalkanes

The influence of structural changes on the α parameter, which represents the effective volume involved in molecular reorganizations, has been determined through the viscosity dependence of the stereoselectivity in the photodenitrogenation of the DBH-type azoalkanes 1a–c. The structural variation reveals that the stereoselective formation of housane is not only subject to the frictional impositions exerted by the solvent molecules on the flap motion of the methylene bridge, but also on the displacement of the bridgehead substituents during the inversion process.