-Interactions in 1,8-bis(dimethylamino)naphthalene -ketimine cations facilitate [1,5]-hydride shift: selective synthesis of 1,2,3,4-tetrahydrobenzo[]quinazolines.

Selective heterocyclization leading to 1,2,3,4-tetrahydrobenzo[]quinazolines from -ketimines of 1,8-bis(dimethylamino)naphthalene () under acid catalysis has been revealed. In contrast to the rather unreactive ,-dimethylaniline -ketimine, readily undergo this transformation without an additional catalyst. This distinction in the reactivity underscores the importance of the second -NMe group in , which facilitates a [1,5]-hydride shift and the subsequent cyclization. The cascade of -interactions emerging between 1-NMe and 8-NMe groups has been identified as a reason for the catalytic effect: (1) the hydrogen bond in the dication constrains 1-NMe in the desired position providing proximity of reaction centers, (2) the repulsion of the lone pairs of 8-NMe group and unrelaxed 1-NMe group arising right after deprotonation process reduces the Gibbs free energy of activation (ΔG) for the straight hydride shift, and (3) the electrostatic interaction between 8-NMe and the charged NCH group in the intermediate increases the Δ for the reverse hydride shift.