A Study of the Correlation between the Bulkiness of peri-Substituents and the Distortion of a Naphthalene Ring

A systematic study on the distortion of a naphthalene ring was performed using steric repulsion between peri-substituents at 1- and 8-positions. The introduction bromo groups into methyl 1,8-dimethylnaphthalene enhanced to distort ring. X-ray crystallography revealed that 1,8-bis(bromomethyl)naphthalene had vertical with 11.0° dihedral angle (α) which disturbed coplanarity On other hand, 1,8-bis(dibromomethyl)naphthalene smaller (α = 8.3°) despite bulkier substituents. In this case, horizontal increased. These distortions should non-electronically activate framework. order evaluate their reactivity, nitration hydrogenation were carried out; however, intact under employed conditions. DFT calculation suggested inertness is presumably due negative hyperconjugation (dibromo)methyl group.