Highly efficient two-step selective synthesis of 2,6-dimethylnaphthalene

2,6-Dimethylnaphthalene (2,6-DMN), a key raw material for poly(ethylene naphthalate) (PEN), was selectively synthesized via a two-step process in an overall 66% yield from commercially available 4-bromotoluene and 3-methyl-3-buten-1-ol. The ligand-free Heck reaction of the starting materials produced γ-(p-tolyl)-substituted aldehyde that was cyclized with an acid to give 2,6-DMN after in situ oxidation. No other isomers of 2,6-DMN were found.