Synthesis of 8-Methylcalamenene and Its Position Isomerst

Abstract

The reaction of 2-methyl-6-xylyl-2-heptanol and 6-methy1-5-xyly1-2-heptanol prepared from m-xylene with the acid catalysts afforded tetralin mixtures consisted of 8-methylcalamenene [6A] and its isomer [7A] as a major product, respectively. By the similar treatment 2-methyl-6-xylyl-2-heptanol and 6-methyl-5-xylyl-2-heptanol prepared from ρ-xylene yielded the tetralin [8A] as a main product. The catalytic hydrogenation of 1, 2-dihydro-4isopropyl-1, 6, 8-trimethylnaphthalene, 3, 4-dihydro-4-isopropyl-1, 5, 7-trimethylnaphthalene, and 3, 4-dihydro-4-isopropyl-1, 5, 8-trimethylnaphthalene afforded the tetralins [6B], [7B]and [8B] as an alone product, respectively.
The trans-configuration are te ntatively assigned to the tetralins [6A], [7A] and [8A]and the cis-configuration to the tetralins [6B], [7B]and [8B].
8-Methylcadalene and two isomeric isopropyltrimethylnaphthalenes were also synthesized.