Iodine-Mediated Aromatization of Himachalenes: Synthesis of Dehydro-7,8-arylhimachalene

Abstract

: Dehydro-7,8-aryl-himachalene is a desired natural benzocycloheptene sesquiterpene found in the essential oil of Atlas cedar (Cedrus atlantica) in minor quantities. Herein, we report a simple and environmentally benign synthesis of this molecule via the aromatization of himachalene mixture (the major constituent of the same oil). : The synthesis of the desired compound has been achieved by iodine/DMSO-mediated aromatization. The synthesized product has been characterized using MS spectrometry and NMR spectroscopy data. : The treatment of the himachalene mixture with iodine led to the formation of dehydro-7,8-arylhimachalene, along with other rearrangement products catalyzed by the hydroiodic acid formed in situ. The use of DMSO as a co-solvent enabled the elimination of the acid formed and the regeneration of iodine. The optimization of the reaction conditions led to the formation of the desired product with a good yield. : The present study highlights the development of a simple and environmentally benign method for the synthesis of a natural benzocycloheptene-based sesquiterpenoid in large quantities in order to explore its biological and chemical properties.