Synthetic Studies on Isoprenoidquinones. I. A Facile Regioand Stereocontrolled Synthesis of Protected Hydroquinones with an Omega-Hydroxyprenyl or Omega-Hydroxygeranyl Side Chain

Regio-and stereocontrolled terminal functionalization of protected 2-prenyl-and 2-geranylhydroquinones (2) was achieved by way of terminal methallylic sulfides (4), which were easily obtained via benzenesulfenyl chloride addition followed by dehydrochlorination or via allylic chlorination with SO2Cl2 followed by sulfenylation, leading to terminal trans-allylic alcohols (5) which are promising intermediates for the synthesis of polyisoprenoidquinones. In this transformation, interesting steric effects of the hydroquinone nucleus with the adjacent arylic methyl group influencing the site-selectivity in the reactions of the isoprenoid side chain were observed.