Rhenium-catalyzed oxidation of arenes - an improved synthesis of vitamin K-3

2-Methylnaphthalene 1 is oxidized to 2-methyl-1,4-naphthoquinone 2 by virtu e of a new catalyst system in high yields and selectivity. A mixture of aqu eous hydrogen peroxide and acetic anhydride is used as oxidant in the prese nce of methyltrioxorhenium(VII) dissolved in acetic acid as solvent. The co ncentration of acetic acid in the reaction mixture plays a crucial role for the activation of acetic anhydride mediated by methyltrioxorhenium(VII). ( C) 1999 Elsevier Science B.V. All rights reserved.