Using microwave irradiation and EPZG® catalyst showed the formation of diacetylation product. See
---Microwave assisted acylation of methoxyarenes catalyzed by EPZG® catalyst
Eva Veverková, Mária Meciarová, Battsengel Gotov and tefan Toma, Green Chem., 2002,4, 361-365
Also see
---First Friedel--Crafts Diacylation of a Phenanthrene as the Basis for an Efficient Synthesis of... Paruch, Kamil; Katz, Thomas J.; Incarvito, Christopher; Kin-Chung Lam; Rhatigan, Brian; Rheingold, Arnold L. Journal of Organic Chemistry. 2000, 65, 7602.