Δ2,6-Hexalin-1,5-dione (I) has been prepared from decalin-1,5-dione (III) as follows. The latter substance was converted to the diketal IX(R1 R2 H) which, on bromination with phenyl-trimethylammonium tribromide in tetrahydrofuran, was transformed into the 2,6-dibromo compound IX(R1 R2 Br). Treatment with potassium t-butoxide in t-butyl alcohol gave the diene diketal X, and this substance on