A solution of 19.4 g (0.1 mol) of dimethyl terephthalate and 23 g (0.1 mol) of 6-acetyl-1,2,3,4-tetrahydro-1,1,4,4-tetramethylnaphthalene in 80 ml of toluene and 20 ml of dimethoxyethane was added dropwise under nitrogen to a suspension of 3.6 g (0.15 mol) of sodium hydride in 21 ml of toluene at 100° C. The mixture was refluxed for 5 h and, after cooling, 50 ml of water were added, and the mixture was acidified with 50% concentrated hydrochloric acid, poured into 500 ml of water and extracted with chloroform. The precipitated product was filtered off with suction, and the chloroform phase was dried over sodium sulfate and concentrated. The residue and crude product were mixed and washed several times with hot methanol. Drying of the crystals resulted in 22.1 g of the title compound of melting point 128° C.
