1: 1,4,4a,9a-tetrahydro-4a-methyl-(1α,4α,4aα,9aα)-1,4-methanoanthracene-9,10-dione With potassium tert-butylate in tetrahydrofuran T=-3 - 0°C; 0.5 h; 2: phytyl bromide in tetrahydrofuran T=0°C; 1.5 h; 3: With dodecyl trimethyl ammonium bromide in acetic acid T=90°C; retro-Diels-Alder reaction; 0.25 h; Title compound not separated from byproducts;