1: 1-naphthaldehyde With n-butyllithium; N,N,N'-trimethyl-ethylenediamine in tetrahydrofuran; hexane T=-20°C; 0.75 h; Inert atmosphere; 2: With n-butyllithium in tetrahydrofuran; hexane T=-20 - 30°C; 2.33333 h; Inert atmosphere; 3: N,N-dimethyl-formamide Further stages;

aluminium trichloride; TEA T=200 - 210°C; 3 h;

PPA T=230 - 240°C; 1 h; Yields of byproduct given;