1: ethylmagnesium bromide; triethylsilylethynylmagnesium bromide in tetrahydrofuran T=20°C; 0.5 h; 2: trifluoromethanesulfonic acid 3,4-dihydronaphthalen-2-yl ester With Co(acetylacetonate)3 in tetrahydrofuran T=20°C; 2 h; Further stages.;