1: With formic acid in tetrahydrofuran; ethanol; water T=40 - 60°C; 1 h; 2: With formic acid in methanol 6 h;

1: With toluene-4-sulfonic acid in water; toluene T=65°C; 0.0333333 h; 2: With orthoformic acid triethyl ester T=63 - 65°C; 0.916667 h; 3: With sodium hydrogencarbonate 0.0833333 h;

1: acetylene With potassium tert-butylate in tetrahydrofuran T=0 - 20°C; 2 h; 2: 7α-methyl-3,3-(ethylenedioxy)-5(10)-estren-17-one; acetylene in tetrahydrofuran T=4 - 8°C; 4 h; 3: With ammonium chloride in water; toluene T=0 - 20°C; 1.75 h;

sodium acetate; toluene-4-sulfonic acid; ethylenediamine; pyridinium chlorochromate Multistep reaction. Title compound not separated from byproducts;