1: N-boc-4-aminothiocarbonylpiperidine With hydrogenchloride in 1,4-dioxane 3 h; 2: formaldehyd With sodium cyanoborohydride; acetic acid in methanol; water T=20°C; 2 h; 3: With sodium hydrogencarbonate in water; ethyl acetate

Lawesson's reagent in tetrahydrofuran; toluene 22 h; Reflux;

in tetrahydrofuran; methanol; conc. aq. NH4OH; 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran; toluene

1.1: 4-(N,N-dimethlyamino)pyridine / acetonitrile / 20 °C 2.1: Lawesson's reagent / dichloromethane; ethylene glycol dimethyl ether / 20 °C 3.1: hydrogenchloride / 1,4-dioxane / 3 h 3.2: 2 h / 20 °C View Scheme

1.1: Lawesson's reagent / dichloromethane; ethylene glycol dimethyl ether / 20 °C 2.1: hydrogenchloride / 1,4-dioxane / 3 h 2.2: 2 h / 20 °C View Scheme