Hydrogen Sulfide → 2-{6-[3-(Tert-butyl-dimethyl-silanyloxy)-propoxy]-pyridin-3-yl}-4,5,6,7-tetrahydro-benzothiazole

Participants

Reaction Conditions

Reaction Steps

H2S gas was passed slowly through a solution of 6-[3-(tert-butyl-dimethyl-silanyloxy)-propoxy]-nicotinonitrile (Example 76, 1.14 g, 3.90 mmol) in DMF (25.0 mL) at rt for 30 minutes. Diethylamine (0.60 mL, 5.85 mmol) was added in one portion, and the resultant light green solution was heated at 60° C. for 4 h. The reaction mixture was purged with a stream of argon, and concentrated under reduced pressure. The crude product was filtered through a short pad of silica gel and eluted with EtOAc. The solvent was removed under reduced pressure. The residue was treated with a solution of 2-chlorocyclohexanone (0.244 g, 1.80 mmol) in 10 mL 1:1 toluene/dioxane. The flask was connected to a Dean-Stark apparatus and heated at 150° C. for 18 h. The reaction mixture was concentrated under reduced pressure, the residue washed with water, and extracted with ethyl acetate. The combined organic extracts were dried over Na2SO4, filtered, and concentrated under reduced pressure. The crude material was purified by silica gel flash chromatography (15% EtOAc in hexanes) to give the title compound (0.29 g, 18%). 1H NMR (400 MHz, CDCl3) δ 8.58 (dd, 1H), 8.02 (dd, 1H), 6.65 (dd, 1H), 4.36 (t, 2H), 3.75 (t, 2H), 2.70-2.82 (m, 4H), 1.90-1.98 (m, 2H), 1.80-1.90 (m, 4H), 0.82 (s, 9H), 0.02 (s, 6H).

Provenance & Evidence