反应详情

To a solution of ethyl 6-hydroxy-5-(3-hydroxypropyl)-3-methylpyrazine-2-carboxylate (1.03 g, 4.29 mmol) and triphenylphosphine (1.69 g, 6.43 mmol) in tetrahydrofuran (86 mL) was added diethyl azodicarboxylate solution (40% wt. % in toluene, 2.92 mL, 6.43 mmol) at room temperature. After being stirred for 50 min, the reaction mixture was concentrated in vacuo. The crude was purified by silica gel column chromatography (hexane:ethyl acetate=9:1 to 7:3), triturated with diisopropyl ether, and silica gel column chromatography (chloroform to chloroform:methanol=19:1) to give ethyl 2-methyl-7,8-dihydro-6H-pyrano[2,3-b]pyrazine-3-carboxylate. MS (APCI): m/z 223 (M+H).

1. concentrationthe reaction mixture was concentrated in vacuo
2. customThe crude was purified by silica gel column chromatography (hexane:ethyl acetate=9:1 to 7:3)
3. customtriturated with diisopropyl ether, and silica gel column chromatography (chloroform to chloroform:methanol=19:1)