反应详情

A THF solution (25 ml) of 2-[(2,2-diethoxyethyl)thio]methyl-3-carboethoxy-5-carbomethoxy-4-(m-nitrophenyl)-6-methyl-1,4-dihydropyridine (5 g), hydroquinone (0.5 g) and oxalic acid (1N water solution, 10 ml) is heated to the reflux temperature, under N2 atmosphere, for one hour, then the THF is evaporated in vacuum and the water layer is extracted with AcOEt (3×20 ml). The organic phases are washed with water (2×5 ml), a satured solution of NaHCO3 (2×5 ml) and water (3×5 ml), dried on Na2SO4 and evaporated to dryness. The residue, after purification by column chromatography (SiO2 120 g; eluent: hexane/isopropyl ether 70/30), yields 3.8 g of pure 2-[(formylmethyl)thio]methyl-3-carboethoxy-5-carbomethoxy-4-(m-nitrophenyl)-6-methyl-1, 4-dihydropyridine, oil.

1. customthe THF is evaporated in vacuum
2. extractionthe water layer is extracted with AcOEt (3×20 ml)
3. washThe organic phases are washed with water (2×5 ml)
4. dry with materiala satured solution of NaHCO3 (2×5 ml) and water (3×5 ml), dried on Na2SO4
5. customevaporated to dryness
6. customThe residue, after purification by column chromatography (SiO2 120 g; eluent: hexane/isopropyl ether 70/30)