Process for the preparation of opicapone and intermediates thereof
A technology for opica and compound, which is applied in the field of preparation of intermediates and can solve problems such as danger and generation of metal wastes
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Embodiment 1
[0109] Embodiment 1: the preparation of 3,4-dimethoxy-5-nitrobenzoic acid (IIIa)
[0110] To a cold solution of 3,4-dimethoxy-5-nitrobenzaldehyde (100 g, 0.474 mol) in DMF (500 ml) was added portionwise Oxone (294.1 g, 0.478 mol) at 5°C-10°C . The reaction mixture was stirred at the same temperature for 30 minutes, allowed to warm to room temperature and stirred for 2-3 hours. After completion, the reaction mixture was diluted with 1500ml of water and filtered. The solid was washed with water until all peroxide was removed and dried under vacuum at 50 °C to give 3,4-dimethoxy-5-nitrobenzoic acid of formula (Ilia) (102 g, 95%).
Embodiment 2
[0111] Example 2: 2,5-dichloro-N'{[(3,4-dimethoxy-5-nitrophenyl)carbonyl]oxy}-4,6-dimethylpyridine-3-methyl Preparation of imidoamide (Va)
[0112] To a solution of 3,4-dimethoxy-5-nitrobenzoic acid (5 g, 0.022 mol) of formula (IIIa) in 60 ml of acetonitrile, N, N'-carbonyldiimidazole (4.28 g, 0.026 mol), and the reaction mixture was stirred at room temperature for 1.5 hours. 2,5-Dichloro-N'-hydroxy-4,6-dimethylnicotinimideamide of formula (IV) (5.4 g, 0.023 mol) was then added and stirring continued for 3 hours. After completion, the reaction mixture was diluted with 240ml water and 300ml dichloromethane. The organic layer was separated, washed with water (200ml×3), and concentrated under reduced pressure to obtain 2,5-dichloro-N'{[(3,4-dimethoxy-5-nitrophenyl) of formula (Va). Carbonyl]oxy}-4,6-lutidine-3-carboximidoamide (8.67 g, 88.9%).
Embodiment 3
[0113] Example 3: 2,5-dichloro-3-[5-(3,4-dimethoxy-5-nitrophenyl)-1,2,4-oxadiazol-3-yl]-4 , Preparation of 6-lutidine (VIa)
[0114] To 2,5-dichloro-N'{[(3,4-dimethoxy-5-nitrophenyl)carbonyl]oxy}-4,6-lutidine-3 of formula (Va) - To a solution of formimidoamide (0.5 g, 0.0011 mol) in 10 ml of dichloromethane was added isopropanol (1 ml) followed by KOH (0.075 g, 0.0011 mol) dissolved in 0.1 ml of water. After stirring at room temperature for 1 hour, the reaction mixture was diluted with 30 ml of dichloromethane and washed with water (10 ml×2). The reaction mixture was concentrated under reduced pressure to obtain 2,5-dichloro-3-[5-(3,4-dimethoxy-5-nitrophenyl)-1,2,4-oxane of formula (VIa). Oxadiazol-3-yl]-4,6-lutidine (0.4 g, 83%).
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