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jsw79(金币+15, 翻译EPI+1):很棒，谢谢！ 2010-10-31 12:32:25
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General procedure for ester cleavage of dimethoxybipyridine: 80mg (0.4mmol) of dimethoxybipyridine is heated under reflux (ca.210℃) in 900mg (8mmol) of pyridinium chloride for 4h. in the case of extremely polar products, pyridinium chloride is subsequently sublimed at 0.1 Torr in Kugelrohr. The residue is stirred in 50ml of absolute chloroform for several hours ( dissolution of the N-methyl pyridinium chloride), filtered with suction and heated in vacuum at 120℃. In the case of less polar products 4f and 7d, the cooled reaction mixture is concentrated 5 times with each of 100 ml of concentrated NH3 solution to dryness. The residue is distilled out 3 times with each of 100ml of chloroform. The combined organic extractions are concentrated, and the residue is recrystallized from chloroform (7d) or from petroleum ether(4f). |
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