2,7-Dihydroxytropone is efficiently prepared from 2-methoxytropone by bromination with N-bromosuccinimide, reaction of the resultant 2-bromo-7-methoxytropone with acetyl trifluoroacetate in situ, and hydrolysis of the 2,7-diacetoxytropone thus obtained with aqueous acetic acid. The intermediacy of a 2-acetoxy-1-bromo-3-methoxytropylium salt in the acetoxylation step is suggested.
用 N-
溴代丁二
酰亚胺溴化 2-甲氧基托普酮,使生成的 2-
溴-7-甲氧基托普酮与
三氟乙酸乙酰基原位反应,然后用
乙酸水溶液
水解得到 2,7-
二乙酰氧基托普酮,从而从 2-甲氧基托普酮高效地制备出 2,7-二羟基托普酮。这表明在乙酰氧基化步骤中存在 2-乙酰氧基-1-
溴-3-甲氧基
托品鎓中间盐。