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鉴于由邻氯甲基苯甲酸乙酯合成4-异色满酮中,邻氯甲基苯甲酸乙酯的制备,需经邻甲苯甲酰氯的高温氯代过程,反应条件难于控制,并要经过六个步骤,故本文提出采用Padwa等制备3-甲氧甲酰基异色满酮-4的方法,由邻甲苯甲酸经五步完成异色满酮-4的合成,(但对(Ⅳ_a)的缩合,用苯代替Padwa所用的二甲亚砜)。此法反应易于控制,产率较高。用5％氢氧化钠乙醇溶液较顺利完成(Ⅴ_a)的脱羧反应尚未见报导。实验表明,二乙酯(Ⅳ_b)的闭环比二甲酯(Ⅳ_a)容易进行。但2-邻羧基苯甲氧基丙酸二甲酯(Ⅻ)用类似闭环法未能得到相应的异色满酮-4。
In view of the synthesis of 4-isochromanone from ethyl o-chloromethylbenzoate, the preparation of o-chloromethylbenzoate requires high temperature chlorination of o-toluyl chloride and the reaction conditions are difficult to control and pass through Therefore, this paper proposes a method of preparing 3-methoxycarbonyl isochroman-4 by Padwa et al., And synthesizes isochromanone-4 from o-toluic acid in 5 steps, Condensation, with benzene instead of dimethyl sulfoxide Padwa). This method reaction easy to control, high yield. The decarboxylation of (Ⅴ_a) with 5% sodium hydroxide in ethanol has not been reported yet. Experiments show that diethyl (Ⅳ_b) ring than the dimethyl ester (Ⅳ_a) easy to carry out. However, dimethyl 2-o-carboxybenzyloxypropionate (XII) failed to give the corresponding isochromanone-4 by a similar ring closure method.