A new synthesis of phthalaldehyde that avoided formation of HBr involved treatment of 1,2-bis(dibromomethyl)benzene with trimethyl orthoformate (1: 6, 90 °C, 10 mol.% ZnCl2) to obtain acyclic diacetal without admixture of cyclic one (1,3-dimethoxy-1,3-dihydrobenzo-[c]furan) followed by hydrolysis to give the target dialdehyde. Phthalaldehyde reacted with CH(OMe)3 in the presence of trifluoroacetic acid to yield exclusively cyclic diacetal. Acyclic diacetal was phosphorylated by treatment with secondary chlorophosphines and by the reaction with PCl3 followed by treatment with PIII acid ester.

中文翻译：

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苯二醛及其二缩醛的合成新方法

一种避免形成 HBr 的苯二醛的新合成涉及用原甲酸三甲酯（1:6，90°C，10 mol.% ZnCl2）处理 1,2-双（二溴甲基）苯以获得无环二缩醛，而没有环状二缩醛（ 1,3-二甲氧基-1,3-二氢苯并-[c]呋喃)，然后水解得到目标二醛。邻苯二甲醛在三氟乙酸存在下与 CH(OMe)3 反应生成仅环状二缩醛。无环二缩醛通过用仲氯膦处理并通过与 PCl3 反应然后用 PIII 酸酯处理而被磷酸化。