改良的黄烷酮合成法

A Novel Synthesis of Flavanones

黄烷酮的合成以往多采用查尔酮的关环或邻羟基苯乙酮与芳香醛的直接缩合关环,近年来,人们主要在关环上做了些改进,但因此类化合物多带羟基,在强酸、强碱中易发生副反应,所以一般须将羟基预先进行保护才能得到较满意的结果,本文采用芳香醛、丙二腈为原料,在乙酸铵和乙酸的催化作用下,先进行Knoevenagel羟醛缩合,得到苯甲叉丙二腈1,然后1与间苯三酚在无水ZnCl_(2)和HCl气体的催化作用下,进行Hoesch单酰基化反应,保留的一个氰基水解成羧基,因是β-酮酸结构,故易脱羧,同时关环,顺利得到黄烷酮2,收率≥60%,可能的反应历程如下式所示。

Herein, a new synthetic method of flavanones is reported. Phenylmethylene-propanedinitriles (1), resulted from Knoevenagel condensation of aromatic aldehydes with malononitrile, have been conveniently converted into a series of flavanones by the Hoesch acylation with phloroglucinol, followed by hydrolysis, decarboxylation, and cyclization. Ten flavanones were prepared with higher yield by this new method, among them seven are new compounds.