The preparation of the acetals of a number of pyrrole mono- and dicarboxaldehydes is described. It is shown that, provided the reactivity of the unsubstituted ring positions on the pyrrole nucleus is not too low, a carboxyaldehyde or a carbonitrile group may be substituted onto the pyrrole ring using the Vilsmeier reaction or chlorosulfonyl isocyanate respectively. Vilsmeier formylation of the diacetal, 2,4-di(5,5-dimethyl- 1,3-dioxan-2-yl)-pyrrole, followed by hydrolysis gave pyrrole-2,3,5-tricarboxaldehyde.
描述了一系列吡咯单酸和二酸的缩醛制备方法。结果表明,只要吡咯核上未取代的位置的反应性不太低,可以使用Vilsmeier反应或氯磺酰异氰酸酯将羧醛或碳氰基取代到吡咯环上。对二缩醛2,4-二(5,5-二甲基-1,3-二氧杂环戊烷-2-基)-吡咯进行Vilsmeier甲酰化反应,然后水解得到吡咯-2,3,5-三酸醛。