二氢苯骈吡喃酮Mannich反应的副反应

By-products from Mannich Reaction of Dihydrobenzopyranones

以Ｍａｎｎｉｃｈ反应拟合成３－胺甲基－４－羟基取代的苯骈吡喃化合物（Ⅲ），得到ＤｉｅｌｓＡｌｄｅｒ缩合产物（Ⅳａ）和（Ⅳｂ），初步探索了反应条件并确定了所得产物的结构。

It was reported that 3-aminoalkyl benzopyranones were obtained by Mannich reaction of 2-monosubstituted benzopyranones with paraformaldehyde.However,all attempts to introduce the 3-aminoalkyl group directly to the 2-disubstituted benzopyranones were unsuccessful in present study.First,the pyrrolidine-catalyzed Aldol condensation with paraformaldehyde in acetic acid led to the methylene compounds which were unstable when they were heated,and then Diels-Alder dimers were formed immediately.The reasons why it was difficult to prepare the 3-aminoalkyl- 2-disubstituted benzopyranone ones by Mannich reaction remain to be further studied.