Mannich反应合成3,6(8)-二取代-2,4-二氢-1,3-苯并噁嗪及其杀菌活性

以取代苯酚、多聚甲醛和取代苯胺为原料，在无催化剂的条件下，通过Mannich缩合反应合成了一系列新型3,6(8)-二取代-2,4-二氢-1,3-苯并噁嗪类化合物。 结果表明，取代苯酚和取代苯胺的取代基为供电子基时，合成产物的产率高于吸电子取代基的。 产物的结构用1H NMR、13C NMR、IR和MS等进行了表征。 初步测试了目标化合物的杀菌活性，部分化合物具有较好的杀菌活性。 当浓度为25 mg/L时，化合物4j和4d对菌核病菌的抑制率分别为86.1％和81.5％，化合物4i对灰霉病菌的抑制率为81.6％。

Synthesis of 3,6 (8)-Disubstituted -2,4-Dihydro-1,3-benzoxazines via Mannich Reaction and Their Fungicidal Activity

A series of novel 3,6(8)-disubstituted 2,4-dihydro-1,3-benzoxazines was synthesized by Mannich reactions of substituted anilines with paraformaldehyde and substituted phenols in the absence of catalyst. The results show that substituted phenols and anilines with electron-donating groups on the phenyl ring give higher yields than those with electron-withdrawing groups. The structures of the products were characterized by 1H NMR, 13C NMR, IR and MS. The fungicidal activity of the title compounds was preliminarily evaluated. Compounds 4j and 4d show 86.1％ and 81.5％ activity against Sclerotonia sclerotiorum at the concentration of 25 mg/L, respectively. Compound 4i exhibits 81.6％ activity against Botrytis cinerea.