6-氨基-5-溴喹喔啉的绿色合成

Mild synthesis of 6-amino-5-bromoquinoxaline

以4-硝基邻苯二胺为起始原料,经环合、催化加氢还原和1,3-二溴-5,5-二甲基海因溴化得到6-氨基-5-溴喹喔啉,各步收率分别为95.1%、83.3%、97.6%。优化合成条件为:①加氢还原反应中,催化剂用量为6-硝基喹喔啉质量的5%,反应温度70℃,压力2 MPa下加氢3 h;②溴化反应中,反应温度20℃,以二氯甲烷为溶剂。在该优化条件下,5-溴-6-氨基喹喔啉的总收率达到77.3%。本体系最优溴化试剂为1,3-二溴-5,5-二甲基海因。

6-Amino-5-bromoquinoxahne is synthesized with 4-nitrobenzene-1,2-diamine as a starting material and followed with eyclization, hydrogenation, brominafion by 1,3-dibromo-5,5-dimethylhydantoin in yields of 95.1%, 83.3 % and 97.6 %, respectively.The optimum conditions are as follows： （1） m （Pd/C） ： m （6-nitroquinoxaline） = 1 ： 20, 70℃ of reaction temperature,2 MPa of reaction pressure and 3 hours of reaction time in a catalytic hydrogenation step; （2）20℃ of reaction temperature, with CH2Cl2 as solvent in a bromination step. The overaU yield can reach 77.3%. 1, 3-Dibromo-5, 5- dimethylhydantoin is determined as the best brominating agent.