1. 第一步反应，反应时间过长，有杂点生成。滴加完毕需及时中控，及时处

1. The first step of the reaction, the reaction time is too long, and there are impurities. After the addition is completed, timely control is required and the reaction is processed in time. 2. The fourth step of the reaction, the entire route is difficult, the yield cannot be improved, and there is no solution at present, and the product cannot be obtained <br>. 3. The final product has a low melting point and can be used with petroleum ether Dissolve and crystallize with a small amount of solvent.

1. The first reaction, the reaction time is too long, there are noise generation. Drop add completed need to be timely central control, timely processing reaction 2. The fourth step of the reaction, the whole route difficult, the yield can not be improved, is not resolved at present, and the product can not get solid<br>3. The end product melting point is low, can be dissolved with petroleum ether, the application of a small amount of solvent crystallization.

1. In the first step, the reaction time is too long, and there are heterospots. The fourth step of the reaction, the whole route is difficult, the yield can not be improved, it is not solved at present, and the product can not get solid<br>3. The melting point of the final product is low, it can be dissolved with petroleum ether, and it can be crystallized with a small amount of solvent.<br>