Study On Synthesis Of 1,3,5-triazines And 1,2,4-oxadiazines Under Metal-free Systems

1,3,5-Triazines and 1,2,4-oxadiazines,as two important heterocyclic compounds,widely present in drug molecules and show good activities in anticancer,antiviral,antibacterial and herbicidal aspects.However,the currently reported methods for synthesizing 1,3,5-triazines and 1,2,4-oxadiazines still have the disadvantages of requiring transition metal catalysis,poor atom economy,and poor practicability.Therefore,it is extremely important to develop more green and practical synthetic methods,so we study the green synthetic methods of 1,3,5-triazine and 1,2,4-oxadiazine compounds,the results are the following two parts:Chapter 1 Study on synthesis of 1,3,5-triazines using formaldehyde as carbon sourceUsing cheap and readily available formaldehyde as carbon source,benzamidine hydrochloride as substrate,through a series of optimization of conditions,a method was developed to synthesize 2,4-dissubstituted 1,3,5-triazines with Cs₂CO₃ as base and NMP as solvent at 90 ^oC for 12 h in air without metal catalysis.The method has the advantages of good substrate applicability,simple operation and good atomic economy.Chapter 2 Study on one-pot synthesis of 1,2,4-oxadiazines from styrenesThe 3,5-disubstituted 1,2,4-oxadiazines were synthesized by one-pot method using styrenes and benzamide oximes in a mixed solvent of water and 1,2-dichloroethane at 80^oC.Using cheap NBS as bromine source and oxidant,water as solvent,the key intermediateα-bromoacetophenone is formed by reacting with styrene,and then the target product can be obtained by reacting with benzamide oxime.The C-H functionalization of styrene was realized and 24 new compounds which have not been reported in literature were synthesized by this method.