Studies On Methodologies For The Synthesis Of 2-Substituted-1,3,4-Oxadiazole Derivatives

1,3,4-Oxadiazole is a class of important five-membered heterocyclic compounds.Compounds with this structure have been widely used in pharmaceutical chemistry and organic electronics.So it is important to develope a simple and efficient synthesis method.In this paper,we mainly study the synthesis of 2-substituted-1,3,4-oxadiazole derivatives by two-step one-pot reaction in I2/O2 system.Part I: The application and synthetic method of 1,3,4-oxadiazole derivatives.1,3,4-Oxadiazole derivatives have many excellent biological activity,such as anti-cancer,sterilization,and also can be as insecticides,herbicides and plant growth regulators.In addition,1,3,4-oxadiazole has been widely used in organic electronics due to its excellent electron transport properties.Based on the high application value of these compounds,many literatures have reported the synthesis of 1,3,4-oxadiazole.According to the different starting materials,we divided into four categories:(1)the synthetic method of aldehydes as starting materials;(2)the synthetic method of carboxylic acid compounds as starting materials;(3)the synthetic method of hydrazide as starting materials;(4)the synthetic method of other compound as a starting material.Part II: The synthetic method of 2-substituded-1,3,4-oxadiazole derivatives.We have studied the synthesis of 2-substituted-1,3,4-oxadiazole derivatives using the hydrazide and styrene/phenacetylene compounds by the two-step one-pot method in the I2/O2 system.It was found that the use of potassium carbonate as a base achieves intromolecular cyclization and C–C bond cleavage.The method does not need to purify the intermediates,readily available starting materials,mild reaction conditions,short reaction time and high yields.