Synthesis of 2-Substituted Benzoxazole Derivatives and their Application in Pharmaceutical Synthesis
2-Substituted benzoxazoles are a kind of important heterocyclic skeleton,which have been widely considered and applied in drug synthesis.In this work,the first and second steps of the reaction were optimized by a one-pot two-step method using inexpensive and readily available o-aminophenol and aromatic aldehyde as raw materials.The first step involved the use of dioxane as a solvent,and the reaction was conducted at room temperature under an air atmosphere for five hours.The second step involved the use of 2,3-dichloro-5,6-dicyanobenzoquinone as an oxidant,and the reaction was carried out at room temperature under an air atmosphere for one hour.This resulted in the synthesis of a number of 2-substituted benzoxazole derivatives through oxidative cyclization.Meanwhile,the approach was applied to the synthesis of the medicine Tafamidis.The structure of the target compound was confirmed by 1H-NMR,13C-NMR,and HRMS.The method has mild conditions,simple and convenient operation,wide substrate universality,and certain practicability,which provides a new idea for the synthesis of the 2-substituted benzoxazole compound.
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