Silver-Catalyzed Deboronation And Decarboxylation Of Aromatic Compounds

Transition metal-catalyzed reactions have wide application in the fields of modern organic synthesis. They have attracted much attention of chemists due to the mild reaction conditions and its flexible reactivity through modification of transition metal catalyst with a ligand in recent years. Compared with other transition metals, such as gold, palladium and rhodium, silver is much cheaper. The silver-catalyzed reaction has been widely used in coupling reactions, heterocyclic synthesis and asymmetric reactions for its characteristics of mild conditions, catalyst easily preparing and storing.Boric acid as good placeholder group has an important application in chiral synthesis. It is significant to explore an effective method to remove the placeholder group. Recently, carboxylic acids also become one of the frontier areas in organic chemistry because they are easily available at low cost. In this thesis, we systematically developed a silver-catalyzed deboronation protocol in aqueous media and a silver-catalyzed decarboxylation of aryl carboxylic acids in DMI. The main contents are as follows:1. A mild and effective protocol of AgNO3-CH3CH2OH/H2O for the deboronation of aryl boronic acids under air was developed. Under the optimized conditions (AgNO36mol%, Et3N1equiv,50%CH3CH2OH/H2O,80℃), the deboronation of aryl boric acids were completed in short times, resulting in the highest isolated yield up to96%for the solid product and a GC yield up to98%for liquid product. Both steric effect and electronic effect only made little impact on the reaction rate. It is noteworthy that various functional groups such as2-OCH3、4-OCH3、4-CN、4-CHO、4-F could be tolerated under the conditions used.2. A fast, convenient and aerobic protocol for the decarboxylation of aryl carboxylic acids was developed using Ag2O as a catalyst. Decarboxylation of2-chloro-4-nitrobenzoic acid was chosen as a model reaction for screening the conditions. Under the optimized conditions (Ag2O5mol%, CH3COOK15mol%, DMI1mL,120℃), the protocol performs effectively to catalyze the decarboxylation of aryl carboxylic acids. The better yields were obtained when carboxylic acids bear substituent group in orthzo-position. The isolated yield can reach up to91%.