Solid State Suzuki Coupling Reaction Study Facilitated By Magnetic Grinding

The Nobel Prize-winning Suzuki-Miyarua cross-coupling reaction is a practical and attractive strategy for C-C bond construction in both academic and industrial Settings.Suzuki coupling reactions in solvents have been well developed,but solvent-free solid Suzuki-Miyaura reactions are still lacking in development.In this paper,the solvent-free Suzuki-Miyaura coupling reaction using the electromagnetic grinder as the experimental instrument and a new method for the preparation of Schiff base compounds under solventfree conditions are proposed as follows:1)Solid Suzuki-Miyaura cross-coupling reaction promoted by ultra-low catalyst load with a new electromagnetic mill under mechanical and chemical conditions.Under the condition of magnetic grinding,by using ultra-low load(0.05mol%)palladium catalyst,without adding liquid molecular dispersants,The solid state SuzukiMiyaura reaction was successfully completed by using aryl halide and aryl boric acid as substrates.This strategy greatly expands the range of substrates and has high functional group tolerance.And it has higher gram synthesis yield.By electromagnetic grinding,the high aggregation of catalysts can be effectively inhibited,and the mixing of solid reactants can be accelerated,which is the key factor to obtain higher reaction efficiency.The developed solid reaction strategy with low load and high catalytic efficiency has been successfully applied to the modification of photoluminescence molecules,the cross-coupling of insoluble compounds and the synthesis of several important bioactive molecules.The solid Suzuki-Miyaura coupling method studied in this paper is friendly to the environment,and the magnetic grinding system developed can be applied in various scientific fields,and the development prospect is huge.2)Using a new electromagnetic grinder to promote the reduction of nitro catalyzed by palladium under mechanical and chemical conditions and to prepare Schiff bases by one-pot method.Schiff base compounds were successfully prepared by series nitro-reduction and Schiff base reaction with nitro compound as substrate under alkaline solvent-free conditions.A new method for preparing Schiff bases directly from nitro compounds was developed.It was found that the reducing effect was caused by the friction between grinding media and falling iron powder.The control experiment showed that the hydrogen donor of the aromatic nitrocompound was water,indicating that the dissociation of water occurred under the action of magnetic field and electric field.By comparing the experimental results under different conditions,we show the uniqueness and novelty of nitro reduction under electromagnetic grinding condition.