Environment-benign O-centered Electrophiles And Their Applications In Suzuki Cross-coupling Reactions

Suzuki coupling reaction is a mean to realize carbon-carbon bond connection.In the past,most of the coupling agents were mainly halogenated substances,such as α-halogenated coumarins,α-halogenated acrylates,etc.Halogenated substances are more serious for environmental pollution,can cause damage to the environment in different ways and pollution control is more difficult.Considering the unfriendly to the environment and the certain danger in the synthesis process,vinyl sulfonic acid esters and α-sulfonic acid ester acrylates were used as coupling agents to reduce the pollution of halogenated substances to the environment and synthesize coumarin compounds and α-substituted acrylates.Coumarins are widely used,which can be used as molecular probes to detect the content of heavy metals,and can also be used as rodenticides to replace traditional rodenticide methods to reduce environmental pollution.Acrylates and their derivatives can be used to make more environmentally friendly adhesives,coatings,and non-toxic and biodegradable pastes.The following two parts of research are mainly conducted in this paper:In the first part,a palladium-catalyzed Suzuki reaction of alkenyl sulfonates as electrophilic couplets was developed to synthesize α-substituted coumarins.The effects of substituent steric variance and compatibility of functional group on the reaction were investigated.The experimental results show that a variety of electrically substituted boric acid and alkenyl sulfonates can obtain coumarin compounds in 20%-93% yields.Finally,water was used to replace part of toluene,which not only obtained coumarin compounds,but also reduced the amount of toluene and environmental pollution.The second part was based on the research of the first part,which the O-centered electrophilic couplets α-sulfoester acrylate was developed.A variety of α-substituted acrylates were synthesized by Suzuki reaction using SPhos as ligand,potassium phosphate as base,water / toluene as solvent and the temperature at 60°C under the palladium-catalyzed.The effects of substituent steric hindrance and functional groups on the reaction were investigated.The experimental results showed that a variety of electrically substituted borates could obtainα-substituted acrylates in 31%-83% yields.Then on the basis of this condition,the water /toluene mixed solvent system was replaced by water / 1,4-dioxane mixed solvent,and the temperature was changed to 80°C to synthesize β-substituted acrylate.The effects of substituent steric variance and compatibility of functional group on the reaction were investigated.The experimental results show that a variety of electrically substituted borates can be obtained in 46%-93% yield.There is still no available reports dealing with the preparation of α-substituted acrylates using O-centered coupling electrophiles,which provides a method for the synthesis of α-substituted acrylates.