Cu(Ⅰ)-Catalyzed 3-Aryl Benzofuranones To Give Z-and E-Styrene With 99/1 Regioselectivity

Olefins containing all-carbon quaternary centers have very important applications in pharmaceuticals,fine chemicals and other fields,such as indole alkaloid,estrogen receptor ligand,elacomine,etc.However,due to their large steric hindrance effect,traditional methods for synthesizing such compounds are inefficient.Therefore,it is a challenging task to study a new methods for the efficient synthesis of olefins containing all-carbon quaternary centers.In addition,3-aryl benzofuranones are widely applicated in pharmaceuticals and material chemistry.Thus,using 3-aryl benzofuranones as stable tertiary carbon units to develop a new synthesis method for 3-aryl benzofuranones with carbon-carbon double bond structure has very important theoretical significance and practical value.Based on the above,this paper mainly studied that by adopting the copper-catalyzed activation of tertiary C(sp~3)-H bond of 3-aryl benzofuranones to form 3-arylbenzofuranone radical which selectively alkenylates with alkynes or alkenes.By simple modifying the oxidants,we developed a general method for the synthesis of(Z)-olefins(Z/E up to 99/1)and(E)-olefins(E/Z up to 99/1)containing all-carbon quaternary centers.The research content includes the following two parts:(1)A copper-catalyzed addition reaction of 3-arylbenzofuranones to phenylacetylene was developed to prepare(Z)-3-(styryl)-3-phenylbenzofuranones with high selectivity(Z/E up to99/1).The reaction is solvent-free and meets the requirements of green chemistry.A diverse range of 3-aryl benzofuran-2(3H)-ones and styrene are well-tolerated and in good yields.After the gram scale experiment,the product yield and the stereoselectivity is basically unchanged.The reaction product can be further reacted,which verifies the practicability of the reaction.A possible reaction mechanism was proposed by combining the experimental conclusions and literature studies.(2)A copper-catalyzed cross-coupling reaction of 3-arylbenzofuranone and styrene was developed to synthesize(E)-3-(styryl)-3-phenylbenzofuranones(E/Z up to 99/1).The reaction is well-tolerated.A gram scale experiment was performed in good yields,while the stereoselectivity are basically unchanged.Finally,a possible reaction mechanism is proposed based on the control experiments and the literature reports.