E-selectivive Isomerizaton Of Aryl Olefins Catalyzed By Cobalt

Olefin is one of the most widely used starting materials in synthetic organic chemistry and chemical production.It can be readily functionalized to synthesize a variety of chemical intermediates and fundamental building blocks.Since the stereo-configuration of olefins greatly affects the physiological and chemical activity,the synthesis of olefins with high regio-and stereoselectivity has always been one of the key research subjects.Efficient E-selective isomerization of aryl olefins through ligand screening,design and synthesis was developed.This paper mainly includes two parts:?1?Cobalt-Catalyzed Z to E Isomerization of Alkenes.Employing the amido-diphosphine ligand?PNP?,an efficient cobalt-catalyzed geometrical isomerization of E/Z mixtures of?-substituted styrenes was developed,delivering the?E?-isomers with good functional tolerance and high stereoselectivity?92/8–100/1 E/Z?.The reaction could be scaled up to gram-scale with a catalyst loading of0.1 mol%with high catalytic efficiency?S/C up to 1000?.Preliminary mechanistic studies indicated that cobalt?I?-hydride and a benzylic-cobalt species were probably involved in the reaction,as supported by experiments and DFT calculations.?2?Cobalt-Catalyzed E?Selective Isomerization of Alkenes.With the phosphine-amido-oxazoline?PAO?ligand,an efficient method to access?E?-trisubstituted alkenes was developed via cobalt-catalyzed isomerization of 1,1-disubstituted alkenes.This protocol is operationally simple and uses readily available starting materials with good functional tolerance and high catalytic efficiency(TOF up to 2400 h^-1).