Asymmetric Arylative Dearomatization Of β-naphthols Catalyzed By A Chiral Phosphoricacid

Phenols and their derivatives are a class of readily available and abundant chemical feedstock,and their asymmetric dearomatization provides chiral multifunctionalized cyclohexadienones,which frequently appear as a structural core in many biologically active natural products and pharmaceuticals.Over the past decades,significant strategies have been successfully developed for the asymmetric dearomatization of phenols and its derivatives.In general,there are oxidative and non-oxidative strategies for the catalytic asymmetric dearomatization reactions.In terms of non-oxidative strategy,most examples are using transition-metals catalysis,which are expensive,high toxicity.Therefore,the development of a green,economic and environmental friendly method for asymmetric dearomatization of phenols avoiding transition metal catalysts is highly desirable.This thesis is divided into two parts.The first chapter reviewed the research progress of asymmetric dearomatization of phenols,and some practical applications of dearomatized products in natural products synthesis.The second chapter is asymmetric arylative dearomatization of β-Naphthols catalyzed by a chiral phosphoric acid.We have developed the first enantioselective arylative dearomatization reaction of β-Naphthols with quinone monoimides using a chiral phosphoric acid as the catalyst,the desired enantioenriched cyclohexadienones were prepared with excellent yields and enantioselectivities by a domino Michael addition and aromatization process(up to 99% yield,up to 98% ee).This process is operationally simple and readily scaled up,as well as a broad substrate scope which includes 1-substituted-2-naphthols with/without 3-substituents.Furthermore,this organocatalytic procedure allows the lowering of catalyst loading to 0.5 mol% without considerable loss in reactivity and enantioselectivity.