NaH/Pd System For Debenzylation And Synthesis Of Imidazolin-2-ones

This thesis includes two sections1.Debenzylation of ethers and estersThe benzyl group is one of the most important protecting groups in synthetic organic chemistry.It can be easily installed and is stable toward a wide range of reaction conditions that are commonly used in various synthetic operations.Moreover,it can be easily removed by transition metals(Pd,Ni et al.)catalyzed hydrogenolysis,Lewis acids mediated hydrolysis,and oxidative removals.Herein we demonstrate that the addition of Pd(OAc)2 as a promotor switches the reactivity of a commonly used base NaH to a nucleophilic reductant.The new reactivity is engineered into a new palladium-catalyzed reductive debenzylation of aryl ethers and esters.This operationally simple,mild protocol displays a broad substrate scope and a broad spectrum of functional group tolerance and high chemoselectivity towards aryl ethers over aliphatic structures.2.Synthesis of imidazolin-2-ones at high temperatureTropone is one of the most important building blocks in synthetic organic chemistry,due to their presence in various natural products with biological interest.The pharmaceutically intriguing troponoids incorported with imidazolin-2-one moieties were efficiently constructed via 4-step cascade process including dipolar[8+2]cycloaddition/Allylic substitution/decarboxylation/[1,5]-sigmtropic hydrogen migration under simple thermal condition,which features novel nitrogen source,catalyst-and oxidant-free conditions,high atomic-and step-economic transformation.