Study On The Synthesis Of Chiral Pyrroloquinoline And Dihydropyrone Catalyzed By N-heterocyclic Carbene

Nitrogen heterocyclic carbene(NHC)plays an important role in the field of small molecule organic catalysis.Due to its advantages such as good reaction selectivity,low pollution and simple operation,it is used in new drug design and synthesis,combinatorial chemistry and natural product synthesis.It is widely used,especially in the synthesis of multi-component reactions and multi-functional groups,so it plays an important role in the construction of chiral compounds.This article mainly studies the formation of a,β-unsaturated acylazole intermediates from a-bromocinnamaldehyde catalyzed by nitrogen heterocyclic carbenes.This intermediate undergoes an asymmetric cycloaddition reaction with a compound having a Michael acceptor to obtain chiral pyrroloquinoline compounds and dihydropyrone derivatives,and a preliminary exploration of the mechanism has been carried out.In this thesis,the research work is divided into three chapters.Chapter 1 It is an introduction of the development of NHC as organocatalyst.Different types of intermediates were presented according to various reaction sites.Chapter 2 The asymmetric cycloaddition reaction of a-bromocinnamaldehyde catalyzed by nitrogen heterocyclic carbene and N-unsubstituted indole with Michael acceptor at position 7 was studied.The reaction expanded 21 pyrroloquinoline compounds with three chiral centers with excellent yield(up to 95%),good diastereoselectivitites(≥ 20:1),and high enantioselectivities(≥ 99% ee).Chapter 3 The [3+3] asymmetric cycloaddition reaction of a-bromocinnamaldehyde with 1,3-dicarbonyl compounds catalyzed by nitrogen heterocyclic carbene has been studied.Finally,19 dihydropyrone skeleton derivatives with indol groups were obtained with good yield(up to 78%),and most of the products with enantioselecitivities of not less than 95%.