Studies On Intramolecular Nucleophlic Addition-Dearomatization And Allylation Reactions Involving Active Imine Intermediates

Reactions between nucleophilic reagents and imines (or active imine intermediates) are frequently utilized to introduce substituents at the a-carbon of an amine. Studies on this field have achieved outstanding successes. Details of theses reactions, including preparation of precursors, controls on stereoselectivity or applications in natural product syntheses, have been thoroughly studied and reported by chemists. But for Lewis acids-catalysed intramolecular nucleophilic addition and dearomatization to an iminium ion which is generated from protonated N-acyl indole for construction of ring-fused indoline skeleton, there is no precedent that has been reported to our knowledge. In addition, researches about insitu-oxidation and allylation of arylbenzylamines are few in number. This thesis describes the studies on nucleophlic addition reactions of active imine intermediates.According to the contents of our study, this thesis can be concluded as three parts:Chapter 1. The development and application of various catalytic asymmetric dearomatization reactions were summarized in this review, which mainly focused on oxidative dearomatization reactions, dearomatization by Diels-Alder and related reactions, alkylative dearomatization reactions, and so on. The contents are classified and introduced by the types of reactions systematically.Chapter 2. A study was made on Al(OTf)3-catalyzed intramolecular reaction sequence toward concise construction of tetrahydropyrido[1,2-a]indole-6-one skeleton. With a simple N-acyl indole as substrate, and the a-position of dimethylester as the nucleophilic precursor, this reaction employs Al(OTf)3 as Lewis acid to coordinate with the dimethylester and an enol aluminium salt was formed. A molecule of HOTf was simultaneously released, so that the 3-position of indole was protonated and the key intermediate N-acyliminium ion was formed.Then it was attacked by the powerful nucleophile to form a C-C bond in a Mannich-like pathway with high efficiency. Preliminary mechanistic studies was indicated by the isotope labeling experiments.Chapter 3. We presented in detail a highly efficient one-pot reaction involving oxidation and allylation of arylbenzylamines. Studies show that in the presence of AgOTf together with oxidant, simple amine substrates can be oxidized to imines, then followed the allylation of imines and homoallylic amines were formed. The substrate scope was investigated and stereoselective control is in progress.