Preparation Of 5-Amino Isoxazolines Using Nitrosamines As Radical Precursors And Design,Synthesis,and Characterization Of Iridium Photosensitizers

Aminocyclopropanes,an important class of nitrogen-containing compounds,have been intensively studied as rigid structural moieties in medicinal chemistry and precursors for accessing more complex scaffolds.This thesis summarizes key concepts and recent progress in ring-opening transformations of aminocyclopropanes via radical intermediates.Herein,we report that N-nitroso amidocyclopropanes could indeed undergo ring-opening reactions under mild conditions and obtain a series of 5-amino isoxazolines,which represent a novel transformation in organic photochemistry.In addition,we synthesized and characterized a series of cationic iridium(III)complexes as potential visible-light photosensitizers by modifying the ligand framework.1.Aminocyclopropanes are versatile building blocks for accessing high-valueadded nitrogen-containing products.We summarizes key concepts and recent progress in ring-opening transformations of aminocyclopropanes via radical intermediates,divided into formal [3+2] cycloadditions and 1,3-difunctionalizations.2.Isoxazolines are widely present in natural products and pharmaceutical molecules.We successfully developed N-NO cyclopropanes as amidyl and NO radical precursors and synthesized a series of 5-amino isoxazoline products by visible-light irradiation.A simple,novel and practical reactions of N-nitroso amidocyclopropanes was developed to prepare isoxazolines by visible light irradiation.The reaction was performed well at room temperature with the tolerance of a series of functional groups.Importantly,the transformation did not require added additives(e.g.,bases or acids),oxidants,and catalysts.Visible light was the sole requirement.3.The wide availability of robust cationic iridium(III)complexes with tunable luminescence is the prerequisite for iridium photosensitizer designs.For robust photosensitizer designs,higher triplet energy,long lifetimes,and high stability are essential figures.In this part,we designed,synthesized,and characterized a series of cationic iridium(III)complexes with bulky substituents beside the ligands,which could lead to rigid cage formation.As aresult,significant improvements for catalyzing phototransformations have been proved with these iridium(III)complexes.