Visible-light-mediated [2+2] Cycloadditions To Construct Spirobutane Oxindoles And Azacyclobutanes Via Energy Transfer

Spirocyclobutyl oxindoles and aza-cyclobutane structural units have play an important role in chemical and pharmaceutical research.The synthesis of these compounds has been one of the hot spots in synthetic chemistry due to their special applications and unique structures.This thesis explores the visible light-catalyzed direct construction of spirobutane oxindoles and aza-cyclobutane analogs via triplet energy transfer [2+2] cycloaddition reactions with the following three main parts :Chapter 1: This chapter reviews the development of [2+2] cycloaddition reactions mediated by ultraviolet light to visible light and introduces the basic principles of triplet energy transfer.Including direct excitation of the substrate to the triplet state and the use of visible light to excite the photocatalyst to indirectly bring the substrate to the triplet state,and highlights the visible light-mediated triplet energy transfer [2+2]cycloaddition reactions that have attracted widespread interest from chemists in recent years.Chapter 2: Spirocyclobutyl oxindoles are found in a variety of pharmaceuticals as well as natural products,such as phosphodiesterase inhibitors,progesterone antagonists and antivirals.We have achieved a direct synthesis of spirocyclobutoxyindole compounds based on visible light-catalyzed triplet energy transfer reactions using a 2-indolone backbone with styrenic receptors in the presence of a photocatalyst for triplet energy transfer [2+2] cycloaddition reactions,providing a mild,concise and efficient method for the synthesis of this class of useful compounds.Chapter 3: Azetidinium is widely present in many drugs and its insertion into the relevant drug Scaffolds can improve the metabolic kinetic properties and metabolic stability of the drug.The light-mediated aza Paternò-Büchi reaction provides a direct and facile approach for the synthesis of such compounds,and we have successfully achieved the intermolecular aza Paternò-Büchi reaction catalyzed by triplet state energy transfer using quinoxaline substrates with olefin receptors under visible light.