Studies On Organic Synthesis Involving Enaminones Via Visible Light Catalysis

Enaminones are a class of highly general building blocks in organic synthesis,and show irreplaceable application in the synthesis of numerous organic molecules.However,the sustainability guided synthesis,such as green photocatalytic chemical transformations in enaminones is yet rather scarce.Therefore,developing green energy such as visible light promoted organic synthesis with enaminones is significant.The main researches of this thesis are the visible light photocatalytic organic reactions on enaminones,consisting of three independent research works.1)Photocatalytic thiocyanation reactions of theα-C-H bond in NH₂-enaminones.In this work,the photocatalytic thiocyanation of NH₂-enaminones and ammonium thiocyante has been studied and realized for the first time,enabling the synthesis ofα-thiocyanoenaminones under mild conditions.In addition,simply modifying reaction conditions and operation can transform the thiocyano enaminone products into 2-amino thiazoles and thiazolino-2-ones.2)Photocatalytic TMEDA and enaminone annulation reactions for pyridine synthesis.By employing NH₂-enaminones and N,N,N’,N’-tetramethylethylene diamine（TMEDA）as substrates,the poly substituted pyridines have been synthesized in the presence of Rose Bengal by visible light irradiation.This work provides a mild and environmentally friendly method for the synthesis of pyridines.3)Visible light photocatalytic enaminone tandem carbon-carbon bond cleavage reactions for the synthesis of imides.Under the conditions of visible light irradiation and Ir₂（ppy）₄Cl₂ as photocatalyst,enaminones react withα-diazo esters and alkyl cyanides for affording imides via carbon-carbon bond cleavage.The cascade transformations of air oxidation,carbon-carbon bond cleavage and Mumm rearrangement etc.have been involved in the reaction.In addition to provide an environmentally benign method for the synthesis of imides,the work also discloses novel transformation modes in organic synthesis.