Visible-Light Driven Annulations Of Alkenes(Alkynes) And Difunctionalizations Of Alkynes

Alkenes and alkynes are commonly used organic precursors,and widely applicated in various types of organic reaction,such as addition,substitution and cyclization reactions.However,it is still a challenging task to construct complicated molecules under mild reaction conditions with one-step by using simple alkenes or alkynes as substrates.In recent years,visible-light driven organic reactions were used as a new and efficient tactic,have been widely used in organic synthesis.It should be noted that this synthetic method has mild conditions and facile operation merits.This dissertation mainly focuses on organic dyes catalyzed annulation of alkenes or alkynes,further difunctionalization of alkynes with alkyl bromides under visible-light irradiation was also studied.Detailed contents as following:1.A direct synthesis of 4-aryl tetralones from aromatic alkenes and O2 catalyzed by Mes-Acr+ClO4–photocatalyst under blue-light irradiation was developed.This synthetic method provided a facile,efficient and environmentally friendly platform to generate a wide range of 4-aryl tetralones.Furthermore,a plausible mechanism was proposed based on the control experiments and electron paramagnetic resonance spectrometer studies.2.A highly regioselective [2+2+2] cyclization of alkynes with nitriles was developed for the preparation of 2,3,6-trisubstituted pyridines under blue-light irradiation using pyrylium salt as photoredox catalyst.Meanwhile,this cyclization had good regioselectivity and broad substrate range;it is further proved that this cyclization was achieved by single-electron transfer process.3.A highly regio-and stereoselective addition of alkyl bromides to arylacetylenes was developed by using Na2-eosin Y as photoredox catalyst under green-light irradiation.This difunctionalization was accomplished under ambient and metal-free conditions to produce alkenyl bromides in high efficiency with a wide range of group tolerance.