Visible Light Induced Decarboxylative Amination Reaction And [3+2]-cycloaddition Reaction,and Asymmetric Michael Reaction Catalyzed By Proteases

It has become the most important scientific issue of the twentyfirst century to search sustainable and clean energy.Solar energy is an abundant and endlessly renewable source of clean energy,and it has received increasing attention in the world energy crisis.The development and use of solar radiant energy have become one of the major scientific challenges of 21 st.Visible-light accounts for 46% of solar radiant energy onto the earth.One fundamental impediment that has limited the use of photochemical reactions is the inability of most organic molecules to absorb visible light.The use of photosensitizer has extended the application of photochemistry and benefited the research aimed at making use of the solar energy to solve global energy needs.Photocatalysis is more environmentally friendly than traditional synthetic methods,and it has been successfully applied in the formation of C-C and C-X bonds.We have devoleped methods of visible-light induced decarboxylative amination reaction and [3+2]-cycloaddition reaction.At present,most light-induced decarboxylation reactions used transition metal complexes as photosensitizer.However,these metal complexes are expensive and potentially toxic.Organic dyes,another kind of photosensitizers,are cheap,metal-free and easily prepared.A decarboxylative amination of azodicarboxylate esters and N-protected indoline-2-carboxylic acids under visible-light has been developed in the second chapter.?-Aminoalkyl radicals have been generated via the oxidation of indoline-2-carboxylic acids and then the ?-aminoalkyl radicals attack azodicarboxylate esters to form aminated prodcuts.13 new amination compounds were obtained in up to 72% yields.We proposed a mechnism based upon a series of control experiments.Pyrrolidinyl spirooxindole skeleton exists in many bioactive alkaloids.The synthesis of these compounds has received extensive attention.A lot of protocols were reported catalyzed by metal-or organo-catalysis.However,there has been no report on the synthesis of such substances by photocatalytic methods.We have developed a novel strategy to synthsis pyrrolidinyl spirooxindoles catalyzed by Rose Bengal under visible light in the third chapter.All the products prepared are new compounds,and their structures have been confirmed by HRMS,1H NMR and 13 C NMR,and 8aa is determined by single-crystal X-ray diffraction.Based on the control experiments,a possible singlet oxygen mechanism was proposed.Coumarin is important structural unit of many naturally occurring compounds and drugs.Coumarin derivatives have been widely studied for their broad biological activity.There are many reports on the synthesis of coumarin derivatives by organocatalysts.However,enzymatic synthesis of these compounds is rarely reported.Enzymes are green and efficient biocatalyst,and e nzyme promiscuity has been extensively used in organic synthesis.We have developed an enzymatic Michael reaction between ketons and 3-benzoyl coumarins in up to 78% yields with up to 99:1 dr and 52% ee in the fourth chapter.A series of controlled experiments showed that the Michael reaction was indeed catalyzed by the protease from Aspergillus mellaus and the reaction took place in the active site of the protease.A possible mechanism was proposed.