Precise Synthesis Of Helical Polyisocyanides And Polyallenes And Their Applications In Cooperative Organic Catalysis

Helical polymers have significant applications in optical materials and catalyticmaterials due to their unique helical conformation and special properties.Through the precise and controllable synthesis of helical polymers,functional materials with controllable molecular weight and topological morphology can be obtained,and they have been widely used in enantioselective crystallization,circularly polarized luminescence,chiral recognition,etc.However,the applications of helical polymers in efficient cooperative or asymmetric catalysis are rarely reported.It is known that cooperative catalysis strategy can greatly improve the reaction conversion,reaction rate,and optical purity of chiral catalytic products.Meanwhile,a large number of products can be obtained with a very small amount of catalyst,and the catalyst can be recycled,which is an economical and environmentally friendly strategy.In this thesis,rigid static helical polyisocyanides and dynamic helical polyallenes with high 2,3-regioselectivity were obtained by precise synthesis,and the helical polyisocyanides supported catalyst was applied to cooperative organic catalysis.It mainly includes the following three parts:1.Taking advantage of the rigid helical structure of polycyanides,we modified cobalt（Ⅲ）porphyrin decorated onto stereoregular polyisocyanides and developed a novel alkyne hydration catalyst.Owing to the preorganization of the rigid polymer skeleton,adjacent pendant cobalt（Ⅲ）porphyrins are arranged in parallel with an average distance of～0.9 nm,in which both the nucleophilic and electrophilic substrates can be dual-activated.The catalytic effectivity is investigated via catalytic hydration of a series of terminal and internal alkynes.Rigid helical polyisocyanides P1-Co exhibits high activity to afford the desired products in good to excellent conversions（>99%）at low catalyst loadings（0.1 mol%for terminal alkynes and 0.3 mol%for internal alkynes）.Conversely,the irregular polymeric analogs as well as the small-molecule control perform poorly due to the lack of a cooperative catalysis approach.To demonstrate its potential application in the pharmaceutical industry,the formal syntheses of four drugs（amfebutamone,haloperidol,propafenone,and bedaquiline）involving hydration of alkynes as the key step are achieved in excellent yields（>85%）.2.We modified chiral Salen-Co（Ⅲ）on the side group of helical polyisocyanides,and an optically active helical polyisocyanide with Salen-Co（Ⅲ）-N3 side group was obtained via ion exchange method.The obtained polymer（P1-Co-N₃）was applied to cooperative kinetic resolution of epoxide compounds and TMSN3.Due to the rigidity of the helical polyisocyanide main chain,the adjacent Salen-Co（Ⅲ）side groups were arranged in parallel.The side group of Co（Ⅲ）coordinated with the oxygen atom of the epoxide compound,while the N3^-group nucleophilic attacked epoxide ring to open it.Meanwhile,the optical active polyisocyanide helical main chain and chiral side groups jointly provided a chiral environment.All above together achieved the effect of cooperative kinetic resolution.The catalyst exhibited high cooperative kinetic resolution activity,and the product was with up to>99%enantiomeric excess（ee value）and isolated yields was close to 50%theoretical yields,while the catalytic activity of small molecular analogs presented lower catalytic activity and enantioselectivity.To demonstrate the substrate universality of the catalyst,we expanded the substrates with different electronic and steric effects,and obtained excellent yields with high optical purity.In addition,the helical polymer-supported catalyst was with the advantage of being recyclable,which could be reused at least 5 times with little loss of yield and ee value.3.While utilizing helical polyisocyanide-supported catalysts,we are also actively exploring the controllable synthesis of new helical polymers.We developed a novel phenyl Ni（Ⅱ）catalyst to achieve high 2,3-regioselective polymerization of allene monomers.Besides,the polyallene with high crystallinity,high 2,3-regioselectivity and high thermal stability has been obtained by using this strategy.We developed a series of novel nickel catalysts by introducing rigid monodentate phosphine ligands on aryl nickel,to initiate the polymerization of various allene monomers efficiently in a fast and living/controlled manner.The well-defined polyallenes were afforded in high yields with a controlled molar mass（Mn）and low molar mass distribution（Mw/Mn）.Moreover,the Ni（Ⅱ）/L4 catalyst exhibited fascinating regioselectivity on the accumulated double bonds of allene monomers,and the 2,3-regioselectivity of the polymerization of allene monomers was up to>99.9%.Remarkably,various monomers with different functional groups including alkyl,alkoxy and substituted phenyl groups could be polymerized effectively using Ni（Ⅱ）/L4 as the initiator,affording polyallenes with higher 2,3-regioselectivity.The regioselectivity,and thermodynamic and crystallization properties of the polyallenes were confirmed by ¹H NMR,DSC,TGA and WAXD,respectively,and we proved that the polyallenes with higher 2,3-selectivity have higher Tg and thermal stability.