The Synthesis And Polymerization Of Chiral Terminal Epoxides With Bulky Group

The status of optically active polymers with helical conformation are reviewed in this dissertation.The synthesis of optically active helical polyethers with bulky pendants are carried out in order to solve current problems,for example,the polyethers could not keep stable helical conformation in solution because of fast dynamic conformation interconversion of polymer links.The relationship between theses pendants and chiral optical properities /conformation of the polyethers are also studied.The key results of research work are listed below:1.The several synthetic methods of chiral terminal epoxides were studied in order to obtain high ee value of terminal epoxides with bulky pendants,we found that optically active epichlorohydrin as building block reacted with organometallic reagents in the absence of catalyst under low temperature to yield chiral terminal epoxides with high ee value.Especially, 1,1-diphenylalkyl lithium,could be skillfully obtained by common organolithium with 1,1-diphenylethylene which provided a simple,facile and efficient way to produce many chiral terminal epoxides with different bulky pendants,such as（S）-4,4-diphenylbutene oxide （（S）-DPBO）,（S）-4,4,4-triphenyl-1-butene oxide（（S）-TPBO）,（R）-4,4,4-triphenyl-1-butene oxide（（R）-TPBO）),（S）-4,4,5-triphenyl-1-pentene oxide（（S）-BDPPO）,（S）-4,4,6,6-tetraphenyl -1-hexene oxide（（S）-TPHO）,（S）-4,4-diphenylnonene oxide（（S）-DPNO）.2.（S）-tritylglycidol（（S）-TGE）,（R）-5,5,5-triphenyl-1-pentene oxide（（R）-TPPO） and （R）-4,4,4-triphenylbutane-1,2-episulfide were prepared by other methods,except for these chiral epoxides,the corresponding racemic epoxides were also synthesized.The structures of new chiral terminal epoxides were determinated by ¹HNMR or ¹³CNMR,and their optical rotation and ee values were also measured,the steric configuration of these compounds were characterized by circular dichroism（CD） spectrum.3.The polymerization of those chiral terminal epoxides under different conditions were studied.Almost all monomers were smoothly polymerized with anionic initiator to give optically active polyethers.It was found that the bulky group on epoxy monomer greatly impacted molecular weight of the polymers:The process of polymerization（S）-TPBO was investigated.4.The relationship between theses pendants and chiral optical properities/conformation of the polyethers showed polyethers from chiral epoxides could form stable one-handed helical structure in solution if the pendants were appropriate.We found that poly（S）-TPBO or （R）-TPBO could keep stable helical conformation in solution,however,other polyethers we obtained could not maintain stable helical stucture in solution since the pendants of these polyethers was not enough bulk or rigid to produce great steric repulsion to maintain stable helical conformation in solution.5.The durability of methanol solvolysis of polyethers were also checked,the results showed that polyethers had great resistance to methanol.6.The results of synthesis of optically active helical polyether from chiral terminal epoxides showed that although the backbone of polyethers from epoxides is flexible and less rigid in solution,polyethers from chiral epoxides,could form stable one-handed helical structure in solution if the pendants on the chain of polyethers are enough bulk and the distance between pendant and main chain is appropriate.