ASYMMETRIC SYNTHESIS OF OPTICALLY ACTIVE POLYMERS HAVING MAIN CHAIN CHIRALITY

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The synthesis of optically active polymers having main chain configurational chirality is an important technology, which is essential for the molecular design of the next generation polymeric materials. A great number of methods for enantioselective transformations including C-C bond forming reactions have been extensively studied. If an asymmetric C-C bond forming reaction proceeds in quantitative conversion without any side reactions, it can be used for optically active polymer synthesis. We have found that the enantioselective addition of allylsilane to an aldehyde (Sakurai-Hosomi allylation reaction) and the enantioselective addition of enol silane to an aldehyde (Mukaiyama aldol reaction) are suitable reaction for the synthesis of optically active polymers. Repetitive Sakurai-Hosomi allylation between bis(allylsilane) and dialdehyde produced a polymer having a chiral homoallylic alcohol unit structure. When a chirally modified Lewis acid catalyst was used, optically active polymers having main chain configurational chirality was obtained. Similarly, repetitive Mukaiyama aldol reaction between bis(enolsilane) andaldehyde produced a polymer having a chiral β-hydroxy carbonyl unit structure.