Asymmetric polymerization using chirally modified Lewis acid
| Project/Area Number |
11650907
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
高分子合成
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| Research Institution | Toyohashi University of Technology |
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Principal Investigator |
ITSUNO Shinichi Toyohashi University of Technology, 工学部, 助教授 (50158755)
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| Project Period (FY) |
1999 – 2000
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| Project Status |
Completed (Fiscal Year 2000)
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| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2000: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1999: ¥2,500,000 (Direct Cost: ¥2,500,000)
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| Keywords | asymmetric polymerization / aldol reaction / allylation reaction / optically active polymer / キラルルイス酸 / オキサザボロリジノン / キラルアシロキシボラン |
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| Research Abstract |
Optically active synthetic polymers have attracted considerable attention. Generation of well-controlled configurational chirality in the polymer main chain is highly desired for development of new methodologies for the synthesis of optically active polymers. A number of excellent asymmetric C-C bond formation reactions have appeared. Thus, one of the most promising ways to obtain optically active polymers having main chain chirality is polymerization based on repetitive asymmetric C-C bond forming reactions. We have focused on two important nucleophilic addition reactions, Sakurai-Hosomi allylation and Mukaiyama aldol reaction. These reactions are powerful method for the construction of C-C bonds together with the possibility of creating a new stereogenic center. In this study we have investigated the new asymmetric polymerizations based on repetitive allylation and aldol reaction.
For asymmetric allylation polymerization, we prepared bis (allylsilane) s and dialdehydes as new monomers
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. Polymerization of these monomers took place to give the corresponding polymers that have a unique main chain structure containing hydroxy and exo methylene groups. Chiral (acyloxy) borane derived from tartaric acid is an excellent catalyst for the asymmetric allylation polymerization. Model reaction between allylsilane and aldehyde using the chiral (acyloxy) borane revealed that high level of asymmetric induction would occur during asymmetric polymerization.
Asymmetric Mukaiyama aldol reaction can be also applied to the synthesis of optically active polymers. We have prepared bis (silyl enol ether) s, bis (silyl ketene acetal), and bis (sily lketene thioacetal) s as monomers of asymmetric aldol polymerization. Reaction between these monomers and dialdehydes occurred smoothly in the presence of chiral Lewis acid catalyst to afford optically active poly (β-hydroxy carbonyl) s. One of the most efficient chiral catalyst is oxazaborolidinone derived from N-sulfonylated amino acid and borane. Some of these chiral polymers could be degraded to give a low-molecular-weight chiral compounds, which were analyzed by chiral HPLC to determine the asymmetric induction during polymerization. Asymmetric induction during polymerization is almost the same as that in the model asymmetric reaction between enolsilane and aldehyde. Less
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Report
(3 results)
Research Products
(10 results)
