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  • 09월 10일 16시 이후 : 초록수정 불가능, 일정확인 및 검색만 가능

제124회 대한화학회 학술발표회, 총회 및 기기전시회 안내 Cascade Polymerization via Controlled Tandem Olefin Metathesis/Metallotropic 1,3-Shift Reactions for the Synthesis of Fully Conjugated Polyenynes

2019년 9월 16일 16시 57분 04초
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목 09시 : 53분
KCS - Oral Presentation for 2019 DOW Korea Award
저자 및
Cheol Kang, Tae-Lim Choi*
Division of Chemistry, Seoul National University, Korea
Since the first discovery in 1969, polyenynes received much attention due to their intriguing optoelectronic properties that made them useful materials for molecular sensors. Although there have been extensive studies for the synthesis of various polyenynes, only a handful of polyenyne motifs were reported to date. Furthermore, most of the synthetic routes to polyenynes relied on topochemical synthesis in solid state, limiting their versatility in applications due to poor solubility. Even though the syntheses of soluble polyenynes were possible by step-growth mechanism, preparation of conjugated polyenynes with high molecular weights in a controlled manner remained elusive.
Very recently, we developed a new cascade polymerization method by combining two different organic reactions; olefin metathesis and metallotropic 1,3-shift. By rationally designing stable multialkyne monomers, a series of metathesis and metallotropy reactions proceeded by Grubbs catalyst in a sequence-specific manner to afford conjugated polymers containing unique polyenyne motifs in their backbone. For example, tetradeca-1,6,8,13-tetrayne moieties underwent a cascade transformation of ring-closing/metallotropic 1,3-shift/ring-closing reactions in a sequence-specific manner to efficiently generate a conjugated polyenyne backbone with a Z-E-Z alkene sequence and one triple bond. In addition to this tetrayne monomers, other two classes of monomers, pentaynes and hexaynes, underwent remarkably complex cascade reactions (up to 5 independent transformations) at high levels of selectivity to afford unprecedented conjugated polyenyne structures. This new polymerization, which we call cascade metathesis and metallotropy (M&M) polymerization, is the first example of making polyenynes by chain-growth mechanism, which enabled the precise control over molecular weights with narrow dispersities. Furthermore, living M&M polymerization realized the synthesis of block copolymers consisting of fully conjugated polyenyne backbones which highlights the uniqueness and versatility of M&M polymerization.