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  • 02월 19일 23시 이후 : 초록수정 불가능, 일정확인 및 검색만 가능

제119회 대한화학회 학술발표회, 총회 및 기기전시회 Unprecedented β‑Regioselectivity in Cyclopolymerization of 1,6-Heptadiynes Using Grubbs Z‑Selective Catalyst

2017년 3월 20일 17시 43분 13초
KCS.O-7 이곳을 클릭하시면 발표코드에 대한 설명을 보실 수 있습니다.
목 11시 : 08분
한국다우케미칼 우수논문상 수상자 구두발표
저자 및
정기정, 강은혜, 손정훈, 최태림*
서울대학교 화학부, Korea

It is well-known that Ru-based Grubbs catalysts undergo a highly selective α-addition to alkynes to promote exo-cyclization during ring-closing enyne metathesis (RCEYM) or to produce conjugated polyenes containing five-membered rings during the cyclopolymerization (CP) of 1,6-heptadiynes. There are a few reports of β-selective addition to alkynes using Schrock catalysts based on Mo but none for readily accessible and easy-to-use Ru-based catalysts. We report the first example of β-selective addition to alkynes using Grubbs Z-selective catalyst, which produces only endo products during the RCEYM reaction of terminal enynes and promotes the CP of 1,6-heptadiyne derivatives to give conjugated polyenes containing a six-membered ring as a major repeat unit. This unique preference for β-selectivity originated from the side-bound approach of alkynes to the catalyst, where the steric hindrance between the chelating N-heterocyclic carbene ligand of the catalyst and the alkynes disfavored α-addition. To enhance the β-selectivity for CP further, one could increase the size of the substrates on the monomers and lower the reaction temperature to obtain conjugated polyenes containing up to 95% six-membered rings. Moreover, the physical properties of the resulting polymer were analyzed in detail and compared with those of the conjugated polyenes containing only five-membered rings prepared from the same monomer but with a conventional Grubbs catalyst.