- Mechanistic and Kinetic Studies of the Ring Opening Metathesis Polymerization of Norbornenyl Monomers by a Grubbs Third Generation Catalyst
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The mechanism of ring-opening metathesis polymerization (ROMP) for a set of functionalized norbornenyl monomers initiated by a Grubbs third generation precatalyst [(H2IMes)(pyr)2(Cl)2Ru═CHPh] was investigated. Through a series of 12C/13C and 1H/2H kinetic isotope effect studies, the rate-determining step for the polymerization was determined to be the formation of the metallacyclobutane ring. This experimental result was further validated through DFT calculations showing that the highest energy transition state is metallacyclobutane formation. The effect of monomer stereochemistry (exo vs endo) of two types of ester substituted monomers was also investigated. Kinetic and spectroscopic evidence supporting the formation of a six-membered chelate through coordination of the proximal polymer ester to the Ru center is presented. This chelation and its impact on the rate of polymerization are shown to vary based on the monomer employed and its stereochemistry. The combination of this knowledge led to the derivation of a generic rate law describing the rate of polymerization of norbornene monomers initiated by a Grubbs third generation catalyst.
- Hyatt, Michael G.,Walsh, Dylan J.,Lord, Richard L.,Andino Martinez, José G.,Guironnet, Damien
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supporting information
p. 17918 - 17925
(2019/11/11)
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- NORBORNENE MONOMER, POLYNORBORNENE DERIVATIVE, LIQUID CRYSTAL PHOTOALIGNMENT FILM CONTAINING THE SAME AND LIQUID CRYSTAL DISPLAY CONTAINING THE SAME
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The present invention relates to a norbornene monomer, a polynorbornene derivative, a liquid crystal alignment film including the same, and a liquid crystal display device including the same. More particularly, the present invention relates to a norbornene monomer, a polynorbornene derivative, a liquid crystal alignment film including the same, and a liquid crystal display device including the same, which have an alignment property by photoreaction, excellent thermal stability and photoreactivity, the increased photo-reaction rate and reliability of the alignment film, thereby showing high manufacturing process efficiency.
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Paragraph 0086-0088
(2014/08/07)
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- Microbial alcohol dehydrogenase screening for enantiopure lactone synthesis: Down-stream process from microtiter plate to bench bioreactor
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One-pot conversion with whole cells of bacteria was performed for biooxidation of meso monocyclic (3a-b) and bicyclic diols (3c-e) into corresponding chiral lactones of bicyclo[4.3.0]nonane structure (2a-b) as well as exo- and endo-bridged lactones with the structure of [2.2.1] (3c-d) and [2.2.2] (3e). Micrococcus sp. DSM 30771 was selected as biocatalyst with significant alcohol dehydrogenase activity. Among tested strains, microbial oxidation of meso diols 3a-e catalyzed by Micrococcus sp. afforded enantiomerically pure ((+)-(2S,3R)-2c (ee = 99%), (+)-(2S,3R)-2e (ee = 99%)) or enriched ((+)-(1S,5R)-2a (ee = 90%), (-)-(1S,5R)-2b (ee = 86%), (+)-(2S,3R)-2d (ee = 80%)) lactone moieties. Comparative study with respect to microbial cultivation as well as biooxidation was undertaken to verify agreement of secondary metabolite biosynthesis in different scales: from MTP (4 mL), across shake flask (100 mL) till bioreactor (4 L). The results from biotransformations showed quite similar dependence in oxidation of all substrates 3a-e in MTP and flasks as well, thereby confirmed the validity and reasonable approach of using MTP for preliminary studies.
- Boratyński,Pannek,Walczak,Janik-Polanowicz,Huszcza,Szczepańska,Martinez-Rojas,Olejniczak
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p. 1637 - 1646
(2015/02/05)
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- Gold-catalyzed reactions of enynals/enynones with norbornenes: Generation and trapping of cyclic o-quinodimethanes (o-QDMs)
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Fan-like structures: An efficient AuIII-catalyzed method to generate the highly reactive cyclic o-quinodimethane (o-QDM) species from easily available enynals or enynones is presented (see scheme). This method produced a variety of structurally unique fan-like products with the advantages of mild reaction conditions, excellent diastereoselectivities, and high functional-group tolerance. Copyright
- Zhu, Shifa,Zhang, Zhicai,Huang, Xiaobing,Jiang, Huanfeng,Guo, Zhengjiang
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supporting information
p. 4695 - 4700
(2013/05/09)
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- ROMP-derived oligomeric phosphates for application in facile benzylation
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The development of new ROMP-based oligomeric benzyl phosphates (OBP n) is reported for use as soluble, stable benzylating reagents. These oligomeric reagents are readily synthesized from commercially available materials and conveniently polymerized and purified in a one-pot process, affording bench-stable, pure white, free-flowing solids on multigram scale. Utilization in benzylation reactions with a variety of nucleophiles is reported.
- Long, Toby R.,Maity, Pradip K.,Samarakoon, Thiwanka B.,Hanson, Paul R.
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supporting information; experimental part
p. 2904 - 2907
(2010/09/30)
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- Free radical reactions on soluble supports from ring-opening metathesis
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Equation presented Free radical reactions were performed on soluble ring-opening metathesis (ROM) polymers. These polymers have high substrate loading, short reaction times, and the benefit of a facile purification. All reactions on these supports were obtained in good yields as white crystalline-like materials readily separated from tin byproducts.
- Enholm, Eric J.,Gallagher, Maria E.
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p. 3397 - 3399
(2007/10/03)
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- 6-(3-Carbamoylbicyclohept-2-yl)hexanoic Acids, a New Class of TxA2 Antagonists
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The synthesis of prostanoids 20-27, 40a, b, and 45a, b starting from the educts 1a, b, and 31 is described.Configurational changes concerning to the positions 2 and 3 of the bicyclic system were proofed by 13C-NMR spectroscopy and were also used for the preparation of the four exo/endo derivatives. 25 and 26 are potent TxA2 antagonists.
- Lieb, Folker,Niewoehner, Ulrich,Wendisch, Detlef
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p. 607 - 616
(2007/10/02)
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- Enzymes in Organic Synthesis. 34. Preparations of Enantiomerically Pure Exo-and Endo-Bridged Bicyclic and Chiral Lactones via Stereospecific Horse Liver Alcohol Dehydrogenase Catalyzed Oxidations of Meso Diols
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Preparative-scale horse liver alcohol dehydrogenase catalyzed oxidations of saturated and unsaturated exo- and endo-bridged bicyclic and meso diols proceed with complete enantiotopic specificity to give high (64-87percent) yields of the corresponding chiral lactones of >=97percent ee.As for previous meso diol oxidations, the stereochemical course of each oxidation (S-center CH2OH oxidation in all cases) is as predicted by the cubic-space model of the active site.An illustration of the asymmetric synthetic value of these chiral lactones is provided by the conversion of one of them into a prostaglandin precursor.
- Lok, Kar P.,Jakovac, Ignac J.,Jones, J.Bryan
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p. 2521 - 2526
(2007/10/02)
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- PHASE TRANSITIONS IN BICYCLIC COMPOUNDS.
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The thermal properties of bicyclic and cyclic compounds obtained by DSC show that substituents such as the anhydride, nitrile, and carbonyl groups retain the polymorphic phase properties of the parent ring systems while groups such as the imide, methylimide, and carboxylic acid exclude the appearance of a disordered solid phase. The phase properties of chloro and hydroxyl derivatives investigated and more varied and depend on the position of these groups on the ring. The variety of compounds studied shows that hysteresis is a common occurrence in all of these ring systems.
- Weinstein,Leffler,Currie
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