- Degradable precision polynorbornenes via ring-opening metathesis polymerization
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In an attempt to introduce monomer sequence control in a growing polynorbornene via ring-opening metathesis polymerization, we employ dioxepins to efficiently determine the location of the monomers on the macromolecule backbone. Owing to the acid-labile a
- Moatsou, Dafni,Nagarkar, Amit,Kilbinger, Andreas F. M.,O'Reilly, Rachel K.
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- Alternating Ring-Opening Metathesis Polymerization Provides Easy Access to Functional and Fully Degradable Polymers
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Polymers with hydrolyzable groups in their backbones have numerous potential applications in biomedicine, lithography, energy storage, and electronics. In this study, acetal and ester functionalities were incorporated into the backbones of copolymers by m
- Boadi, Francis O.,Zhang, Jingling,Yu, Xiaoxi,Bhatia, Surita R.,Sampson, Nicole S.
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- Monofunctional metathesis polymers via sacrificial diblock copolymers
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(Chemical Equation Presented) A small price to pay: The second block of a diblock copolymer is "sacrificed" in order to leave behind a monofunctionalized metathesis polymer with a hydroxy end group. By incorporation of a dioxepine unit into the copolymer, a breaking point is created between the block to be end-functionalized and the block to be sacrificed.
- Hilf, Stefan,Berger-Nicoletti, Elena,Grubbs, Robert H.,Kilbinger, Andreas F. M.
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- Lewis Acid-Catalyzed Vinyl Acetal Rearrangement of 4,5-Dihydro-1,3-dioxepines: Stereoselective Synthesis of cis- And trans-2,3-Disubstituted Tetrahydrofurans
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Lewis acid-catalyzed rearrangements of 4,5-dihydro-1,3-dioxepines have been investigated. Rearrangement of vinyl acetals under a variety of conditions resulted in cis- and trans-2,3-disubstituted tetrahydrofuran derivatives in a highly stereoselective man
- Ghosh, Arun K.,Belcher, Miranda R.
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p. 10399 - 10412
(2020/09/02)
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- Rhodium-Catalyzed Intramolecular C-H Bond Activation with Triazoles: Preparation of Stereodefined Pyrrolidines and Other Related Cyclic Compounds
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On treatment of triazoles having an N-sulfonyl-protected benzylamine moiety with [Rh2(C7H15CO2)4], intramolecular C-H bond insertion takes place at the benzylic position to give cis-N-sulfonyl-2-aryl-3-[(sulfonylimino)methyl]pyrrolidines in good yields and with highly stereoselectivities. Analogously, the similar treatment of triazoles having an ether or even an alkyl moiety affords 2-alkyl- or 2-aryl-3-[(sulfonylimino)methyl]tetrahydrofurans or a 2-alkyl-3-[(sulfonylimino)methyl]cyclopentane in good yields. Three is a magic number: On treatment of triazoles with [Rh2(C7H15CO2)4], the rhodium catalyst plays three roles, denitrogenation, C-H bond activation, and stereoselective cyclization, providing a new method for heterocycle synthesis. Intramolecular C-H bond insertion takes place at the benzylic position to give pyrrolidines and related heterocycles in good yields.
- Senoo, Masato,Furukawa, Ayana,Hata, Takeshi,Urabe, Hirokazu
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supporting information
p. 890 - 895
(2016/01/16)
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- 2,4,4,6-Tetrabromo-2,5-cyclohexadienone (TABCO) as a versatile, efficient, and chemoselective catalyst for the acetalization and transacetalization of carbonyl compounds, the preparation of acetonides from epoxides and acylals (1,1-diacetates) from aldehydes
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The efficient and chemoselective preparation of acetals and ketals from carbonyl compounds, transacetalization reactions, the conversion of epoxides to acetonides, and the preparation of acylals from aldehydes in the presence of catalytic amounts of 2,4,4,6-tetrabromo-2,5-cyclohexadienone (TABCO) are described.
- Firouzabadi, Habib,Iranpoor, Nasser,Shaterian, Hamid Reza
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p. 2195 - 2205
(2007/10/03)
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- Asymmetric synthesis of thietanose
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Syntheses of optically active thietanose, (2R,3R,4R)-4-acetoxymethyl-3-(tert-butyldimethylsilyl)oxy-2-ethoxythietane (6) and (2R,3R,4R)-3-(tertbutyldimethylsiIyl)oxy-4-[(/m-butyldimethylsilyl)oxy]methyl-2- ethoxythietane (23) are described. The key interm
- Uenishi, JuN'Ichi,Motoyama, Mitsuhiro,Kimura, Yumi,Yonemitsu, Osamu
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p. 439 - 451
(2007/10/03)
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- Isomer Selectivity in Stereocontrolled Payne Rearrangement-epoxide Cleavage of 2,3-Epoxy Alcohols in Aprotic Solvents: Application to an Enantioselective Total Synthesis of (+)-exo-Brevicomin
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Organo-copper and -cuprate reagents may be used to trap the more reactive epoxy alkoxide isomer in a Lewis acid-catalysed Payne rearrangement process.This methodology has been used as the key step in a five-step enantioselective total synthesis of (+)-exo
- Page, Philip C. Bulman,Rayner, Christopher M.,Sutherland, Ian O.
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p. 1375 - 1382
(2007/10/02)
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- Photochemistry and Photophysics of 3-(2-Isoxazolinyl)-phenylketones
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3-Benzoyl-Δ2-1,2-oxazolines (1-6) are formed by 1,3-dipolar cycloaddition between benzoylnitril-N-oxide (8) and dihydrofurane 9 or 1,3-dioxep-5-enes (10a-c).The preparative yields are small due to the competitive dimerization of the dipole 8.Tw
- Timpe, H.-J.,Schmidt, M.,Fisera, L'.
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p. 735 - 747
(2007/10/02)
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A general method for the synthesis of chiral epoxides starting from the bifunctionalised epoxide synthon 2is described. This approach is useful for the preparation of saturated epoxides. β,γ - unsaturated analogues could not be easily obtained. In this case, the use of metallic acetylides with BF3. (C2H5)2O proved very helpful.
- Soulie,Lampilas,Lallemand
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p. 2701 - 2708
(2007/10/02)
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- A FACILE CLEAVAGE OF BENZYLIDENE ACETALS WITH DIISOBUTYLALUMINUM HYDRIDE
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Benzylidene acetals of 1,2- and 1,3-glycols are easily cleft by diisobutylaluminum hydride in a toluene solution at 0 deg C - room temperature to give the corresponding monobenzyl ethers of the glycols.In general the reaction proceeds excellently in regioselective manner depending on the stereochemical environment.
- Takano, Seiichi,Akiyama, Masashi,Sato, Seiji,Ogasawara, Kunio
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p. 1593 - 1596
(2007/10/02)
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- Fragmentation of Cyclic Carboxonium Ions, III. 1,3-Dioxepan-4-ylium Ions, a Key for the Synthesis of Tetrahydrofuran-3-carbaldehydes
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The formation of 1,3-dioxepane-4-ylium ions (3) is achieved by protonation of 4,5-dihydro-1,3-dioxepines (2).These are prepared by ?-bond isomerization of 4,7-dihydro-1,3-dioxepines (1) under basic conditions.Thermal fragmentation of 3 and subsequent recy
- Scharf, Hans-Dieter,Frauenrath, Herbert
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p. 1472 - 1479
(2007/10/02)
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