- Organotellurium-mediated Synthesis of Oxazolidin-2-ones from Alkenes
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Phenyltellurinyl trifluoroacetate in combination with ethyl carbamate and boron trifluoride-diethyl ether reacted with alkenes in refluxed 1,2-dichloroethane, regio- and stereo-selectively giving oxazolidin-2-ones in high yields.
- Hu, Nan X.,Aso, Yoshio,Otsubo, Tetsuo,Ogura, Fumio
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- A facile synthesis of 2-oxazolidinones via Hofmann rearrangement mediated by bis(trifluoroacetoxy)iodobenzene
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A mild and efficient synthesis of 2-oxazolidinones from β-hydroxypropionamides via Hofmann rearrangement was achieved in 96% to quantitative yield using bis(trifluoroacetoxy)iodobenzene (BTI) in acetonitrile. The method should be useful in both solution- and solid-phase construction of 2-oxazolidinone libraries.
- Yu, Chengzhi,Jiang, Yongying,Liu, Bin,Hu, Longqin
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- Versatile Cp*Co(III)(LX) Catalyst System for Selective Intramolecular C-H Amidation Reactions
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Herein, we report the development of a tailored cobalt catalyst system of Cp*Co(III)(LX) toward intramolecular C-H nitrene insertion of azidoformates to afford cyclic carbamates. The cobalt complexes were easy to prepare and bench-stable, thus offering a convenient reaction protocol. The catalytic reactivity was significantly improved by the electronic tuning of the bidentate LX ligands, and the observed regioselectivity was rationalized by the conformational analysis and DFT calculations of the transition states. The superior performance of the newly developed cobalt catalyst system could be broadly applied to both C(sp2)-H and C(sp3)-H carbamation reactions under mild conditions.
- Chang, Sukbok,Jung, Hoimin,Kim, Dongwook,Lee, Jeonghyo,Lee, Jia,Park, Juhyeon
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supporting information
p. 12324 - 12332
(2020/08/06)
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- Synthesis of oxazolidinones: Rhodium-catalyzed C-H amination of: N -mesyloxycarbamates
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N-Mesyloxycarbamates undergo intramolecular C-H amination reactions to afford oxazolidinones in good to excellent yields in the presence of rhodium(ii) carboxylate catalysts. The reaction is performed under green conditions and potassium carbonate is used, forming biodegradable potassium mesylate as a reaction by-product. This method enables the production of electron-rich, electron-deficient, aromatic and heteroaromatic oxazolidinones in good to excellent yields. Conformationally restricted cyclic secondary N-mesyloxycarbamates furnish cis-oxazolidinones in high yields and selectivity; DFT calculations are provided to account for the observed selectivity. trans-Oxazolidinones were prepared from acyclic secondary N-mesyloxycarbamates using Rh2(oct)4. The selectivity was reverted with a cytoxazone N-mesyloxycarbamate precursor using large chiral rhodium(ii) carboxylate complexes, affording the corresponding cis-oxazolidinone. This orthogonal selectivity was used to achieve the formal synthesis of (-)-cytoxazone.
- Lebel, Hélène,Mamani Laparra, Laura,Khalifa, Maroua,Trudel, Carl,Audubert, Clément,Szponarski, Mathieu,Dicaire Leduc, Cédric,Azek, Emna,Ernzerhof, Matthias
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p. 4144 - 4158
(2017/07/10)
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- Interaction of substrate and catalyst during the formation of oxazolidinones from 2-aminoalcohols and diethyl carbonate using recyclable 1,3-dichlorodistannoxanes
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An efficient synthesis of oxazolidinone (OXZ) using 2-aminoalcohols (2AAs) and diethyl carbonate (DEC) as reagents in the presence of recyclable catalyst 1,3-dichloro-1,1,3,3-tetraalkyldistannoxane, [(RR′SnCl)2O] 2 (1) is reported. 0.5 mol% (with respect to 2AA) of 1 provides OXZ quantitatively within 1 h at 80 °C with turnover frequency (TOF) of 200 h-1. The observed TOF is much higher than the reported value (4 h-1) of the most convenient and commercially feasible K 2CO3 catalyst. Chiral 2AAs produce OXZs with 99% ee. Molar dependency of 1, DEC and 2AA is found to be 1:2:2. Molar conductivities (Ω-1 cm2 mol-1) in DMSO at 25 °C are 6.41 for 1a (R = R′ = Bu), 5.25 for 1b (R = Bu, R′ = Ph), 2.87 for 1c (R = Ph, R′ = Bu), and 2.21 for 1d (R = R′ = Ph) which reveal the mobility of bridged Cl in 1 during reaction. The study of a broad range of substrates and reaction parameters supports a reaction pathway that begins with initial attack by -OH of the pre-formed 2-ethylcarbamato aminoalcohol (2ECA) of 2AA on Snb of 1 displacing the bridged Cl. Change in the reaction rates resulted due to various alkyl and aryl substituents on Sn provides better understanding of the distannoxane catalysis, which has not been attempted before for the said reaction.
- Pulla, Sharon,Unnikrishnan, Vineed,Ramidi, Punnamchandar,Sullivan, Shane Z.,Ghosh, Anindya,Dallas, Jerry L.,Munshi, Pradip
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experimental part
p. 33 - 43
(2011/05/02)
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- Enzymatic dynamic kinetic resolution of (±)-cis-N-(Alkoxycarbonyl) cyclopentane-1,2-diamines based on spontaneous racemization
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Lipase B from Candida antarctica is an excellent catalyst for the enantioselective acetylation of different (±)-cis-N-(alkoxycarbonyl) cyclopentane-1,2-diamines. Depending on the alkoxycarbonyl group, a simple kinetic resolution (Boc-derivative) or an interesting dynamic kinetic resolution (DKR with Cbz-, Alloc, and ethoxycarbonyl derivatives) has been developed. Racemization for the DKR occurred due to the N,N′ intramolecular migration of the alkoxycarbonyl group.
- Quijada, F. Javier,Gotor, Vicente,Rebolledo, Francisca
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supporting information; experimental part
p. 3602 - 3605
(2010/11/05)
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- An Enantiospecific Synthesis of Allosamizoline
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An enantiospecific synthesis of allosamizoline 4, the aglycone of the chitinase inhibitor allosamidin 3, has been achieved, starting from readily available glucosamine.The key step in the synthesis involves the cyclisation of a carbon-centred radical onto
- Simpkins, Nigel S.,Stokes, Stephen,Whittle, Alan J.
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p. 2471 - 2478
(2007/10/02)
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- Aminotellurinylation of Olefins and Its Utilization for Synthesis of 2-Oxazolidinones
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Benzenetellurinyl acetate or trifluoroacetate in combination with ethyl carbamate effected regio- and stereoselective aminotellurinylation of olefins in the presence of boron trifluoride etherate in chloroform under reflux to give ethyl carbamates in high yields.Benzenetellurinyl trifluoromethanesulfonate similarly did it even at the lower temperature of refluxing dichloromethane without Lewis acid.This reaction was successfully extended to cyclofunctionalization of olefinic carbamates into nitrogen heterocycles.Furthermore, when the aminotellurinylation was carried out in refluxing 1,2-dichloroethane, 2-oxazolidinone was obtained in a high yield.A mechanism of addition followed by intramolecular substitution in proposed on the basis of the stereochemistry of 2-oxazolidinone derivatives.
- Hu, Nan Xing,Aso, Yoshio,Otsubo, Tetsuo,Ogura, Fumio
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p. 4398 - 4404
(2007/10/02)
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- A GENERAL METHOD FOR STEREO- AND REGIO-SPECIFIC OXYAMINATION OF OLEFINS
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A new synthetic method for stereo and regioscpecific oxyamination of olefins is described.
- Das, Jagabandhu
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p. 907 - 916
(2007/10/02)
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- NEW SYNTHETIC REACTIONS USING ARENETELLURINIC ANHYDRIDES
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New synthetic reactions utilizing arenetellurinic acid anhydrides are described.The anhydrides proved to be very useful reagents for the transformation of various functional groups.Furthermore they induced various intramolecular cyclofunctionalizations to yield many oxygen and nitrogen heterocycles.
- Hu, Nan Xing,Aso, Yoshio,Otsubo, Tetsuo,Ogura, Fumio
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p. 177 - 190
(2007/10/02)
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