- Intramolecular conversion of N,N-bis(2-picolyl)ureas to cyclic carbamates
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Herein, we present a new methodology for preparing 6-membered ring carbamates from a CuI-promoted cyclization of N,N-bis(2-picolyl)amine substituted ureas. The reactions work best in the presence of up to five-fold excess of CuCl at room temper
- Jakob, Uwe,Bannwarth, Willi
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- Testing the limits of radical-anionic CH-amination: A 10-million-fold decrease in basicity opens a new path to hydroxyisoindolines via a mixed C-N/C-O-forming cascade
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An intramolecular C(sp3)-H amidation proceeds in the presence of t-BuOK, molecular oxygen, and DMF. This transformation is initiated by the deprotonation of an acidic N-H bond and selective radical activation of a benzylic C-H bond towards hydrogen atom transfer (HAT). Cyclization of this radical-anion intermediate en route to a two-centered/three-electron (2c,3e) C-N bond removes electron density from nitrogen. As this electronegative element resists such an oxidation , making nitrogen more electron rich is key to overcoming this problem. This work dramatically expands the range of N-anions that can participate in this process by using amides instead of anilines. The resulting 107-fold decrease in the N-component basicity (and nucleophilicity) doubles the activation barrier for C-N bond formation and makes this process nearly thermoneutral. Remarkably, this reaction also converts a weak reductant into a much stronger reductant. Such reductant upconversion allows mild oxidants like molecular oxygen to complete the first part of the cascade. In contrast, the second stage of NH/CH activation forms a highly stabilized radical-anion intermediate incapable of undergoing electron transfer to oxygen. Because the oxidation is unfavored, an alternative reaction path opens via coupling between the radical anion intermediate and either superoxide or hydroperoxide radical. The hydroperoxide intermediate transforms into the final hydroxyisoindoline products under basic conditions. The use of TEMPO as an additive was found to activate less reactive amides. The combination of experimental and computational data outlines a conceptually new mechanism for conversion of unprotected amides into hydroxyisoindolines proceeding as a sequence of C-H amidation and C-H oxidation.
- Alabugin, Igor V.,Dos Passos Gomes, Gabriel,Elliott, Quintin,Evoniuk, Christopher J.
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p. 6539 - 6555
(2020/07/15)
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- The Reaction of o-Aminoacetophenone N-Tosylhydrazone and CO2 toward 1,4-Dihydro-2H-3,1-benzoxazin-2-ones
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A transition-metal-free reaction of o-aminoacetophenone N-tosylhydrazone and CO2 has been developed, leading to a series of 1,4-dihydro-2H-3,1-benzoxazin-2-ones in moderate to good yields. This procedure proceeds with the sequential fixation of CO2 by amino leading to carbamic acid and the intra- molecular insertion of hydroxyl to carbene. (Figure presented.).
- Xiong, Hao,Wu, Xiaopeng,Wang, Hepan,Sun, Song,Yu, Jin-Tao,Cheng, Jiang
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supporting information
p. 3538 - 3542
(2019/07/10)
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- Sunlight-Driven Forging of Amide/Ester Bonds from Three Independent Components: An Approach to Carbamates
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A photoredox catalytic route to carbamates enabled by visible irradiation (or simply sunlight) has been developed. This process leads to a novel approach to the construction of heterocyclic rings wherein the amide or ester motifs of carbamates were assembled from three isolated components. Large-scale experiments were realized by employing continuous flow techniques, and reuse of photocatalyst demonstrated the green and sustainable aspects of this method.
- Zhao, Yating,Huang, Binbin,Yang, Chao,Chen, Qingqing,Xia, Wujiong
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p. 5572 - 5575
(2016/11/17)
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- From in vitro to in cellulo: Structure-activity relationship of (2-nitrophenyl)methanol derivatives as inhibitors of PqsD in Pseudomonas aeruginosa
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Recent studies have shown that compounds based on a (2-nitrophenyl)methanol scaffold are promising inhibitors of PqsD, a key enzyme of signal molecule biosynthesis in the cell-to-cell communication of Pseudomonas aeruginosa. The most promising molecule displayed anti-biofilm activity and a tight-binding mode of action. Herein, we report on the convenient synthesis and biochemical evaluation of a comprehensive series of (2-nitrophenyl)methanol derivatives. The in vitro potency of these inhibitors against recombinant PqsD as well as the effect of selected compounds on the production of the signal molecules HHQ and PQS in P. aeruginosa were examined. The gathered data allowed the establishment of a structure-activity relationship, which was used to design fluorescent inhibitors, and finally, led to the discovery of (2-nitrophenyl)methanol derivatives with improved in cellulo efficacy providing new perspectives towards the application of PqsD inhibitors as anti-infectives. This journal is the Partner Organisations 2014.
- Storz, Michael P.,Allegretta, Giuseppe,Kirsch, Benjamin,Empting, Martin,Hartmann, Rolf W.
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supporting information
p. 6094 - 6104
(2014/08/05)
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- PROCESS FOR THE SYNTHESIS OF CYCLIC CARBAMATES
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The invention is directed to a process for the preparation of cyclic carbamates of formula (I) and/or a salt thereof, from the corresponding o-aminobenzyl alcohol and/or a salt thereof.
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Page/Page column 7-8
(2010/11/03)
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- Facile double-lithiation of a transient urea: Vicarious ortho -metalation of aniline derivatives
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A convenient one-pot method for the conversion of phenylisocyanate into ortho-functionalized aniline derivatives has been developed. The reaction proceeds via the selective ortho-metalation of a transient labile urea, which can be considered as a synthetic equivalent of 2-lithio-phenylisocyanate, a highly improbable intermediate.
- Houlden, Chris E.,Lloyd-Jones, Guy C.,Booker-Milburn, Kevin I.
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supporting information; experimental part
p. 3090 - 3092
(2010/09/05)
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- Synthesis of 1,4-dihydro-benzo[d][1,3]oxazin-2-ones from phthalides via an aminolysis-Hofmann rearrangement protocol
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A simple two-step procedure for the conversion of readily available phthalides to the corresponding benzoxazinones was developed. Initial ring-opening aminolysis to form a primary 2-hydroxymethylbenzamide, followed by reaction with bis(trifluoroacetoxy)iodobenzene (BTI) conveniently, provided a variety of 4-substituted benzoxazinones.
- Hernández, Eliud,Vélez, Jessica M.,Vlaar, Cornelis P.
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p. 8972 - 8975
(2008/03/18)
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- Metal catalyzed deoxygenation by carbon monoxide of o-substituted nitrobenzenes. Synthesis of 1,4-dihydro-2H-3,1-benzoxazin-2-one derivatives
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The reductive carbonylation of o-nitrobenzylalcohols, o-NO2C6H4CR1R2OH 1 = R2 = H (1); R1 = R2 = CH3 (2); R1 = H, R2 = CH3 (3); R1 = H, R2 = C6H5 (4)>, catalyzed by ruthenium and palladium-based catalytic systems gives the corresponding 1,4-dihydro-2H-3,1-benzoxazin-2-one derivatives, 1a-4a.Reaction conditions used were 20-60 atm of carbon monoxide and 100-170 deg C.The palladium catalyst has been shown to be far superior to the ruthenium catalyst in this reaction as far as selectivity is concerned.By carbonylation of o-nitrophenethylalcohol (5) with the palladium system as catalyst a mixture of the monomeric 5a and dimeric 5b cyclic carbamates has been obtained.
- Cenini, S.,Console, S.,Crotti, C.,Tollari, S.
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p. 157 - 162
(2007/10/02)
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