1664-65-9Relevant academic research and scientific papers
NovelN-transfer reagent for converting α-amino acid derivatives to α-diazo compounds
Lu, Guan-Han,Huang, Tzu-Chia,Hsueh, Hsiao-Chin,Yang, Shin-Cherng,Cho, Ting-Wei,Chou, Ho-Hsuan
, p. 4839 - 4842 (2021/05/25)
A novel universalN-transfer reagent for direct and effective transformation of α-amino ketones, acetamides, and esters to the corresponding α-diazo products under mild basic conditions has been developed. This one-step synthetic approach not only allows for generation of α-substituted-α-diazo carbonyl compounds from α-amino acid derivatives but also permits preparation of α-diazo dipeptides fromN-terminal dipeptides (32 examples, up to 91%).
Deconstructive di-functionalization of unstrained, benzo cyclic amines by C-N bond cleavage using a recyclable tungsten catalyst
Zhang, Yujing,Sun, Shuai,Su, Yijin,Zhao, Jian,Li, Yong-Hong,Han, Bo,Shi, Feng
supporting information, p. 4970 - 4974 (2019/05/29)
With H2WO4 as the catalyst and H2O2 as the oxidant, we herein report a deconstructive difunctionalization of the C-N bond in unstrained, benzo cyclic amines to generate an ester group and nitro group simultaneously. The preliminary mechanistic studies suggested that the corresponding hydroxamic acid is the key intermediate for this transformation. Importantly, with the utilization of this transformation, we achieved an interesting approach for the ring contraction of quinoline to indole, an example of scaffold hopping in a hetero-aromatic system.
Reductive cyclizations of nitroarenes to hydroxamic acids by visible light photoredox catalysis
Cismesia, Megan A.,Ischay, Michael A.,Yoon, Tehshik P.
supporting information, p. 2699 - 2705 (2013/10/21)
We have developed a photocatalytic reduction of nitroarenes as an efficient, chemoselective route to biologically important N-phenyl hydroxamic acid scaffolds. Optimal conditions call for 2.5 mol% of a ruthenium photocatalyst, visible light irradiation, and a dihydropyridine terminal reductant. Because of the mild nature of the visible light activation, functional groups that might be sensitive to other non-photochemical reduction methods are easily tolerated. Georg Thieme Verlag Stuttgart New York.
Nitric acid in the presence of P2O5 supported on silica gel - A useful reagent for nitration of aromatic compounds under solvent-free conditions
Hajipour, Abdol Reza,Ruoho, Arnold E.
, p. 8307 - 8310 (2007/10/03)
A variety of aromatic compounds are nitrated to parent nitro aromatic compounds under solvent-free conditions using 65% nitric acid in the presence of P2O5 supported on silica gel is described. This methodology is useful for nitration of activated and deactivated aromatic rings.
Suspension Ring-Opening Metathesis Polymerization: The Preparation of Norbornene-Based Resins for Application in Organic Synthesis
Lee, Byoung Se,Mahajan, Suresh,Clapham, Bruce,Janda, Kim D.
, p. 3319 - 3329 (2007/10/03)
A series of norbornene-based resin beads were obtained by aqueous suspension ring-opening metathesis polymerization (ROMP) and used as polymeric supports for organic synthesis. These resins were prepared from norbornene, norborn-2-ene-5-methanol, and cross-linkers such as bis(norborn-2-ene-5-methoxy)alkanes, di(norborn-2-ene-5-methyl)ether, and 1,3-di(norborn-2-ene-5-methoxy)benzene. The resulting unsaturated ROMP (U-ROMP) resins containing olefin repeat units were chemically modified using hydrogenation, hydrofluorination, chlorination, and bromination reactions to produce saturated ROMP resins with different chemical and physical properties. The hydrogenated ROMP (H-ROMP) resin was found to be highly resistant to acidic, basic, Lewis acid, and Birch reduction conditions and was assessed as a polymeric support in a series of solid-phase synthetic applications. The H-ROMP resin was found to have superior performance compared to polystyrene-divinylbenzene (PS-DVB) copolymers in aromatic nitration and acylation reactions. In a conventional five-step solid-phase synthesis of a hydantoin, similar results were obtained for both the H-ROMP and PS-DVB resins. The U-ROMP resin was also shown to be effective in the solid-phase syntheses of benzimidazoles and benzimidazolones.
A fast and mild method for nitration of aromatic rings
Hajipour, Abdol R.,Ruoho, Arnold E.
, p. 221 - 226 (2007/10/03)
The use of benzyltriphenylphosphonium nitrate (PhCH2Ph 3P+NO3-) (BTPPN) as a useful reagent for nitration aromatic compounds in the presence of methanesulfonic anhydride under solvent-free conditions is described. This methodology is useful for nitration of activated aromatic rings.
5′-(2-Nitrophenylalkanoyl)-2′-deoxy-5-fluorouridines as potential prodrugs of FUDR for reductive activation
Liu, Bin,Hu, Longqin
, p. 3889 - 3899 (2007/10/03)
Four 5′-(2-nitrophenylalkanoyl)-2′-deoxy-5-fluorouridines (1a-d) were designed and synthesized as potential prodrugs of FUDR for reductive activation. Two methyl groups were introduced α to the ester carbonyl to increase both the rate of cyclization activation and the stability of the conjugates towards serum esterases. Chemical reduction of the nitro group into an amino leads to cyclization and release of the active FUDR. Kinetic analysis of the cyclization activation process indicates that the two methyl groups α to the ester carbonyl restrict the rotational freedom of ground state molecule and promote the cyclization reaction. However, the two methyl groups also were found to render the conjugates as poor substrates of E. coli B nitroreductase. Conjugate 1c, without the two methyl groups, was reduced by E. coli B nitroreductase (t1/2=8 h) to give two products, a N-hydroxyl lactam and the drug FUDR, suggesting that the enzymatic reduction and subsequent cyclization activation proceeded through the hydroxylamine intermediate. These results indicate that cyclization activation will occur once the nitro group is reduced either to an amino or to a hydroxylamino group. The fact that the amino intermediates cyclized easily to release the incorporated drug FUDR suggests the feasibility of using peptide-linked acyl 2-aminophenylalkanoic acid esters as potential prodrugs for proteolytic activation.
Wilkinson's catalyst catalyzed selective hydrogenation of olefin in the presence of an aromatic nitro function: A remarkable solvent effect
Jourdant, Angelique,Gonzalez-Zamora, Eduardo,Zhu, Jieping
, p. 3163 - 3164 (2007/10/03)
Optimal conditions for chlorotris(triphenylphosphine)rhodium(I) (Wilkinson's catalyst) catalyzed selective saturation of a double bond in the presence of a nitro function are developed. Aryl iodide and benzyl ether are also tolerated under these hydrogenation conditions.
Palladium-Catalyzed Cross-Coupling Reaction of Alkyltrifluorosilanes with Aryl Halides
Matsuhashi, Hayao,Asai, Satoshi,Hirabayashi, Kazunori,Hatanaka, Yasuo,Mori, Atsunori,Hiyama, Tamejiro
, p. 437 - 444 (2007/10/03)
A cross-coupling reaction of alkyltrifluorosilanes with aryl halides was achieved using a catalytic amount of tetrakis-(triphenylphosphine)palladium(0) and excess of tetrabutylammonium fluoride (TBAF) at 100°C with high chemoselectitvity. Functional groups like nitro, ketone carbonyl, and formyl tolerated the coupling conditions. Because potassium(18-crown-6) alkyltetrafluorosilicates also underwent a cross-coupling reaction in the presence of an additional molar amount of TBAF, the active species of the coupling reaction was assumed to be pentacoordinate silicates. TBAF in excess was considered to be required for trapping the tetrafluorosilane produced in the catalytic cycle of the cross-coupling reaction.
Palladium catalyzed cross-coupling reaction of functionalized alkyltrifluorosilanes with aryl halides
Matsuhashi, Hayao,Kuroboshi, Manabu,Hatanaka, Yasuo,Hiyama, Tamejiro
, p. 6507 - 6510 (2007/10/02)
A variety of alkyltrifluorosilanes were found to couple with aryl halides in the presence of Pd(PPh3)4 catalyst and tetrabutylammonium fluoride (TBAF) to give the corresponding cross-coupled products in moderate to good yields.
