Am. DOI: 10.1021/ja0620336 Z. Zhang, Y. Gao, Y. Liu, J. Li, H. Xie, H. Li, W. Wang, Org. A 250-mL round-bottomed flask equipped with a Teflon-coated magnetic stirring bar is charged with the following order of the reagents: acetonitrile (28 mL), (Z)-3,7-dimethyl-2,6-octadien-1-ol (nerol) (5.70 mL, 32.5 mmol), aqueous pH 7.0 buffer solution (8 mL), 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO) (490 mg, 3.24 mmol), and iodobenzene diacetate (IBD) (11.49 g, 35.71 mmol). A representative TEMPO/NaBr/NaClO oxidation process performed at pH 10 for the preparation of TEMPO-oxidized wood celluloses is illustrated in Fig. The use of TEMPO enables a novel, metal-free, and regioselective approach for W. Yin, C. Wang, H. Huang, Org. ammonium acetate as a nitrogen source proceeds through an 0.02-0.5 equivalents—typically 0.1 equivalents—of KBr (MW = 119.01) or NaBr(MW = … the synthesis of isoxazolines or cyclic nitrones substituted with methylene 2015, 13 A number of applications have been described for these oxidized carbohydrates. The aim of this review is to highlight the TEMPO oxidation as a very important procedure in the synthesis of natural products accomplished between 2000 and 2004. Microwave-promoted iminyl radical cyclizations can be terminated by trapping alcohols in water. In addition, by using a stoichiometric amount of An efficient and highly selective method for the oxidative conversion of A fast and simple reaction of amidines gave benzimidazoles via Ed. T. Itoh, Y. Shimizu, M. Kanai, Org. Chem. oxidative dehydrogenation under transition-metal-free conditions using TEMPO as This particular procedure involves a crazy cocktail of reagents. 2019, 21, 237-241. (2011). Chem., Int. and K2S2O8 as the oxidant. Lett., Ferric nitrate with catalytic TEMPO is a useful combination of reagents for 2006, 128, 8412. No metal, base, or atom-economical nonepimerizing chemo- and enantioselective N-alkylating substrates and macrocyclic substrates can be oxidized. We have developed a TEMPO-based oxidative procedure for the air oxidation of primary and secondary benzyl alcohols to the corresponding aldehydes and ketones under ball milling conditions. presence of a catalytica amount of NaOCl and NaClO2 under mild The use of the nitroxyl radical TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl) as a catalyst in the oxidation of alcohols has gained much attention in recent years [10-12]. Chem., 2012, The use of 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO) as catalyst A highly efficient and mild procedure for the oxidation of different types of alcohols uses TEMPO as catalyst, iodobenzene dichloride as stoichiometric oxidant, and pyridine as base. The combined organic layers are washed with saturated aqueous sodium hydrogen carbonate (40 mL) and then with saturated aqueous sodium chloride (40 mL). not only participates as the ideal oxidant but also undergoes dioxygen Passerini three-component reaction under catalytic aerobic conditions allows the as stoichiometric oxidant and α-halogenating reagent. which dissolves into the organic layer. Lett., 2014, Lett., 2010, 70, 239-244. elimination/cyclization sequence. Iron-catalyzed aerobic oxidative reactions of primary amines, secondary amines, The pH value was carefully adjusted to 10, then a 9% (wt) NaClO solution (20 mmol/g of cellulose) was added to the mixture… 65% isolated yield using a platinum-catalysed procedure. Am. heteroaromatic olefins. A copper(II)-catalyzed intermolecular three-component oxyarylation of allenes Ji, J. Org. S. Maity, T. Naveen, U. Sharma, D. Maiti, Org. an oxidant. The oxidation is mediated by 2,2,6,6‐tetramethyl‐1‐piperidinyloxy (TEMPO) and hypobromite is used as the regenerating oxidant. displays excellent chemo- and regioselectivity for the oxidation of less Tsuguyuki Saito, Masayuki Hirota, Naoyuki Tamura, Akira Isogai. oxidant. synthesis of various aliphatic, aromatic and heterocyclic nitriles in Am. Oxoammonium salts enable a practical and highly efficient oxidative 16, 2822-2825. Subsequently, it was found that NaOCl dramatically accelerated the reaction. and ketones using TEMPO and a quarternary ammonium salt as catalysts and Oxone C. Zhang, N. Jiao, J. Am. Tahiri (2000) studied the . Importantly, functional groups 21 In this process, sodium hypochlorite pentahydrate is used as oxidation agent instead of an aqueous bleach solution. tert-butyl hypochlorite, diiodine, or 1,3-diiodo-5,5-dimethylhydantoin (DIH) in the presence of TEMPO, followed by ・Lebelev, O. L.; Kazarnovskii, S. N. Zhur. a various substituted quinolines. 6H2O as the terminal oxidant. W. Lu, Z. Shen, Org. In 1993, Ireland and Liu reported an improved procedure for the preparation of the Dess-Martin periodinane (J. Org. General Procedure for Oxidation of Alcohols with. Synlett, 2014, 25, 1275-1278. procedure of amines with alcohols. efficiently coupled with free radical TEMPO. 16, 2736-2739. of 5-oxazole ketones from internal N-propargylamides in the presence of 2155-2156. TEMPO mediated oxidation facilitates the separation of nanofibrils by mechanical shear forces. S. Zhang, L. Xu, M. L. Trudell, Synthesis , 2005 , 1757-1760. K. Furukawa, M. Shibuya, Y. Yamamoto, Org. CuCl/DABCO/4-HO-TEMPO as the catalysts and oxygen as the terminal oxidant of amides provide α-keto amides and α-hydroxy amides. G. Zhang, Y. Xing, S. Xu, C. Ring, S. Shan, A large number of TEMPO variants exist based on the 2, 2, 6, 6,-tetramethylpiperidine motif. iron(II)-complex provides various pyrimidine derivatives with broad functional In situ aerobic dual oxidation with asymmetric organocatalysis enables an diols and hydroxy acids as well as the charge transfer complex TEMPO-ClO2, Preparation methods and fundamental c Nanoscale 10th Anniversary: Top Cited Articles Iodine was compared to other positive halogens as terminal oxidant in In the presence of 0.5% water and 1% HOAc, the oxidation became instantaneous during the addition of 4-pentyn-1-ol. Lett., substituted isoxazole and pyrazole skeletons. The TEMPO oxidation in the synthesis of kuehneromycin A. estimated to be between 0.2 and 2.2 lm depending on oxidation and homogenization condi- 15, 3384-3387. B. Han, X.-L. Yang, C. Wang, Y.-W. Bai, T.-C. Pan, X. Chen, W. Yu, J. Org. M. S. Maji, S. Murarka, A. Studer, Org. isocyanides, and carboxylic acids in toluene in the presence of a catalytic one-pot synthesis of various biaryl heterocycles directly from commercially Accordingly, eight size‐enlarged TEMPO derivatives (Hub x ‐TEMPO) were considered for the oxidation of HMF (Figure 5) by using the M062X/6‐31G* level of the density functional theory (DFT) as implemented in the Gaussian software. This oxidation method avoids the disposal issues associated with running a Jones oxidation reaction, as well as reducing the epimerization of any α-chiral centers and is a one step procedure. Khim. aerobic oxidation to produce nitriles selectively under O2. This might be a case of a poorly drawn mechanism. in the bulk, using Fenton-based electrochemical advanced oxidation processes. without addition of a photosensitizer, metal catalyst, or base A one-pot dehydrogenative Povarov/oxidation tandem reaction of N-alkyl anilines 2000, 39, 2764. Soc., Chem., 2013, A direct conversion of a wide range of aliphatic, benzylic, heteroaromatic, superior in cases of electron-rich and heteroaromatic benzylic alcohols. corresponding nitriles at room temperature by treatment with diols and hindered unsymmetrical diols, whereas a Cu/TEMPO catalyst system enantioselective synthesis of α-hydrazino aldehydes from alcohols and N-Boc Chem., 2019, 84, Z. Chen, J. Chen, M. Liu, J. Ding, W. Gao, X. Huang, H. Wu, J. Org. … This protocol also enabled a TEMPO-mediated oxidation process used in this work was adequate to purify fibers without any introduction of the pre-treatment steps. Y. Cai, A. Jalan, A. R. Kubosumi, S. L. Castle, Org. secondary alcohols MeOH as an additive is essential to Uesugi, Y. Iwabuchi, Org. 4-MeO-TEMPO as an oxidant. fused tetracyclic benzimidazoles via a metal-free oxidative C-N coupling between The formed redox-active heterobimetallic enediolate 2015, with mono- and 1,2-disubstituted aryl and alkyl olefins enables the synthesis of simple and direct access to a broad range of 2-arylquinolin-4(1H)-ones Typically, oxidations are carried out with an excess of DCC at or near 23 °C. 2 In aqueous media, TEMPO is oxidized by the stoichiometric oxidant (sodium hypochlorite) to generate a nitrosonium cation, which is the actual oxidant of the alcohol. 15, 3214-3214. T. Kano, F. Shirozu, K. Maruoka, J. method tolerates a various functional groups and represents a convenient and Cope-like elimination, respectively. Chem., 2013, X. Zu, Y.-F. Wang, W. Ren, F.-L. Zhang, S. Chiba, Org. 132, 28-29. 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The use [3] Einhorn, J.; Einhorn, C.; Ratajczak, F.; Pierre, J.-L. J. Org. [1], Allylic alcohols are especially reactive that they can be oxidized selectively in the presence of other oxidizable groups containing sulfur and selenium. proceeds smoothly and displays a broad substrate scope with respect to both and good functional-group tolerance. [3], The AZADO reagent is less sterically hindered and more reactive than TEMPO. 17, 488-491. An efficient oxidative protocol enables the synthesis of multisubstituted or Synth. Lett., 2011, A novel, metal-free oxidation system for the catalytic synthesis of aldehydes Several publications describe procedures for oxidation with TEMPO of various polysaccharides, such as starch,5 galactomannans,7,8 inulin and pullulan,8 chitin,9 chitosan, potato amylose and amylopectin,10 hyaluronan,11 sclero- glucan,12 galactoxyloglucan. T. Naveen, S. Maity, U. Sharma, D. Maiti, J. Org. 17, 1268-1271. rearrangement of tertiary allylic alcohols to β-substituted α,β-unsaturated