- 1-Disulfo-[2,2-bipyridine]-1,1-diium chloride ionic liquid as an efficient catalyst for the green synthesis of 5-substituted 1H-tetrazoles
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A simple, green and efficient method has been developed for the synthesis of 5-substituted 1H-tetrazole derivatives through [2+3] cycloaddition reaction in good to excellent yields between various benzonitriles and sodium azide. For this purpose, 1-disulfo-[2,2-bipyridine]-1,1-diium chloride ([BiPy](HSO3)2Cl2) system as an ionic liquid catalyst have been extended for the construction of these valuable products. This procedure has significant advantages, including using ethylene glycol as a green solvent. The other advantages of this method are inexpensive and ease the preparation of the catalyst, mild reaction conditions, green reaction medium, easy workup, short reaction time, and simple experimental process.
- Aali, Elaheh,Gholizadeh, Mostafa,Noroozi-Shad, Nazanin
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- Indium(III) Chloride Catalyzed Synthesis of 5-Substituted 1 H -Tetrazoles from Oximes and Sodium Azide
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A simple and efficient protocol has been developed for the synthesis of 5-substituted 1H-tetrazole derivatives in good to excellent yields from various oximes and sodium azide by using indium(III) chloride as a Lewis acid catalyst. The present method has
- Guggilapu, Sravanthi Devi,Prajapti, Santosh Kumar,Nagarsenkar, Atulya,Gupta, Keshav Kumar,Babu, Bathini Nagendra
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- The conversion of secondary amides to tetrazoles with trifluoromethanesulfonic anhydride and sodium azide
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Due to the interest in tetrazoles as medicinal agents, a new, mild one-step method for the conversion of amides to tetrazoles employing triphenylphosphine, diethyl azodicarboxylate, and trimethylsilyl azide was recently introduced. An alternate and equally simple method employing trifluoromethanesulfonic anhydride and sodium azide was devised. This method was used to synthesize a series of 1,5-substituted tetrazoles from readily available secondary amides. A 1H-substituted tetrazole was also synthesized by this method from an amide substituted with a cyanoethyl protecting group.
- Thomas
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- Catalytic conversion of 2,4,5-trisubstituted imidazole and 5-substituted 1H-tetrazole derivatives using a new series of half-sandwich (η6-p-cymene)Ruthenium(II) complexes with thiophene-2-carboxylic acid hydrazone ligands
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A new series of half-sandwich (η6-p-cymene) ruthenium(II) complexes with thiophene-2-carboxylic acid hydrazide derivatives [Ru(η6-p-cymene)(Cl)(L)] [L = N'-(naphthalen-1-ylmethylene)thiophene-2-carbohydrazide (L1), N'-(anthracen-9-ylmethylene)thiophene-2-carbohydrazide (L2) and N'-(pyren-1-ylmethylene)thiophene-2-carbohydrazide (L3)] were synthesized. The ligand precursors and their Ru(II) complexes (1–3) were structurally characterized by spectral (IR, UV–Vis, NMR and mass spectrometry) and elemental analysis. The molecular structures of the ruthenium(II) complexes 1–3 were determined by single-crystal X-ray diffraction. All complexes were used as catalysts for the one-pot three-component syntheses of 2,4,5-trisubstitued imidazole and 5-substituted 1H-tetrazole derivatives. The catalytic studies optimized parameters as solvent, temperature and catalyst. The catalysts revealed very active for a broad range of aromatic aldehydes presenting either electron attractor or electron donor substituents and, although less active, moderate to high activities were observed for alkyl aldehydes.
- Vinoth, Govindasamy,Indira, Sekar,Bharathi, Madheswaran,Archana, Govindhasamy,Alves, Luis G.,Martins, Ana M.,Shanmuga Bharathi, Kuppannan
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- Batch Versus Flow Lithiation–Substitution of 1,3,4-Oxadiazoles: Exploitation of Unstable Intermediates Using Flow Chemistry
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1,3,4-Oxadiazoles are a common motif in pharmaceutical chemistry, but few convenient methods for their modification exist. A fast, convenient, high yielding and general α-substitution of 1,3,4-oxadiazoles has been developed using a metalation-electrophilic trapping protocol both in batch and under continuous flow conditions in contradiction to previous reports which suggest that α-metalation of this ring system results in ring fragmentation. In batch, lithiation is accomplished at an industrially convenient temperature, ?30 °C, with subsequent trapping giving isolated yields of up to 91 %. Under continuous flow conditions, metalation is carried out at room temperature, and subsequent in flow electrophilic trapping gave up to quantitative isolated yields. Notably, lithiation in batch at room temperature results only in ring fragmentation and we propose that the superior mixing in flow allows interception and exploitation of an unstable intermediate before decomposition can occur.
- Wong, Jeff Y. F.,Tobin, John M.,Vilela, Filipe,Barker, Graeme
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supporting information
p. 12439 - 12445
(2019/09/06)
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- Lithiation Substitution of Unprotected Benzyltetrazoles
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1H-Tetrazoles occupy an important role in modern medicinal chemistry, but few methods for their modification exist. Many extant protocols require the use of a difficult to remove N-alkyl-protecting group, precluding the products from use as carboxylate bioisosteres, the major role of tetrazoles in pharmaceuticals. We herein report a convenient, protecting-group-free lithiation-substitution protocol for benzylic tetrazoles. Metalation with n-BuLi at 0 °C followed by electrophilic trapping gave a range of α-functionalized benzyltetrazoles in up to 91% yield.
- Wong, Jeff Y. F.,Lewandowska, Agnieszka,Trowse, Benjamin R.,Barker, Graeme
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supporting information
p. 7069 - 7072
(2019/09/30)
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- An efficient synthesis of 5-substituted 1H-tetrazoles via B(C 6F5)3 catalyzed [3+2] cycloaddition of nitriles and sodium azide
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A simple and efficient protocol is developed for the synthesis of 5-substituted 1H-tetrazole derivatives from various nitriles and sodium azide (NaN3) via [3+2] cycloaddition reaction using B(C6F 5)3 as a catalyst. The present synthetic method displayed significant advantages such as low catalyst loading, mild reaction conditions, low toxicity, easy work-up, high yields, and compatibility with other functional groups.
- Prajapti, Santosh Kumar,Nagarsenkar, Atulya,Babu, Bathini Nagendra
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p. 3507 - 3510
(2014/06/10)
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- Efficient transformation of inactive nitriles into 5-substituted 1 H-tetrazoles using microwave irradiation and their applications
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Efficient transformations of inactive nitriles into 5-substituted 1H-tetrazoles in DMF in a microwave reactor are described. The present method is applied to the synthesis of tetrazolato-bridged dinuclear platinum(II) complex and tetrazole C1-ribonucleoside phosphoramidite. Georg Thieme Verlag Stuttgart, New York.
- Yoneyama, Hiroki,Usami, Yoshihide,Komeda, Seiji,Harusawa, Shinya
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p. 1051 - 1059
(2013/05/09)
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- A novel method for the synthesis of 5-substituted 1H-tetrazole from oxime and sodium azide
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A simple and efficient protocol is developed for the synthesis of 5-substituted 1H-tetrazoles from various oximes and sodium azide (NaN 3) by using copper acetate as a catalyst.
- Patil, Umakant B.,Kumthekar, Kedar R.,Nagarkar, Jayashree M.
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experimental part
p. 3706 - 3709
(2012/09/21)
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- Ionic liquid-assisted synthesis of 5-monoand 1,5-disubstituted tetrazoles
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Interaction of aliphatic, aromatic and heteroaromatic nitriles with NaN3 or activated nitriles with organic azides in ionic liquids affords the corresponding 5-mono- and 1,5-disubstituted tetrazoles, ionic liquids functioning both as a reaction medium and as a catalyst.
- Epishina, Margarita A.,Kulikov, Alexander S.,Ignat'Ev, Nikolai V.,Schulte, Michael,Makhova, Nina N.
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experimental part
p. 334 - 336
(2012/01/14)
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- Safe and fast tetrazole formation in ionic liquids
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The [2+3] cycloaddition of nitriles and azides is reliable for intramolecular reactions, but the hazards with volatile azides in intermolecular reactions are tremendous. Zinc catalysis in aqueous solution is a magnificent improvement, but requires the removal of the zinc salts from the acidic product. Herein, we report safe solvents featuring low vapor pressure and good solubility of NaN3. Ionic liquids based on alkylated imidazoles combined with microwave heating turned out to be a solution for the given tasks.
- Schmidt, Boris,Meid, Daniela,Kieser, Daniel
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p. 492 - 496
(2007/10/03)
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- Three Synthetic Routes to a Sterically Hindered Tetrazole. A New One-Step Mild Conversion of an Amide into a Tetrazole
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5--1H-tetrazole (6), which contains a sterically hindered o-tetrazole group, was synthesized by three different routes, one of them employing a new tetrazole synthesis.The first involved the reaction of trialkyltin azides with 4'-methyl-1,1'-biphenyl-2-carbonitrile (3).The resultant trimethyltin-tetrazole adduct could be hydrolyzed with acid to yield biphenylyltetrazole 6.The tri-n-butyltin-tetrazole adduct, however, was transformed into the corresponding N-trityl-protected tetrazole 5 to permit removal of the organic soluble tri-n-butyltin byproducts.The trityl group also permits 5 to be brominated at the benzylic position and then alkylated by imidazole derivatives.Subsequent acid hydrolysis of the trityl protecting group of 5 yielded biphenylyltetrazole 6.The second synthesis involved the nitrosation of an N-(2-cyanoethyl)-protected biphenylamidrazone 10 using N2O4 (g) to yield N-(2-cyanoethyl)-protected tetrazole 12.Aqueous base removes the cyanoethyl protecting group to yield biphenylyltetrazole 6.The third method involves the novel transformation of an N-(2-cyanoethyl)-substituted amide into the corresponding N-(2-cyanoethyl)-protected tetrazole in one step using triphenylphosphine, diethyl azodicarboxylate (DEAD), and azidotrimethylsilane.Subsequent base hydrolysis of the cyanoethyl group yielded 6 as before.Examples are also provided of the application of this new reaction to other N-(2-cyanoethyl)-protected carboxamides.
- Duncia, John V.,Pierce, Michael E.,Santella, Joseph B.
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p. 2395 - 2400
(2007/10/02)
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