- Preparation of 1,5-fused tetrazoles under solvent-free conditions
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A facile and efficient procedure is developed for a one-pot synthesis of fused 1,5-disubstituted tetrazoles from cyclic ketones and sodium azide in the presence of aluminum chloride in solvent-free media. Advantages of this method are chemoselectivity, with high yields in a simple operation, and short reaction time under solvent-free conditions. Copyright Taylor & Francis, Inc.
- Eshghi, Hossein,Hassankhani, Asadollah
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- Stereospecific synthesis of 1,5-disubstituted tetrazoles from ketoximes via a Beckmann rearrangement facilitated by diphenyl phosphorazidate
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A novel method for the stereospecific synthesis of 1,5-disubstituted tetrazoles from ketoximes via the Beckmann rearrangement was developed using diphenyl phosphorazidate (DPPA) as both the oxime activator and azide source. Various ketoximes were transformed into the corresponding 1,5-disubstituted tetrazoles with exclusive trans-group migration and no E-Z isomerization of the ketoxime. This method enables the preparation of 1,5-disubstituted tetrazoles without using toxic or explosive azidation reagents.
- Ishihara, Kotaro,Shioiri, Takayuki,Matsugi, Masato
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p. 1295 - 1298
(2019/04/13)
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- An Interrupted Schmidt Reaction: C-C Bond Formation Arising from Nitrilium Ion Capture
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The rerouting of the nitrilium ion formed in the Schmidt reaction of ketones and TMSN3 to encompass C-C bond formation with an electron-rich aromatic group is reported. Thus, when the reaction is carried out in HFIP using AlCl3 or Al
- Charaschanya, Manwika,Li, Kelin,Motiwala, Hashim F.,Aubé, Jeffrey
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supporting information
p. 6354 - 6358
(2018/10/15)
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- Remodeling and Enhancing Schmidt Reaction Pathways in Hexafluoroisopropanol
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The effect of carrying out two variations of the Schmidt reaction with ketone electrophiles in hexafluoroisopropanol (HFIP) solvent has been studied. When TMSN3 is reacted with ketones in the presence of triflic acid (TfOH) promoter, tetrazoles are obtained as the major products. This observation is in contrast to established methods, which usually lead to amides or lactams arising from formal NH insertion as the major products. The full product profiles of several examples of this reaction are also reported and found to include mechanistically interesting products (e.g., double ring expansion). Application of TfOH promoter in HFIP was also found to promote the reaction of a hydroxyalkyl azide with a ketone, which affords lactams following nucleophilic opening of initially formed iminium ether more efficiently than previously reported methods. (Chemical Equation Presented).
- Motiwala, Hashim F.,Charaschanya, Manwika,Day, Victor W.,Aubé, Jeffrey
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p. 1593 - 1609
(2016/03/01)
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- Convergent Three-Component Tetrazole Synthesis
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A microwave-accelerated, simple, and efficient method for the construction of the 1,5-tetrazole scaffold was developed. It comprises a multicomponent reaction of an amine, a carboxylic acid derivative, and an azide source. On the basis of the availability of the archetypical starting materials, this method provided very versatile synthetic access to 1,5-disubstituted tetrazoles. The usefulness of this method was demonstrated in the synthesis of biologically important fused tetrazole scaffolds and the marketed drug cilostazol.
- Chandgude, Ajay L.,D?mling, Alexander
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p. 2383 - 2387
(2016/06/01)
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- Tetrazolation of side chains and anhydrous conductivity in a hydrophobic polymer
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1H-Tetrazoles possess the lowest pKa within the azole family of nitrogen-containing heterocycles, making them attractive amphoteric moieties for anhydrous proton conduction. The synthesis of a styrenic, random coil polymer with pendent C-substituted 1H-tetrazoles is described in detail. This facile route results in a polymer containing free proton-bearing tetrazoles, limits side reactions, and proceeds using low polarity, halogenated solvents (e.g., 1,2-dichlorobenzene or chlorobenzene), which improve solubility during tetrazole cyclization. The resulting polymer, when probed by NMR spectroscopy and elemental analysis, had no measurable salt content, ensuring accurate proton conductivity measurements. Utilizing interdigitated electrodes (IDEs) in conjunction with electrochemical impedance spectroscopy (EIS), undoped anhydrous proton conductivities were measured to be as high as 10-5 S cm -1 at 120 °C. This weakly acidic, 1H-tetrazole-bearing polymer is thermally stable to 210 °C, possesses two distinct glass transitions (Tg) at 49 and 74 °C, and exhibits surprisingly low water uptake, despite its acidic and amphoteric nature. Reduction of Tgs, achieved by synthesis of low molecular weight poly(4-vinylphenol) via acid polymerization, shows a minimal dependence of anhydrous proton conductivity on backbone motion.
- Ricks-Laskoski, Holly L.,Chaloux, Brian L.,Deese, Stephen M.,Laskoski, Matthew,Miller, Joel B.,Buckley, Mary A.,Baldwin, Jeffrey W.,Hickner, Michael A.,Saunders, Kaitlin M.,Christensen, Caroline M.
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p. 4243 - 4250
(2014/07/22)
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- Efficient uncatalyzed conversion of primary and secondary thioamides into 1-substituted, 5-substituted, 1, 5-disubstituted and annulated tetrazoles
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Unprecedented high-yield simple and mild conversion of primary aliphatic and aromatic thioamides into 5-substituted tetrazoles on treatment with a combination of tetrachlorosilane and sodium azide in refluxing acetonitrile has been achieved. Secondary acyclic, cyclic, and heterocyclic thioamides could also be transformed in high yields into 1-substituted, 1,5-disubstituted, or annulated tetrazoles under the same reaction condition. Copyright Taylor & Francis Group, LLC.
- El-Ahl, Abdel-Aziz S.,Amer, Fatty A.,Elbeheery, Akram H.
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experimental part
p. 2226 - 2235
(2012/03/26)
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- SYNTHESIS OF 1,5-SUBSTITUTED TETRAZOLES FROM SECONDARY THIOAMIDES
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A new, rather simple method for the conversion of thiamides and similar structures into 1,5-substituted tetrazoles is described.The procedure employs TMS-N3 and mild Lewis acid, like SnCl4 in an inert solvent at room temperature and leads to high yields.Such compounds are of increasing interest for their pharmaceutical properties.
- Lehnhoff, Stefan,Ugi, Ivar
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p. 801 - 808
(2007/10/02)
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- A facile and convenient synthesis of substituted tetrazole derivatives from ketones or α,β-unsaturated ketones.
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Triazidochlorosilane (SiCl4-NaN3 in situ) is a new and efficient reagent for the direct conversion of ketones or α,β-unsaturated ketones to the corresponding tetrazole derivatives in nearly quantitative yield.
- El-Ahl, Abdel-Aziz S.,Elmorsy, Saad S.,Soliman, Hanan,Amer, Fathy A.
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p. 7337 - 7340
(2007/10/02)
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- Improved Schmidt synthesis of 1,5-disubstituted 1H-tetrazoles from ketones
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On treatment with an excess of sodium azide in the presence of titanium(IV) chloride in boiling acetonitrile, both aliphatic and aromatic ketones are smoothly converted to 1,5-disubstituted 1H-tetrazoles in high yields.
- Suzuki,Hwang,Nakaya,Matano
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p. 1218 - 1220
(2007/10/02)
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- TiCl4-Catalyzed Addition of HN3 to Aldehydes and Ketones. Thermolysis and Photolysis of α-Azido Ethers
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Aldehydes react with hydrazoic acid and alcohols in the presence of catalytic amounts of TiCl4 to produce α-azido ethers.The conversion of simple ketones to methyl α-azido alkyl ethers can be accomplished by means of hydrazoic acid and methyl orthoformate.Both gas-phase thermolysis and photolysis of representative α-azido ethers were studied and shown to produce mainly imino ethers.In the thermolysis, migratory preference decreases in the series H >> CH3 > Ph >> OR.
- Hassner, Alfred,Fibiger, Richard,Amarasekara, Ananda S.
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- Reaction of Trimethylsilyl Azide with C=N-O Bond
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Trimethylsilyl azide (TMSA) was reacted with an oxime ester or a Reissert salt in the presence of trimethylsilyl trifluoromethanesulfonate to give tetrazole derivative.The details of these reactions are examined.
- Nishiyama, Kozaburo,Miyata, Izumi
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p. 2419 - 2420
(2007/10/02)
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- ADDITION REACTION OF TRIMETHYLSILYL AZIDE TOWARDS KETONES AND FACILE FORMATION OF TETRAZOLE DERIVATIVES
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In the presence of Lewis acid such as SnCl2, the reactions of trimethylsilyl azide with ketones readily gave 1:1- or 1:2-adduct, which reacted with Lewis acid to afford tetrazole.
- Nishiyama, Kozaburo,Watanabe, Akio
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p. 455 - 458
(2007/10/02)
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- Pharmaceutical composition and process of treatment
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A process for alleviating proliferative skin diseases such as psoriasis, atopic dermatitis, etc. comprising administering to humans, or domesticated animals, topically and/or systemically a composition comprising a pharmaceutical carrier and at least one active compound selected from the groups, substituted alkyl zanthines, tricyclic antidepressants, organic nitrates, antihypertensives, anti-asthma agents and central nervous system depressants and combinations of certain compounds from specifically named groups of compounds.
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