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Koidan G, Zahorulko S, Hurieva A, Shvydenko T, Rusanov EB, Rozhenko AB, Manthe U, Kostyuk A. Straightforward Synthesis of Halopyridine Aldehydes via Diaminomethylation. Chemistry 2023; 29:e202301675. [PMID: 37458183 DOI: 10.1002/chem.202301675] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Indexed: 08/31/2023]
Abstract
A novel two-step method for formylation of fluoropyridines with silylformamidine Me3 SiC(=NMe)NMe2 (1) under catalyst-free conditions was developed. A series of all possible 18 fluoropyridines featuring one to four fluorine atoms were subjected to the reaction with 1 existing in equilibrium with its carbenic form Me2 NC(:)N(Me)SiMe3 (1'). Among them, 12 fluoropyridines were shown to react via C-H insertion. The reaction proceeded either at β- or γ-positions affording the corresponding aminals. The more fluorine atoms in pyridines, the easier the reaction proceeded. We also hypothesized that the pyridines in which the fluorine was substituted by other halogens would react in a similar manner. To test the hypothesis, a set of 3,5-disubstituted pyridines with various combination of halogen atoms was prepared. 3,5-Difluoropyridine was taken as a compound for comparison. All the pyridines in the series also reacted likewise. In most cases, hydrolysis of the aminals afforded the corresponding aldehydes. As DFT calculations indicate, the reaction mechanism includes deprotonation of pyridine by 1' as a strong base and the following rearrangement of the formed tight ionic pair to the final product. An alternative reaction pathway involving addition of 1' to the pyridine carbon with the following hydrogen transfer via a three-membered transition state structure required much higher activation energy.
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Affiliation(s)
- Georgyi Koidan
- Institute of Organic Chemistry, Academician Kukhar str. 5, 02094, Kyiv, Ukraine
| | - Serhii Zahorulko
- Institute of Organic Chemistry, Academician Kukhar str. 5, 02094, Kyiv, Ukraine
| | - Anastasiia Hurieva
- Institute of Organic Chemistry, Academician Kukhar str. 5, 02094, Kyiv, Ukraine
| | - Tetiana Shvydenko
- Institute of Organic Chemistry, Academician Kukhar str. 5, 02094, Kyiv, Ukraine
| | - Eduard B Rusanov
- Institute of Organic Chemistry, Academician Kukhar str. 5, 02094, Kyiv, Ukraine
| | - Alexander B Rozhenko
- Institute of Organic Chemistry, Academician Kukhar str. 5, 02094, Kyiv, Ukraine
- University of Bielefeld, Universitätstr. 25, 33615, Bielefeld, Germany
- National Technical University of Ukraine, Igor Sikorsky Kyiv Polytechnic Institute, Beresteiskyi prosp. 37, 03056, Kyiv, Ukraine
| | - Uwe Manthe
- University of Bielefeld, Universitätstr. 25, 33615, Bielefeld, Germany
| | - Aleksandr Kostyuk
- Institute of Organic Chemistry, Academician Kukhar str. 5, 02094, Kyiv, Ukraine
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Singh MK, Akula HK, Satishkumar S, Stahl L, Lakshman MK. Ruthenium-Catalyzed C-H Bond Activation Approach to Azolyl Aminals and Hemiaminal Ethers, Mechanistic Evaluations, and Isomer Interconversion. ACS Catal 2016; 6:1921-1928. [PMID: 27563492 DOI: 10.1021/acscatal.5b02603] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
C(sp3)-N bond-forming reactions between benzotriazole and 5,6-dimethylbenzotriazole with N-methylpyrrolidinone, tetrahydrofuran, tetrahydropyran, diethyl ether, 1,4-dioxane, and isochroman have been conducted using RuCl3•3H2O/t-BuOOH in 1,2-dichloroethane. In all cases, N1 and N2 alkylation products were obtained, and these are readily separated by chromatography. One of these products, 1-(isochroman-1-yl)-5,6-dimethyl-1H-benzotriazole, was examined by X-ray crystallography. It is the first such compound to be analyzed by this method, and notably, the benzotriazolyl moiety is quasi-axially disposed, consistent with the anomeric effect. This has plausible consequences, not observed previously. In contrast to other hemiaminal ether-forming reactions, which proceed via radicals, this Ru-catalyzed process is not suppressed in the presence of a radical inhibitor. Therefore, an oxoruthenium-species-mediated rapid formation of an oxocarbenium intermediate is believed to occur. In the radical-trapping experiment, previously unknown products containing both the benzotriazole and the TEMPO unit have been identified. In these products, it is likely that the benzotriazole is introduced via a Ru-catalyzed C-N bond formation, whereas C-O bond-formation with TEMPO occurs via a radical reaction. We show that reactions of THF with TEMPO are influenced by ambient light. A competitive reaction of THF and THF-d8 with benzotriazole indicated that C-H bond cleavage occurs ca. 5 times faster than C-D cleavage. This is comparable to other metal-mediated radical reactions of THF, but lower than that observed for a reaction catalyzed by n-Bu4N+I-. Detailed mechanistic experiments and comparisons are described. The catalytic system was also evaluated for reactions of benzimidazole, imidazole, 1,2,4-triazole, and 1,2,3-triazole with THF, and successful reactions were achieved in each case. In the course of our studies, we discovered an unexpected but significant isomerization of some of the benzotriazolyl hemiaminal ethers. This is plausibly attributable to the pseudoaxial orientation of the heterocycle in the products and the stability of oxocarbenium ions, both of which can contribute to C-N bond cleavage and reformation. Predominantly, the N2-isomers rearrange to the N1-isomers even upon storage at low temperature! This previously unknown phenomenon has also been studied and described.
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Affiliation(s)
- Manish K. Singh
- Department of Chemistry, The City College of New York, 160 Convent Avenue, New York, New York 10031, United States
- The Ph.D. Program in Chemistry, The Graduate Center of The City University of New York, New York, New York 10016, United States
| | - Hari K. Akula
- Department of Chemistry, The City College of New York, 160 Convent Avenue, New York, New York 10031, United States
- The Ph.D. Program in Chemistry, The Graduate Center of The City University of New York, New York, New York 10016, United States
| | - Sakilam Satishkumar
- Department of Chemistry, The City College of New York, 160 Convent Avenue, New York, New York 10031, United States
| | - Lothar Stahl
- Department of Chemistry, The University of North Dakota, 151 Cornell Street Stop 9024, Grand Forks, North Dakota 58202, United States
| | - Mahesh K. Lakshman
- Department of Chemistry, The City College of New York, 160 Convent Avenue, New York, New York 10031, United States
- The Ph.D. Program in Chemistry, The Graduate Center of The City University of New York, New York, New York 10016, United States
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Yu X, Guttenberger N, Fuchs E, Peters M, Weber H, Breinbauer R. Diversity-Oriented Synthesis of a Library of Star-Shaped 2H-Imidazolines. ACS Comb Sci 2015; 17:682-90. [PMID: 26402035 DOI: 10.1021/acscombsci.5b00107] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
A library of star-shaped 2H-imidazolines has been synthesized via Debus-Radziszewski condensation from 1,2-diketones and ketone starting materials. Selective reduction of one imine group of the 2H-imidazole intermediate with LiAlH4 or catalytic flow hydrogenation furnished 2H-imidazolines, which could be conveniently diversified by reacting the amine N with electrophiles, resulting in a set of 21 amide-, carbamate-, urea-, and allylamine-containing products. In total, five points of diversification could be used, which allow the production of a set of functionally diverse compounds. The synthesis of acylated 2H-imidazolidines resulted in intrinsically labile compounds, which spontaneously degraded to acyclic derivatives, as shown for the reaction of 2H-imidazolidine with hexylisocyanate.
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Affiliation(s)
- Xuepu Yu
- Institute of Organic Chemistry, Graz University of Technology, A-8010 Graz, Austria
| | | | - Elisabeth Fuchs
- Institute of Organic Chemistry, Graz University of Technology, A-8010 Graz, Austria
| | - Martin Peters
- Institute of Organic Chemistry, Graz University of Technology, A-8010 Graz, Austria
| | - Hansjörg Weber
- Institute of Organic Chemistry, Graz University of Technology, A-8010 Graz, Austria
| | - Rolf Breinbauer
- Institute of Organic Chemistry, Graz University of Technology, A-8010 Graz, Austria
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Richers MT, Zhao C, Seidel D. Selective copper(II) acetate and potassium iodide catalyzed oxidation of aminals to dihydroquinazoline and quinazolinone alkaloids. Beilstein J Org Chem 2013; 9:1194-201. [PMID: 23843914 PMCID: PMC3701376 DOI: 10.3762/bjoc.9.135] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Accepted: 05/28/2013] [Indexed: 11/23/2022] Open
Abstract
Copper(II) acetate/acetic acid/O2 and potassium iodide/tert-butylhydroperoxide systems are shown to affect the selective oxidation of ring-fused aminals to dihydroquinazolines and quinazolinones, respectively. These methods enable the facile preparation of a number of quinazoline alkaloid natural products and their analogues.
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Affiliation(s)
- Matthew T Richers
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, USA
| | - Chenfei Zhao
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, USA
| | - Daniel Seidel
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, USA
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