- Facile guanidine formation under mild acidic conditions
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An efficient method for converting isothioureas into guanidines was developed. The use of amine salts of bis(trifluoromethanesulfonyl)imide as a nitrogen source was found to induce an efficient conversion under weak acidic conditions at 50 °C. The conversion was applicable to the various amines and carbamate-protected thioureas, and various carbamate-protected cyclic guanidines were obtained in high yields. In particular, ammonium bis(trifluoromethanesulfonyl)imide salt is a useful N1 source with which to construct monoprotected cyclic guanidines.
- Takeuchi, Kohei,Nakayama, Atsushi,Tanino, Keiji,Namba, Kosuke
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- Synthesis of five- and six-membered cyclic guanidines by guanylation with isothiouronium iodides and amines under mild conditions
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Cyclic guanidine hydroiodides were obtained in one step by the reactions of isothiouronium iodides with an equimolar amount of various amines in tetrahydrofuran. The obtained hydroiodides were neutralized with sodium hydroxide or anionic exchange resin to afford the corresponding substituted cyclic guanidines in quantitative yields.
- Aoyagi, Naoto,Endo, Takeshi
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p. 442 - 448
(2017/02/24)
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- C-N Bond forming reactions in the synthesis of substituted 2-aminoimidazole derivatives
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Carbon-nitrogen bond forming reactions oriented to the synthesis of 2-amino-imidazolidines and imidazoles have been investigated. The C-2 amination of imidazolidinones, via the corresponding 2-chlorodihydroimidazoles, led to 2-benzylaminodihydroimidazole or bis(dihydroimidazole)amino derivatives by choosing the adequate experimental conditions. On the other hand, the use of N-acyl-2-methylsulfanyldihydroimidazoles allowed carrying out the reactions with aromatic amines, such as p-anisidine. Finally, palladium catalyzed Buchwald- Hartwig amination was the method of choice for C-N coupling between 2-haloimidazoles and aromatic amines in the synthesis of the corresponding imidazoles.
- Gomez-SanJuan, Asier,Botija, Jose Manuel,Mendez, Almudena,Sotomayor, Nuria,Letea, Esther
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- Efficient synthesis of 2-(N-Substituted)-2-imidazolines and 2-(N-Substituted)-1,4,5, 6-tetrahydropyrimidines
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A general method for the preparation of 2-(N-Substituted)-2-imidazolines and 2-(N-Substituted)-1,4,5,6-tetrahydropyrimidines is described. These heterocycles can be synthesized from their respective anilines with 2-chloro-2-imidazoline or 2-chloro-1,4,5,6-tetrahydropyrimidine, generated in situ from imidazolidin-2-one and tetrahydropyrimidin-2(1H)-one activated by dimethyl chlorophosphate, in good to excellent yields. Copyright Taylor & Francis, Inc.
- Kan, Wai Ming,Lin, Shih-Hsun,Chern, Ching-Yuh
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p. 2633 - 2639
(2007/10/03)
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- Substituted 6,7-dihydroimidazo[1,2-al]purin-9 (4H)-ones
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The synthesis of a series of substituted 6,7-dihydroimidazo[1,2-a]purin-9(4H)-ones is described. Several members of the series exhibit enhanced antiallergic and bronchodilator activity and reduced side effects as compared to theophylline. Structure-activity relationships and metabolic considerations are discussed for the series. Analogues substituted with a 4-(4-chlorobenzyl) moiety, such as 33 and 40, show an optimal balance of antiallergic and bronchodilator activity and are of particular interest. Compound 33 is significantly more potent than theophylline against both metacholine- and antigen-induced bronchospasms, does not affect spontaneous motor activity, and shows minimal cardiovascular effects in the rat.
- Temple Jr.,Yevich,Catt,Owens,Hanning,Covington,Seidehamel,Dungan
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p. 1188 - 1198
(2007/10/02)
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