Heterocycle synthesis sodium azide

Boyer and Gunasekaren reported the synthesis of the furazan-based heterocycle NOTO (44), which contains 50 % by mass of nitrogen and is a liquid at room temperature. The flve-step synthesis of NOTO (44) starts from the diazotization of 4,4 -diamino-3,3 -azoxyfurazan (DAAF) (27), followed by reaction with sodium azide to form the diazide (42). Heating the diazide (42) as a solution in acetonitrile induces cyclization to the triazole (43) and this is followed by reduction and oxidation of the remaining azide group to complete the synthesis of NOTO (44). 

It has been shown also that both thiocarbamoylimidazoles 147 and 148 can react with sodium azide. These compounds were successfully used to prepare heterocycle-peptide conjugates as peptidomimetics. A-Terminal aminothiatriazole modified amino acids have been synthesized using two methods (Scheme 35). To prepare monosubstituted aminothiatriazoles 151 the amino acid derivatives were converted into the thiocarbamoyl imidazoles of type 147 that can react with azide ion to form the thiatriazole ring. On the other hand, for the synthesis of disubstituted amino acid derivatives of 1,2,3,4-thiatriazoles 153 and 155 the activation of the thiocarbonyl group via a salt of type 148 was required. The reaction conditions and the yields of thiatriazoles 151, 153, and 154 prepared by this approach are shown in Scheme 35. 

From these examples, the versatility of 1,3-cycloaddition reactions in the synthesis of 1,2,3-triazoles is apparent. Other strategies, however, are available. Greif and coworkers developed perfluoroalkyl-substituted p-chlorovinylaldehydes as new building blocks for a number of fluorinated heterocyclic systems such as thiazoles, pyridines, pyrazoles, and benzimidazoles. Reaction of the chlorovinylaldehydes with sodium azide leads to the formation of moderate to good yields of 4-perfluor-... 

The number of five-membered heterocycles with four hetero atoms is limited to those with nitrogen atoms. Thus, the tetrazole acyclonucleo-sides were formed from sugars N,N -diphenylformazanes by the action of AT-bromosuccinimide or lead tetraacetate [133,134]. The synthesis of the tetra-O-benzoyl-D-lyxononitrile and its conversion to (o-lyxo-tetritol-l-yl)-tetrazole derivatives upon reaction with sodium azide was reported [133, 134]. A pseudo C-nucleoside including a tetrazole ring was achieved by conversion of 3- 0-benzyl- 1,2-O-isopropylidene-D-ribo-pentodialdehydo-1,4-furanose to the respective nitrile and then reaction with sodiiun azide [86]. 

The synthesis, characterization, and energetic properties of various heterocycles containing azide groups are reported. Compound 105 is prepared by the reaction of cyanuric chloride with sodium azide. The preparation of 106 utilizes the conversion of a pyrazole derivative by reaction with hydrazine to form the hydrazo intermediate which is subsequently reacted with NaN02. 2,5,8-Trichloro-s-heptazine is converted quantitatively into 2,5,8-triazido-s-heptazine (107) with trimethylsilyl azide. The nucleophilic reaction of hydrazine with 4,4, 6,6 -tetra(chloro)hydrazo-l,3,5-triazine... 

Other copper-based heterogeneous methodologies recently reported afford 1,2,3-triazoles from organic halides, aromatic terminal aUcynes, and sodium azide [70], As illustrated in Scheme 3.37, Wan and Cai described the efficient and green synthesis of 1,4-substituted 1,2,3-triazoles 71 catalyzed by silica-immobilized A-heterocyclic carbene-Cu(I) 72 (Scheme 3.37). 

Keywords Alkyl halides, alkynes, sodium azide, CU2O, methanol, room temperature, multi-component reaction, click synthesis, heterocycles, substituted 5-alkynyl 1,2,3-triazoles... 

The rapid development of C-H functionalization has helped in accomplishing the synthesis of a variety of complex heterocycles from simple precursors. Recendy, Ramana and co-worker demonstrated a simple one-pot procedure for the Cu(I)-catalyzed SNAr reaction of o-bromochalcones 1 with sodium azide followed by intramolecular cyclization through nitrene C-H insertion to provide 2-aroylindole derivatives 2 [56] (Scheme 7.1) on the basis of their previous work [57]. Furthermore, this methodology is also applicable with the 2 -bromocinnamates giving the indole-2-carboxylates. 

Wu and co-workers presented an efficient domino reaction for the rapid synthesis of 5-phenyl-[l,2,3]triazolo[l,5-c]quinazolines derivatives (80) from simple and readily available (E)-l-bromo-2-(2-nitrovinyl)benzenes 79, aldehydes, and sodium azide (Scheme 7.56) [124]. This reaction cascade comprised [3 + 2] cycloaddition, copper-catalyzed SnAt, reduction, cyclization, and oxidation. It is noteworthy that sodium azide is used as a dual nitrogen source in the construction of these fascinating fused A-heterocycles. 

A new synthesis was developed by Y. Kashman et al. for the preparation of the parent pyrido[2,3,4-/c/]acridine skeleton utilizing the Doebner-Miller synthesis. In the first step, 3-aminoacetanilide was reacted with vinyl phenyl ketone in the presence of m-nitrobenzenesulfonic acid sodium salt and acetic acid to afford the corresponding 4-phenylquinolines. The acetamide group was then converted to the corresponding aryl azide, which underwent intramolecular nitrene insertion upon thermolysis to give the desired heterocyclic skeleton. 

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