Direct oxidative SNH amidation of 1,3,7-triazapyrene

Ureas as new nucleophilic reagents for SNH amination and carbamoyl amination reactions in the 1,3,7-triazapyrene series

“…We have shown further that, as in the case of secondary benzamides, 28 1,3-dimethyl urea, containing two secondary amido groups does not react with 1,3,7-triazapyrene under the same conditions. This is due to spatial hindrance for S N H adduct formation as well as the impossibility to obtain its dianion which could then be oxidized by air oxygen at the aromatization stage (Scheme 3).…”

“…The obvious reason for this is the low nucleophilicity of the reagent. As in the cases of aryl amination 27 and amidation 28 reactions, in order to increase its nucleophilicity we generated a urea anion by the action of sodium hydride in anhydrous dimethyl sulfoxide. It is known that DMSO is a versatile and powerful solvent which provides maximum nucleophilicity of an anionic nucleophiles due to the absence of the solvate shell.…”

“…These properties include an unusual ease of oxidative nucleophilic substitution of hydrogen, such as hydroxylation, 21 and even amidation. 28 Another unusual feature of 1,3,7-triazapyrenes is that the greater part of these transformations can be carried out in aqueous media. Note that peri-annelated azines, including 1,3,7-triazapyrene, are now of practical interest for electronic applications, especially as organic light-emitting diodes (OLEDs).…”

“…[31][32][33][34] Ureas were used earlier as specific nitrogen nucleophiles in the palladium(II)-catalyzed amino carbonylation of unsaturated amines, 35 in intramolecular cyclisation of ureido acids and esters, 36 in the synthesis of a di-and triarylamines by interaction with unactivated aryl halides under palladium catalysis 37 and in Biginelli reactions. 38 In the course of this study, and taking into account the results of oxidative nucleophilic amidation of 1,3,7-triazapyrene, 28 we have tested the possibility of S N H carbamoyl amination of this heterocycle using urea as the nucleophilic reagent.…”

Ureas as a New Nucleophilic Reagents for SNAr Amination and Carbamoyl Amination Reactions in 1,3,7‐Triazapyrene Series

“…The obvious reason for this is the low nucleophilicity of the reagent. As in the cases of aryl amination and amidation reactions, in order to increase its nucleophilicity, we generated further urea anion by action of sodium hydride in anhydrous DMSO.…”