Acid-Free Copper-Catalyzed Electrophilic Nitration of Electron-Rich Arenes with Guanidine Nitrate

Abstract

A practical copper-catalyzed nitration of electron-rich arenes with trimethylsilyl chloride and guanidine nitrate is reported. A variety of nitrated products were generated in moderate to excellent yields (32–99%) at ambient temperature under acid-free, open-flask, and operationally simple conditions.

Nitration of Derivatives of Imidazo[1,5‐a]pyridine via C−H Functionalization with Fe(NO3)3 ⋅ 9H2O as a Promoter and a Nitro Source

“…[35][36][37][38][39] Two other main strategies [40][41][42][43][44][45][46] include (i) ipso-nitration of prefunctionalized aromatic compounds, e. g., arylboronic acids, aryl carboxylic acids, aryl halides and pseudohalides, and aryl metal compounds; and (ii) transition-metal-catalyzed C(sp 2 )À H nitration of arenes. [19,21,[47][48][49][50][51][52][53][54][55] Recent studies by several groups revealed that the use of ingeniously designed nitrate reagents or N-nitro-type reagents, e. g., 3-disulfonic acid imidazolium nitrate, [56] guanidine nitrate, [57] 1-sulfopyridinium nitrate, [58] thiourea nitrate, [59] N-nitropyrazole, [60] N-nitrosuccinimide, [61] dinitro-5,5-dimethylhydantoin, [62] and N-nitrosaccharin, [63] etc., as nitro sources, are attractive and powerful methods for nitrating arenes. Despite the effectiveness of these synthetic strategies, they also suffer from several drawbacks, including functional group intolerance originating from the use of strong acids, the requirement of prefunctionalized arenes for ipso-nitration, the use of prefunctionalized direct groups as chelating moieties for transition metal-catalyzed nitration reactions, and the use of precious metals as catalysts.…”