Diels–Alder cycloadditions of N-arylpyrroles via aryne intermediates using diaryliodonium salts

Abstract

With a strategy of the formation of benzynes by using diaryliodonium salts, a cycloaddition reaction of N-arylpyrroles with benzynes was reported. A wide range of bridge-ring amines with various substituents have been synthesized in moderate to excellent yields (35–96%). Furthermore, with a catalytic amount of TsOH·H2O, these amines can be converted into the corresponding N-phenylamine derivatives easily, which are potentially useful in photosensitive dyes.

Arynes and Their Precursors from Arylboronic Acids via Catalytic C–H Silylation

“…Unless otherwise stated, all the other reagents, transition-metal salts, anthranilamide, silanes, and norbornene were obtained commercially and used without further purification. 1 H, 13 C, and 19 F NMR spectra Crystallography. Single-crystal X-ray diffraction was performed on a Bruker APEX-II single-crystal X-ray diffractometer at 150 K using Mo Kα radiation, and the structures were solved using direct methods (ShlexS-2014) 34 refined by full-matrix least-squares procedures using OLEX2.…”

“…13 C{ 1 H} NMR (100 MHz, CDCl 3 ): δ 150.7 (d, J CF = 239.6 Hz), 147.9 (d, J CF = 12.5 Hz), 137.9, 134.2, 130.9 (d, J CF = 4.0 Hz), 129.2, 127.8, 126.5, 120.1 (d, J CF = 5.6 Hz), 116.6 (d, J CF = 18.3 Hz), −2.4. 19 2-(Dimethyl(phenyl)silyl)-4-(trifluoromethyl)phenol (4h). Prepared according to general procedure A.…”

“…Otherwise, the use of strong stoichiometric bases to remove a proton ortho to a good leaving group continues to underpin a substantial portion of modern aryne methodology. 19 Our interest in C−H functionalization and aryne chemistry 20 led us to envisage an alternative, operationally simple route to aryne precursors, and even arynes themselves, predicated on Ru-catalyzed 21 catalytic C−H silylation 22 of arylboronates as the key step.…”

Iodonium Salts as Benzyne Precursors

“…Very recently,W ang andc o-workers reported the cycloaddition reaction of benzyne speciesusing N-arylpyrroles as trapping reagent instead of furan. [79] The reactiono fd iaryliodonium salts 36 with N-arylpyrrole 37 in the presence of LHMDS afforded the corresponding bridged amines 38 in moderate to good yields (Scheme 12). Theo btained compounds 38 could be easily converted to the N-phenylamine derivatives by treatment with p-toluenesulfonic acid.…”

“…Very recently, Wang and co‐workers reported the cycloaddition reaction of benzyne species using N ‐arylpyrroles as trapping reagent instead of furan . The reaction of diaryliodonium salts 36 with N ‐arylpyrrole 37 in the presence of LHMDS afforded the corresponding bridged amines 38 in moderate to good yields (Scheme ).…”