Suzuki Coupling of Activated Aryltriazenes for Practical Synthesis of Biaryls from Anilines

Abstract

Aryltriazenes can hardly take part in productive organic transformations unless stoichiometric Brönsted or Lewis acid activators are used. We report here for the first time a palladiumcatalyzed Suzuki coupling of aryltriazenes activated by a sulfonyl group at N3 atom under the common basic conditions. Benefiting from elimination of stoichiometric acid activators, activated aryltriazenes could efficiently couple with arylboronic acids to afford diaryls in modest to excellent yields by using a simple catalyst at low loading, 0.3 mol% Pd(PPh 3 ) 2 Cl 2 . Scope and limitation of the coupling are demonstrated with 26 examples.

LiO-t-Bu/CsF-Mediated Formal Hydrolysis of Trifluoromethyl Arenes

“…The crude material was purified by column chromatography on silica gel (hexane:EtOAc 10:1) to afford 2a (59.5 mg, 0.280 mmol, 94%) as a white solid; mp 116–118 °C (Lit. 43 mp 114–115 °C).…”

Nickel-Catalyzed Suzuki Coupling of Phenols Enabled by SuFEx of Tosyl Fluoride

“…Sulfur(VI) fluoride exchange (SuFEx), the so-called second generation of click reaction [ 36 , 37 , 38 , 39 ], has proven to be a privileged protocol in activating phenolic C Ar -OH group via chemoselective formation of sulfonates with SO 2 F-containing reagents in the presence of various other nucleophiles [ 37 , 40 ]. As a part of our continuous efforts to develop practical procedures for construction of biaryls from pseudohalides [ 41 , 42 , 43 , 44 ], we report herein a SuFEx enabled, nickel/phosphine catalyzed Suzuki coupling of phenols via in situ formation of tosylates with tosyl fluoride (TsF) using trans -NiCl( o -Tol)(PCy 3 ) 2 /2PCy 3 as a catalyst to practically and efficiently synthesize various biaryls with good functional group comparability.…”

“…The following supporting information can be downloaded at: , Characterization data and copies of 1 H & 13 C NMR spectra of products (References [ 21 , 42 , 43 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 ] are cited in the Supplementary Materials).…”

Mechanoredox/Nickel Co-Catalyzed Cross Electrophile Coupling of Benzotriazinones with Alkyl (Pseudo)halides

“…24 Shortly after our report, Walsh and Mao have expanded the halide counterpart to aryl bromides using zinc powders as the reductant to afford ortho-arylated benzamides. 25 As a cyclic analogue of activated triazenes, 26 we anticipated that the denitrogenative ring-opening of benzotriazinones may be facilitated under mild mechanochemical conditions by coordination of metal, single-electron-transfer (SET) and effects of ball-milling including local and short-time high pressure and temperature induced by mechanical impacts of collision, tear, and friction. Herein, we report the development of an air-tolerant mechanoredox/nickel cocatalyzed manganese-mediated cross electrophile coupling of benzotriazinones with alkyl (pseudo)halides, taking advantage of mechanical metal activation to eliminate chemical activator and mechanoredox cocatalysis to compensate for decrease in reactivities of alkyl (pseudo)halides under mild liquid-assisted grinding (LAG) conditions.…”