Widely applicable (radio)dihalogenation of alkynes and alkenes using two different nucleophilic alkali metal halides

Abstract

We have developed a hydrogen bond network-assisted highly regio and stereoselective (radio)dihalogenation of alkynes and alkenes using two nucleophilic alkali metal salts (MX1/MX2, X1, X2 = Cl, Br, I, SCN,...

Nickel-catalyzed cross-electrophile coupling of aryl thiols with aryl bromides via C–S bond activation

“…In sharp contrast, no cross-coupling occurred when the model reaction was performed in the absence of either the nickel catalyst or magnesium (entries 16 and 17). In addition, the product yield decreased when the reaction was conducted in the absence of lithium chloride 15,16 (entry 18), or by reducing the amount of Ni(PPh 3 ) 2 Cl 2 from 10 mol% to 5 mol% (entry 19), or by running the reaction at 60 °C (entry 20).…”

“…Initially, the Ni(0) species A is in situ generated through the interaction of Ni(PPh 3 ) 2 Cl 2 with Mg, and is subsequently inserted into the C–S bond of aryl thiol 1 to give the aryl nickel( ii ) complex B . 18 Simultaneously, magnesium oxidatively adds to aryl bromide 2 in the presence of lithium chloride 15,16 to form the Grignard reagent 2′ . The following transmetallation of aryl nickel( ii ) B with organomagnesium 2′ produces the bisaryl-substituted nickel( ii ) intermediate C , which then undergoes reductive elimination to furnish the cross-coupled product 3 or 4 , along with the regeneration of Ni(0) species A which is subsequently used in the next catalytic cycle.…”

Electrochemical (radio)-halodesilylation of aromatic silanes

“…14 Recently, our group has focused on using hydrogen bond networks generated from strong hydrogen bond donor solvents such as HFIP and AcOH to modulate reactivity, 15 especially the application to radiohalogenation. 16 Herein, we are pleased to report a safe, green, and efficient electrochemical halodesilylation of stable trimethylsilanes to synthesize aryl halides using a simple reaction device without extra electrolytes and catalysts (Scheme 1d). In the meantime, this electrochemical method is also applicable to radioiodine labeling.…”