Nickel-Catalyzed Borylation of Aryl- and Benzyltrimethylammonium Salts via C–N Bond Cleavage

Abstract

By developing a mild Ni-catalyzed system, a method for direct borylation of sp(2) and sp(3) C-N bonds has been established. The key to this hightly efficient C-N bond borylative cleavage depends on the appropriate choice of the nickel catalyst Ni(COD)2, ICy·HCl as a ligand, and the use of 2-ethoxyethanol as the cosolvent. This transformation shows good functional group compatibility and can serve as a powerful synthetic tool for gram-scale synthesis and late-stage C-N borylation of complex compounds.

Palladium-catalyzed regioselective and stereo-invertive ring-opening borylation of 2-arylaziridines with bis(pinacolato)diboron: experimental and computational studies

“…10a , c , 11b Also, our C–B coupling system represents the first example of a formal S N 2-type borylative C(sp 3 )–N bond cleavage of neutral compounds. 18 It should be noted that the present C–B coupling proceeds smoothly under neutral conditions as in the cases of borylative substitution of allyl carboxylates 19 and carbonates. 19a , 20 In these cases, the leaving group-derived oxy anions (RCO 2 – and RO – ) serve as the internal bases, while the metal catalyzed borylative substitution of alkyl halides usually requires the addition of stoichiometric external base or activator to promote transmetalation.…”

Stille coupling via C–N bond cleavage

“… 26 (Ni-catalyst and Grignard reagent). Other protocols have been developed by MacMillan 27 (Ni-catalyst and arylboron reagent), Wang 28 (Ni-catalyst and organozinc reagent), Watson 29 (Ni-catalyst and aryl/alkylboron reagent) and others 30 31 32 33 34 35 36 37 , and it is well established that quaternary organo-ammonium salts show diverse reactivity and synthetic utility as efficient substitutes for halides. However, the Stille reaction via C–N bond cleavage in such substrates has remained a missing piece in cross-coupling chemistry.…”

Base‐Free Palladium‐Catalyzed Borylation of Aryl Chlorides with Diborons

“…[1] Thus, the developmento fnew methods to synthesize arylboronate esters under mild reaction conditions is important in moderno rganic chemistry. [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] Accordingly,transition-metal-catalyzed borylation reactions of aryl halides with diborons have emerged as efficient and reliable methods. [2-4, 5b, 6b, 9f,g,11] In these catalytic borylation reactions, the presenceo fabase is essential to activate the diboron for smooth boryl transfer.I tw ould be desirable to develop basefree conditions to achieve the synthesis of arylboronates bearing base-sensitive functional groups.…”