Convenient Synthesis of Arylboronates through a Synergistic Pd/Cu‐Catalyzed Miyaura Borylation Reaction under Atmospheric Conditions

Abstract

A highly efficient and practical borylation reaction of aryl iodides with bis(pinacolato)diboron has been established. By using Pd(OAc)2, CuI, and PPh3 as a ligand at room temperature under air in the presence of Cs2CO3, the protocol proved to be general. Various functionalized arylboronates were obtained in moderate to excellent yields. In addition, a possible reaction mechanism was proposed.

Layered Double Hydroxides as Bifunctional Catalysts for the Aryl Borylation under Ligand-Free Conditions

“…A relatively high copper loading was, however, necessary to increase the substrate conversion. As pointed out, this fact has already been observed by Ratnyom [12] and other groups [13] but involving a typically homogeneous catalytic system based on Cu or Pd/Cu combined with phosphines. Regarding the usual organometallic mechanism, it is interesting to note that the LDH surface is possibly responsible for the presence of basic species involved in the preactivation step.…”

“…Since then, several efficient methodologies have been reported based on similar reaction conditions [9][10][11]. Recently, Ratniyom and coworkers [12] reported an efficient cooperative catalysis based on Pd(0)/Cu(I) in the presence of triphenylphosphine with good results towards aryl iodides and bis(pinacolate)diboron. However, the yields were very sensitive to the nature of the base and reduced drastically with the use of aryl bromides/chlorides.…”

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

“…Thus, the development of new methods to synthesize arylboronate esters under mild reaction conditions is important in modern organic chemistry . Accordingly, transition‐metal‐catalyzed borylation reactions of aryl halides with diborons have emerged as efficient and reliable methods . In these catalytic borylation reactions, the presence of a base is essential to activate the diboron for smooth boryl transfer.…”

“…[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.…”

Copper-boryl mediated organic synthesis

“…Since then further developments of this copper variant of the classical palladium catalysed Miyaura boryation have included borylations in shorter reaction times using designer bicyclic NHC ligands, 128 the use of alternative diboron reagents (e.g. Bin-Bdan) leading to aryl-Bdan esters, 129 co-catalyst combinations that give even greater functional group tolerance enabling phenols, amides, esters and ketones to be used in reactions undertaken open to the air (Scheme 30iii), 130 and applications to other nucleofuges, including arylfluorides, although this last transformation probably proceeds by an S RN 1 pathway (Scheme 30iv). 131,132 In a similar fashion, alkyl (sp 3 ) halides can undergo coppermediated borylation.…”