Catalysis of the coupling reaction of aryl chlorides with bis(pinacolato)diboron by tricyclohexylphosphine-cyclopalladated ferrocenylimine complexes

Abstract

Tricyclohexylphosphine-cyclopalladated ferrocenylimine complexes were found to be very efficient catalysts for the one-pot borylation/Suzuki cross-coupling reactions of aryl chlorides with bis(pinacolato)diboron. Typically, using 0.5-1.0 mol% of catalyst in the presence of 3.0 equivalents of K 2 CO 3 as base in dioxane at 100°C provided the corresponding symmetrical biaryls in good to excellent yields.

Synthesis of a Naphthodiazaborinine and Its Verification by Planarization with Atomic Force Microscopy

“…In contrast to the well-established Miyaura borylation of aryl halides with diboronate esters as reagents (bis­(pinacolato)­diboron = B 2 pin 2 and others), − the analogous direct introduction of Bdan boryl units from HBdan is much less explored . In fact, it was only recently that a chemoselective transfer of Bdan units from (pin)­B–B­(dan) to a series of aryl halides was reported .…”

Diboron(4) Compounds: From Structural Curiosity to Synthetic Workhorse

“…Additional palladacyclic catalyst precursors have been shown to be effective catalysts for the borylation of aryl halides and subsequent Suzuki–Miyaura reactions (Scheme ). − Notably, two reports also demonstrated that aryl bromides can be generated and subsequently borylated in situ with N -bromosuccinimide as the brominating agent. , …”

Mechanism of the Palladium-Catalyzed Borylation of Aryl Halides with Pinacolborane

“…Arylboronic acids and their esters are versatile and useful reagents in organic synthesis . Traditionally, arylboron compounds are prepared by transmetalation between arylmagnesium or aryllithium reagents and trialkylborates. ,, While the recently developed rhodium- and iridium-catalyzed direct borylation of arene C−H bonds represents a major breakthrough, the palladium-catalyzed cross-coupling of bis(pinacolato)diborane(4) (B 2 pin 2 ) (pin = pinacolato = OCMe 2 CMe 2 O) with aryl halides (eq ), reported by Miyaura et al in 1995, still represents one of the most important synthetic routes to arylboronates . The cost of B 2 pin 2 , however, led Masuda et al to develop an attractive, alternative palladium-catalyzed process using HBpin (eq 2).…”