Aryl–Aryl Bond Formation by the Fluoride‐Free Cross‐Coupling of Aryldisiloxanes with Aryl Bromides

Abstract

The prevalence of the biaryl structural motif in biologically interesting and synthetically important molecules has inspired considerable interest in the development of methods for aryl-aryl bond formation. Herein we describe a novel strategy for this process involving the fluoride-free, palladium-catalysed cross-coupling of readily accessible aryldisiloxanes and aryl bromides. Using a statistical-based optimisation process, preparatively useful reaction conditions were formulated to allow the cross-coupling of a wide range of different substrates. This methodology represents an attractive, cost-efficient, flexible and robust alternative to the traditional transition-metal-catalysed routes typically used to generate molecules containing the privileged biaryl scaffold.

Mechanism of the Transmetalation of Organosilanes to Gold

“…This is the first computational study of at ransmetalation of organosilanes to gold under fluoride-freec onditions, representing ad ifferent reactivity manifold than the classic activation of silanes as silicates using external fluorides ources. [23] The present results provide the first key insight into the mechanism of transfero ft he organic fragment from silane to gold and establishes that the reactivity of gold is similar to that of palladiumi nt he Hiyamatype coupling. We proposet hat the gold silanolate is not the active species (as proposed during experimental studies) but is, in fact, ar esting state during the transmetalation process, as ac oncerted step is preferred.…”

Disiloxane Synthesis Based on Silicon–Hydrogen Bond Activation using Gold and Platinum on Carbon in Water or Heavy Water

“…Substrates 1a , m – o were purchased from commercial suppliers. Substrates 1b – l were prepared according to refs − .…”

“…Siloxane possessing a silicon (Si)–oxygen (O) linkage is an important core of functional materials, such as liquid crystals and thermosets, and bioactive compounds (e.g., muscle relaxant). Furthermore, aryl- or vinyl-substituted disiloxanes can be Hiyama-type coupling partners in organic chemistry . The transformation of hydrosilanes to disiloxanes is a straightforward synthetic method, and the direct disiloxane synthesis based on the InBr 3 -catalyzed air oxidation of hydrosilanes and the homogeneous transition-metal-catalyzed reduction of carbonyl compounds by hydrosilanes , have been reported.…”

Silver(i)-catalyzed oxidative coupling of hydrosilanes with DMF to symmetrical and unsymmetrical disiloxanes

“…Disiloxanes are important frameworks for functional materials and coupling partners for Hiyama-type cross coupling. 1 In addition, unsymmetrical siloxanes have important applications in liquid crystalline polymers and low-dielectric-constant materials. 2 Given the widespread applications of silicone as a functional material, the synthesis of disiloxanes directly from readily available compounds is very important.…”