C(sp²)−Si Bond Functionalization through Intramolecular Activation by Alkoxides

Abstract

Organosilicon reagents are invaluable tools in the hands of the modern chemist that allow accomplishing a number of synthetically useful transformations. While some are standard reactions, others are more complex transformations, such as the Brook rearrangement and its variants. This carbon‐to‐oxygen silyl migration represents a privileged method to generate transient carbanionic species well suited to undergo functionalization upon electrophilic substitution in the presence of an electrophile. This minireview focuses on recent advances in C(sp2)−Si bond functionalization through intramolecular activation by alkoxides. The key elements of reactivity will be highlighted in the introduction to allow the proper understanding of the migration process. Then, an overview of the reactivity of substrates incorporating the C(sp2)−Si motif and their synthetic applications will be provided.

Palladium-catalyzed synthesis of 4-sila-4H-benzo[d][1,3]oxazines by intramolecular Hiyama coupling

“…This reaction presumably took place through intramolecular transmetalation of a phenyl group from silicon to palladium with the aid of the acyl group on nitrogen instead of 1,5-palladium migration. 10 The overall process here can therefore be described as an intramolecular Hiyama coupling reaction, but it is quite different from the typical Hiyama coupling, where a carboncarbon bond formation between organic (pseudo)halides and organosilanes is the primary process, and the resulting silicon moiety aer the reaction is considered as a low-value byproduct and usually treated as waste. 11 On the other hand, the present reaction of 1b to give 3b is a rare example in that the Hiyama coupling provides a silicon-containing heterocycle as the valueadded main product.…”

C3−H Silylation of Furfurylimines: Direct Access to a Novel Biobased Versatile Synthetic Platform Derived from Furfural

“…Accordingly, we envisaged a particularly attractive strategy involving the synthesis of C3‐silyl furfural derivatives and the subsequent transformation of the newly generated C(sp 2 )−SiR 3 bond (Scheme 2). [38,39] Indeed, it is well established that organosilanes are robust carbanion surrogates that allow to perform a number of synthetically useful transformations [40–42] . Herein, we disclose the C3 selective Ir‐catalyzed C−H‐to‐C−Si bond transformation of furfurylimines [43] .…”

“…[38,39] Indeed, it is well established that organosilanes are robust carbanion surrogates that allow to perform a number of synthetically useful transformations. [40][41][42] Herein, we disclose the C3 selective Ir-catalyzed CÀ H-to-CÀ Si bond transformation of furfurylimines. [43] Furthermore, we demonstrate the successful fluoride-mediated CÀ Si-to-CÀ C and CÀ Si-to-CÀ X (X = halogen) conversion, which enables the synthesis of a broad range of polyfunctionalized furanic synthons.…”

Modular synthesis of 2-furyl carbinols from 3-benzyldimethylsilylfurfural platforms relying on oxygen-assisted C–Si bond functionalization

“…Addition reactions of nucleophiles to the C-O double bond of furfurals represent an obvious synthetic approach to 2-furyl carbinols. We reasoned that for carbinols derived from C3-triorganosilyl-substituted furfurals, the OH unit could be exploited to assist C-Si bond activation [19]. Thereby, C3-triorganosilyl-substituted furfurals could be suitable platforms to develop a two-step modular approach to 3-substituted 2-furyl carbinols, entailing nucleophilic addition to the aldehyde function and oxygen-assisted electrophilic substitution of the C-Si bond (Scheme 1).…”