The Hiyama Cross‐Coupling Reaction: New Discoveries

Abstract

ABSTRACT:In this review article recent developments in the Hiyama cross-coupling reaction from 2010 up today are presented. The most important methodology involves formation of biaryl systems by using aryl bromides or iodides and aryl trialkoxy silanes: other variants are far less studied. The most useful procedures are collected paying special attention to the synthetic application of this methodology in synthetic organic chemistry.

One-Pot Tandem Hiyama Alkynylation/Cyclizations by Palladium(II) Acyclic Diaminocarbene (ADC) Complexes Yielding Biologically Relevant Benzofuran Scaffolds

“…The Hiyama alkynylation coupling was also performed under environment-friendly and much desired fluoride-free conditions. − More importantly, the Hiyama coupling by the representative palladium ADC complex 4 represents the first ever report of a C sp 2 –C sp coupling between an aryl halide substrate containing a C sp 2 center and a triethoxysilylalkyne reagent containing a C sp center. We have earlier reported the more common C sp 2 –C sp 2 variant of the Hiyama coupling with the palladium NHC complexes and abnormal NHC complexes …”

Dissecting Transmetalation Reactions at the Molecular Level: Role of the Coordinated Anion in Gas-Phase Models for the Transmetalation Step of the Hiyama Cross-Coupling Reaction

“…Attack of the arylpalladium intermediate 2 at the α carbon of the vinyl group of 1 proceeds via transmetalation to give intermediate 3 followed by reductive elimination to give the Hiyama cross-coupled product 4 (Path A of Scheme A). , In many cases, a fluoride additive is used, which has been shown to play three roles: (i) it favors transmetalation by formation of the more reactive trans -ArPdFL 2 (L = PPh 3 ) complexes; (ii) it catalyzes reductive elimination from trans -ArPdAr′L 2 generated via transmetalation; (iii) unreactive pentavalent fluorosiliconates are formed . As a result of the third, negative effect, the rate of the rate-determining transmetalation is controlled by the ratio of the concentration of fluoride anions relative to the organosilane, which must be less or close to one to ensure fast transmetalation . Of the various mechanistic scenarios to account for the role of the fluoride in the transmetalation step, direct involvement of a coordinated fluoride has been suggested ( 2 in Scheme A, where X = F) and DFT calculations on model systems reveal that a four-centered transition state is involved .…”

Diastereodivergent Hydrosilylative Enyne Cyclization Catalyzed by N‐Heterocyclic Carbene‐Ni(0)†

“…Transition metal‐catalyzed hydrosilylative cyclization is a renowned strategy to prepare key intermediates for more complicated products. [ 1‐4 ] Notable methodologies have been developed over the years to utilize those silylated products, in which Hiyama coupling [ 5‐9 ] and Fleming‐Tamao oxidations are often exploited. [ 10‐12 ] In particular, the catalytic hydrosilylative enyne cyclizations have received a lot of attention over decades and efficiently construct various carbo‐/hetero‐cycles (Scheme 1a).…”